Merge from vendor branch OPENSSH:

[dragonfly.git] / contrib / cvs-1.12 / src / rcs.c

/*
 * Copyright (C) 1986-2005 The Free Software Foundation, Inc.
 *
 * Portions Copyright (C) 1998-2005 Derek Price, Ximbiot <http://ximbiot.com>,
 *                                  and others.
 *
 * Portions Copyright (C) 1992, Brian Berliner and Jeff Polk
 * Portions Copyright (C) 1989-1992, Brian Berliner
 * 
 * You may distribute under the terms of the GNU General Public License as
 * specified in the README file that comes with the CVS source distribution.
 * 
 * The routines contained in this file do all the rcs file parsing and
 * manipulation
 */

#include "cvs.h"
#include "edit.h"
#include "hardlink.h"

/* These need to be source after cvs.h or HAVE_MMAP won't be set... */
#ifdef HAVE_MMAP
# include "getpagesize.h"
# include <sys/mman.h>

/* Define MAP_FILE when it isn't otherwise.  */
# ifndef MAP_FILE
#  define MAP_FILE 0
# endif
/* Define MAP_FAILED for old systems which neglect to.  */
# ifndef MAP_FAILED
#  define MAP_FAILED ((void *)-1)
# endif
#endif

/* The RCS -k options, and a set of enums that must match the array.
   These come first so that we can use enum kflag in function
   prototypes.  */
static const char *const kflags[] =
  {"kv", "kvl", "k", "v", "o", "b", NULL};
enum kflag { KFLAG_KV = 0, KFLAG_KVL, KFLAG_K, KFLAG_V, KFLAG_O, KFLAG_B };

/* A structure we use to buffer the contents of an RCS file.  The
   various fields are only referenced directly by the rcsbuf_*
   functions.  We declare the struct here so that we can allocate it
   on the stack, rather than in memory.  */

struct rcsbuffer
{
    /* Points to the current position in the buffer.  */
    char *ptr;
    /* Points just after the last valid character in the buffer.  */
    char *ptrend;
    /* The file.  */
    FILE *fp;
    /* The name of the file, used for error messages.  */
    const char *filename;
    /* The starting file position of the data in the buffer.  */
    unsigned long pos;
    /* The length of the value.  */
    size_t vlen;
    /* Whether the value contains an '@' string.  If so, we can not
       compress whitespace characters.  */
    int at_string;
    /* The number of embedded '@' characters in an '@' string.  If
       this is non-zero, we must search the string for pairs of '@'
       and convert them to a single '@'.  */
    int embedded_at;
};

static RCSNode *RCS_parsercsfile_i (FILE * fp, const char *rcsfile);
static char *RCS_getdatebranch (RCSNode * rcs, const char *date,
                                const char *branch);
static void rcsbuf_open (struct rcsbuffer *, FILE *fp,
                         const char *filename, unsigned long pos);
static void rcsbuf_close (struct rcsbuffer *);
static int rcsbuf_getkey (struct rcsbuffer *, char **keyp, char **valp);
static int rcsbuf_getrevnum (struct rcsbuffer *, char **revp);
static char *rcsbuf_fill (struct rcsbuffer *, char *ptr, char **keyp,
                          char **valp);
static int rcsbuf_valcmp (struct rcsbuffer *);
static char *rcsbuf_valcopy (struct rcsbuffer *, char *val, int polish,
                             size_t *lenp);
static void rcsbuf_valpolish (struct rcsbuffer *, char *val, int polish,
                              size_t *lenp);
static void rcsbuf_valpolish_internal (struct rcsbuffer *, char *to,
                                       const char *from, size_t *lenp);
static off_t rcsbuf_ftello (struct rcsbuffer *);
static void rcsbuf_get_buffered (struct rcsbuffer *, char **datap,
                                 size_t *lenp);
static void rcsbuf_cache (RCSNode *, struct rcsbuffer *);
static void rcsbuf_cache_close (void);
static void rcsbuf_cache_open (RCSNode *, off_t, FILE **, struct rcsbuffer *);
static int checkmagic_proc (Node *p, void *closure);
static void do_branches (List * list, char *val);
static void do_symbols (List * list, char *val);
static void do_locks (List * list, char *val);
static void free_rcsnode_contents (RCSNode *);
static void free_rcsvers_contents (RCSVers *);
static void rcsvers_delproc (Node * p);
static char *translate_symtag (RCSNode *, const char *);
static char *RCS_addbranch (RCSNode *, const char *);
static char *truncate_revnum_in_place (char *);
static char *truncate_revnum (const char *);
static char *printable_date (const char *);
static char *escape_keyword_value (const char *, int *);
static void expand_keywords (RCSNode *, RCSVers *, const char *,
                             const char *, size_t, enum kflag, char *,
                             size_t, char **, size_t *);
static void cmp_file_buffer (void *, const char *, size_t);

/* Routines for reading, parsing and writing RCS files. */
static RCSVers *getdelta (struct rcsbuffer *, char *, char **, char **);
static Deltatext *RCS_getdeltatext (RCSNode *, FILE *, struct rcsbuffer *);
static void freedeltatext (Deltatext *);

static void RCS_putadmin (RCSNode *, FILE *);
static void RCS_putdtree (RCSNode *, char *, FILE *);
static void RCS_putdesc (RCSNode *, FILE *);
static void putdelta (RCSVers *, FILE *);
static int putrcsfield_proc (Node *, void *);
static int putsymbol_proc (Node *, void *);
static void RCS_copydeltas (RCSNode *, FILE *, struct rcsbuffer *, FILE *,
                            Deltatext *, char *);
static int count_delta_actions (Node *, void *);
static void putdeltatext (FILE *, Deltatext *);

static FILE *rcs_internal_lockfile (char *);
static void rcs_internal_unlockfile (FILE *, char *);
static char *rcs_lockfilename (const char *);

/* The RCS file reading functions are called a lot, and they do some
   string comparisons.  This macro speeds things up a bit by skipping
   the function call when the first characters are different.  It
   evaluates its arguments multiple times.  */
#define STREQ(a, b) (*(char *)(a) == *(char *)(b) && strcmp ((a), (b)) == 0)

static char * getfullCVSname (char *, char **);

/*
 * We don't want to use isspace() from the C library because:
 *
 * 1. The definition of "whitespace" in RCS files includes ASCII
 *    backspace, but the C locale doesn't.
 * 2. isspace is an very expensive function call in some implementations
 *    due to the addition of wide character support.
 */
static const char spacetab[] = {
        0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, /* 0x00 - 0x0f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x10 - 0x1f */
        1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x20 - 0x2f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x30 - 0x3f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x40 - 0x4f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x50 - 0x5f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x60 - 0x8f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x70 - 0x7f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x80 - 0x8f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0x90 - 0x9f */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0xa0 - 0xaf */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0xb0 - 0xbf */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0xc0 - 0xcf */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0xd0 - 0xdf */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0xe0 - 0xef */
        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0  /* 0xf0 - 0xff */
};

#define whitespace(c)   (spacetab[(unsigned char)c] != 0)

static char *rcs_lockfile = NULL;
static int rcs_lockfd = -1;



/*
 * char *
 * locate_rcs ( const char* file, const char *repository , int *inattic )
 *
 * Find an RCS file in the repository, case insensitively when the cased name
 * doesn't exist, we are running as the server, and a client has asked us to
 * ignore case.
 *
 * Most parts of CVS will want to rely instead on RCS_parse which calls this
 * function and is called by recurse.c which then puts the result in useful
 * places like the rcs field of struct file_info.
 *
 * INPUTS
 *
 *  repository          the repository (including the directory)
 *  file                the filename within that directory (without RCSEXT).
 *  inattic             NULL or a pointer to the output boolean
 *
 * OUTPUTS
 *
 *  inattic             If this input was non-null, the destination will be
 *                      set to true if the file was found in the attic or
 *                      false if not.  If no RCS file is found, this value
 *                      is undefined.
 *
 * RETURNS
 *
 *  a newly-malloc'd array containing the absolute pathname of the RCS
 *  file that was found or NULL when none was found.
 *
 * ERRORS
 *
 *  errno can be set by the return value of the final call to
 *  locate_file_in_dir().  This should resolve to the system's existence error
 *  value (sometime ENOENT) if the Attic directory did not exist and ENOENT if
 *  the Attic was found but no matching files were found in the Attic or its
 *  parent.
 */
static char *
locate_rcs (const char *repository, const char *file, int *inattic)
{
    char *retval;

    /* First, try to find the file as cased. */
    retval = xmalloc (strlen (repository)
                      + sizeof (CVSATTIC)
                      + strlen (file)
                      + sizeof (RCSEXT)
                      + 3);
    sprintf (retval, "%s/%s%s", repository, file, RCSEXT);
    if (isreadable (retval))
    {
        if (inattic)
            *inattic = 0;
        return retval;
    }
    sprintf (retval, "%s/%s/%s%s", repository, CVSATTIC, file, RCSEXT);
    if (isreadable (retval))
    {
        if (inattic)
            *inattic = 1;
        return retval;
    }
    free (retval);

    return NULL;
}



/* A few generic thoughts on error handling, in particular the
   printing of unexpected characters that we find in the RCS file
   (that is, why we use '\x%x' rather than %c or some such).

   * Avoiding %c means we don't have to worry about what is printable
   and other such stuff.  In error handling, often better to keep it
   simple.

   * Hex rather than decimal or octal because character set standards
   tend to use hex.

   * Saying "character 0x%x" might make it sound like we are printing
   a file offset.  So we use '\x%x'.

   * Would be nice to print the offset within the file, but I can
   imagine various portability hassles (in particular, whether
   unsigned long is always big enough to hold file offsets).  */

/* Parse an rcsfile given a user file name and a repository.  If there is
   an error, we print an error message and return NULL.  If the file
   does not exist, we return NULL without printing anything (I'm not
   sure this allows the caller to do anything reasonable, but it is
   the current behavior).  */
RCSNode *
RCS_parse (const char *file, const char *repos)
{
    RCSNode *rcs;
    FILE *fp;
    RCSNode *retval = NULL;
    char *rcsfile;
    int inattic;

    /* We're creating a new RCSNode, so there is no hope of finding it
       in the cache.  */
    rcsbuf_cache_close ();

    if (!(rcsfile = locate_rcs (repos, file, &inattic)))
    {
        /* Handle the error cases */
    }
    else if ((fp = CVS_FOPEN (rcsfile, FOPEN_BINARY_READ))) 
    {
        rcs = RCS_parsercsfile_i (fp, rcsfile);
        if (rcs)
        {       
            rcs->flags |= VALID;
            if (inattic)
                rcs->flags |= INATTIC;
        }

        free (rcsfile);
        retval = rcs;
    }
    else if (!existence_error (errno))
    {
        error (0, errno, "cannot open `%s'", rcsfile);
        free (rcsfile);
    }

    return retval;
}



/*
 * Parse a specific rcsfile.
 */
RCSNode *
RCS_parsercsfile (const char *rcsfile)
{
    FILE *fp;
    RCSNode *rcs;

    /* We're creating a new RCSNode, so there is no hope of finding it
       in the cache.  */
    rcsbuf_cache_close ();

    /* open the rcsfile */
    if ((fp = CVS_FOPEN (rcsfile, FOPEN_BINARY_READ)) == NULL)
    {
        error (0, errno, "Couldn't open rcs file `%s'", rcsfile);
        return NULL;
    }

    rcs = RCS_parsercsfile_i (fp, rcsfile);

    return rcs;
}



/*
 */ 
static RCSNode *
RCS_parsercsfile_i (FILE *fp, const char *rcsfile)
{
    RCSNode *rdata;
    struct rcsbuffer rcsbuf;
    char *key, *value;

    /* make a node */
    rdata = xmalloc (sizeof (RCSNode));
    memset (rdata, 0, sizeof (RCSNode));
    rdata->refcount = 1;
    rdata->path = xstrdup (rcsfile);
    rdata->print_path = xstrdup (primary_root_inverse_translate (rcsfile));

    /* Process HEAD, BRANCH, and EXPAND keywords from the RCS header.

       Most cvs operations on the main branch don't need any more
       information.  Those that do call RCS_reparsercsfile to parse
       the rest of the header and the deltas.  */

    rcsbuf_open (&rcsbuf, fp, rcsfile, 0);

    if (! rcsbuf_getkey (&rcsbuf, &key, &value))
        goto l_error;
    if (STREQ (key, RCSDESC))
        goto l_error;

    if (STREQ (RCSHEAD, key) && value != NULL)
        rdata->head = rcsbuf_valcopy (&rcsbuf, value, 0, NULL);

    if (! rcsbuf_getkey (&rcsbuf, &key, &value))
        goto l_error;
    if (STREQ (key, RCSDESC))
        goto l_error;

    if (STREQ (RCSBRANCH, key) && value != NULL)
    {
        char *cp;

        rdata->branch = rcsbuf_valcopy (&rcsbuf, value, 0, NULL);
        if ((numdots (rdata->branch) & 1) != 0)
        {
            /* turn it into a branch if it's a revision */
            cp = strrchr (rdata->branch, '.');
            *cp = '\0';
        }
    }

    /* Look ahead for expand, stopping when we see desc or a revision
       number.  */
    while (1)
    {
        char *cp;

        if (STREQ (RCSEXPAND, key))
        {
            rdata->expand = rcsbuf_valcopy (&rcsbuf, value, 0, NULL);
            break;
        }

        for (cp = key;
             (isdigit ((unsigned char)*cp) || *cp == '.') && *cp != '\0';
             cp++)
            /* do nothing */ ;
        if (*cp == '\0')
            break;

        if (STREQ (RCSDESC, key))
            break;

        if (! rcsbuf_getkey (&rcsbuf, &key, &value))
            break;
    }

    rdata->flags |= PARTIAL;

    rcsbuf_cache (rdata, &rcsbuf);

    return rdata;

l_error:
    error (0, 0, "`%s' does not appear to be a valid rcs file",
           rcsfile);
    rcsbuf_close (&rcsbuf);
    freercsnode (&rdata);
    fclose (fp);
    return NULL;
}



/* Do the real work of parsing an RCS file.

   On error, die with a fatal error; if it returns at all it was successful.

   If PFP is NULL, close the file when done.  Otherwise, leave it open
   and store the FILE * in *PFP.  */
void
RCS_reparsercsfile (RCSNode *rdata, FILE **pfp, struct rcsbuffer *rcsbufp)
{
    FILE *fp;
    char *rcsfile;
    struct rcsbuffer rcsbuf;
    Node *q, *kv;
    RCSVers *vnode;
    int gotkey;
    char *cp;
    char *key, *value;

    assert (rdata != NULL);
    rcsfile = rdata->path;

    rcsbuf_cache_open (rdata, 0, &fp, &rcsbuf);

    /* make a node */
    /* This probably shouldn't be done until later: if a file has an
       empty revision tree (which is permissible), rdata->versions
       should be NULL. -twp */
    rdata->versions = getlist ();

    /*
     * process all the special header information, break out when we get to
     * the first revision delta
     */
    gotkey = 0;
    for (;;)
    {
        /* get the next key/value pair */
        if (!gotkey)
        {
            if (! rcsbuf_getkey (&rcsbuf, &key, &value))
            {
                error (1, 0, "`%s' does not appear to be a valid rcs file",
                       rcsfile);
            }
        }

        gotkey = 0;

        /* Skip head, branch and expand tags; we already have them. */
        if (STREQ (key, RCSHEAD)
            || STREQ (key, RCSBRANCH)
            || STREQ (key, RCSEXPAND))
        {
            continue;
        }

        if (STREQ (key, "access"))
        {
            if (value != NULL)
            {
                /* We pass the POLISH parameter as 1 because
                   RCS_addaccess expects nothing but spaces.  FIXME:
                   It would be easy and more efficient to change
                   RCS_addaccess.  */
                if (rdata->access)
                {
                    error (0, 0,
                           "Duplicate `access' keyword found in RCS file.");
                    free (rdata->access);
                }
                rdata->access = rcsbuf_valcopy (&rcsbuf, value, 1, NULL);
            }
            continue;
        }

        /* We always save lock information, so that we can handle
           -kkvl correctly when checking out a file. */
        if (STREQ (key, "locks"))
        {
            if (value != NULL)
            {
                if (rdata->locks_data)
                {
                    error (0, 0,
                           "Duplicate `locks' keyword found in RCS file.");
                    free (rdata->locks_data);
                }
                rdata->locks_data = rcsbuf_valcopy (&rcsbuf, value, 0, NULL);
            }
            if (! rcsbuf_getkey (&rcsbuf, &key, &value))
            {
                error (1, 0, "premature end of file reading %s", rcsfile);
            }
            if (STREQ (key, "strict") && value == NULL)
            {
                rdata->strict_locks = 1;
            }
            else
                gotkey = 1;
            continue;
        }

        if (STREQ (RCSSYMBOLS, key))
        {
            if (value != NULL)
            {
                if (rdata->symbols_data)
                {
                    error (0, 0,
                           "Duplicate `%s' keyword found in RCS file.",
                           RCSSYMBOLS);
                    free (rdata->symbols_data);
                }
                rdata->symbols_data = rcsbuf_valcopy (&rcsbuf, value, 0, NULL);
            }
            continue;
        }

        /*
         * check key for '.''s and digits (probably a rev) if it is a
         * revision or `desc', we are done with the headers and are down to the
         * revision deltas, so we break out of the loop
         */
        for (cp = key;
             (isdigit ((unsigned char) *cp) || *cp == '.') && *cp != '\0';
             cp++)
             /* do nothing */ ;
        /* Note that when comparing with RCSDATE, we are not massaging
           VALUE from the string found in the RCS file.  This is OK
           since we know exactly what to expect.  */
        if (*cp == '\0' && strncmp (RCSDATE, value, (sizeof RCSDATE) - 1) == 0)
            break;

        if (STREQ (key, RCSDESC))
            break;

        if (STREQ (key, "comment"))
        {
            if (rdata->comment)
            {
                error (0, 0,
                       "warning: duplicate key `%s' in RCS file `%s'",
                       key, rcsfile);
                free (rdata->comment);
            }
            rdata->comment = rcsbuf_valcopy (&rcsbuf, value, 0, NULL);
            continue;
        }
        if (rdata->other == NULL)
            rdata->other = getlist ();
        kv = getnode ();
        kv->type = rcsbuf_valcmp (&rcsbuf) ? RCSCMPFLD : RCSFIELD;
        kv->key = xstrdup (key);
        kv->data = rcsbuf_valcopy (&rcsbuf, value, kv->type == RCSFIELD, NULL);
        if (addnode (rdata->other, kv) != 0)
        {
            error (0, 0, "warning: duplicate key `%s' in RCS file `%s'",
                   key, rcsfile);
            freenode (kv);
        }

        /* if we haven't grabbed it yet, we didn't want it */
    }

    /* We got out of the loop, so we have the first part of the first
       revision delta in KEY (the revision) and VALUE (the date key
       and its value).  This is what getdelta expects to receive.  */

    while ((vnode = getdelta (&rcsbuf, rcsfile, &key, &value)) != NULL)
    {
        /* get the node */
        q = getnode ();
        q->type = RCSVERS;
        q->delproc = rcsvers_delproc;
        q->data = vnode;
        q->key = vnode->version;

        /* add the nodes to the list */
        if (addnode (rdata->versions, q) != 0)
        {
#if 0
                purify_printf("WARNING: Adding duplicate version: %s (%s)\n",
                         q->key, rcsfile);
                freenode (q);
#endif
        }
    }

    /* Here KEY and VALUE are whatever caused getdelta to return NULL.  */

    if (STREQ (key, RCSDESC))
    {
        if (rdata->desc != NULL)
        {
            error (0, 0,
                   "warning: duplicate key `%s' in RCS file `%s'",
                   key, rcsfile);
            free (rdata->desc);
        }
        rdata->desc = rcsbuf_valcopy (&rcsbuf, value, 1, NULL);
    }

    rdata->delta_pos = rcsbuf_ftello (&rcsbuf);

    if (pfp == NULL)
        rcsbuf_cache (rdata, &rcsbuf);
    else
    {
        *pfp = fp;
        *rcsbufp = rcsbuf;
    }
    rdata->flags &= ~PARTIAL;
}



/* Move RCS into or out of the Attic, depending on TOATTIC.  If the
   file is already in the desired place, return without doing
   anything.  At some point may want to think about how this relates
   to RCS_rewrite but that is a bit hairy (if one wants renames to be
   atomic, or that kind of thing).  If there is an error, print a message
   and return 1.  On success, return 0.  */
int
RCS_setattic (RCSNode *rcs, int toattic)
{
    char *newpath;
    const char *p;
    char *q;

    /* Some systems aren't going to let us rename an open file.  */
    rcsbuf_cache_close ();

    /* Could make the pathname computations in this file, and probably
       in other parts of rcs.c too, easier if the REPOS and FILE
       arguments to RCS_parse got stashed in the RCSNode.  */

    if (toattic)
    {
        mode_t omask;

        if (rcs->flags & INATTIC)
            return 0;

        /* Example: rcs->path is "/foo/bar/baz,v".  */
        newpath = xmalloc (strlen (rcs->path) + sizeof CVSATTIC + 5);
        p = last_component (rcs->path);
        strncpy (newpath, rcs->path, p - rcs->path);
        strcpy (newpath + (p - rcs->path), CVSATTIC);

        /* Create the Attic directory if it doesn't exist.  */
        omask = umask (cvsumask);
        if (CVS_MKDIR (newpath, 0777) < 0 && errno != EEXIST)
            error (0, errno, "cannot make directory %s", newpath);
        (void) umask (omask);

        strcat (newpath, "/");
        strcat (newpath, p);

        if (CVS_RENAME (rcs->path, newpath) < 0)
        {
            int save_errno = errno;

            /* The checks for isreadable look awfully fishy, but
               I'm going to leave them here for now until I
               can think harder about whether they take care of
               some cases which should be handled somehow.  */

            if (isreadable (rcs->path) || !isreadable (newpath))
            {
                error (0, save_errno, "cannot rename %s to %s",
                       rcs->path, newpath);
                free (newpath);
                return 1;
            }
        }
    }
    else
    {
        if (!(rcs->flags & INATTIC))
            return 0;

        newpath = xmalloc (strlen (rcs->path));

        /* Example: rcs->path is "/foo/bar/Attic/baz,v".  */
        p = last_component (rcs->path);
        strncpy (newpath, rcs->path, p - rcs->path - 1);
        newpath[p - rcs->path - 1] = '\0';
        q = newpath + (p - rcs->path - 1) - (sizeof CVSATTIC - 1);
        assert (strncmp (q, CVSATTIC, sizeof CVSATTIC - 1) == 0);
        strcpy (q, p);

        if (CVS_RENAME (rcs->path, newpath) < 0)
        {
            error (0, errno, "failed to move `%s' out of the attic",
                   rcs->path);
            free (newpath);
            return 1;
        }
    }

    free (rcs->path);
    rcs->path = newpath;

    return 0;
}



/*
 * Fully parse the RCS file.  Store all keyword/value pairs, fetch the
 * log messages for each revision, and fetch add and delete counts for
 * each revision (we could fetch the entire text for each revision,
 * but the only caller, log_fileproc, doesn't need that information,
 * so we don't waste the memory required to store it).  The add and
 * delete counts are stored on the OTHER field of the RCSVERSNODE
 * structure, under the names ";add" and ";delete", so that we don't
 * waste the memory space of extra fields in RCSVERSNODE for code
 * which doesn't need this information.
 */
void
RCS_fully_parse (RCSNode *rcs)
{
    FILE *fp;
    struct rcsbuffer rcsbuf;

    RCS_reparsercsfile (rcs, &fp, &rcsbuf);

    while (1)
    {
        char *key, *value;
        Node *vers;
        RCSVers *vnode;

        /* Rather than try to keep track of how much information we
           have read, just read to the end of the file.  */
        if (!rcsbuf_getrevnum (&rcsbuf, &key))
            break;

        vers = findnode (rcs->versions, key);
        if (vers == NULL)
            error (1, 0,
                   "mismatch in rcs file %s between deltas and deltatexts (%s)",
                   rcs->print_path, key);

        vnode = vers->data;

        while (rcsbuf_getkey (&rcsbuf, &key, &value))
        {
            if (!STREQ (key, "text"))
            {
                Node *kv;

                if (vnode->other == NULL)
                    vnode->other = getlist ();
                kv = getnode ();
                kv->type = rcsbuf_valcmp (&rcsbuf) ? RCSCMPFLD : RCSFIELD;
                kv->key = xstrdup (key);
                kv->data = rcsbuf_valcopy (&rcsbuf, value, kv->type == RCSFIELD,
                                           NULL);
                if (addnode (vnode->other, kv) != 0)
                {
                    error (0, 0,
                           "\
warning: duplicate key `%s' in version `%s' of RCS file `%s'",
                           key, vnode->version, rcs->print_path);
                    freenode (kv);
                }

                continue;
            }

            if (!STREQ (vnode->version, rcs->head))
            {
                unsigned long add, del;
                char buf[50];
                Node *kv;

                /* This is a change text.  Store the add and delete
                   counts.  */
                add = 0;
                del = 0;
                if (value != NULL)
                {
                    size_t vallen;
                    const char *cp;

                    rcsbuf_valpolish (&rcsbuf, value, 0, &vallen);
                    cp = value;
                    while (cp < value + vallen)
                    {
                        char op;
                        unsigned long count;

                        op = *cp++;
                        if (op != 'a' && op  != 'd')
                            error (1, 0, "\
unrecognized operation '\\x%x' in %s",
                                   op, rcs->print_path);
                        (void) strtoul (cp, (char **) &cp, 10);
                        if (*cp++ != ' ')
                            error (1, 0, "space expected in %s revision %s",
                                   rcs->print_path, vnode->version);
                        count = strtoul (cp, (char **) &cp, 10);
                        if (*cp++ != '\012')
                            error (1, 0, "linefeed expected in %s revision %s",
                                   rcs->print_path, vnode->version);

                        if (op == 'd')
                            del += count;
                        else
                        {
                            add += count;
                            while (count != 0)
                            {
                                if (*cp == '\012')
                                    --count;
                                else if (cp == value + vallen)
                                {
                                    if (count != 1)
                                        error (1, 0, "\
premature end of value in %s revision %s",
                                               rcs->print_path, vnode->version);
                                    else
                                        break;
                                }
                                ++cp;
                            }
                        }
                    }
                }

                sprintf (buf, "%lu", add);
                kv = getnode ();
                kv->type = RCSFIELD;
                kv->key = xstrdup (";add");
                kv->data = xstrdup (buf);
                if (addnode (vnode->other, kv) != 0)
                {
                    error (0, 0,
                           "\
warning: duplicate key `%s' in version `%s' of RCS file `%s'",
                           key, vnode->version, rcs->print_path);
                    freenode (kv);
                }

                sprintf (buf, "%lu", del);
                kv = getnode ();
                kv->type = RCSFIELD;
                kv->key = xstrdup (";delete");
                kv->data = xstrdup (buf);
                if (addnode (vnode->other, kv) != 0)
                {
                    error (0, 0,
                           "\
warning: duplicate key `%s' in version `%s' of RCS file `%s'",
                           key, vnode->version, rcs->print_path);
                    freenode (kv);
                }
            }

            /* We have found the "text" key which ends the data for
               this revision.  Break out of the loop and go on to the
               next revision.  */
            break;
        }
    }

    rcsbuf_cache (rcs, &rcsbuf);
}



/*
 * freercsnode - free up the info for an RCSNode
 */
void
freercsnode (RCSNode **rnodep)
{
    if (rnodep == NULL || *rnodep == NULL)
        return;

    ((*rnodep)->refcount)--;
    if ((*rnodep)->refcount != 0)
    {
        *rnodep = NULL;
        return;
    }
    free ((*rnodep)->path);
    free ((*rnodep)->print_path);
    if ((*rnodep)->head != NULL)
        free ((*rnodep)->head);
    if ((*rnodep)->branch != NULL)
        free ((*rnodep)->branch);
    free_rcsnode_contents (*rnodep);
    free (*rnodep);
    *rnodep = NULL;
}



/*
 * free_rcsnode_contents - free up the contents of an RCSNode without
 * freeing the node itself, or the file name, or the head, or the
 * path.  This returns the RCSNode to the state it is in immediately
 * after a call to RCS_parse.
 */
static void
free_rcsnode_contents (RCSNode *rnode)
{
    dellist (&rnode->versions);
    if (rnode->symbols != NULL)
        dellist (&rnode->symbols);
    if (rnode->symbols_data != NULL)
        free (rnode->symbols_data);
    if (rnode->expand != NULL)
        free (rnode->expand);
    if (rnode->other != NULL)
        dellist (&rnode->other);
    if (rnode->access != NULL)
        free (rnode->access);
    if (rnode->locks_data != NULL)
        free (rnode->locks_data);
    if (rnode->locks != NULL)
        dellist (&rnode->locks);
    if (rnode->comment != NULL)
        free (rnode->comment);
    if (rnode->desc != NULL)
        free (rnode->desc);
}



/* free_rcsvers_contents -- free up the contents of an RCSVers node,
   but also free the pointer to the node itself. */
/* Note: The `hardlinks' list is *not* freed, since it is merely a
   pointer into the `hardlist' structure (defined in hardlink.c), and
   that structure is freed elsewhere in the program. */
static void
free_rcsvers_contents (RCSVers *rnode)
{
    if (rnode->branches != NULL)
        dellist (&rnode->branches);
    if (rnode->date != NULL)
        free (rnode->date);
    if (rnode->next != NULL)
        free (rnode->next);
    if (rnode->author != NULL)
        free (rnode->author);
    if (rnode->state != NULL)
        free (rnode->state);
    if (rnode->other != NULL)
        dellist (&rnode->other);
    if (rnode->other_delta != NULL)
        dellist (&rnode->other_delta);
    if (rnode->text != NULL)
        freedeltatext (rnode->text);
    free (rnode);
}



/*
 * rcsvers_delproc - free up an RCSVers type node
 */
static void
rcsvers_delproc (Node *p)
{
    free_rcsvers_contents (p->data);
}



/* These functions retrieve keys and values from an RCS file using a
   buffer.  We use this somewhat complex approach because it turns out
   that for many common operations, CVS spends most of its time
   reading keys, so it's worth doing some fairly hairy optimization.  */

/* The number of bytes we try to read each time we need more data.  */

#define RCSBUF_BUFSIZE (8192)

/* The buffer we use to store data.  This grows as needed.  */

static char *rcsbuf_buffer = NULL;
static size_t rcsbuf_buffer_size = 0;

/* Whether rcsbuf_buffer is in use.  This is used as a sanity check.  */

static int rcsbuf_inuse;

/* Set up to start gathering keys and values from an RCS file.  This
   initializes RCSBUF.  */

static void
rcsbuf_open (struct rcsbuffer *rcsbuf, FILE *fp, const char *filename,
             long unsigned int pos)
{
    if (rcsbuf_inuse)
        error (1, 0, "rcsbuf_open: internal error");
    rcsbuf_inuse = 1;

#ifdef HAVE_MMAP
    {
        /* When we have mmap, it is much more efficient to let the system do the
         * buffering and caching for us
         */
        struct stat fs;
        size_t mmap_off = 0;

        if ( fstat (fileno(fp), &fs) < 0 )
            error ( 1, errno, "Could not stat RCS archive %s for mapping", filename );

        if (pos)
        {
            size_t ps = getpagesize ();
            mmap_off = ( pos / ps ) * ps;
        }

        /* Map private here since this particular buffer is read only */
        rcsbuf_buffer = mmap ( NULL, fs.st_size - mmap_off,
                                PROT_READ | PROT_WRITE,
                                MAP_PRIVATE, fileno(fp), mmap_off );
        if ( rcsbuf_buffer == NULL || rcsbuf_buffer == MAP_FAILED )
            error ( 1, errno, "Could not map memory to RCS archive %s", filename );

        rcsbuf_buffer_size = fs.st_size - mmap_off;
        rcsbuf->ptr = rcsbuf_buffer + pos - mmap_off;
        rcsbuf->ptrend = rcsbuf_buffer + fs.st_size - mmap_off;
        rcsbuf->pos = mmap_off;
    }
#else /* !HAVE_MMAP */
    if (rcsbuf_buffer_size < RCSBUF_BUFSIZE)
        expand_string (&rcsbuf_buffer, &rcsbuf_buffer_size, RCSBUF_BUFSIZE);

    rcsbuf->ptr = rcsbuf_buffer;
    rcsbuf->ptrend = rcsbuf_buffer;
    rcsbuf->pos = pos;
#endif /* HAVE_MMAP */
    rcsbuf->fp = fp;
    rcsbuf->filename = filename;
    rcsbuf->vlen = 0;
    rcsbuf->at_string = 0;
    rcsbuf->embedded_at = 0;
}



/* Stop gathering keys from an RCS file.  */
static void
rcsbuf_close (struct rcsbuffer *rcsbuf)
{
    if (! rcsbuf_inuse)
        error (1, 0, "rcsbuf_close: internal error");
#ifdef HAVE_MMAP
    munmap ( rcsbuf_buffer, rcsbuf_buffer_size );
#endif
    rcsbuf_inuse = 0;
}



/* Read a key/value pair from an RCS file.  This sets *KEYP to point
   to the key, and *VALUEP to point to the value.  A missing or empty
   value is indicated by setting *VALUEP to NULL.

   This function returns 1 on success, or 0 on EOF.  If there is an
   error reading the file, or an EOF in an unexpected location, it
   gives a fatal error.

   This sets *KEYP and *VALUEP to point to storage managed by
   rcsbuf_getkey.  Moreover, *VALUEP has not been massaged from the
   RCS format: it may contain embedded whitespace and embedded '@'
   characters.  Call rcsbuf_valcopy or rcsbuf_valpolish to do
   appropriate massaging.  */

/* Note that the extreme hair in rcsbuf_getkey is because profiling
   statistics show that it was worth it. */
static int
rcsbuf_getkey (struct rcsbuffer *rcsbuf, char **keyp, char **valp)
{
    register const char * const my_spacetab = spacetab;
    register char *ptr, *ptrend;
    char c;

#define my_whitespace(c)        (my_spacetab[(unsigned char)c] != 0)

    rcsbuf->vlen = 0;
    rcsbuf->at_string = 0;
    rcsbuf->embedded_at = 0;

    ptr = rcsbuf->ptr;
    ptrend = rcsbuf->ptrend;

    /* Sanity check.  */
    assert (ptr >= rcsbuf_buffer && ptr <= rcsbuf_buffer + rcsbuf_buffer_size);
    assert (ptrend >= rcsbuf_buffer && ptrend <= rcsbuf_buffer + rcsbuf_buffer_size);

#ifndef HAVE_MMAP
    /* If the pointer is more than RCSBUF_BUFSIZE bytes into the
       buffer, move back to the start of the buffer.  This keeps the
       buffer from growing indefinitely.  */
    if (ptr - rcsbuf_buffer >= RCSBUF_BUFSIZE)
    {
        int len;

        len = ptrend - ptr;

        /* Sanity check: we don't read more than RCSBUF_BUFSIZE bytes
           at a time, so we can't have more bytes than that past PTR.  */
        assert (len <= RCSBUF_BUFSIZE);

        /* Update the POS field, which holds the file offset of the
           first byte in the RCSBUF_BUFFER buffer.  */
        rcsbuf->pos += ptr - rcsbuf_buffer;

        memcpy (rcsbuf_buffer, ptr, len);
        ptr = rcsbuf_buffer;
        ptrend = ptr + len;
        rcsbuf->ptrend = ptrend;
    }
#endif /* HAVE_MMAP */

    /* Skip leading whitespace.  */

    while (1)
    {
        if (ptr >= ptrend)
        {
            ptr = rcsbuf_fill (rcsbuf, ptr, NULL, NULL);
            if (ptr == NULL)
                return 0;
            ptrend = rcsbuf->ptrend;
        }

        c = *ptr;
        if (! my_whitespace (c))
            break;

        ++ptr;
    }

    /* We've found the start of the key.  */

    *keyp = ptr;

    if (c != ';')
    {
        while (1)
        {
            ++ptr;
            if (ptr >= ptrend)
            {
                ptr = rcsbuf_fill (rcsbuf, ptr, keyp, NULL);
                if (ptr == NULL)
                    error (1, 0, "EOF in key in RCS file %s",
                           primary_root_inverse_translate (rcsbuf->filename));
                ptrend = rcsbuf->ptrend;
            }
            c = *ptr;
            if (c == ';' || my_whitespace (c))
                break;
        }
    }

    /* Here *KEYP points to the key in the buffer, C is the character
       we found at the of the key, and PTR points to the location in
       the buffer where we found C.  We must set *PTR to \0 in order
       to terminate the key.  If the key ended with ';', then there is
       no value.  */

    *ptr = '\0';
    ++ptr;

    if (c == ';')
    {
        *valp = NULL;
        rcsbuf->ptr = ptr;
        return 1;
    }

    /* C must be whitespace.  Skip whitespace between the key and the
       value.  If we find ';' now, there is no value.  */

    while (1)
    {
        if (ptr >= ptrend)
        {
            ptr = rcsbuf_fill (rcsbuf, ptr, keyp, NULL);
            if (ptr == NULL)
                error (1, 0, "EOF while looking for value in RCS file %s",
                       primary_root_inverse_translate (rcsbuf->filename));
            ptrend = rcsbuf->ptrend;
        }
        c = *ptr;
        if (c == ';')
        {
            *valp = NULL;
            rcsbuf->ptr = ptr + 1;
            return 1;
        }
        if (! my_whitespace (c))
            break;
        ++ptr;
    }

    /* Now PTR points to the start of the value, and C is the first
       character of the value.  */

    if (c != '@')
        *valp = ptr;
    else
    {
        char *pat;
        size_t vlen;

        /* Optimize the common case of a value composed of a single
           '@' string.  */

        rcsbuf->at_string = 1;

        ++ptr;

        *valp = ptr;

        while (1)
        {
            while ((pat = memchr (ptr, '@', ptrend - ptr)) == NULL)
            {
                /* Note that we pass PTREND as the PTR value to
                   rcsbuf_fill, so that we will wind up setting PTR to
                   the location corresponding to the old PTREND, so
                   that we don't search the same bytes again.  */
                ptr = rcsbuf_fill (rcsbuf, ptrend, keyp, valp);
                if (ptr == NULL)
                    error (1, 0,
                           "EOF while looking for end of string in RCS file %s",
                           primary_root_inverse_translate (rcsbuf->filename));
                ptrend = rcsbuf->ptrend;
            }

            /* Handle the special case of an '@' right at the end of
               the known bytes.  */
            if (pat + 1 >= ptrend)
            {
                /* Note that we pass PAT, not PTR, here.  */
                pat = rcsbuf_fill (rcsbuf, pat, keyp, valp);
                if (pat == NULL)
                {
                    /* EOF here is OK; it just means that the last
                       character of the file was an '@' terminating a
                       value for a key type which does not require a
                       trailing ';'.  */
                    pat = rcsbuf->ptrend - 1;

                }
                ptrend = rcsbuf->ptrend;

                /* Note that the value of PTR is bogus here.  This is
                   OK, because we don't use it.  */
            }

            if (pat + 1 >= ptrend || pat[1] != '@')
                break;

            /* We found an '@' pair in the string.  Keep looking.  */
            ++rcsbuf->embedded_at;
            ptr = pat + 2;
        }

        /* Here PAT points to the final '@' in the string.  */

        *pat = '\0';

        vlen = pat - *valp;
        if (vlen == 0)
            *valp = NULL;
        rcsbuf->vlen = vlen;

        ptr = pat + 1;
    }

    /* Certain keywords only have a '@' string.  If there is no '@'
       string, then the old getrcskey function assumed that they had
       no value, and we do the same.  */

    {
        char *k;

        k = *keyp;
        if (STREQ (k, RCSDESC)
            || STREQ (k, "text")
            || STREQ (k, "log"))
        {
            if (c != '@')
                *valp = NULL;
            rcsbuf->ptr = ptr;
            return 1;
        }
    }

    /* If we've already gathered a '@' string, try to skip whitespace
       and find a ';'.  */
    if (c == '@')
    {
        while (1)
        {
            char n;

            if (ptr >= ptrend)
            {
                ptr = rcsbuf_fill (rcsbuf, ptr, keyp, valp);
                if (ptr == NULL)
                    error (1, 0, "EOF in value in RCS file %s",
                           primary_root_inverse_translate (rcsbuf->filename));
                ptrend = rcsbuf->ptrend;
            }
            n = *ptr;
            if (n == ';')
            {
                /* We're done.  We already set everything up for this
                   case above.  */
                rcsbuf->ptr = ptr + 1;
                return 1;
            }
            if (! my_whitespace (n))
                break;
            ++ptr;
        }

        /* The value extends past the '@' string.  We need to undo the
           '@' stripping done in the default case above.  This
           case never happens in a plain RCS file, but it can happen
           if user defined phrases are used.  */
        ((*valp)--)[rcsbuf->vlen++] = '@';
    }

    /* Here we have a value which is not a simple '@' string.  We need
       to gather up everything until the next ';', including any '@'
       strings.  *VALP points to the start of the value.  If
       RCSBUF->VLEN is not zero, then we have already read an '@'
       string, and PTR points to the data following the '@' string.
       Otherwise, PTR points to the start of the value.  */

    while (1)
    {
        char *start, *psemi, *pat;

        /* Find the ';' which must end the value.  */
        start = ptr;
        while ((psemi = memchr (ptr, ';', ptrend - ptr)) == NULL)
        {
            int slen;

            /* Note that we pass PTREND as the PTR value to
               rcsbuf_fill, so that we will wind up setting PTR to the
               location corresponding to the old PTREND, so that we
               don't search the same bytes again.  */
            slen = start - *valp;
            ptr = rcsbuf_fill (rcsbuf, ptrend, keyp, valp);
            if (ptr == NULL)
                error (1, 0, "EOF in value in RCS file %s",
                       primary_root_inverse_translate (rcsbuf->filename));
            start = *valp + slen;
            ptrend = rcsbuf->ptrend;
        }

        /* See if there are any '@' strings in the value.  */
        pat = memchr (start, '@', psemi - start);

        if (pat == NULL)
        {
            size_t vlen;

            /* We're done with the value.  Trim any trailing
               whitespace.  */

            rcsbuf->ptr = psemi + 1;

            start = *valp;
            while (psemi > start && my_whitespace (psemi[-1]))
                --psemi;
            *psemi = '\0';

            vlen = psemi - start;
            if (vlen == 0)
                *valp = NULL;
            rcsbuf->vlen = vlen;

            return 1;
        }

        /* We found an '@' string in the value.  We set RCSBUF->AT_STRING
           and RCSBUF->EMBEDDED_AT to indicate that we won't be able to
           compress whitespace correctly for this type of value.
           Since this type of value never arises in a normal RCS file,
           this should not be a big deal.  It means that if anybody
           adds a phrase which can have both an '@' string and regular
           text, they will have to handle whitespace compression
           themselves.  */

        rcsbuf->at_string = 1;
        rcsbuf->embedded_at = -1;

        ptr = pat + 1;

        while (1)
        {
            while ((pat = memchr (ptr, '@', ptrend - ptr)) == NULL)
            {
                /* Note that we pass PTREND as the PTR value to
                   rcsbuff_fill, so that we will wind up setting PTR
                   to the location corresponding to the old PTREND, so
                   that we don't search the same bytes again.  */
                ptr = rcsbuf_fill (rcsbuf, ptrend, keyp, valp);
                if (ptr == NULL)
                    error (1, 0,
                           "EOF while looking for end of string in RCS file %s",
                           primary_root_inverse_translate (rcsbuf->filename));
                ptrend = rcsbuf->ptrend;
            }

            /* Handle the special case of an '@' right at the end of
               the known bytes.  */
            if (pat + 1 >= ptrend)
            {
                ptr = rcsbuf_fill (rcsbuf, ptr, keyp, valp);
                if (ptr == NULL)
                    error (1, 0, "EOF in value in RCS file %s",
                           primary_root_inverse_translate (rcsbuf->filename));
                ptrend = rcsbuf->ptrend;
            }

            if (pat[1] != '@')
                break;

            /* We found an '@' pair in the string.  Keep looking.  */
            ptr = pat + 2;
        }

        /* Here PAT points to the final '@' in the string.  */
        ptr = pat + 1;
    }

#undef my_whitespace
}



/* Read an RCS revision number from an RCS file.  This sets *REVP to
   point to the revision number; it will point to space that is
   managed by the rcsbuf functions, and is only good until the next
   call to rcsbuf_getkey or rcsbuf_getrevnum.

   This function returns 1 on success, or 0 on EOF.  If there is an
   error reading the file, or an EOF in an unexpected location, it
   gives a fatal error.  */
static int
rcsbuf_getrevnum (struct rcsbuffer *rcsbuf, char **revp)
{
    char *ptr, *ptrend;
    char c;

    ptr = rcsbuf->ptr;
    ptrend = rcsbuf->ptrend;

    *revp = NULL;

    /* Skip leading whitespace.  */

    while (1)
    {
        if (ptr >= ptrend)
        {
            ptr = rcsbuf_fill (rcsbuf, ptr, NULL, NULL);
            if (ptr == NULL)
                return 0;
            ptrend = rcsbuf->ptrend;
        }

        c = *ptr;
        if (! whitespace (c))
            break;

        ++ptr;
    }

    if (! isdigit ((unsigned char) c) && c != '.')
        error (1, 0,
               "\
unexpected '\\x%x' reading revision number in RCS file %s",
               c, primary_root_inverse_translate (rcsbuf->filename));

    *revp = ptr;

    do
    {
        ++ptr;
        if (ptr >= ptrend)
        {
            ptr = rcsbuf_fill (rcsbuf, ptr, revp, NULL);
            if (ptr == NULL)
                error (1, 0,
                       "unexpected EOF reading revision number in RCS file %s",
                       primary_root_inverse_translate (rcsbuf->filename));
            ptrend = rcsbuf->ptrend;
        }

        c = *ptr;
    }
    while (isdigit ((unsigned char) c) || c == '.');

    if (! whitespace (c))
        error (1, 0, "\
unexpected '\\x%x' reading revision number in RCS file %s",
               c, primary_root_inverse_translate (rcsbuf->filename));

    *ptr = '\0';

    rcsbuf->ptr = ptr + 1;

    return 1;
}



/* Fill RCSBUF_BUFFER with bytes from the file associated with RCSBUF,
   updating PTR and the PTREND field.  If KEYP and *KEYP are not NULL,
   then *KEYP points into the buffer, and must be adjusted if the
   buffer is changed.  Likewise for VALP.  Returns the new value of
   PTR, or NULL on error.  */
static char *
rcsbuf_fill (struct rcsbuffer *rcsbuf, char *ptr, char **keyp, char **valp)
{
#ifdef HAVE_MMAP
    return NULL;
#else /* HAVE_MMAP */
    int got;

    if (rcsbuf->ptrend - rcsbuf_buffer + RCSBUF_BUFSIZE > rcsbuf_buffer_size)
    {
        int poff, peoff, koff, voff;

        poff = ptr - rcsbuf_buffer;
        peoff = rcsbuf->ptrend - rcsbuf_buffer;
        koff = keyp == NULL ? 0 : *keyp - rcsbuf_buffer;
        voff = valp == NULL ? 0 : *valp - rcsbuf_buffer;

        expand_string (&rcsbuf_buffer, &rcsbuf_buffer_size,
                       rcsbuf_buffer_size + RCSBUF_BUFSIZE);

        ptr = rcsbuf_buffer + poff;
        rcsbuf->ptrend = rcsbuf_buffer + peoff;
        if (keyp != NULL)
            *keyp = rcsbuf_buffer + koff;
        if (valp != NULL)
            *valp = rcsbuf_buffer + voff;
    }

    got = fread (rcsbuf->ptrend, 1, RCSBUF_BUFSIZE, rcsbuf->fp);
    if (got == 0)
    {
        if (ferror (rcsbuf->fp))
            error (1, errno, "cannot read %s", rcsbuf->filename);
        return NULL;
    }

    rcsbuf->ptrend += got;

    return ptr;
#endif /* HAVE_MMAP */
}



/* Test whether the last value returned by rcsbuf_getkey is a composite
   value or not. */
static int
rcsbuf_valcmp (struct rcsbuffer *rcsbuf)
{
    return rcsbuf->at_string && rcsbuf->embedded_at < 0;
}



/* Copy the value VAL returned by rcsbuf_getkey into a memory buffer,
   returning the memory buffer.  Polish the value like
   rcsbuf_valpolish, q.v.  */
static char *
rcsbuf_valcopy (struct rcsbuffer *rcsbuf, char *val, int polish, size_t *lenp)
{
    size_t vlen;
    int embedded_at;
    char *ret;

    if (val == NULL)
    {
        if (lenp != NULL)
            *lenp = 0;
        return NULL;
    }

    vlen = rcsbuf->vlen;
    embedded_at = rcsbuf->embedded_at < 0 ? 0 : rcsbuf->embedded_at;

    ret = xmalloc (vlen - embedded_at + 1);

    if (rcsbuf->at_string ? embedded_at == 0 : ! polish)
    {
        /* No special action to take.  */
        memcpy (ret, val, vlen + 1);
        if (lenp != NULL)
            *lenp = vlen;
        return ret;
    }

    rcsbuf_valpolish_internal (rcsbuf, ret, val, lenp);
    return ret;
}



/* Polish the value VAL returned by rcsbuf_getkey.  The POLISH
   parameter is non-zero if multiple embedded whitespace characters
   should be compressed into a single whitespace character.  Note that
   leading and trailing whitespace was already removed by
   rcsbuf_getkey.  Within an '@' string, pairs of '@' characters are
   compressed into a single '@' character regardless of the value of
   POLISH.  If LENP is not NULL, set *LENP to the length of the value.  */
static void
rcsbuf_valpolish (struct rcsbuffer *rcsbuf, char *val, int polish,
                  size_t *lenp)
{
    if (val == NULL)
    {
        if (lenp != NULL)
            *lenp= 0;
        return;
    }

    if (rcsbuf->at_string ? rcsbuf->embedded_at == 0 : ! polish)
    {
        /* No special action to take.  */
        if (lenp != NULL)
            *lenp = rcsbuf->vlen;
        return;
    }

    rcsbuf_valpolish_internal (rcsbuf, val, val, lenp);
}



/* Internal polishing routine, called from rcsbuf_valcopy and
   rcsbuf_valpolish.  */
static void
rcsbuf_valpolish_internal (struct rcsbuffer *rcsbuf, char *to,
                           const char *from, size_t *lenp)
{
    size_t len;

    len = rcsbuf->vlen;

    if (! rcsbuf->at_string)
    {
        char *orig_to;
        size_t clen;

        orig_to = to;

        for (clen = len; clen > 0; ++from, --clen)
        {
            char c;

            c = *from;
            if (whitespace (c))
            {
                /* Note that we know that clen can not drop to zero
                   while we have whitespace, because we know there is
                   no trailing whitespace.  */
                while (whitespace (from[1]))
                {
                    ++from;
                    --clen;
                }
                c = ' ';
            }
            *to++ = c;
        }

        *to = '\0';

        if (lenp != NULL)
            *lenp = to - orig_to;
    }
    else
    {
        const char *orig_from;
        char *orig_to;
        int embedded_at;
        size_t clen;

        orig_from = from;
        orig_to = to;

        embedded_at = rcsbuf->embedded_at;
        assert (embedded_at > 0);

        if (lenp != NULL)
            *lenp = len - embedded_at;

        for (clen = len; clen > 0; ++from, --clen)
        {
            char c;

            c = *from;
            *to++ = c;
            if (c == '@')
            {
                ++from;

                /* Sanity check.
                 *
                 * FIXME: I restored this to an abort from an assert based on
                 * advice from Larry Jones that asserts should not be used to
                 * confirm the validity of an RCS file...  This leaves two
                 * issues here: 1) I am uncertain that the fact that we will
                 * only find double '@'s hasn't already been confirmed; and:
                 * 2) If this is the proper place to spot the error in the RCS
                 * file, then we should print a much clearer error here for the
                 * user!!!!!!!
                 *
                 *      - DRP
                 */
                if (*from != '@' || clen == 0)
                    abort ();

                --clen;

                --embedded_at;
                if (embedded_at == 0)
                {
                    /* We've found all the embedded '@' characters.
                       We can just memcpy the rest of the buffer after
                       this '@' character.  */
                    if (orig_to != orig_from)
                        memcpy (to, from + 1, clen - 1);
                    else
                        memmove (to, from + 1, clen - 1);
                    from += clen;
                    to += clen - 1;
                    break;
                }
            }
        }

        /* Sanity check.  */
        assert (from == orig_from + len
            && to == orig_to + (len - rcsbuf->embedded_at));

        *to = '\0';
    }
}



#ifdef PRESERVE_PERMISSIONS_SUPPORT

/* Copy the next word from the value VALP returned by rcsbuf_getkey into a
   memory buffer, updating VALP and returning the memory buffer.  Return
   NULL when there are no more words. */

static char *
rcsbuf_valword (struct rcsbuffer *rcsbuf, char **valp)
{
    register const char * const my_spacetab = spacetab;
    register char *ptr, *pat;
    char c;

# define my_whitespace(c)       (my_spacetab[(unsigned char)c] != 0)

    if (*valp == NULL)
        return NULL;

    for (ptr = *valp; my_whitespace (*ptr); ++ptr) ;
    if (*ptr == '\0')
    {
        assert (ptr - *valp == rcsbuf->vlen);
        *valp = NULL;
        rcsbuf->vlen = 0;
        return NULL;
    }

    /* PTR now points to the start of a value.  Find out whether it is
       a num, an id, a string or a colon. */
    c = *ptr;
    if (c == ':')
    {
        rcsbuf->vlen -= ++ptr - *valp;
        *valp = ptr;
        return xstrdup (":");
    }

    if (c == '@')
    {
        int embedded_at = 0;
        size_t vlen;

        pat = ++ptr;
        while ((pat = strchr (pat, '@')) != NULL)
        {
            if (pat[1] != '@')
                break;
            ++embedded_at;
            pat += 2;
        }

        /* Here PAT points to the final '@' in the string.  */
        *pat++ = '\0';
        assert (rcsbuf->at_string);
        vlen = rcsbuf->vlen - (pat - *valp);
        rcsbuf->vlen = pat - ptr - 1;
        rcsbuf->embedded_at = embedded_at;
        ptr = rcsbuf_valcopy (rcsbuf, ptr, 0, NULL);
        *valp = pat;
        rcsbuf->vlen = vlen;
        if (strchr (pat, '@') == NULL)
            rcsbuf->at_string = 0;
        else
            rcsbuf->embedded_at = -1;
        return ptr;
    }

    /* *PTR is neither `:', `;' nor `@', so it should be the start of a num
       or an id.  Make sure it is not another special character. */
    if (c == '$' || c == '.' || c == ',')
        error (1, 0, "invalid special character in RCS field in %s",
               primary_root_inverse_translate (rcsbuf->filename));

    pat = ptr;
    while (1)
    {
        /* Legitimate ID characters are digits, dots and any `graphic
           printing character that is not a special.' This test ought
           to do the trick. */
        c = *++pat;
        if (!isprint ((unsigned char) c) ||
            c == ';' || c == '$' || c == ',' || c == '@' || c == ':')
            break;
    }

    /* PAT points to the last non-id character in this word, and C is
       the character in its memory cell.  Check to make sure that it
       is a legitimate word delimiter -- whitespace or end. */
    if (c != '\0' && !my_whitespace (c))
        error (1, 0, "invalid special character in RCS field in %s",
               primary_root_inverse_translate (rcsbuf->filename));

    *pat = '\0';
    rcsbuf->vlen -= pat - *valp;
    *valp = pat;
    return xstrdup (ptr);

# undef my_whitespace
}

#endif /* PRESERVE_PERMISSIONS_SUPPORT */



/* Return the current position of an rcsbuf.  */
static off_t
rcsbuf_ftello (struct rcsbuffer *rcsbuf)
{
    return rcsbuf->pos + rcsbuf->ptr - rcsbuf_buffer;
}



/* Return a pointer to any data buffered for RCSBUF, along with the
   length.  */
static void
rcsbuf_get_buffered (struct rcsbuffer *rcsbuf, char **datap, size_t *lenp)
{
    *datap = rcsbuf->ptr;
    *lenp = rcsbuf->ptrend - rcsbuf->ptr;
}



/* CVS optimizes by quickly reading some header information from a
   file.  If it decides it needs to do more with the file, it reopens
   it.  We speed that up here by maintaining a cache of a single open
   file, to save the time it takes to reopen the file in the common
   case.  */
static RCSNode *cached_rcs;
static struct rcsbuffer cached_rcsbuf;

/* Cache RCS and RCSBUF.  This takes responsibility for closing
   RCSBUF->FP.  */
static void
rcsbuf_cache (RCSNode *rcs, struct rcsbuffer *rcsbuf)
{
    if (cached_rcs != NULL)
        rcsbuf_cache_close ();
    cached_rcs = rcs;
    ++rcs->refcount;
    cached_rcsbuf = *rcsbuf;
}



/* If there is anything in the cache, close it.  */
static void
rcsbuf_cache_close (void)
{
    if (cached_rcs != NULL)
    {
        rcsbuf_close (&cached_rcsbuf);
        if (fclose (cached_rcsbuf.fp) != 0)
            error (0, errno, "cannot close %s", cached_rcsbuf.filename);
        freercsnode (&cached_rcs);
        cached_rcs = NULL;
    }
}



/* Open an rcsbuffer for RCS, getting it from the cache if possible.
   Set *FPP to the file, and *RCSBUFP to the rcsbuf.  The file should
   be put at position POS.  */
static void
rcsbuf_cache_open (RCSNode *rcs, off_t pos, FILE **pfp,
                   struct rcsbuffer *prcsbuf)
{
#ifndef HAVE_MMAP
    if (cached_rcs == rcs)
    {
        if (rcsbuf_ftello (&cached_rcsbuf) != pos)
        {
            if (fseeko (cached_rcsbuf.fp, pos, SEEK_SET) != 0)
                error (1, 0, "cannot fseeko RCS file %s",
                       cached_rcsbuf.filename);
            cached_rcsbuf.ptr = rcsbuf_buffer;
            cached_rcsbuf.ptrend = rcsbuf_buffer;
            cached_rcsbuf.pos = pos;
        }
        *pfp = cached_rcsbuf.fp;

        /* When RCS_parse opens a file using fopen_case, it frees the
           filename which we cached in CACHED_RCSBUF and stores a new
           file name in RCS->PATH.  We avoid problems here by always
           copying the filename over.  FIXME: This is hackish.  */
        cached_rcsbuf.filename = rcs->path;

        *prcsbuf = cached_rcsbuf;

        cached_rcs = NULL;

        /* Removing RCS from the cache removes a reference to it.  */
        --rcs->refcount;
        if (rcs->refcount <= 0)
            error (1, 0, "rcsbuf_cache_open: internal error");
    }
    else
    {
#endif /* ifndef HAVE_MMAP */
        /* FIXME:  If these routines can be rewritten to not write to the
         * rcs file buffer, there would be a considerably larger memory savings
         * from using mmap since the shared file would never need be copied to
         * process memory.
         *
         * If this happens, cached mmapped buffers would be usable, but don't
         * forget to make sure rcs->pos < pos here...
         */
        if (cached_rcs != NULL)
            rcsbuf_cache_close ();

        *pfp = CVS_FOPEN (rcs->path, FOPEN_BINARY_READ);
        if (*pfp == NULL)
            error (1, 0, "unable to reopen `%s'", rcs->path);
#ifndef HAVE_MMAP
        if (pos != 0)
        {
            if (fseeko (*pfp, pos, SEEK_SET) != 0)
                error (1, 0, "cannot fseeko RCS file %s", rcs->path);
        }
#endif /* ifndef HAVE_MMAP */
        rcsbuf_open (prcsbuf, *pfp, rcs->path, pos);
#ifndef HAVE_MMAP
    }
#endif /* ifndef HAVE_MMAP */
}



/*
 * process the symbols list of the rcs file
 */
static void
do_symbols (List *list, char *val)
{
    Node *p;
    char *cp = val;
    char *tag, *rev;

    assert (cp);

    for (;;)
    {
        /* skip leading whitespace */
        while (whitespace (*cp))
            cp++;

        /* if we got to the end, we are done */
        if (*cp == '\0')
            break;

        /* split it up into tag and rev */
        tag = cp;
        cp = strchr (cp, ':');
        *cp++ = '\0';
        rev = cp;
        while (!whitespace (*cp) && *cp != '\0')
            cp++;
        if (*cp != '\0')
            *cp++ = '\0';

        /* make a new node and add it to the list */
        p = getnode ();
        p->key = xstrdup (tag);
        p->data = xstrdup (rev);
        (void) addnode (list, p);
    }
}



/*
 * process the locks list of the rcs file
 * Like do_symbols, but hash entries are keyed backwards: i.e.
 * an entry like `user:rev' is keyed on REV rather than on USER.
 */
static void
do_locks (List *list, char *val)
{
    Node *p;
    char *cp = val;
    char *user, *rev;

    assert (cp);

    for (;;)
    {
        /* skip leading whitespace */
        while (whitespace (*cp))
            cp++;

        /* if we got to the end, we are done */
        if (*cp == '\0')
            break;

        /* split it up into user and rev */
        user = cp;
        cp = strchr (cp, ':');
        *cp++ = '\0';
        rev = cp;
        while (!whitespace (*cp) && *cp != '\0')
            cp++;
        if (*cp != '\0')
            *cp++ = '\0';

        /* make a new node and add it to the list */
        p = getnode ();
        p->key = xstrdup (rev);
        p->data = xstrdup (user);
        (void) addnode (list, p);
    }
}



/*
 * process the branches list of a revision delta
 */
static void
do_branches (List *list, char *val)
{
    Node *p;
    char *cp = val;
    char *branch;

    for (;;)
    {
        /* skip leading whitespace */
        while (whitespace (*cp))
            cp++;

        /* if we got to the end, we are done */
        if (*cp == '\0')
            break;

        /* find the end of this branch */
        branch = cp;
        while (!whitespace (*cp) && *cp != '\0')
            cp++;
        if (*cp != '\0')
            *cp++ = '\0';

        /* make a new node and add it to the list */
        p = getnode ();
        p->key = xstrdup (branch);
        (void) addnode (list, p);
    }
}



/*
 * Version Number
 * 
 * Returns the requested version number of the RCS file, satisfying tags and/or
 * dates, and walking branches, if necessary.
 * 
 * The result is returned; null-string if error.
 */
char *
RCS_getversion (RCSNode *rcs, const char *tag, const char *date,
                int force_tag_match, int *simple_tag)
{
    if (simple_tag != NULL)
        *simple_tag = 0;

    /* make sure we have something to look at... */
    assert (rcs != NULL);

    if (tag && date)
    {
        char *branch, *rev;

        if (! RCS_nodeisbranch (rcs, tag))
        {
            /* We can't get a particular date if the tag is not a
               branch.  */
            return NULL;
        }

        /* Work out the branch.  */
        if (! isdigit ((unsigned char) tag[0]))
            branch = RCS_whatbranch (rcs, tag);
        else
            branch = xstrdup (tag);

        /* Fetch the revision of branch as of date.  */
        rev = RCS_getdatebranch (rcs, date, branch);
        free (branch);
        return rev;
    }
    else if (tag)
        return RCS_gettag (rcs, tag, force_tag_match, simple_tag);
    else if (date)
        return RCS_getdate (rcs, date, force_tag_match);
    else
        return RCS_head (rcs);

}



/*
 * Get existing revision number corresponding to tag or revision.
 * Similar to RCS_gettag but less interpretation imposed.
 * For example:
 * -- If tag designates a magic branch, RCS_tag2rev
 *    returns the magic branch number.
 * -- If tag is a branch tag, returns the branch number, not
 *    the revision of the head of the branch.
 * If tag or revision is not valid or does not exist in file,
 * return NULL.
 */
char *
RCS_tag2rev (RCSNode *rcs, char *tag)
{
    char *rev, *pa, *pb;
    int i;

    assert (rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* If a valid revision, try to look it up */
    if ( RCS_valid_rev (tag) )
    {
        /* Make a copy so we can scribble on it */
        rev =  xstrdup (tag);

        /* If revision exists, return the copy */
        if (RCS_exist_rev (rcs, tag))
            return rev;

        /* Nope, none such. If tag is not a branch we're done. */ 
        i = numdots (rev);
        if ((i & 1) == 1 )
        {
            pa = strrchr (rev, '.');
            if (i == 1 || *(pa-1) != RCS_MAGIC_BRANCH || *(pa-2) != '.')
            {
                free (rev);
                error (1, 0, "revision `%s' does not exist", tag);
            }
        }

        /* Try for a real (that is, exists in the RCS deltas) branch
           (RCS_exist_rev just checks for real revisions and revisions
           which have tags pointing to them).  */
        pa = RCS_getbranch (rcs, rev, 1);
        if (pa != NULL)
        {
            free (pa);
            return rev;
        }

       /* Tag is branch, but does not exist, try corresponding 
        * magic branch tag.
        *
        * FIXME: assumes all magic branches are of       
        * form "n.n.n ... .0.n".  I'll fix if somebody can
        * send me a method to get a magic branch tag with
        * the 0 in some other position -- <dan@gasboy.com>
        */ 
        pa = strrchr (rev, '.');
        if (!pa)
            /* This might happen, for instance, if an RCS file only contained
             * revisions 2.x and higher, and REV == "1".
             */
            error (1, 0, "revision `%s' does not exist", tag);

        *pa++ = 0;
        pb = Xasprintf ("%s.%d.%s", rev, RCS_MAGIC_BRANCH, pa);
        free (rev);
        rev = pb;
        if (RCS_exist_rev (rcs, rev))
            return rev;
        error (1, 0, "revision `%s' does not exist", tag);
    }


    RCS_check_tag (tag); /* exit if not a valid tag */

    /* If tag is "HEAD", special case to get head RCS revision */
    if (tag && STREQ (tag, TAG_HEAD))
        return RCS_head (rcs);

    /* If valid tag let translate_symtag say yea or nay. */
    rev = translate_symtag (rcs, tag);

    if (rev)
        return rev;

    /* Trust the caller to print warnings. */
    return NULL;
}



/*
 * Find the revision for a specific tag.
 * If force_tag_match is set, return NULL if an exact match is not
 * possible otherwise return RCS_head ().  We are careful to look for
 * and handle "magic" revisions specially.
 * 
 * If the matched tag is a branch tag, find the head of the branch.
 * 
 * Returns pointer to newly malloc'd string, or NULL.
 */
char *
RCS_gettag (RCSNode *rcs, const char *symtag, int force_tag_match,
            int *simple_tag)
{
    char *tag;

    if (simple_tag != NULL)
        *simple_tag = 0;

    /* make sure we have something to look at... */
    assert (rcs != NULL);

    /* XXX this is probably not necessary, --jtc */
    if (rcs->flags & PARTIAL) 
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* If symtag is "HEAD", special case to get head RCS revision */
    if (symtag && STREQ (symtag, TAG_HEAD))
#if 0 /* This #if 0 is only in the Cygnus code.  Why?  Death support?  */
        if (force_tag_match && (rcs->flags & VALID) && (rcs->flags & INATTIC))
            return NULL;        /* head request for removed file */
        else
#endif
            return RCS_head (rcs);

    if (!isdigit ((unsigned char) symtag[0]))
    {
        char *version;

        /* If we got a symbolic tag, resolve it to a numeric */
        version = translate_symtag (rcs, symtag);
        if (version != NULL)
        {
            int dots;
            char *magic, *branch, *cp;

            tag = version;

            /*
             * If this is a magic revision, we turn it into either its
             * physical branch equivalent (if one exists) or into
             * its base revision, which we assume exists.
             */
            dots = numdots (tag);
            if (dots > 2 && (dots & 1) != 0)
            {
                branch = strrchr (tag, '.');
                cp = branch++ - 1;
                while (*cp != '.')
                    cp--;

                /* see if we have .magic-branch. (".0.") */
                magic = xmalloc (strlen (tag) + 1);
                (void) sprintf (magic, ".%d.", RCS_MAGIC_BRANCH);
                if (strncmp (magic, cp, strlen (magic)) == 0)
                {
                    /* it's magic.  See if the branch exists */
                    *cp = '\0';         /* turn it into a revision */
                    (void) sprintf (magic, "%s.%s", tag, branch);
                    branch = RCS_getbranch (rcs, magic, 1);
                    free (magic);
                    if (branch != NULL)
                    {
                        free (tag);
                        return branch;
                    }
                    return tag;
                }
                free (magic);
            }
        }
        else
        {
            /* The tag wasn't there, so return the head or NULL */
            if (force_tag_match)
                return NULL;
            else
                return RCS_head (rcs);
        }
    }
    else
        tag = xstrdup (symtag);

    /* tag is always allocated and numeric now.  */

    /*
     * numeric tag processing:
     *          1) revision number - just return it
     *          2) branch number   - find head of branch
     */

    /* strip trailing dots */
    while (tag[strlen (tag) - 1] == '.')
        tag[strlen (tag) - 1] = '\0';

    if ((numdots (tag) & 1) == 0)
    {
        char *branch;

        /* we have a branch tag, so we need to walk the branch */
        branch = RCS_getbranch (rcs, tag, force_tag_match);
        free (tag);
        return branch;
    }
    else
    {
        Node *p;

        /* we have a revision tag, so make sure it exists */
        p = findnode (rcs->versions, tag);
        if (p != NULL)
        {
            /* We have found a numeric revision for the revision tag.
               To support expanding the RCS keyword Name, if
               SIMPLE_TAG is not NULL, tell the the caller that this
               is a simple tag which co will recognize.  FIXME: Are
               there other cases in which we should set this?  In
               particular, what if we expand RCS keywords internally
               without calling co?  */
            if (simple_tag != NULL)
                *simple_tag = 1;
            return tag;
        }
        else
        {
            /* The revision wasn't there, so return the head or NULL */
            free (tag);
            if (force_tag_match)
                return NULL;
            else
                return RCS_head (rcs);
        }
    }
}



/*
 * Return a "magic" revision as a virtual branch off of REV for the RCS file.
 * A "magic" revision is one which is unique in the RCS file.  By unique, I
 * mean we return a revision which:
 *      - has a branch of 0 (see rcs.h RCS_MAGIC_BRANCH)
 *      - has a revision component which is not an existing branch off REV
 *      - has a revision component which is not an existing magic revision
 *      - is an even-numbered revision, to avoid conflicts with vendor branches
 * The first point is what makes it "magic".
 *
 * As an example, if we pass in 1.37 as REV, we will look for an existing
 * branch called 1.37.2.  If it did not exist, we would look for an
 * existing symbolic tag with a numeric part equal to 1.37.0.2.  If that
 * didn't exist, then we know that the 1.37.2 branch can be reserved by
 * creating a symbolic tag with 1.37.0.2 as the numeric part.
 *
 * This allows us to fork development with very little overhead -- just a
 * symbolic tag is used in the RCS file.  When a commit is done, a physical
 * branch is dynamically created to hold the new revision.
 *
 * Note: We assume that REV is an RCS revision and not a branch number.
 */
static char *check_rev;
char *
RCS_magicrev (RCSNode *rcs, char *rev)
{
    int rev_num;
    char *xrev, *test_branch, *local_branch_num;

    xrev = xmalloc (strlen (rev) + 14); /* enough for .0.number */
    check_rev = xrev;

    local_branch_num = getenv("CVS_LOCAL_BRANCH_NUM");
    if (local_branch_num)
    {
      rev_num = atoi(local_branch_num);
      if (rev_num < 2)
        rev_num = 2;
      else
        rev_num &= ~1;
    }
    else
      rev_num = 2;

    /* only look at even numbered branches */
    for ( ; ; rev_num += 2)
    {
        /* see if the physical branch exists */
        (void) sprintf (xrev, "%s.%d", rev, rev_num);
        test_branch = RCS_getbranch (rcs, xrev, 1);
        if (test_branch != NULL)        /* it did, so keep looking */
        {
            free (test_branch);
            continue;
        }

        /* now, create a "magic" revision */
        (void) sprintf (xrev, "%s.%d.%d", rev, RCS_MAGIC_BRANCH, rev_num);

        /* walk the symbols list to see if a magic one already exists */
        if (walklist (RCS_symbols(rcs), checkmagic_proc, NULL) != 0)
            continue;

        /* we found a free magic branch.  Claim it as ours */
        return xrev;
    }
}



/*
 * walklist proc to look for a match in the symbols list.
 * Returns 0 if the symbol does not match, 1 if it does.
 */
static int
checkmagic_proc (Node *p, void *closure)
{
    if (STREQ (check_rev, p->data))
        return 1;
    else
        return 0;
}



/*
 * Given an RCSNode, returns non-zero if the specified revision number 
 * or symbolic tag resolves to a "branch" within the rcs file.
 *
 * FIXME: this is the same as RCS_nodeisbranch except for the special 
 *        case for handling a null rcsnode.
 */
int
RCS_isbranch (RCSNode *rcs, const char *rev)
{
    /* numeric revisions are easy -- even number of dots is a branch */
    if (isdigit ((unsigned char) *rev))
        return (numdots (rev) & 1) == 0;

    /* assume a revision if you can't find the RCS info */
    if (rcs == NULL)
        return 0;

    /* now, look for a match in the symbols list */
    return RCS_nodeisbranch (rcs, rev);
}



/*
 * Given an RCSNode, returns non-zero if the specified revision number
 * or symbolic tag resolves to a "branch" within the rcs file.  We do
 * take into account any magic branches as well.
 */
int
RCS_nodeisbranch (RCSNode *rcs, const char *rev)
{
    int dots;
    char *version;

    assert (rcs != NULL);

    /* numeric revisions are easy -- even number of dots is a branch */
    if (isdigit ((unsigned char) *rev))
        return (numdots (rev) & 1) == 0;

    version = translate_symtag (rcs, rev);
    if (version == NULL)
        return 0;
    dots = numdots (version);
    if ((dots & 1) == 0)
    {
        free (version);
        return 1;
    }

    /* got a symbolic tag match, but it's not a branch; see if it's magic */
    if (dots > 2)
    {
        char *magic;
        char *branch = strrchr (version, '.');
        char *cp = branch - 1;
        while (*cp != '.')
            cp--;

        /* see if we have .magic-branch. (".0.") */
        magic = Xasprintf (".%d.", RCS_MAGIC_BRANCH);
        if (strncmp (magic, cp, strlen (magic)) == 0)
        {
            free (magic);
            free (version);
            return 1;
        }
        free (magic);
    }
    free (version);
    return 0;
}



/*
 * Returns a pointer to malloc'ed memory which contains the branch
 * for the specified *symbolic* tag.  Magic branches are handled correctly.
 */
char *
RCS_whatbranch (RCSNode *rcs, const char *rev)
{
    char *version;
    int dots;

    /* assume no branch if you can't find the RCS info */
    if (rcs == NULL)
        return NULL;

    /* now, look for a match in the symbols list */
    version = translate_symtag (rcs, rev);
    if (version == NULL)
        return NULL;
    dots = numdots (version);
    if ((dots & 1) == 0)
        return version;

    /* got a symbolic tag match, but it's not a branch; see if it's magic */
    if (dots > 2)
    {
        char *magic;
        char *branch = strrchr (version, '.');
        char *cp = branch++ - 1;
        while (*cp != '.')
            cp--;

        /* see if we have .magic-branch. (".0.") */
        magic = xmalloc (strlen (version) + 1);
        (void) sprintf (magic, ".%d.", RCS_MAGIC_BRANCH);
        if (strncmp (magic, cp, strlen (magic)) == 0)
        {
            /* yep.  it's magic.  now, construct the real branch */
            *cp = '\0';                 /* turn it into a revision */
            (void) sprintf (magic, "%s.%s", version, branch);
            free (version);
            return magic;
        }
        free (magic);
    }
    free (version);
    return NULL;
}



/*
 * Get the head of the specified branch.  If the branch does not exist,
 * return NULL or RCS_head depending on force_tag_match.
 * Returns NULL or a newly malloc'd string.
 */
char *
RCS_getbranch (RCSNode *rcs, const char *tag, int force_tag_match)
{
    Node *p, *head;
    RCSVers *vn;
    char *xtag;
    char *nextvers;
    char *cp;

    /* make sure we have something to look at... */
    assert (rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* find out if the tag contains a dot, or is on the trunk */
    cp = strrchr (tag, '.');

    /* trunk processing is the special case */
    if (cp == NULL)
    {
        xtag = Xasprintf ("%s.", tag);
        for (cp = rcs->head; cp != NULL;)
        {
            if (strncmp (xtag, cp, strlen (xtag)) == 0)
                break;
            p = findnode (rcs->versions, cp);
            if (p == NULL)
            {
                free (xtag);
                if (force_tag_match)
                    return NULL;
                else
                    return RCS_head (rcs);
            }
            vn = p->data;
            cp = vn->next;
        }
        free (xtag);
        if (cp == NULL)
        {
            if (force_tag_match)
                return NULL;
            else
                return RCS_head (rcs);
        }
        return xstrdup (cp);
    }

    /* if it had a `.', terminate the string so we have the base revision */
    *cp = '\0';

    /* look up the revision this branch is based on */
    p = findnode (rcs->versions, tag);

    /* put the . back so we have the branch again */
    *cp = '.';

    if (p == NULL)
    {
        /* if the base revision didn't exist, return head or NULL */
        if (force_tag_match)
            return NULL;
        else
            return RCS_head (rcs);
    }

    /* find the first element of the branch we are looking for */
    vn = p->data;
    if (vn->branches == NULL)
        return NULL;
    xtag = Xasprintf ("%s.", tag);
    head = vn->branches->list;
    for (p = head->next; p != head; p = p->next)
        if (strncmp (p->key, xtag, strlen (xtag)) == 0)
            break;
    free (xtag);

    if (p == head)
    {
        /* we didn't find a match so return head or NULL */
        if (force_tag_match)
            return NULL;
        else
            return RCS_head (rcs);
    }

    /* now walk the next pointers of the branch */
    nextvers = p->key;
    do
    {
        p = findnode (rcs->versions, nextvers);
        if (p == NULL)
        {
            /* a link in the chain is missing - return head or NULL */
            if (force_tag_match)
                return NULL;
            else
                return RCS_head (rcs);
        }
        vn = p->data;
        nextvers = vn->next;
    } while (nextvers != NULL);

    /* we have the version in our hand, so go for it */
    return xstrdup (vn->version);
}



/* Returns the head of the branch which REV is on.  REV can be a
   branch tag or non-branch tag; symbolic or numeric.

   Returns a newly malloc'd string.  Returns NULL if a symbolic name
   isn't found.  */
char *
RCS_branch_head (RCSNode *rcs, char *rev)
{
    char *num;
    char *br;
    char *retval;

    assert (rcs != NULL);

    if (RCS_nodeisbranch (rcs, rev))
        return RCS_getbranch (rcs, rev, 1);

    if (isdigit ((unsigned char) *rev))
        num = xstrdup (rev);
    else
    {
        num = translate_symtag (rcs, rev);
        if (num == NULL)
            return NULL;
    }
    br = truncate_revnum (num);
    retval = RCS_getbranch (rcs, br, 1);
    free (br);
    free (num);
    return retval;
}



/* Get the branch point for a particular branch, that is the first
   revision on that branch.  For example, RCS_getbranchpoint (rcs,
   "1.3.2") will normally return "1.3.2.1".  TARGET may be either a
   branch number or a revision number; if a revnum, find the
   branchpoint of the branch to which TARGET belongs.

   Return RCS_head if TARGET is on the trunk or if the root node could
   not be found (this is sort of backwards from our behavior on a branch;
   the rationale is that the return value is a revision from which you
   can start walking the next fields and end up at TARGET).
   Return NULL on error.  */
static char *
RCS_getbranchpoint (RCSNode *rcs, char *target)
{
    char *branch, *bp;
    Node *vp;
    RCSVers *rev;
    int dots, isrevnum, brlen;

    dots = numdots (target);
    isrevnum = dots & 1;

    if (dots == 1)
        /* TARGET is a trunk revision; return rcs->head. */
        return RCS_head (rcs);

    /* Get the revision number of the node at which TARGET's branch is
       rooted.  If TARGET is a branch number, lop off the last field;
       if it's a revision number, lop off the last *two* fields. */
    branch = xstrdup (target);
    bp = strrchr (branch, '.');
    if (bp == NULL)
        error (1, 0, "%s: confused revision number %s",
               rcs->print_path, target);
    if (isrevnum)
        while (*--bp != '.')
            ;
    *bp = '\0';

    vp = findnode (rcs->versions, branch);
    if (vp == NULL)
    {   
        error (0, 0, "%s: can't find branch point %s", rcs->print_path, target);
        free (branch);
        return NULL;
    }
    rev = vp->data;

    *bp++ = '.';
    while (*bp && *bp != '.')
        ++bp;
    brlen = bp - branch;

    vp = rev->branches->list->next;
    while (vp != rev->branches->list)
    {
        /* BRANCH may be a genuine branch number, e.g. `1.1.3', or
           maybe a full revision number, e.g. `1.1.3.6'.  We have
           found our branch point if the first BRANCHLEN characters
           of the revision number match, *and* if the following
           character is a dot. */
        if (strncmp (vp->key, branch, brlen) == 0 && vp->key[brlen] == '.')
            break;
        vp = vp->next;
    }

    free (branch);
    if (vp == rev->branches->list)
    {
        error (0, 0, "%s: can't find branch point %s", rcs->print_path, target);
        return NULL;
    }
    else
        return xstrdup (vp->key);
}



/*
 * Get the head of the RCS file.  If branch is set, this is the head of the
 * branch, otherwise the real head.
 *
 * INPUTS
 *   rcs        The parsed rcs node information.
 *
 * RETURNS
 *   NULL when rcs->branch exists and cannot be found.
 *   A newly malloc'd string, otherwise.
 */
char *
RCS_head (RCSNode *rcs)
{
    /* make sure we have something to look at... */
    assert (rcs);

    /*
     * NOTE: we call getbranch with force_tag_match set to avoid any
     * possibility of recursion
     */
    if (rcs->branch)
        return RCS_getbranch (rcs, rcs->branch, 1);
    else
        return xstrdup (rcs->head);
}



/*
 * Get the most recent revision, based on the supplied date, but use some
 * funky stuff and follow the vendor branch maybe
 */
char *
RCS_getdate (RCSNode *rcs, const char *date, int force_tag_match)
{
    char *cur_rev = NULL;
    char *retval = NULL;
    Node *p;
    RCSVers *vers = NULL;

    /* make sure we have something to look at... */
    assert (rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* if the head is on a branch, try the branch first */
    if (rcs->branch != NULL)
    {
        retval = RCS_getdatebranch (rcs, date, rcs->branch);
        if (retval != NULL)
            return retval;
    }

    /* otherwise if we have a trunk, try it */
    if (rcs->head)
    {
        p = findnode (rcs->versions, rcs->head);
        if (p == NULL)
        {
            error (0, 0, "%s: head revision %s doesn't exist", rcs->print_path,
                   rcs->head);
        }
        while (p != NULL)
        {
            /* if the date of this one is before date, take it */
            vers = p->data;
            if (RCS_datecmp (vers->date, date) <= 0)
            {
                cur_rev = vers->version;
                break;
            }

            /* if there is a next version, find the node */
            if (vers->next != NULL)
                p = findnode (rcs->versions, vers->next);
            else
                p = NULL;
        }
    }
    else
        error (0, 0, "%s: no head revision", rcs->print_path);

    /*
     * at this point, either we have the revision we want, or we have the
     * first revision on the trunk (1.1?) in our hands, or we've come up
     * completely empty
     */

    /* if we found what we're looking for, and it's not 1.1 return it */
    if (cur_rev != NULL)
    {
        if (! STREQ (cur_rev, "1.1"))
            return xstrdup (cur_rev);

        /* This is 1.1;  if the date of 1.1 is not the same as that for the
           1.1.1.1 version, then return 1.1.  This happens when the first
           version of a file is created by a regular cvs add and commit,
           and there is a subsequent cvs import of the same file.  */
        p = findnode (rcs->versions, "1.1.1.1");
        if (p)
        {
            char *date_1_1 = vers->date;

            vers = p->data;
            if (RCS_datecmp (vers->date, date_1_1) != 0)
                return xstrdup ("1.1");
        }
    }

    /* look on the vendor branch */
    retval = RCS_getdatebranch (rcs, date, CVSBRANCH);

    /*
     * if we found a match, return it; otherwise, we return the first
     * revision on the trunk or NULL depending on force_tag_match and the
     * date of the first rev
     */
    if (retval != NULL)
        return retval;

    if (vers && (!force_tag_match || RCS_datecmp (vers->date, date) <= 0))
        return xstrdup (vers->version);
    else
        return NULL;
}



/*
 * Look up the last element on a branch that was put in before or on
 * the specified date and time (return the rev or NULL)
 */
static char *
RCS_getdatebranch (RCSNode *rcs, const char *date, const char *branch)
{
    char *cur_rev = NULL;
    char *cp;
    char *xbranch, *xrev;
    Node *p;
    RCSVers *vers;

    /* look up the first revision on the branch */
    xrev = xstrdup (branch);
    cp = strrchr (xrev, '.');
    if (cp == NULL)
    {
        free (xrev);
        return NULL;
    }
    *cp = '\0';                         /* turn it into a revision */

    assert (rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    p = findnode (rcs->versions, xrev);
    free (xrev);
    if (p == NULL)
        return NULL;
    vers = p->data;

    /* Tentatively use this revision, if it is early enough.  */
    if (RCS_datecmp (vers->date, date) <= 0)
        cur_rev = vers->version;

    /* If no branches list, return now.  This is what happens if the branch
       is a (magic) branch with no revisions yet.  */
    if (vers->branches == NULL)
        return xstrdup (cur_rev);

    /* walk the branches list looking for the branch number */
    xbranch = Xasprintf ("%s.", branch);
    for (p = vers->branches->list->next; p != vers->branches->list; p = p->next)
        if (strncmp (p->key, xbranch, strlen (xbranch)) == 0)
            break;
    free (xbranch);
    if (p == vers->branches->list)
    {
        /* This is what happens if the branch is a (magic) branch with
           no revisions yet.  Similar to the case where vers->branches ==
           NULL, except here there was a another branch off the same
           branchpoint.  */
        return xstrdup (cur_rev);
    }

    p = findnode (rcs->versions, p->key);

    /* walk the next pointers until you find the end, or the date is too late */
    while (p != NULL)
    {
        vers = p->data;
        if (RCS_datecmp (vers->date, date) <= 0)
            cur_rev = vers->version;
        else
            break;

        /* if there is a next version, find the node */
        if (vers->next != NULL)
            p = findnode (rcs->versions, vers->next);
        else
            p = NULL;
    }

    /* Return whatever we found, which may be NULL.  */
    return xstrdup (cur_rev);
}



/*
 * Compare two dates in RCS format. Beware the change in format on January 1,
 * 2000, when years go from 2-digit to full format.
 */
int
RCS_datecmp (const char *date1, const char *date2)
{
    int length_diff = strlen (date1) - strlen (date2);

    return length_diff ? length_diff : strcmp (date1, date2);
}



/* Look up revision REV in RCS and return the date specified for the
   revision minus FUDGE seconds (FUDGE will generally be one, so that the
   logically previous revision will be found later, or zero, if we want
   the exact date).

   The return value is the date being returned as a time_t, or (time_t)-1
   on error (previously was documented as zero on error; I haven't checked
   the callers to make sure that they really check for (time_t)-1, but
   the latter is what this function really returns).  If DATE is non-NULL,
   then it must point to MAXDATELEN characters, and we store the same
   return value there in DATEFORM format.  */
time_t
RCS_getrevtime (RCSNode *rcs, const char *rev, char *date, int fudge)
{
    char *tdate;
    struct tm xtm, *ftm;
    struct timespec revdate;
    Node *p;
    RCSVers *vers;

    /* make sure we have something to look at... */
    assert (rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* look up the revision */
    p = findnode (rcs->versions, rev);
    if (p == NULL)
        return -1;
    vers = p->data;

    /* split up the date */
    if (sscanf (vers->date, SDATEFORM, &xtm.tm_year, &xtm.tm_mon,
                &xtm.tm_mday, &xtm.tm_hour, &xtm.tm_min, &xtm.tm_sec) != 6)
        error (1, 0, "%s: invalid date for revision %s (%s)", rcs->print_path,
               rev, vers->date);

    /* If the year is from 1900 to 1999, RCS files contain only two
       digits, and sscanf gives us a year from 0-99.  If the year is
       2000+, RCS files contain all four digits and we subtract 1900,
       because the tm_year field should contain years since 1900.  */

    if (xtm.tm_year >= 100 && xtm.tm_year < 2000)
        error (0, 0, "%s: non-standard date format for revision %s (%s)",
               rcs->print_path, rev, vers->date);
    if (xtm.tm_year >= 1900)
        xtm.tm_year -= 1900;

    /* put the date in a form getdate can grok */
    tdate = Xasprintf ("%d-%d-%d %d:%d:%d -0000",
                       xtm.tm_year + 1900, xtm.tm_mon, xtm.tm_mday,
                       xtm.tm_hour, xtm.tm_min, xtm.tm_sec);

    /* Turn it into seconds since the epoch.
     *
     * We use a struct timespec since that is what getdate requires, then
     * truncate the nanoseconds.
     */
    if (!get_date (&revdate, tdate, NULL))
    {
        free (tdate);
        return (time_t)-1;
    }
    free (tdate);

    revdate.tv_sec -= fudge;    /* remove "fudge" seconds */
    if (date)
    {
        /* Put an appropriate string into `date', if we were given one. */
        ftm = gmtime (&revdate.tv_sec);
        (void) sprintf (date, DATEFORM,
                        ftm->tm_year + (ftm->tm_year < 100 ? 0 : 1900),
                        ftm->tm_mon + 1, ftm->tm_mday, ftm->tm_hour,
                        ftm->tm_min, ftm->tm_sec);
    }

    return revdate.tv_sec;
}



List *
RCS_getlocks (RCSNode *rcs)
{
    assert(rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (rcs->locks_data) {
        rcs->locks = getlist ();
        do_locks (rcs->locks, rcs->locks_data);
        free(rcs->locks_data);
        rcs->locks_data = NULL;
    }

    return rcs->locks;
}



List *
RCS_symbols(RCSNode *rcs)
{
    assert(rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (rcs->symbols_data) {
        rcs->symbols = getlist ();
        do_symbols (rcs->symbols, rcs->symbols_data);
        free(rcs->symbols_data);
        rcs->symbols_data = NULL;
    }

    return rcs->symbols;
}



/*
 * Return the version associated with a particular symbolic tag.
 * Returns NULL or a newly malloc'd string.
 */
static char *
translate_symtag (RCSNode *rcs, const char *tag)
{
    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (rcs->symbols != NULL)
    {
        Node *p;

        /* The symbols have already been converted into a list.  */
        p = findnode (rcs->symbols, tag);
        if (p == NULL)
            return NULL;

        return xstrdup (p->data);
    }

    if (rcs->symbols_data != NULL)
    {
        size_t len;
        char *cp, *last;

        /* Look through the RCS symbols information.  This is like
           do_symbols, but we don't add the information to a list.  In
           most cases, we will only be called once for this file, so
           generating the list is unnecessary overhead.  */

        len = strlen (tag);
        cp = rcs->symbols_data;
        /* Keeping track of LAST below isn't strictly necessary, now that tags
         * should be parsed for validity before they are accepted, but tags
         * with spaces used to cause the code below to loop indefintely, so
         * I have corrected for that.  Now, in the event that I missed
         * something, the server cannot be hung.  -DRP
         */
        last = NULL;
        while ((cp = strchr (cp, tag[0])) != NULL)
        {
            if (cp == last) break;
            if ((cp == rcs->symbols_data || whitespace (cp[-1]))
                && strncmp (cp, tag, len) == 0
                && cp[len] == ':')
            {
                char *v, *r;

                /* We found the tag.  Return the version number.  */

                cp += len + 1;
                v = cp;
                while (! whitespace (*cp) && *cp != '\0')
                    ++cp;
                r = xmalloc (cp - v + 1);
                strncpy (r, v, cp - v);
                r[cp - v] = '\0';
                return r;
            }

            while (! whitespace (*cp) && *cp != '\0')
                ++cp;
            if (*cp == '\0')
                break;
            last = cp;
        }
    }

    return NULL;
}



/*
 * The argument ARG is the getopt remainder of the -k option specified on the
 * command line.  This function returns malloc'ed space that can be used
 * directly in calls to RCS V5, with the -k flag munged correctly.
 */
char *
RCS_check_kflag (const char *arg)
{
    static const char *const  keyword_usage[] =
    {
      "%s %s: invalid RCS keyword expansion mode\n",
      "Valid expansion modes include:\n",
      "   -kkv\tGenerate keywords using the default form.\n",
      "   -kkvl\tLike -kkv, except locker's name inserted.\n",
      "   -kk\tGenerate only keyword names in keyword strings.\n",
      "   -kv\tGenerate only keyword values in keyword strings.\n",
      "   -ko\tGenerate the old keyword string (no changes from checked in file).\n",
      "   -kb\tGenerate binary file unmodified (merges not allowed) (RCS 5.7).\n",
      "(Specify the --help global option for a list of other help options)\n",
      NULL,
    };
    char const *const *cpp = NULL;

    if (arg)
    {
        for (cpp = kflags; *cpp != NULL; cpp++)
        {
            if (STREQ (arg, *cpp))
                break;
        }
    }

    if (arg == NULL || *cpp == NULL)
    {
        usage (keyword_usage);
    }

    return Xasprintf ("-k%s", *cpp);
}



/*
 * Do some consistency checks on the symbolic tag... These should equate
 * pretty close to what RCS checks, though I don't know for certain.
 */
void
RCS_check_tag (const char *tag)
{
    char *invalid = "$,.:;@";           /* invalid RCS tag characters */
    const char *cp;

    /*
     * The first character must be an alphabetic letter. The remaining
     * characters cannot be non-visible graphic characters, and must not be
     * in the set of "invalid" RCS identifier characters.
     */
    if (isalpha ((unsigned char) *tag))
    {
        for (cp = tag; *cp; cp++)
        {
            if (!isgraph ((unsigned char) *cp))
                error (1, 0, "tag `%s' has non-visible graphic characters",
                       tag);
            if (strchr (invalid, *cp))
                error (1, 0, "tag `%s' must not contain the characters `%s'",
                       tag, invalid);
        }
    }
    else
        error (1, 0, "tag `%s' must start with a letter", tag);
}



/*
 * TRUE if argument has valid syntax for an RCS revision or 
 * branch number.  All characters must be digits or dots, first 
 * and last characters must be digits, and no two consecutive 
 * characters may be dots.
 *
 * Intended for classifying things, so this function doesn't 
 * call error.
 */
int 
RCS_valid_rev (const char *rev)
{
   char last, c;
   last = *rev++;
   if (!isdigit ((unsigned char) last))
       return 0;
   while ((c = *rev++))   /* Extra parens placate -Wall gcc option */
   {
       if (c == '.')
       {
           if (last == '.')
               return 0;
           continue;
       }
       last = c;
       if (!isdigit ((unsigned char) c))
           return 0;
   }
   if (!isdigit ((unsigned char) last))
       return 0;
   return 1;
}



/*
 * Return true if RCS revision with TAG is a dead revision.
 */
int
RCS_isdead (RCSNode *rcs, const char *tag)
{
    Node *p;
    RCSVers *version;

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    p = findnode (rcs->versions, tag);
    if (p == NULL)
        return 0;

    version = p->data;
    return version->dead;
}



/* Return the RCS keyword expansion mode.  For example "b" for binary.
   Returns a pointer into storage which is allocated and freed along with
   the rest of the RCS information; the caller should not modify this
   storage.  Returns NULL if the RCS file does not specify a keyword
   expansion mode; for all other errors, die with a fatal error.  */
char *
RCS_getexpand (RCSNode *rcs)
{
    /* Since RCS_parsercsfile_i now reads expand, don't need to worry
       about RCS_reparsercsfile.  */
    assert (rcs != NULL);
    return rcs->expand;
}



/* Set keyword expansion mode to EXPAND.  For example "b" for binary.  */
void
RCS_setexpand (RCSNode *rcs, const char *expand)
{
    /* Since RCS_parsercsfile_i now reads expand, don't need to worry
       about RCS_reparsercsfile.  */
    assert (rcs != NULL);
    if (rcs->expand != NULL)
        free (rcs->expand);
    rcs->expand = xstrdup (expand);
}



/* RCS keywords, and a matching enum.  */
enum keyword
{
    KEYWORD_AUTHOR = 0,
    KEYWORD_DATE,
    KEYWORD_CVSHEADER,
    KEYWORD_HEADER,
    KEYWORD_ID,
    KEYWORD_LOCKER,
    KEYWORD_LOG,
    KEYWORD_NAME,
    KEYWORD_RCSFILE,
    KEYWORD_REVISION,
    KEYWORD_SOURCE,
    KEYWORD_STATE,
    KEYWORD_LOCALID
};
struct rcs_keyword
{
    const char *string;
    size_t len;
    enum keyword expandto;
    bool expandit;
};



static inline struct rcs_keyword *
new_keywords (void)
{
    struct rcs_keyword *new;
    new = xcalloc (KEYWORD_LOCALID + 2, sizeof (struct rcs_keyword));

#define KEYWORD_INIT(k, i, s) \
        k[i].string = s; \
        k[i].len = sizeof s - 1; \
        k[i].expandto = i; \
        k[i].expandit = true

    KEYWORD_INIT (new, KEYWORD_AUTHOR, "Author");
    KEYWORD_INIT (new, KEYWORD_DATE, "Date");
    KEYWORD_INIT (new, KEYWORD_CVSHEADER, "CVSHeader");
    KEYWORD_INIT (new, KEYWORD_HEADER, "Header");
    KEYWORD_INIT (new, KEYWORD_ID, "Id");
    KEYWORD_INIT (new, KEYWORD_LOCKER, "Locker");
    KEYWORD_INIT (new, KEYWORD_LOG, "Log");
    KEYWORD_INIT (new, KEYWORD_NAME, "Name");
    KEYWORD_INIT (new, KEYWORD_RCSFILE, "RCSfile");
    KEYWORD_INIT (new, KEYWORD_REVISION, "Revision");
    KEYWORD_INIT (new, KEYWORD_SOURCE, "Source");
    KEYWORD_INIT (new, KEYWORD_STATE, "State");

    return new;
}



void
free_keywords (void *keywords)
{
    free (keywords);
}



/* Convert an RCS date string into a readable string.  This is like
   the RCS date2str function.  */
static char *
printable_date (const char *rcs_date)
{
    int year, mon, mday, hour, min, sec;
    char buf[100];

    (void) sscanf (rcs_date, SDATEFORM, &year, &mon, &mday, &hour, &min,
                   &sec);
    if (year < 1900)
        year += 1900;
    sprintf (buf, "%04d/%02d/%02d %02d:%02d:%02d", year, mon, mday,
             hour, min, sec);
    return xstrdup (buf);
}



/* Escape the characters in a string so that it can be included in an
   RCS value.  */
static char *
escape_keyword_value (const char *value, int *free_value)
{
    char *ret, *t;
    const char *s;

    for (s = value; *s != '\0'; s++)
    {
        char c;

        c = *s;
        if (c == '\t'
            || c == '\n'
            || c == '\\'
            || c == ' '
            || c == '$')
        {
            break;
        }
    }

    if (*s == '\0')
    {
        *free_value = 0;
        return (char *) value;
    }

    ret = xmalloc (strlen (value) * 4 + 1);
    *free_value = 1;

    for (s = value, t = ret; *s != '\0'; s++, t++)
    {
        switch (*s)
        {
        default:
            *t = *s;
            break;
        case '\t':
            *t++ = '\\';
            *t = 't';
            break;
        case '\n':
            *t++ = '\\';
            *t = 'n';
            break;
        case '\\':
            *t++ = '\\';
            *t = '\\';
            break;
        case ' ':
            *t++ = '\\';
            *t++ = '0';
            *t++ = '4';
            *t = '0';
            break;
        case '$':
            *t++ = '\\';
            *t++ = '0';
            *t++ = '4';
            *t = '4';
            break;
        }
    }

    *t = '\0';

    return ret;
}



/* Expand RCS keywords in the memory buffer BUF of length LEN.  This
   applies to file RCS and version VERS.  If NAME is not NULL, and is
   not a numeric revision, then it is the symbolic tag used for the
   checkout.  EXPAND indicates how to expand the keywords.  This
   function sets *RETBUF and *RETLEN to the new buffer and length.
   This function may modify the buffer BUF.  If BUF != *RETBUF, then
   RETBUF is a newly allocated buffer.  */
static void
expand_keywords (RCSNode *rcs, RCSVers *ver, const char *name, const char *log,
                 size_t loglen, enum kflag expand, char *buf, size_t len,
                 char **retbuf, size_t *retlen)
{
    struct expand_buffer
    {
        struct expand_buffer *next;
        char *data;
        size_t len;
        int free_data;
    } *ebufs = NULL;
    struct expand_buffer *ebuf_last = NULL;
    size_t ebuf_len = 0;
    char *locker;
    char *srch, *srch_next;
    size_t srch_len;
    const struct rcs_keyword *keywords;

    if (!config /* For `cvs init', config may not be set.  */
        ||expand == KFLAG_O || expand == KFLAG_B)
    {
        *retbuf = buf;
        *retlen = len;
        return;
    }

    if (!config->keywords) config->keywords = new_keywords ();
    keywords = config->keywords;

    /* If we are using -kkvl, dig out the locker information if any.  */
    locker = NULL;
    if (expand == KFLAG_KVL)
    {
        Node *lock;
        lock = findnode (RCS_getlocks(rcs), ver->version);
        if (lock != NULL)
            locker = xstrdup (lock->data);
    }

    /* RCS keywords look like $STRING$ or $STRING: VALUE$.  */
    srch = buf;
    srch_len = len;
    while ((srch_next = memchr (srch, '$', srch_len)) != NULL)
    {
        char *s, *send;
        size_t slen;
        const struct rcs_keyword *keyword;
        char *value;
        int free_value;
        char *sub;
        size_t sublen;

        srch_len -= (srch_next + 1) - srch;
        srch = srch_next + 1;

        /* Look for the first non alphabetic character after the '$'.  */
        send = srch + srch_len;
        for (s = srch; s < send; s++)
            if (! isalpha ((unsigned char) *s))
                break;

        /* If the first non alphabetic character is not '$' or ':',
           then this is not an RCS keyword.  */
        if (s == send || (*s != '$' && *s != ':'))
            continue;

        /* See if this is one of the keywords.  */
        slen = s - srch;
        for (keyword = keywords; keyword->string != NULL; keyword++)
        {
            if (keyword->expandit
                && keyword->len == slen
                && strncmp (keyword->string, srch, slen) == 0)
            {
                break;
            }
        }
        if (keyword->string == NULL)
            continue;

        /* If the keyword ends with a ':', then the old value consists
           of the characters up to the next '$'.  If there is no '$'
           before the end of the line, though, then this wasn't an RCS
           keyword after all.  */
        if (*s == ':')
        {
            for (; s < send; s++)
                if (*s == '$' || *s == '\n')
                    break;
            if (s == send || *s != '$')
                continue;
        }

        /* At this point we must replace the string from SRCH to S
           with the expansion of the keyword KW.  */

        /* Get the value to use.  */
        free_value = 0;
        if (expand == KFLAG_K)
            value = NULL;
        else
        {
            switch (keyword->expandto)
            {
            default:
                assert (!"unreached");

            case KEYWORD_AUTHOR:
                value = ver->author;
                break;

            case KEYWORD_DATE:
                value = printable_date (ver->date);
                free_value = 1;
                break;

            case KEYWORD_CVSHEADER:
            case KEYWORD_HEADER:
            case KEYWORD_ID:
            case KEYWORD_LOCALID:
                {
                    const char *path;
                    int free_path;
                    char *date;
                    char *old_path;

                    old_path = NULL;
                    if (keyword->expandto == KEYWORD_HEADER)
                        path = rcs->print_path;
                    else if (keyword->expandto == KEYWORD_CVSHEADER)
                        path = getfullCVSname (rcs->print_path, &old_path);
                    else
                        path = last_component (rcs->print_path);
                    path = escape_keyword_value (path, &free_path);
                    date = printable_date (ver->date);
                    value = Xasprintf ("%s %s %s %s %s%s%s",
                                       path, ver->version, date, ver->author,
                                       ver->state,
                                       locker != NULL ? " " : "",
                                       locker != NULL ? locker : "");
                    if (free_path)
                        /* If free_path is set then we know we allocated path
                         * and we can discard the const.
                         */
                        free ((char *)path);
                    if (old_path)
                        free (old_path);
                    free (date);
                    free_value = 1;
                }
                break;

            case KEYWORD_LOCKER:
                value = locker;
                break;

            case KEYWORD_LOG:
            case KEYWORD_RCSFILE:
                value = escape_keyword_value (last_component (rcs->print_path),
                                              &free_value);
                break;

            case KEYWORD_NAME:
                if (name != NULL && ! isdigit ((unsigned char) *name))
                    value = (char *) name;
                else
                    value = NULL;
                break;

            case KEYWORD_REVISION:
                value = ver->version;
                break;

            case KEYWORD_SOURCE:
                value = escape_keyword_value (rcs->print_path, &free_value);
                break;

            case KEYWORD_STATE:
                value = ver->state;
                break;
            }
        }

        sub = xmalloc (keyword->len
                       + (value == NULL ? 0 : strlen (value))
                       + 10);
        if (expand == KFLAG_V)
        {
            /* Decrement SRCH and increment S to remove the $
               characters.  */
            --srch;
            ++srch_len;
            ++s;
            sublen = 0;
        }
        else
        {
            strcpy (sub, keyword->string);
            sublen = strlen (keyword->string);
            if (expand != KFLAG_K)
            {
                sub[sublen] = ':';
                sub[sublen + 1] = ' ';
                sublen += 2;
            }
        }
        if (value != NULL)
        {
            strcpy (sub + sublen, value);
            sublen += strlen (value);
        }
        if (expand != KFLAG_V && expand != KFLAG_K)
        {
            sub[sublen] = ' ';
            ++sublen;
            sub[sublen] = '\0';
        }

        if (free_value)
            free (value);

        /* The Log keyword requires special handling.  This behaviour
           is taken from RCS 5.7.  The special log message is what RCS
           uses for ci -k.  */
        if (keyword->expandto == KEYWORD_LOG
            && (sizeof "checked in with -k by " <= loglen
                || log == NULL
                || strncmp (log, "checked in with -k by ",
                            sizeof "checked in with -k by " - 1) != 0))
        {
            char *start;
            char *leader;
            size_t leader_len, leader_sp_len;
            const char *logend;
            const char *snl;
            int cnl;
            char *date;
            const char *sl;

            /* We are going to insert the trailing $ ourselves, before
               the log message, so we must remove it from S, if we
               haven't done so already.  */
            if (expand != KFLAG_V)
                ++s;

            /* CVS never has empty log messages, but old RCS files might.  */
            if (log == NULL)
                log = "";

            /* Find the start of the line.  */
            start = srch;
            leader_len = 0;
            while (start > buf && start[-1] != '\n'
                   && leader_len <= xsum (config->MaxCommentLeaderLength,
                                          expand != KFLAG_V ? 1 : 0))
            {
                --start;
                ++leader_len;
            }

            if (expand != KFLAG_V)
                /* When automagically determined and !KFLAG_V, we wish to avoid
                 * including the leading `$' of the Log keyword in our leader.
                 */
                --leader_len;

            /* If the automagically determined leader exceeds the limit set in
             * CVSROOT/config, try to use a fallback.
             */
            if (leader_len > config->MaxCommentLeaderLength)
            {
                if (config->UseArchiveCommentLeader && rcs->comment)
                {
                    leader = xstrdup (rcs->comment);
                    leader_len = strlen (rcs->comment);
                }
                else
                {
                    error (0, 0,
"Skipping `$" "Log$' keyword due to excessive comment leader.");
                    continue;
                }
            }
            else /* leader_len <= config->MaxCommentLeaderLength */
            {
                /* Copy the start of the line to use as a comment leader.  */
                leader = xmalloc (leader_len);
                memcpy (leader, start, leader_len);
            }

            leader_sp_len = leader_len;
            while (leader_sp_len > 0 && isspace (leader[leader_sp_len - 1]))
                --leader_sp_len;

            /* RCS does some checking for an old style of Log here,
               but we don't bother.  RCS issues a warning if it
               changes anything.  */

            /* Count the number of newlines in the log message so that
               we know how many copies of the leader we will need.  */
            cnl = 0;
            logend = log + loglen;
            for (snl = log; snl < logend; snl++)
                if (*snl == '\n')
                    ++cnl;

            /* If the log message did not end in a newline, increment
             * the newline count so we have space for the extra leader.
             * Failure to do so results in a buffer overrun.
             */
            if (loglen && snl[-1] != '\n')
                ++cnl;

            date = printable_date (ver->date);
            sub = xrealloc (sub,
                            (sublen
                             + sizeof "Revision"
                             + strlen (ver->version)
                             + strlen (date)
                             + strlen (ver->author)
                             + loglen
                               /* Use CNL + 2 below:  One leader for each log
                                * line, plus the Revision/Author/Date line,
                                * plus a trailing blank line.
                                */
                             + (cnl + 2) * leader_len
                             + 20));
            if (expand != KFLAG_V)
            {
                sub[sublen] = '$';
                ++sublen;
            }
            sub[sublen] = '\n';
            ++sublen;
            memcpy (sub + sublen, leader, leader_len);
            sublen += leader_len;
            sprintf (sub + sublen, "Revision %s  %s  %s\n",
                     ver->version, date, ver->author);
            sublen += strlen (sub + sublen);
            free (date);

            sl = log;
            while (sl < logend)
            {
                if (*sl == '\n')
                {
                    memcpy (sub + sublen, leader, leader_sp_len);
                    sublen += leader_sp_len;
                    sub[sublen] = '\n';
                    ++sublen;
                    ++sl;
                }
                else
                {
                    const char *slnl;

                    memcpy (sub + sublen, leader, leader_len);
                    sublen += leader_len;
                    for (slnl = sl; slnl < logend && *slnl != '\n'; ++slnl)
                        ;
                    if (slnl < logend)
                        ++slnl;
                    memcpy (sub + sublen, sl, slnl - sl);
                    sublen += slnl - sl;
                    if (slnl == logend && slnl[-1] != '\n')
                    {
                        /* There was no EOL at the end of the log message.  Add
                         * one.
                         */
                        sub[sublen] = '\n';
                        ++sublen;
                    }
                    sl = slnl;
                }
            }

            memcpy (sub + sublen, leader, leader_sp_len);
            sublen += leader_sp_len;

            free (leader);
        }

        /* Now SUB contains a string which is to replace the string
           from SRCH to S.  SUBLEN is the length of SUB.  */

        if (srch + sublen == s)
        {
            memcpy (srch, sub, sublen);
            free (sub);
        }
        else
        {
            struct expand_buffer *ebuf;

            /* We need to change the size of the buffer.  We build a
               list of expand_buffer structures.  Each expand_buffer
               structure represents a portion of the final output.  We
               concatenate them back into a single buffer when we are
               done.  This minimizes the number of potentially large
               buffer copies we must do.  */

            if (ebufs == NULL)
            {
                ebufs = xmalloc (sizeof *ebuf);
                ebufs->next = NULL;
                ebufs->data = buf;
                ebufs->free_data = 0;
                ebuf_len = srch - buf;
                ebufs->len = ebuf_len;
                ebuf_last = ebufs;
            }
            else
            {
                assert (srch >= ebuf_last->data);
                assert (srch <= ebuf_last->data + ebuf_last->len);
                ebuf_len -= ebuf_last->len - (srch - ebuf_last->data);
                ebuf_last->len = srch - ebuf_last->data;
            }

            ebuf = xmalloc (sizeof *ebuf);
            ebuf->data = sub;
            ebuf->len = sublen;
            ebuf->free_data = 1;
            ebuf->next = NULL;
            ebuf_last->next = ebuf;
            ebuf_last = ebuf;
            ebuf_len += sublen;

            ebuf = xmalloc (sizeof *ebuf);
            ebuf->data = s;
            ebuf->len = srch_len - (s - srch);
            ebuf->free_data = 0;
            ebuf->next = NULL;
            ebuf_last->next = ebuf;
            ebuf_last = ebuf;
            ebuf_len += srch_len - (s - srch);
        }

        srch_len -= (s - srch);
        srch = s;
    }

    if (locker != NULL)
        free (locker);

    if (ebufs == NULL)
    {
        *retbuf = buf;
        *retlen = len;
    }
    else
    {
        char *ret;

        ret = xmalloc (ebuf_len);
        *retbuf = ret;
        *retlen = ebuf_len;
        while (ebufs != NULL)
        {
            struct expand_buffer *next;

            memcpy (ret, ebufs->data, ebufs->len);
            ret += ebufs->len;
            if (ebufs->free_data)
                free (ebufs->data);
            next = ebufs->next;
            free (ebufs);
            ebufs = next;
        }
    }
}



/* Check out a revision from an RCS file.

   If PFN is not NULL, then ignore WORKFILE and SOUT.  Call PFN zero
   or more times with the contents of the file.  CALLERDAT is passed,
   uninterpreted, to PFN.  (The current code will always call PFN
   exactly once for a non empty file; however, the current code
   assumes that it can hold the entire file contents in memory, which
   is not a good assumption, and might change in the future).

   Otherwise, if WORKFILE is not NULL, check out the revision to
   WORKFILE.  However, if WORKFILE is not NULL, and noexec is set,
   then don't do anything.

   Otherwise, if WORKFILE is NULL, check out the revision to SOUT.  If
   SOUT is RUN_TTY, then write the contents of the revision to
   standard output.  When using SOUT, the output is generally a
   temporary file; don't bother to get the file modes correct.  When
   NOEXEC is set, WORKFILEs are not written but SOUTs are.

   REV is the numeric revision to check out.  It may be NULL, which
   means to check out the head of the default branch.

   If NAMETAG is not NULL, and is not a numeric revision, then it is
   the tag that should be used when expanding the RCS Name keyword.

   OPTIONS is a string such as "-kb" or "-kv" for keyword expansion
   options.  It may be NULL to use the default expansion mode of the
   file, typically "-kkv".

   On an error which prevented checking out the file, either print a
   nonfatal error and return 1, or give a fatal error.  On success,
   return 0.  */

/* This function mimics the behavior of `rcs co' almost exactly.  The
   chief difference is in its support for preserving file ownership,
   permissions, and special files across checkin and checkout -- see
   comments in RCS_checkin for some issues about this. -twp */
int
RCS_checkout (RCSNode *rcs, const char *workfile, const char *rev,
              const char *nametag, const char *options, const char *sout,
              RCSCHECKOUTPROC pfn, void *callerdat)
{
    int free_rev = 0;
    enum kflag expand;
    FILE *fp,
         *ofp = NULL; /* Initialize since -Wall doesn't understand that
                       * error (1, ...) does not return.
                       */
    struct stat sb;
    struct rcsbuffer rcsbuf;
    char *key;
    char *value;
    size_t len;
    int free_value = 0;
    char *log = NULL;
    size_t loglen = 0;
    Node *vp = NULL;
#ifdef PRESERVE_PERMISSIONS_SUPPORT
    uid_t rcs_owner = (uid_t) -1;
    gid_t rcs_group = (gid_t) -1;
    mode_t rcs_mode;
    int change_rcs_owner_or_group = 0;
    int change_rcs_mode = 0;
    int special_file = 0;
    unsigned long devnum_long;
    dev_t devnum = 0;
#endif

    TRACE (TRACE_FUNCTION, "RCS_checkout (%s, %s, %s, %s, %s)",
           rcs->path,
           rev != NULL ? rev : "",
           nametag != NULL ? nametag : "",
           options != NULL ? options : "",
           (pfn != NULL ? "(function)"
            : (workfile != NULL ? workfile
               : (sout != RUN_TTY ? sout
                  : "(stdout)"))));

    assert (rev == NULL || isdigit ((unsigned char) *rev));

    if (noexec && !server_active && workfile != NULL)
        return 0;

    assert (sout == RUN_TTY || workfile == NULL);
    assert (pfn == NULL || (sout == RUN_TTY && workfile == NULL));

    /* Some callers, such as Checkin or remove_file, will pass us a
       branch.  */
    if (rev != NULL && (numdots (rev) & 1) == 0)
    {
        rev = RCS_getbranch (rcs, rev, 1);
        if (rev == NULL)
            error (1, 0, "internal error: bad branch tag in checkout");
        free_rev = 1;
    }

    if (rev == NULL || STREQ (rev, rcs->head))
    {
        int gothead;

        /* We want the head revision.  Try to read it directly.  */

        if (rcs->flags & PARTIAL)
            RCS_reparsercsfile (rcs, &fp, &rcsbuf);
        else
            rcsbuf_cache_open (rcs, rcs->delta_pos, &fp, &rcsbuf);

        gothead = 0;
        if (! rcsbuf_getrevnum (&rcsbuf, &key))
            error (1, 0, "unexpected EOF reading %s", rcs->print_path);
        while (rcsbuf_getkey (&rcsbuf, &key, &value))
        {
            if (STREQ (key, "log"))
            {
                if (log)
                {
                    error (0, 0,
"Duplicate log keyword found for head revision in RCS file.");
                    free (log);
                }
                log = rcsbuf_valcopy (&rcsbuf, value, 0, &loglen);
            }
            else if (STREQ (key, "text"))
            {
                gothead = 1;
                break;
            }
        }

        if (! gothead)
        {
            error (0, 0, "internal error: cannot find head text");
            if (free_rev)
                /* It's okay to discard the const when free_rev is set, because
                 * we know we allocated it in this function.
                 */
                free ((char *)rev);
            return 1;
        }

        rcsbuf_valpolish (&rcsbuf, value, 0, &len);

        if (fstat (fileno (fp), &sb) < 0)
            error (1, errno, "cannot fstat %s", rcs->path);

        rcsbuf_cache (rcs, &rcsbuf);
    }
    else
    {
        struct rcsbuffer *rcsbufp;

        /* It isn't the head revision of the trunk.  We'll need to
           walk through the deltas.  */

        fp = NULL;
        if (rcs->flags & PARTIAL)
            RCS_reparsercsfile (rcs, &fp, &rcsbuf);

        if (fp == NULL)
        {
            /* If RCS_deltas didn't close the file, we could use fstat
               here too.  Probably should change it thusly....  */
            if (stat (rcs->path, &sb) < 0)
                error (1, errno, "cannot stat %s", rcs->path);
            rcsbufp = NULL;
        }
        else
        {
            if (fstat (fileno (fp), &sb) < 0)
                error (1, errno, "cannot fstat %s", rcs->path);
            rcsbufp = &rcsbuf;
        }

        RCS_deltas (rcs, fp, rcsbufp, rev, RCS_FETCH, &value, &len,
                    &log, &loglen);
        free_value = 1;
    }

    /* If OPTIONS is NULL or the empty string, then the old code would
       invoke the RCS co program with no -k option, which means that
       co would use the string we have stored in rcs->expand.  */
    if ((options == NULL || options[0] == '\0') && rcs->expand == NULL)
        expand = KFLAG_KV;
    else
    {
        const char *ouroptions;
        const char * const *cpp;

        if (options != NULL && options[0] != '\0')
        {
            assert (options[0] == '-' && options[1] == 'k');
            ouroptions = options + 2;
        }
        else
            ouroptions = rcs->expand;

        for (cpp = kflags; *cpp != NULL; cpp++)
            if (STREQ (*cpp, ouroptions))
                break;

        if (*cpp != NULL)
            expand = (enum kflag) (cpp - kflags);
        else
        {
            error (0, 0,
                   "internal error: unsupported substitution string -k%s",
                   ouroptions);
            expand = KFLAG_KV;
        }
    }

#ifdef PRESERVE_PERMISSIONS_SUPPORT
    /* Handle special files and permissions, if that is desired. */
    if (preserve_perms)
    {
        RCSVers *vers;
        Node *info;

        vp = findnode (rcs->versions, rev == NULL ? rcs->head : rev);
        if (vp == NULL)
            error (1, 0, "internal error: no revision information for %s",
                   rev == NULL ? rcs->head : rev);
        vers = vp->data;

        /* First we look for symlinks, which are simplest to handle. */
        info = findnode (vers->other_delta, "symlink");
        if (info != NULL)
        {
            char *dest;

            if (pfn != NULL || (workfile == NULL && sout == RUN_TTY))
                error (1, 0, "symbolic link %s:%s cannot be piped",
                       rcs->path, vers->version);
            if (workfile == NULL)
                dest = sout;
            else
                dest = workfile;

            /* Remove `dest', just in case.  It's okay to get ENOENT here,
               since we just want the file not to be there.  (TODO: decide
               whether it should be considered an error for `dest' to exist
               at this point.  If so, the unlink call should be removed and
               `symlink' should signal the error. -twp) */
            if (CVS_UNLINK (dest) < 0 && !existence_error (errno))
                error (1, errno, "cannot remove %s", dest);
            if (symlink (info->data, dest) < 0)
                error (1, errno, "cannot create symbolic link from %s to %s",
                       dest, (char *)info->data);
            if (free_value)
                free (value);
            if (free_rev)
                /* It's okay to discard the const when free_rev is set, because
                 * we know we allocated it in this function.
                 */
                free ((char *)rev);
            return 0;
        }

        /* Next, we look at this file's hardlinks field, and see whether
           it is linked to any other file that has been checked out.
           If so, we don't do anything else -- just link it to that file.

           If we are checking out a file to a pipe or temporary storage,
           none of this should matter.  Hence the `workfile != NULL'
           wrapper around the whole thing. -twp */

        if (workfile != NULL)
        {
            List *links = vers->hardlinks;
            if (links != NULL)
            {
                Node *uptodate_link;

                /* For each file in the hardlinks field, check to see
                   if it exists, and if so, if it has been checked out
                   this iteration.  When walklist returns, uptodate_link
                   should point to a hardlist node representing a file
                   in `links' which has recently been checked out, or
                   NULL if no file in `links' has yet been checked out. */

                uptodate_link = NULL;
                (void) walklist (links, find_checkedout_proc, &uptodate_link);
                dellist (&links);

                /* If we've found a file that `workfile' is supposed to be
                   linked to, and it has been checked out since CVS was
                   invoked, then simply link workfile to that file and return.

                   If one of these conditions is not met, then
                   workfile is the first one in its hardlink group to
                   be checked out, and we must continue with a full
                   checkout. */

                if (uptodate_link != NULL)
                {
                    struct hardlink_info *hlinfo = uptodate_link->data;

                    if (link (uptodate_link->key, workfile) < 0)
                        error (1, errno, "cannot link %s to %s",
                               workfile, uptodate_link->key);
                    hlinfo->checked_out = 1;    /* probably unnecessary */
                    if (free_value)
                        free (value);
                    if (free_rev)
                        /* It's okay to discard the const when free_rev is set,
                         * because we know we allocated it in this function.
                         */
                        free ((char *)rev);
                    return 0;
                }
            }
        }

        info = findnode (vers->other_delta, "owner");
        if (info != NULL)
        {
            change_rcs_owner_or_group = 1;
            rcs_owner = (uid_t) strtoul (info->data, NULL, 10);
        }
        info = findnode (vers->other_delta, "group");
        if (info != NULL)
        {
            change_rcs_owner_or_group = 1;
            rcs_group = (gid_t) strtoul (info->data, NULL, 10);
        }
        info = findnode (vers->other_delta, "permissions");
        if (info != NULL)
        {
            change_rcs_mode = 1;
            rcs_mode = (mode_t) strtoul (info->data, NULL, 8);
        }
        info = findnode (vers->other_delta, "special");
        if (info != NULL)
        {
            /* If the size of `devtype' changes, fix the sscanf call also */
            char devtype[16];

            if (sscanf (info->data, "%15s %lu",
                        devtype, &devnum_long) < 2)
                error (1, 0, "%s:%s has bad `special' newphrase %s",
                       workfile, vers->version, (char *)info->data);
            devnum = devnum_long;
            if (STREQ (devtype, "character"))
                special_file = S_IFCHR;
            else if (STREQ (devtype, "block"))
                special_file = S_IFBLK;
            else
                error (0, 0, "%s is a special file of unsupported type `%s'",
                       workfile, (char *)info->data);
        }
    }
#endif /* PRESERVE_PERMISSIONS_SUPPORT */

    if (expand != KFLAG_O && expand != KFLAG_B)
    {
        char *newvalue;

        /* Don't fetch the delta node again if we already have it. */
        if (vp == NULL)
        {
            vp = findnode (rcs->versions, rev == NULL ? rcs->head : rev);
            if (vp == NULL)
                error (1, 0, "internal error: no revision information for %s",
                       rev == NULL ? rcs->head : rev);
        }

        expand_keywords (rcs, vp->data, nametag, log, loglen,
                         expand, value, len, &newvalue, &len);

        if (newvalue != value)
        {
            if (free_value)
                free (value);
            value = newvalue;
            free_value = 1;
        }
    }

    if (free_rev)
        /* It's okay to discard the const when free_rev is set, because
         * we know we allocated it in this function.
         */
        free ((char *)rev);

    if (log != NULL)
    {
        free (log);
        log = NULL;
    }

    if (pfn != NULL)
    {
#ifdef PRESERVE_PERMISSIONS_SUPPORT
        if (special_file)
            error (1, 0, "special file %s cannot be piped to anything",
                   rcs->path);
#endif
        /* The PFN interface is very simple to implement right now, as
           we always have the entire file in memory.  */
        if (len != 0)
            pfn (callerdat, value, len);
    }
#ifdef PRESERVE_PERMISSIONS_SUPPORT
    else if (special_file)
    {
# ifdef HAVE_MKNOD
        char *dest;

        /* Can send either to WORKFILE or to SOUT, as long as SOUT is
           not RUN_TTY. */
        dest = workfile;
        if (dest == NULL)
        {
            if (sout == RUN_TTY)
                error (1, 0, "special file %s cannot be written to stdout",
                       rcs->path);
            dest = sout;
        }

        /* Unlink `dest', just in case.  It's okay if this provokes a
           ENOENT error. */
        if (CVS_UNLINK (dest) < 0 && existence_error (errno))
            error (1, errno, "cannot remove %s", dest);
        if (mknod (dest, special_file, devnum) < 0)
            error (1, errno, "could not create special file %s",
                   dest);
# else
        error (1, 0,
"cannot create %s: unable to create special files on this system",
workfile);
# endif
    }
#endif
    else
    {
        /* Not a special file: write to WORKFILE or SOUT. */
        if (workfile == NULL)
        {
            if (sout == RUN_TTY)
                ofp = stdout;
            else
            {
                /* Symbolic links should be removed before replacement, so that
                   `fopen' doesn't follow the link and open the wrong file. */
                if (islink (sout))
                    if (unlink_file (sout) < 0)
                        error (1, errno, "cannot remove %s", sout);
                ofp = CVS_FOPEN (sout, expand == KFLAG_B ? "wb" : "w");
                if (ofp == NULL)
                    error (1, errno, "cannot open %s", sout);
            }
        }
        else
        {
            /* Output is supposed to go to WORKFILE, so we should open that
               file.  Symbolic links should be removed first (see above). */
            if (islink (workfile))
                if (unlink_file (workfile) < 0)
                    error (1, errno, "cannot remove %s", workfile);

            ofp = CVS_FOPEN (workfile, expand == KFLAG_B ? "wb" : "w");

            /* If the open failed because the existing workfile was not
               writable, try to chmod the file and retry the open.  */
            if (ofp == NULL && errno == EACCES
                && isfile (workfile) && !iswritable (workfile))
            {
                xchmod (workfile, 1);
                ofp = CVS_FOPEN (workfile, expand == KFLAG_B ? "wb" : "w");
            }

            if (ofp == NULL)
            {
                error (0, errno, "cannot open %s", workfile);
                if (free_value)
                    free (value);
                return 1;
            }
        }

        if (workfile == NULL && sout == RUN_TTY)
        {
            if (expand == KFLAG_B)
                cvs_output_binary (value, len);
            else
            {
                /* cvs_output requires the caller to check for zero
                   length.  */
                if (len > 0)
                    cvs_output (value, len);
            }
        }
        else
        {
            /* NT 4.0 is said to have trouble writing 2099999 bytes
               (for example) in a single fwrite.  So break it down
               (there is no need to be writing that much at once
               anyway; it is possible that LARGEST_FWRITE should be
               somewhat larger for good performance, but for testing I
               want to start with a small value until/unless a bigger
               one proves useful).  */
#define LARGEST_FWRITE 8192
            size_t nleft = len;
            size_t nstep = (len < LARGEST_FWRITE ? len : LARGEST_FWRITE);
            char *p = value;

            while (nleft > 0)
            {
                if (fwrite (p, 1, nstep, ofp) != nstep)
                {
                    error (0, errno, "cannot write %s",
                           (workfile != NULL
                            ? workfile
                            : (sout != RUN_TTY ? sout : "stdout")));
                    if (free_value)
                        free (value);
                    return 1;
                }
                p += nstep;
                nleft -= nstep;
                if (nleft < nstep)
                    nstep = nleft;
            }
        }
    }

    if (free_value)
        free (value);

    if (workfile != NULL)
    {
        int ret;

#ifdef PRESERVE_PERMISSIONS_SUPPORT
        if (!special_file && fclose (ofp) < 0)
        {
            error (0, errno, "cannot close %s", workfile);
            return 1;
        }

        if (change_rcs_owner_or_group)
        {
            if (chown (workfile, rcs_owner, rcs_group) < 0)
                error (0, errno, "could not change owner or group of %s",
                       workfile);
        }

        ret = chmod (workfile,
                     change_rcs_mode
                     ? rcs_mode
                     : sb.st_mode & ~(S_IWRITE | S_IWGRP | S_IWOTH));
#else
        if (fclose (ofp) < 0)
        {
            error (0, errno, "cannot close %s", workfile);
            return 1;
        }

        ret = chmod (workfile,
                     sb.st_mode & ~(S_IWRITE | S_IWGRP | S_IWOTH));
#endif
        if (ret < 0)
        {
            error (0, errno, "cannot change mode of file %s",
                   workfile);
        }
    }
    else if (sout != RUN_TTY)
    {
        if (
#ifdef PRESERVE_PERMISSIONS_SUPPORT
            !special_file &&
#endif
            fclose (ofp) < 0)
        {
            error (0, errno, "cannot close %s", sout);
            return 1;
        }
    }

#ifdef PRESERVE_PERMISSIONS_SUPPORT
    /* If we are in the business of preserving hardlinks, then
       mark this file as having been checked out. */
    if (preserve_perms && workfile != NULL)
        update_hardlink_info (workfile);
#endif

    return 0;
}



/* Find the delta currently locked by the user.  From the `ci' man page:

        "If rev is omitted, ci tries to  derive  the  new  revision
         number  from  the  caller's  last lock.  If the caller has
         locked the tip revision of a branch, the new  revision  is
         appended  to  that  branch.   The  new  revision number is
         obtained by incrementing the tip revision number.  If  the
         caller  locked a non-tip revision, a new branch is started
         at that revision by incrementing the highest branch number
         at  that  revision.   The default initial branch and level
         numbers are 1.

         If rev is omitted and the caller has no lock, but owns the
         file  and  locking is not set to strict, then the revision
         is appended to the default branch (normally the trunk; see
         the -b option of rcs(1))."

   RCS_findlock_or_tip finds the unique revision locked by the caller
   and returns its delta node.  If the caller has not locked any
   revisions (and is permitted to commit to an unlocked delta, as
   described above), return the tip of the default branch. */
static RCSVers *
RCS_findlock_or_tip (RCSNode *rcs)
{
    char *user = getcaller();
    Node *lock, *p;
    List *locklist;

    /* Find unique delta locked by caller. This code is very similar
       to the code in RCS_unlock -- perhaps it could be abstracted
       into a RCS_findlock function. */
    locklist = RCS_getlocks (rcs);
    lock = NULL;
    for (p = locklist->list->next; p != locklist->list; p = p->next)
    {
        if (STREQ (p->data, user))
        {
            if (lock != NULL)
            {
                error (0, 0, "\
%s: multiple revisions locked by %s; please specify one", rcs->print_path, user);
                return NULL;
            }
            lock = p;
        }
    }

    if (lock != NULL)
    {
        /* Found an old lock, but check that the revision still exists. */
        p = findnode (rcs->versions, lock->key);
        if (p == NULL)
        {
            error (0, 0, "%s: can't unlock nonexistent revision %s",
                   rcs->print_path,
                   lock->key);
            return NULL;
        }
        return p->data;
    }

    /* No existing lock.  The RCS rule is that this is an error unless
       locking is nonstrict AND the file is owned by the current
       user.  Trying to determine the latter is a portability nightmare
       in the face of NT, VMS, AFS, and other systems with non-unix-like
       ideas of users and owners.  In the case of CVS, we should never get
       here (as long as the traditional behavior of making sure to call
       RCS_lock persists).  Anyway, we skip the RCS error checks
       and just return the default branch or head.  The reasoning is that
       those error checks are to make users lock before a checkin, and we do
       that in other ways if at all anyway (e.g. rcslock.pl).  */

    p = findnode (rcs->versions, RCS_getbranch (rcs, rcs->branch, 0));
    if (!p)
    {
        error (0, 0, "RCS file `%s' does not contain its default revision.",
               rcs->path);
        return NULL;
    }

    return p->data;
}



/* Revision number string, R, must contain a `.'.
   Return a newly-malloc'd copy of the prefix of R up
   to but not including the final `.'.  */
static char *
truncate_revnum (const char *r)
{
    size_t len;
    char *new_r;
    char *dot = strrchr (r, '.');

    assert (dot);
    len = dot - r;
    new_r = xmalloc (len + 1);
    memcpy (new_r, r, len);
    *(new_r + len) = '\0';
    return new_r;
}



/* Revision number string, R, must contain a `.'.
   R must be writable.  Replace the rightmost `.' in R with
   the NUL byte and return a pointer to that NUL byte.  */
static char *
truncate_revnum_in_place (char *r)
{
    char *dot = strrchr (r, '.');
    assert (dot);
    *dot = '\0';
    return dot;
}



/* Revision number strings, R and S, must each contain a `.'.
   R and S must be writable and must have the same number of dots.
   Truncate R and S for the comparison, then restored them to their
   original state.
   Return the result (see compare_revnums) of comparing R and S
   ignoring differences in any component after the rightmost `.'.  */
static int
compare_truncated_revnums (char *r, char *s)
{
    char *r_dot = truncate_revnum_in_place (r);
    char *s_dot = truncate_revnum_in_place (s);
    int cmp;

    assert (numdots (r) == numdots (s));

    cmp = compare_revnums (r, s);

    *r_dot = '.';
    *s_dot = '.';

    return cmp;
}



/* Return a malloc'd copy of the string representing the highest branch
   number on BRANCHNODE.  If there are no branches on BRANCHNODE, return NULL.
   FIXME: isn't the max rev always the last one?
   If so, we don't even need a loop.  */
static char *
max_rev (const RCSVers *branchnode)
{
    Node *head;
    Node *bp;
    char *max;

    if (branchnode->branches == NULL)
    {
        return NULL;
    }

    max = NULL;
    head = branchnode->branches->list;
    for (bp = head->next; bp != head; bp = bp->next)
    {
        if (max == NULL || compare_truncated_revnums (max, bp->key) < 0)
        {
            max = bp->key;
        }
    }
    assert (max);

    return truncate_revnum (max);
}



/* Create BRANCH in RCS's delta tree.  BRANCH may be either a branch
   number or a revision number.  In the former case, create the branch
   with the specified number; in the latter case, create a new branch
   rooted at node BRANCH with a higher branch number than any others.
   Return the number of the tip node on the new branch. */
static char *
RCS_addbranch (RCSNode *rcs, const char *branch)
{
    char *branchpoint, *newrevnum;
    Node *nodep, *bp;
    Node *marker;
    RCSVers *branchnode;

    assert (branch);

    /* Append to end by default.  */
    marker = NULL;

    branchpoint = xstrdup (branch);
    if ((numdots (branchpoint) & 1) == 0)
    {
        truncate_revnum_in_place (branchpoint);
    }

    /* Find the branch rooted at BRANCHPOINT. */
    nodep = findnode (rcs->versions, branchpoint);
    if (nodep == NULL)
    {
        error (0, 0, "%s: can't find branch point %s", rcs->print_path, branchpoint);
        free (branchpoint);
        return NULL;
    }
    free (branchpoint);
    branchnode = nodep->data;

    /* If BRANCH was a full branch number, make sure it is higher than MAX. */
    if ((numdots (branch) & 1) == 1)
    {
        if (branchnode->branches == NULL)
        {
            /* We have to create the first branch on this node, which means
               appending ".2" to the revision number. */
            newrevnum = Xasprintf ("%s.2", branch);
        }
        else
        {
            char *max = max_rev (branchnode);
            assert (max);
            newrevnum = increment_revnum (max);
            free (max);
        }
    }
    else
    {
        newrevnum = xstrdup (branch);

        if (branchnode->branches != NULL)
        {
            Node *head;
            Node *bp;

            /* Find the position of this new branch in the sorted list
               of branches.  */
            head = branchnode->branches->list;
            for (bp = head->next; bp != head; bp = bp->next)
            {
                char *dot;
                int found_pos;

                /* The existing list must be sorted on increasing revnum.  */
                assert (bp->next == head
                        || compare_truncated_revnums (bp->key,
                                                      bp->next->key) < 0);
                dot = truncate_revnum_in_place (bp->key);
                found_pos = (compare_revnums (branch, bp->key) < 0);
                *dot = '.';

                if (found_pos)
                {
                    break;
                }
            }
            marker = bp;
        }
    }

    newrevnum = xrealloc (newrevnum, strlen (newrevnum) + 3);
    strcat (newrevnum, ".1");

    /* Add this new revision number to BRANCHPOINT's branches list. */
    if (branchnode->branches == NULL)
        branchnode->branches = getlist();
    bp = getnode();
    bp->key = xstrdup (newrevnum);

    /* Append to the end of the list by default, that is, just before
       the header node, `list'.  */
    if (marker == NULL)
        marker = branchnode->branches->list;

    {
        int fail;
        fail = insert_before (branchnode->branches, marker, bp);
        assert (!fail);
    }

    return newrevnum;
}



/* Check in to RCSFILE with revision REV (which must be greater than
   the largest revision) and message MESSAGE (which is checked for
   validity).  If FLAGS & RCS_FLAGS_DEAD, check in a dead revision.
   If FLAGS & RCS_FLAGS_QUIET, tell ci to be quiet.  If FLAGS &
   RCS_FLAGS_MODTIME, use the working file's modification time for the
   checkin time.  WORKFILE is the working file to check in from, or
   NULL to use the usual RCS rules for deriving it from the RCSFILE.
   If FLAGS & RCS_FLAGS_KEEPFILE, don't unlink the working file;
   unlinking the working file is standard RCS behavior, but is rarely
   appropriate for CVS.

   UPDATE_DIR is used to print the path for the file.  This argument is
   unnecessary when FLAGS & RCS_FLAGS_QUIET since the path won't be printed
   anyhow.

   This function should almost exactly mimic the behavior of `rcs ci'.  The
   principal point of difference is the support here for preserving file
   ownership and permissions in the delta nodes.  This is not a clean
   solution -- precisely because it diverges from RCS's behavior -- but
   it doesn't seem feasible to do this anywhere else in the code. [-twp]
   
   Return value is -1 for error (and errno is set to indicate the
   error), positive for error (and an error message has been printed),
   or zero for success.  */
int
RCS_checkin (RCSNode *rcs, const char *update_dir, const char *workfile_in,
             const char *message, const char *rev, time_t citime, int flags)
{
    RCSVers *delta, *commitpt;
    Deltatext *dtext;
    Node *nodep;
    char *tmpfile, *changefile;
    int dargc = 0;
    size_t darg_allocated = 0;
    char **dargv = NULL;
    size_t bufsize;
    int status, checkin_quiet;
    struct tm *ftm;
    time_t modtime;
    int adding_branch = 0;
    char *workfile = xstrdup (workfile_in);
#ifdef PRESERVE_PERMISSIONS_SUPPORT
    struct stat sb;
#endif
    Node *np;

    commitpt = NULL;

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* Get basename of working file.  Is there a library function to
       do this?  I couldn't find one. -twp */
    if (workfile == NULL)
    {
        char *p;
        int extlen = strlen (RCSEXT);
        assert (rcs->path);
        workfile = xstrdup (last_component (rcs->path));
        p = workfile + (strlen (workfile) - extlen);
        assert (strncmp (p, RCSEXT, extlen) == 0);
        *p = '\0';
    }

    /* If the filename is a symbolic link, follow it and replace it
       with the destination of the link.  We need to do this before
       calling rcs_internal_lockfile, or else we won't put the lock in
       the right place. */
    resolve_symlink (&(rcs->path));

    checkin_quiet = flags & RCS_FLAGS_QUIET;
    if (!(checkin_quiet || really_quiet))
    {
        cvs_output (rcs->path, 0);
        cvs_output ("  <--  ", 7);
        if (update_dir && strlen (update_dir))
        {
            cvs_output (update_dir, 0);
            cvs_output ("/", 1);
        }
        cvs_output (workfile, 0);
        cvs_output ("\n", 1);
    }

    /* Create new delta node. */
    delta = xmalloc (sizeof (RCSVers));
    memset (delta, 0, sizeof (RCSVers));
    delta->author = xstrdup (getcaller ());
    if (flags & RCS_FLAGS_MODTIME)
    {
        struct stat ws;
        if (stat (workfile, &ws) < 0)
        {
            error (1, errno, "cannot stat %s", workfile);
        }
        modtime = ws.st_mtime;
    }
    else if (flags & RCS_FLAGS_USETIME)
        modtime = citime;
    else
        (void) time (&modtime);
    ftm = gmtime (&modtime);
    delta->date = Xasprintf (DATEFORM,
                             ftm->tm_year + (ftm->tm_year < 100 ? 0 : 1900),
                             ftm->tm_mon + 1, ftm->tm_mday, ftm->tm_hour,
                             ftm->tm_min, ftm->tm_sec);
    if (flags & RCS_FLAGS_DEAD)
    {
        delta->state = xstrdup (RCSDEAD);
        delta->dead = 1;
    }
    else
        delta->state = xstrdup ("Exp");

    delta->other_delta = getlist();

    /* save the commit ID */
    np = getnode();
    np->type = RCSFIELD;
    np->key = xstrdup ("commitid");
    np->data = xstrdup(global_session_id);
    addnode (delta->other_delta, np);


#ifdef PRESERVE_PERMISSIONS_SUPPORT
    /* If permissions should be preserved on this project, then
       save the permission info. */
    if (preserve_perms)
    {
        Node *np;
        char buf[64];   /* static buffer should be safe: see usage. -twp */

        delta->other_delta = getlist();

        if (lstat (workfile, &sb) < 0)
            error (1, errno, "cannot lstat %s", workfile);

        if (S_ISLNK (sb.st_mode))
        {
            np = getnode();
            np->type = RCSFIELD;
            np->key = xstrdup ("symlink");
            np->data = Xreadlink (workfile, sb.st_size);
            addnode (delta->other_delta, np);
        }
        else
        {
            (void) sprintf (buf, "%u", sb.st_uid);
            np = getnode();
            np->type = RCSFIELD;
            np->key = xstrdup ("owner");
            np->data = xstrdup (buf);
            addnode (delta->other_delta, np);

            (void) sprintf (buf, "%u", sb.st_gid);
            np = getnode();
            np->type = RCSFIELD;
            np->key = xstrdup ("group");
            np->data = xstrdup (buf);
            addnode (delta->other_delta, np);
            
            (void) sprintf (buf, "%o", sb.st_mode & 07777);
            np = getnode();
            np->type = RCSFIELD;
            np->key = xstrdup ("permissions");
            np->data = xstrdup (buf);
            addnode (delta->other_delta, np);

            /* Save device number. */
            switch (sb.st_mode & S_IFMT)
            {
                case S_IFREG: break;
                case S_IFCHR:
                case S_IFBLK:
# ifdef HAVE_STRUCT_STAT_ST_RDEV
                    np = getnode();
                    np->type = RCSFIELD;
                    np->key = xstrdup ("special");
                    sprintf (buf, "%s %lu",
                             ((sb.st_mode & S_IFMT) == S_IFCHR
                              ? "character" : "block"),
                             (unsigned long) sb.st_rdev);
                    np->data = xstrdup (buf);
                    addnode (delta->other_delta, np);
# else
                    error (0, 0,
"can't preserve %s: unable to save device files on this system",
workfile);
# endif
                    break;

                default:
                    error (0, 0, "special file %s has unknown type", workfile);
            }

            /* Save hardlinks. */
            delta->hardlinks = list_linked_files_on_disk (workfile);
        }
    }
#endif

    /* Create a new deltatext node. */
    dtext = xmalloc (sizeof (Deltatext));
    memset (dtext, 0, sizeof (Deltatext));

    dtext->log = make_message_rcsvalid (message);

    /* If the delta tree is empty, then there's nothing to link the
       new delta into.  So make a new delta tree, snarf the working
       file contents, and just write the new RCS file. */
    if (rcs->head == NULL)
    {
        char *newrev;
        FILE *fout;

        /* Figure out what the first revision number should be. */
        if (rev == NULL || *rev == '\0')
            newrev = xstrdup ("1.1");
        else if (numdots (rev) == 0)
        {
            newrev = Xasprintf ("%s.1", rev);
        }
        else
            newrev = xstrdup (rev);

        /* Don't need to xstrdup NEWREV because it's already dynamic, and
           not used for anything else.  (Don't need to free it, either.) */
        rcs->head = newrev;
        delta->version = xstrdup (newrev);
        nodep = getnode();
        nodep->type = RCSVERS;
        nodep->delproc = rcsvers_delproc;
        nodep->data = delta;
        nodep->key = delta->version;
        (void) addnode (rcs->versions, nodep);

        dtext->version = xstrdup (newrev);
        bufsize = 0;
#ifdef PRESERVE_PERMISSIONS_SUPPORT
        if (preserve_perms && !S_ISREG (sb.st_mode))
            /* Pretend file is empty.  */
            bufsize = 0;
        else
#endif
        get_file (workfile, workfile,
                  rcs->expand != NULL && STREQ (rcs->expand, "b") ? "rb" : "r",
                  &dtext->text, &bufsize, &dtext->len);

        if (!(checkin_quiet || really_quiet))
        {
            cvs_output ("initial revision: ", 0);
            cvs_output (rcs->head, 0);
            cvs_output ("\n", 1);
        }

        /* We are probably about to invalidate any cached file.  */
        rcsbuf_cache_close ();

        fout = rcs_internal_lockfile (rcs->path);
        RCS_putadmin (rcs, fout);
        RCS_putdtree (rcs, rcs->head, fout);
        RCS_putdesc (rcs, fout);
        rcs->delta_pos = ftello (fout);
        if (rcs->delta_pos == -1)
            error (1, errno, "cannot ftello for %s", rcs->path);
        putdeltatext (fout, dtext);
        rcs_internal_unlockfile (fout, rcs->path);

        if ((flags & RCS_FLAGS_KEEPFILE) == 0)
        {
            if (unlink_file (workfile) < 0)
                /* FIXME-update-dir: message does not include update_dir.  */
                error (0, errno, "cannot remove %s", workfile);
        }

        status = 0;
        goto checkin_done;
    }

    /* Derive a new revision number.  From the `ci' man page:

         "If rev  is  a revision number, it must be higher than the
         latest one on the branch to which  rev  belongs,  or  must
         start a new branch.

         If  rev is a branch rather than a revision number, the new
         revision is appended to that branch.  The level number  is
         obtained  by  incrementing the tip revision number of that
         branch.  If rev  indicates  a  non-existing  branch,  that
         branch  is  created  with  the  initial  revision numbered
         rev.1."

       RCS_findlock_or_tip handles the case where REV is omitted.
       RCS 5.7 also permits REV to be "$" or to begin with a dot, but
       we do not address those cases -- every routine that calls
       RCS_checkin passes it a numeric revision. */

    if (rev == NULL || *rev == '\0')
    {
        /* Figure out where the commit point is by looking for locks.
           If the commit point is at the tip of a branch (or is the
           head of the delta tree), then increment its revision number
           to obtain the new revnum.  Otherwise, start a new
           branch. */
        commitpt = RCS_findlock_or_tip (rcs);
        if (commitpt == NULL)
        {
            status = 1;
            goto checkin_done;
        }
        else if (commitpt->next == NULL
                 || STREQ (commitpt->version, rcs->head))
            delta->version = increment_revnum (commitpt->version);
        else
            delta->version = RCS_addbranch (rcs, commitpt->version);
    }
    else
    {
        /* REV is either a revision number or a branch number.  Find the
           tip of the target branch. */
        char *branch, *tip, *newrev, *p;
        int dots, isrevnum;

        assert (isdigit ((unsigned char) *rev));

        newrev = xstrdup (rev);
        dots = numdots (newrev);
        isrevnum = dots & 1;

        branch = xstrdup (rev);
        if (isrevnum)
        {
            p = strrchr (branch, '.');
            *p = '\0';
        }

        /* Find the tip of the target branch.  If we got a one- or two-digit
           revision number, this will be the head of the tree.  Exception:
           if rev is a single-field revision equal to the branch number of
           the trunk (usually "1") then we want to treat it like an ordinary
           branch revision. */
        if (dots == 0)
        {
            tip = xstrdup (rcs->head);
            if (atoi (tip) != atoi (branch))
            {
                newrev = xrealloc (newrev, strlen (newrev) + 3);
                strcat (newrev, ".1");
                dots = isrevnum = 1;
            }
        }
        else if (dots == 1)
            tip = xstrdup (rcs->head);
        else
            tip = RCS_getbranch (rcs, branch, 1);

        /* If the branch does not exist, and we were supplied an exact
           revision number, signal an error.  Otherwise, if we were
           given only a branch number, create it and set COMMITPT to
           the branch point. */
        if (tip == NULL)
        {
            if (isrevnum)
            {
                error (0, 0, "%s: can't find branch point %s",
                       rcs->print_path, branch);
                free (branch);
                free (newrev);
                status = 1;
                goto checkin_done;
            }
            delta->version = RCS_addbranch (rcs, branch);
            if (!delta->version)
            {
                free (branch);
                free (newrev);
                status = 1;
                goto checkin_done;
            }
            adding_branch = 1;
            p = strrchr (branch, '.');
            *p = '\0';
            tip = xstrdup (branch);
        }
        else
        {
            if (isrevnum)
            {
                /* NEWREV must be higher than TIP. */
                if (compare_revnums (tip, newrev) >= 0)
                {
                    error (0, 0,
                           "%s: revision %s too low; must be higher than %s",
                           rcs->print_path,
                           newrev, tip);
                    free (branch);
                    free (newrev);
                    free (tip);
                    status = 1;
                    goto checkin_done;
                }
                delta->version = xstrdup (newrev);
            }
            else
                /* Just increment the tip number to get the new revision. */
                delta->version = increment_revnum (tip);
        }

        nodep = findnode (rcs->versions, tip);
        commitpt = nodep->data;

        free (branch);
        free (newrev);
        free (tip);
    }

    assert (delta->version != NULL);

    /* If COMMITPT is locked by us, break the lock.  If it's locked
       by someone else, signal an error. */
    nodep = findnode (RCS_getlocks (rcs), commitpt->version);
    if (nodep != NULL)
    {
        if (! STREQ (nodep->data, delta->author))
        {
            /* If we are adding a branch, then leave the old lock around.
               That is sensible in the sense that when adding a branch,
               we don't need to use the lock to tell us where to check
               in.  It is fishy in the sense that if it is our own lock,
               we break it.  However, this is the RCS 5.7 behavior (at
               the end of addbranch in ci.c in RCS 5.7, it calls
               removelock only if it is our own lock, not someone
               else's).  */

            if (!adding_branch)
            {
                error (0, 0, "%s: revision %s locked by %s",
                       rcs->print_path,
                       nodep->key, (char *)nodep->data);
                status = 1;
                goto checkin_done;
            }
        }
        else
            delnode (nodep);
    }

    dtext->version = xstrdup (delta->version);

    /* Obtain the change text for the new delta.  If DELTA is to be the
       new head of the tree, then its change text should be the contents
       of the working file, and LEAFNODE's change text should be a diff.
       Else, DELTA's change text should be a diff between LEAFNODE and
       the working file. */

    tmpfile = cvs_temp_name();
    status = RCS_checkout (rcs, NULL, commitpt->version, NULL,
                           ((rcs->expand != NULL
                             && STREQ (rcs->expand, "b"))
                            ? "-kb"
                            : "-ko"),
                           tmpfile,
                           NULL, NULL);
    if (status != 0)
        error (1, 0,
               "could not check out revision %s of `%s'",
               commitpt->version, rcs->print_path);

    bufsize = 0;
    changefile = cvs_temp_name();

    /* Diff options should include --binary if the RCS file has -kb set
       in its `expand' field. */
    run_add_arg_p (&dargc, &darg_allocated, &dargv, "-a");
    run_add_arg_p (&dargc, &darg_allocated, &dargv, "-n");
    if (rcs->expand != NULL && STREQ (rcs->expand, "b"))
        run_add_arg_p (&dargc, &darg_allocated, &dargv, "--binary");

    if (STREQ (commitpt->version, rcs->head) &&
        numdots (delta->version) == 1)
    {
        /* If this revision is being inserted on the trunk, the change text
           for the new delta should be the contents of the working file ... */
        bufsize = 0;
#ifdef PRESERVE_PERMISSIONS_SUPPORT
        if (preserve_perms && !S_ISREG (sb.st_mode))
            /* Pretend file is empty.  */
            ;
        else
#endif
        get_file (workfile, workfile,
                  rcs->expand != NULL && STREQ (rcs->expand, "b") ? "rb" : "r",
                  &dtext->text, &bufsize, &dtext->len);

        /* ... and the change text for the old delta should be a diff. */
        commitpt->text = xmalloc (sizeof (Deltatext));
        memset (commitpt->text, 0, sizeof (Deltatext));

        bufsize = 0;
        switch (diff_exec (workfile, tmpfile, NULL, NULL,
                           dargc, dargv, changefile))
        {
            case 0:
            case 1:
                break;
            case -1:
                /* FIXME-update-dir: message does not include update_dir.  */
                error (1, errno, "error diffing %s", workfile);
                break;
            default:
                /* FIXME-update-dir: message does not include update_dir.  */
                error (1, 0, "error diffing %s", workfile);
                break;
        }

        /* OK, the text file case here is really dumb.  Logically
           speaking we want diff to read the files in text mode,
           convert them to the canonical form found in RCS files
           (which, we hope at least, is independent of OS--always
           bare linefeeds), and then work with change texts in that
           format.  However, diff_exec both generates change
           texts and produces output for user purposes (e.g. patch.c),
           and there is no way to distinguish between the two cases.
           So we actually implement the text file case by writing the
           change text as a text file, then reading it as a text file.
           This should cause no harm, but doesn't strike me as
           immensely clean.  */
        get_file (changefile, changefile,
                  rcs->expand != NULL && STREQ (rcs->expand, "b") ? "rb" : "r",
                  &commitpt->text->text, &bufsize, &commitpt->text->len);

        /* If COMMITPT->TEXT->TEXT is NULL, it means that CHANGEFILE
           was empty and that there are no differences between revisions.
           In that event, we want to force RCS_rewrite to write an empty
           string for COMMITPT's change text.  Leaving the change text
           field set NULL won't work, since that means "preserve the original
           change text for this delta." */
        if (commitpt->text->text == NULL)
        {
            commitpt->text->text = xstrdup ("");
            commitpt->text->len = 0;
        }
    }
    else
    {
        /* This file is not being inserted at the head, but on a side
           branch somewhere.  Make a diff from the previous revision
           to the working file. */
        switch (diff_exec (tmpfile, workfile, NULL, NULL,
                           dargc, dargv, changefile))
        {
            case 0:
            case 1:
                break;
            case -1:
                /* FIXME-update-dir: message does not include update_dir.  */
                error (1, errno, "error diffing %s", workfile);
                break;
            default:
                /* FIXME-update-dir: message does not include update_dir.  */
                error (1, 0, "error diffing %s", workfile);
                break;
        }
        /* See the comment above, at the other get_file invocation,
           regarding binary vs. text.  */
        get_file (changefile, changefile, 
                  rcs->expand != NULL && STREQ (rcs->expand, "b") ? "rb" : "r",
                  &dtext->text, &bufsize,
                  &dtext->len);
        if (dtext->text == NULL)
        {
            dtext->text = xstrdup ("");
            dtext->len = 0;
        }
    }

    run_arg_free_p (dargc, dargv);
    free (dargv);

    /* Update DELTA linkage.  It is important not to do this before
       the very end of RCS_checkin; if an error arises that forces
       us to abort checking in, we must not have malformed deltas
       partially linked into the tree.

       If DELTA and COMMITPT are on different branches, do nothing --
       DELTA is linked to the tree through COMMITPT->BRANCHES, and we
       don't want to change `next' pointers.

       Otherwise, if the nodes are both on the trunk, link DELTA to
       COMMITPT; otherwise, link COMMITPT to DELTA. */

    if (numdots (commitpt->version) == numdots (delta->version))
    {
        if (STREQ (commitpt->version, rcs->head))
        {
            delta->next = rcs->head;
            rcs->head = xstrdup (delta->version);
        }
        else
            commitpt->next = xstrdup (delta->version);
    }

    /* Add DELTA to RCS->VERSIONS. */
    if (rcs->versions == NULL)
        rcs->versions = getlist();
    nodep = getnode();
    nodep->type = RCSVERS;
    nodep->delproc = rcsvers_delproc;
    nodep->data = delta;
    nodep->key = delta->version;
    (void) addnode (rcs->versions, nodep);
        
    /* Write the new RCS file, inserting the new delta at COMMITPT. */
    if (!(checkin_quiet || really_quiet))
    {
        cvs_output ("new revision: ", 14);
        cvs_output (delta->version, 0);
        cvs_output ("; previous revision: ", 21);
        cvs_output (commitpt->version, 0);
        cvs_output ("\n", 1);
    }

    RCS_rewrite (rcs, dtext, commitpt->version);

    if ((flags & RCS_FLAGS_KEEPFILE) == 0)
    {
        if (unlink_file (workfile) < 0)
            /* FIXME-update-dir: message does not include update_dir.  */
            error (1, errno, "cannot remove %s", workfile);
    }
    if (unlink_file (tmpfile) < 0)
        error (0, errno, "cannot remove %s", tmpfile);
    free (tmpfile);
    if (unlink_file (changefile) < 0)
        error (0, errno, "cannot remove %s", changefile);
    free (changefile);

 checkin_done:
    free (workfile);

    if (commitpt != NULL && commitpt->text != NULL)
    {
        freedeltatext (commitpt->text);
        commitpt->text = NULL;
    }

    freedeltatext (dtext);
    if (status != 0)
    {
        /* If delta has not been added to a List, then freeing the Node key
         * won't free delta->version.
         */
        if (delta->version) free (delta->version);
        free_rcsvers_contents (delta);
    }

    return status;
}



/* This structure is passed between RCS_cmp_file and cmp_file_buffer.  */
struct cmp_file_data
{
    const char *filename;
    FILE *fp;
    int different;
};

/* Compare the contents of revision REV1 of RCS file RCS with the
   contents of REV2 if given, otherwise, compare with the contents of
   the file FILENAME.  OPTIONS is a string for the keyword
   expansion options.  Return 0 if the contents of the revision are
   the same as the contents of the file, 1 if they are different.  */
int
RCS_cmp_file (RCSNode *rcs, const char *rev1, char **rev1_cache,
              const char *rev2, const char *options, const char *filename)
{
    int binary;

    TRACE (TRACE_FUNCTION, "RCS_cmp_file( %s, %s, %s, %s, %s )",
           rcs->path ? rcs->path : "(null)",
           rev1 ? rev1 : "(null)", rev2 ? rev2 : "(null)",
           options ? options : "(null)", filename ? filename : "(null)");

    if (options != NULL && options[0] != '\0')
        binary = STREQ (options, "-kb");
    else
    {
        char *expand;

        expand = RCS_getexpand (rcs);
        if (expand != NULL && STREQ (expand, "b"))
            binary = 1;
        else
            binary = 0;
    }

#ifdef PRESERVE_PERMISSIONS_SUPPORT
    /* If CVS is to deal properly with special files (when
       PreservePermissions is on), the best way is to check out the
       revision to a temporary file and call `xcmp' on the two disk
       files.  xcmp needs to handle non-regular files properly anyway,
       so calling it simplifies RCS_cmp_file.  We *could* just yank
       the delta node out of the version tree and look for device
       numbers, but writing to disk and calling xcmp is a better
       abstraction (therefore probably more robust). -twp */

    if (preserve_perms)
    {
        char *tmp;
        int retcode;

        tmp = cvs_temp_name();
        retcode = RCS_checkout(rcs, NULL, rev, NULL, options, tmp, NULL, NULL);
        if (retcode != 0)
            return 1;

        retcode = xcmp (tmp, filename);
        if (CVS_UNLINK (tmp) < 0)
            error (0, errno, "cannot remove %s", tmp);
        free (tmp);
        return retcode;
    }
    else
#endif
    {
        FILE *fp;
        struct cmp_file_data data;
        const char *use_file1;
        char *tmpfile = NULL;

        if (rev2 != NULL)
        {
            /* Open & cache rev1 */
            tmpfile = cvs_temp_name();
            if (RCS_checkout (rcs, NULL, rev1, NULL, options, tmpfile,
                              NULL, NULL))
                error (1, errno,
                       "cannot check out revision %s of %s",
                       rev1, rcs->print_path);
            use_file1 = tmpfile;
            if (rev1_cache != NULL)
                *rev1_cache = tmpfile;
        }
        else
            use_file1 = filename;

        fp = CVS_FOPEN (use_file1, binary ? FOPEN_BINARY_READ : "r");
        if (fp == NULL)
            /* FIXME-update-dir: should include update_dir in message.  */
            error (1, errno, "cannot open file %s for comparing", use_file1);
        
        data.filename = use_file1;
        data.fp = fp;
        data.different = 0;
        
        if (RCS_checkout (rcs, NULL, rev2 ? rev2 : rev1, NULL, options,
                          RUN_TTY, cmp_file_buffer, &data ))
                error (1, errno,
                       "cannot check out revision %s of %s",
                       rev2 ? rev2 : rev1, rcs->print_path);

        /* If we have not yet found a difference, make sure that we are at
           the end of the file.  */
        if (!data.different)
        {
            if (getc (fp) != EOF)
                data.different = 1;
        }
        
        fclose (fp);
        if (rev1_cache == NULL && tmpfile)
        {
            if (CVS_UNLINK (tmpfile ) < 0)
                error (0, errno, "cannot remove %s", tmpfile);
            free (tmpfile);
        }

        return data.different;
    }
}



/* This is a subroutine of RCS_cmp_file.  It is passed to
   RCS_checkout.  */
#define CMP_BUF_SIZE (8 * 1024)

static void
cmp_file_buffer (void *callerdat, const char *buffer, size_t len)
{
    struct cmp_file_data *data = callerdat;
    char *filebuf;

    /* If we've already found a difference, we don't need to check
       further.  */
    if (data->different)
        return;

    filebuf = xmalloc (len > CMP_BUF_SIZE ? CMP_BUF_SIZE : len);

    while (len > 0)
    {
        size_t checklen;

        checklen = len > CMP_BUF_SIZE ? CMP_BUF_SIZE : len;
        if (fread (filebuf, 1, checklen, data->fp) != checklen)
        {
            if (ferror (data->fp))
                error (1, errno, "cannot read file %s for comparing",
                       data->filename);
            data->different = 1;
            free (filebuf);
            return;
        }

        if (memcmp (filebuf, buffer, checklen) != 0)
        {
            data->different = 1;
            free (filebuf);
            return;
        }

        buffer += checklen;
        len -= checklen;
    }

    free (filebuf);
}



/* For RCS file RCS, make symbolic tag TAG point to revision REV.
   This validates that TAG is OK for a user to use.  Return value is
   -1 for error (and errno is set to indicate the error), positive for
   error (and an error message has been printed), or zero for success.  */
int
RCS_settag (RCSNode *rcs, const char *tag, const char *rev)
{
    List *symbols;
    Node *node;

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* FIXME: This check should be moved to RCS_check_tag.  There is no
       reason for it to be here.  */
    if (STREQ (tag, TAG_BASE)
        || STREQ (tag, TAG_HEAD))
    {
        /* Print the name of the tag might be considered redundant
           with the caller, which also prints it.  Perhaps this helps
           clarify why the tag name is considered reserved, I don't
           know.  */
        error (0, 0, "Attempt to add reserved tag name %s", tag);
        return 1;
    }

    /* A revision number of NULL means use the head or default branch.
       If rev is not NULL, it may be a symbolic tag or branch number;
       expand it to the correct numeric revision or branch head. */
    if (rev == NULL)
        rev = rcs->branch ? rcs->branch : rcs->head;

    /* At this point rcs->symbol_data may not have been parsed.
       Calling RCS_symbols will force it to be parsed into a list
       which we can easily manipulate.  */
    symbols = RCS_symbols (rcs);
    if (symbols == NULL)
    {
        symbols = getlist ();
        rcs->symbols = symbols;
    }
    node = findnode (symbols, tag);
    if (node != NULL)
    {
        free (node->data);
        node->data = xstrdup (rev);
    }
    else
    {
        node = getnode ();
        node->key = xstrdup (tag);
        node->data = xstrdup (rev);
        (void)addnode_at_front (symbols, node);
    }

    return 0;
}



/* Delete the symbolic tag TAG from the RCS file RCS.  Return 0 if
   the tag was found (and removed), or 1 if it was not present.  (In
   either case, the tag will no longer be in RCS->SYMBOLS.) */
int
RCS_deltag (RCSNode *rcs, const char *tag)
{
    List *symbols;
    Node *node;
    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    symbols = RCS_symbols (rcs);
    if (symbols == NULL)
        return 1;

    node = findnode (symbols, tag);
    if (node == NULL)
        return 1;

    delnode (node);

    return 0;
}



/* Set the default branch of RCS to REV.  */
int
RCS_setbranch (RCSNode *rcs, const char *rev)
{
    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (rev && ! *rev)
        rev = NULL;

    if (rev == NULL && rcs->branch == NULL)
        return 0;
    if (rev != NULL && rcs->branch != NULL && STREQ (rev, rcs->branch))
        return 0;

    if (rcs->branch != NULL)
        free (rcs->branch);
    rcs->branch = xstrdup (rev);

    return 0;
}



/* Lock revision REV.  LOCK_QUIET is 1 to suppress output.  FIXME:
   Most of the callers only call us because RCS_checkin still tends to
   like a lock (a relic of old behavior inherited from the RCS ci
   program).  If we clean this up, only "cvs admin -l" will still need
   to call RCS_lock.  */

/* FIXME-twp: if a lock owned by someone else is broken, should this
   send mail to the lock owner?  Prompt user?  It seems like such an
   obscure situation for CVS as almost not worth worrying much
   about. */
int
RCS_lock (RCSNode *rcs, const char *rev, int lock_quiet)
{
    List *locks;
    Node *p;
    char *user;
    char *xrev = NULL;

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    locks = RCS_getlocks (rcs);
    if (locks == NULL)
        locks = rcs->locks = getlist();
    user = getcaller();

    /* A revision number of NULL means lock the head or default branch. */
    if (rev == NULL)
        xrev = RCS_head (rcs);
    else
        xrev = RCS_gettag (rcs, rev, 1, NULL);

    /* Make sure that the desired revision exists.  Technically,
       we can update the locks list without even checking this,
       but RCS 5.7 did this.  And it can't hurt. */
    if (xrev == NULL || findnode (rcs->versions, xrev) == NULL)
    {
        if (!lock_quiet)
            error (0, 0, "%s: revision %s absent", rcs->print_path, rev);
        free (xrev);
        return 1;
    }

    /* Is this rev already locked? */
    p = findnode (locks, xrev);
    if (p != NULL)
    {
        if (STREQ (p->data, user))
        {
            /* We already own the lock on this revision, so do nothing. */
            free (xrev);
            return 0;
        }

#if 0
        /* Well, first of all, "rev" below should be "xrev" to avoid
           core dumps.  But more importantly, should we really be
           breaking the lock unconditionally?  What CVS 1.9 does (via
           RCS) is to prompt "Revision 1.1 is already locked by fred.
           Do you want to break the lock? [ny](n): ".  Well, we don't
           want to interact with the user (certainly not at the
           server/protocol level, and probably not in the command-line
           client), but isn't it more sensible to give an error and
           let the user run "cvs admin -u" if they want to break the
           lock?  */

        /* Break the lock. */       
        if (!lock_quiet)
        {
            cvs_output (rev, 0);
            cvs_output (" unlocked\n", 0);
        }
        delnode (p);
#else
        error (1, 0, "Revision %s is already locked by %s",
               xrev, (char *)p->data);
#endif
    }

    /* Create a new lock. */
    p = getnode();
    p->key = xrev;      /* already xstrdupped */
    p->data = xstrdup (getcaller());
    (void)addnode_at_front (locks, p);

    if (!lock_quiet)
    {
        cvs_output (xrev, 0);
        cvs_output (" locked\n", 0);
    }

    return 0;
}



/* Unlock revision REV.  UNLOCK_QUIET is 1 to suppress output.  FIXME:
   Like RCS_lock, this can become a no-op if we do the checkin
   ourselves.

   If REV is not null and is locked by someone else, break their
   lock and notify them.  It is an open issue whether RCS_unlock
   queries the user about whether or not to break the lock. */
int
RCS_unlock (RCSNode *rcs, char *rev, int unlock_quiet)
{
    Node *lock;
    List *locks;
    char *user;
    char *xrev = NULL;

    user = getcaller();
    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    /* If rev is NULL, unlock the revision held by the caller; if more
       than one, make the user specify the revision explicitly.  This
       differs from RCS which unlocks the latest revision (first in
       rcs->locks) held by the caller. */
    if (rev == NULL)
    {
        Node *p;

        /* No-ops: attempts to unlock an empty tree or an unlocked file. */
        if (rcs->head == NULL)
        {
            if (!unlock_quiet)
                cvs_outerr ("can't unlock an empty tree\n", 0);
            return 0;
        }

        locks = RCS_getlocks (rcs);
        if (locks == NULL)
        {
            if (!unlock_quiet)
                cvs_outerr ("No locks are set.\n", 0);
            return 0;
        }

        lock = NULL;
        for (p = locks->list->next; p != locks->list; p = p->next)
        {
            if (STREQ (p->data, user))
            {
                if (lock != NULL)
                {
                    if (!unlock_quiet)
                        error (0, 0, "\
%s: multiple revisions locked by %s; please specify one", rcs->print_path, user);
                    return 1;
                }
                lock = p;
            }
        }
        if (lock == NULL)
        {
            if (!unlock_quiet)
                error (0, 0, "No locks are set for %s.\n", user);
            return 0;   /* no lock found, ergo nothing to do */
        }
        xrev = xstrdup (lock->key);
    }
    else
    {
        xrev = RCS_gettag (rcs, rev, 1, NULL);
        if (xrev == NULL)
        {
            error (0, 0, "%s: revision %s absent", rcs->print_path, rev);
            return 1;
        }
    }

    lock = findnode (RCS_getlocks (rcs), xrev);
    if (lock == NULL)
    {
        /* This revision isn't locked. */
        free (xrev);
        return 0;
    }

    if (! STREQ (lock->data, user))
    {
        /* If the revision is locked by someone else, notify
           them.  Note that this shouldn't ever happen if RCS_unlock
           is called with a NULL revision, since that means "whatever
           revision is currently locked by the caller." */
        char *repos, *workfile;
        if (!unlock_quiet)
            error (0, 0, "\
%s: revision %s locked by %s; breaking lock", rcs->print_path, xrev,
                   (char *)lock->data);
        repos = xstrdup (rcs->path);
        workfile = strrchr (repos, '/');
        *workfile++ = '\0';
        notify_do ('C', workfile, NULL, user, NULL, NULL, repos);
        free (repos);
    }

    delnode (lock);
    if (!unlock_quiet)
    {
        cvs_output (xrev, 0);
        cvs_output (" unlocked\n", 0);
    }

    free (xrev);
    return 0;
}



/* Add USER to the access list of RCS.  Do nothing if already present.
   FIXME-twp: check syntax of USER to make sure it's a valid id. */

void
RCS_addaccess (RCSNode *rcs, char *user)
{
    char *access, *a;

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (rcs->access == NULL)
        rcs->access = xstrdup (user);
    else
    {
        access = xstrdup (rcs->access);
        for (a = strtok (access, " "); a != NULL; a = strtok (NULL, " "))
        {
            if (STREQ (a, user))
            {
                free (access);
                return;
            }
        }
        free (access);
        rcs->access = xrealloc (rcs->access,
                                strlen (rcs->access) + strlen (user) + 2);
        strcat (rcs->access, " ");
        strcat (rcs->access, user);
    }
}



/* Remove USER from the access list of RCS. */
void
RCS_delaccess (RCSNode *rcs, char *user)
{
    char *p, *s;
    int ulen;

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (rcs->access == NULL)
        return;

    if (user == NULL)
    {
        free (rcs->access);
        rcs->access = NULL;
        return;
    }

    p = rcs->access;
    ulen = strlen (user);
    while (p != NULL)
    {
        if (strncmp (p, user, ulen) == 0 && (p[ulen] == '\0' || p[ulen] == ' '))
            break;
        p = strchr (p, ' ');
        if (p != NULL)
            ++p;
    }

    if (p == NULL)
        return;

    s = p + ulen;
    while (*s != '\0')
        *p++ = *s++;
    *p = '\0';
}



char *
RCS_getaccess (RCSNode *rcs)
{
    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    return rcs->access;
}



/* Return a nonzero value if the revision specified by ARG is found.  */
static int
findtag (Node *node, void *arg)
{
    char *rev = arg;

    if (STREQ (node->data, rev))
        return 1;
    else
        return 0;
}



/* Delete revisions between REV1 and REV2.  The changes between the two
   revisions must be collapsed, and the result stored in the revision
   immediately preceding the lower one.  Return 0 for successful completion,
   1 otherwise.

   Solution: check out the revision preceding REV1 and the revision
   following REV2.  Use call_diff to find aggregate diffs between
   these two revisions, and replace the delta text for the latter one
   with the new aggregate diff.  Alternatively, we could write a
   function that takes two change texts and combines them to produce a
   new change text, without checking out any revs or calling diff.  It
   would be hairy, but so, so cool.

   If INCLUSIVE is set, then TAG1 and TAG2, if non-NULL, tell us to
   delete that revision as well (cvs admin -o tag1:tag2).  If clear,
   delete up to but not including that revision (cvs admin -o tag1::tag2).
   This does not affect TAG1 or TAG2 being NULL; the meaning of the start
   point in ::tag2 and :tag2 is the same and likewise for end points.  */
int
RCS_delete_revs (RCSNode *rcs, char *tag1, char *tag2, int inclusive)
{
    char *next;
    Node *nodep;
    RCSVers *revp = NULL;
    RCSVers *beforep;
    int status, found;
    int save_noexec;

    char *branchpoint = NULL;
    char *rev1 = NULL;
    char *rev2 = NULL;
    int rev1_inclusive = inclusive;
    int rev2_inclusive = inclusive;
    char *before = NULL;
    char *after = NULL;
    char *beforefile = NULL;
    char *afterfile = NULL;
    char *outfile = NULL;

    if (tag1 == NULL && tag2 == NULL)
        return 0;

    /* Assume error status until everything is finished. */
    status = 1;

    /* Make sure both revisions exist. */
    if (tag1 != NULL)
    {
        rev1 = RCS_gettag (rcs, tag1, 1, NULL);
        if (rev1 == NULL || (nodep = findnode (rcs->versions, rev1)) == NULL)
        {
            error (0, 0, "%s: Revision %s doesn't exist.", rcs->print_path, tag1);
            goto delrev_done;
        }
    }
    if (tag2 != NULL)
    {
        rev2 = RCS_gettag (rcs, tag2, 1, NULL);
        if (rev2 == NULL || (nodep = findnode (rcs->versions, rev2)) == NULL)
        {
            error (0, 0, "%s: Revision %s doesn't exist.", rcs->print_path, tag2);
            goto delrev_done;
        }
    }

    /* If rev1 is on the trunk and rev2 is NULL, rev2 should be
       RCS->HEAD.  (*Not* RCS_head(rcs), which may return rcs->branch
       instead.)  We need to check this special case early, in order
       to make sure that rev1 and rev2 get ordered correctly. */
    if (rev2 == NULL && numdots (rev1) == 1)
    {
        rev2 = xstrdup (rcs->head);
        rev2_inclusive = 1;
    }

    if (rev2 == NULL)
        rev2_inclusive = 1;

    if (rev1 != NULL && rev2 != NULL)
    {
        /* A range consisting of a branch number means the latest revision
           on that branch. */
        if (RCS_isbranch (rcs, rev1) && STREQ (rev1, rev2))
        {
            char *tmp = RCS_getbranch (rcs, rev1, 0);
            free (rev1);
            free (rev2);
            rev1 = rev2 = tmp;
        }
        else
        {
            /* Make sure REV1 and REV2 are ordered correctly (in the
               same order as the next field).  For revisions on the
               trunk, REV1 should be higher than REV2; for branches,
               REV1 should be lower.  */
            /* Shouldn't we just be giving an error in the case where
               the user specifies the revisions in the wrong order
               (that is, always swap on the trunk, never swap on a
               branch, in the non-error cases)?  It is not at all
               clear to me that users who specify -o 1.4:1.2 really
               meant to type -o 1.2:1.4, and the out of order usage
               has never been documented, either by cvs.texinfo or
               rcs(1).  */
            char *temp;
            int temp_inclusive;
            if (numdots (rev1) == 1)
            {
                if (compare_revnums (rev1, rev2) <= 0)
                {
                    temp = rev2;
                    rev2 = rev1;
                    rev1 = temp;

                    temp_inclusive = rev2_inclusive;
                    rev2_inclusive = rev1_inclusive;
                    rev1_inclusive = temp_inclusive;
                }
            }
            else if (compare_revnums (rev1, rev2) > 0)
            {
                temp = rev2;
                rev2 = rev1;
                rev1 = temp;

                temp_inclusive = rev2_inclusive;
                rev2_inclusive = rev1_inclusive;
                rev1_inclusive = temp_inclusive;
            }
        }
    }

    /* Basically the same thing; make sure that the ordering is what we
       need.  */
    if (rev1 == NULL)
    {
        assert (rev2 != NULL);
        if (numdots (rev2) == 1)
        {
            /* Swap rev1 and rev2.  */
            int temp_inclusive;

            rev1 = rev2;
            rev2 = NULL;

            temp_inclusive = rev2_inclusive;
            rev2_inclusive = rev1_inclusive;
            rev1_inclusive = temp_inclusive;
        }
    }

    /* Put the revision number preceding the first one to delete into
       BEFORE (where "preceding" means according to the next field).
       If the first revision to delete is the first revision on its
       branch (e.g. 1.3.2.1), BEFORE should be the node on the trunk
       at which the branch is rooted.  If the first revision to delete
       is the head revision of the trunk, set BEFORE to NULL.

       Note that because BEFORE may not be on the same branch as REV1,
       it is not very handy for navigating the revision tree.  It's
       most useful just for checking out the revision preceding REV1. */
    before = NULL;
    branchpoint = RCS_getbranchpoint (rcs, rev1 != NULL ? rev1 : rev2);
    if (rev1 == NULL)
    {
        rev1 = xstrdup (branchpoint);
        if (numdots (branchpoint) > 1)
        {
            char *bp;
            bp = strrchr (branchpoint, '.');
            while (*--bp != '.')
                ;
            *bp = '\0';
            /* Note that this is exclusive, always, because the inclusive
               flag doesn't affect the meaning when rev1 == NULL.  */
            before = xstrdup (branchpoint);
            *bp = '.';
        }
    }
    else if (! STREQ (rev1, branchpoint))
    {
        /* Walk deltas from BRANCHPOINT on, looking for REV1. */
        nodep = findnode (rcs->versions, branchpoint);
        revp = nodep->data;
        while (revp->next != NULL && ! STREQ (revp->next, rev1))
        {
            revp = nodep->data;
            nodep = findnode (rcs->versions, revp->next);
        }
        if (revp->next == NULL)
        {
            error (0, 0, "%s: Revision %s doesn't exist.", rcs->print_path, rev1);
            goto delrev_done;
        }
        if (rev1_inclusive)
            before = xstrdup (revp->version);
        else
        {
            before = rev1;
            nodep = findnode (rcs->versions, before);
            rev1 = xstrdup (((RCSVers *)nodep->data)->next);
        }
    }
    else if (!rev1_inclusive)
    {
        before = rev1;
        nodep = findnode (rcs->versions, before);
        rev1 = xstrdup (((RCSVers *)nodep->data)->next);
    }
    else if (numdots (branchpoint) > 1)
    {
        /* Example: rev1 is "1.3.2.1", branchpoint is "1.3.2.1".
           Set before to "1.3".  */
        char *bp;
        bp = strrchr (branchpoint, '.');
        while (*--bp != '.')
            ;
        *bp = '\0';
        before = xstrdup (branchpoint);
        *bp = '.';
    }

    /* If any revision between REV1 and REV2 is locked or is a branch point,
       we can't delete that revision and must abort. */
    after = NULL;
    next = rev1;
    found = 0;
    while (!found && next != NULL)
    {
        nodep = findnode (rcs->versions, next);
        revp = nodep->data;

        if (rev2 != NULL)
            found = STREQ (revp->version, rev2);
        next = revp->next;

        if ((!found && next != NULL) || rev2_inclusive || rev2 == NULL)
        {
            if (findnode (RCS_getlocks (rcs), revp->version))
            {
                error (0, 0, "%s: can't remove locked revision %s",
                       rcs->print_path,
                       revp->version);
                goto delrev_done;
            }
            if (revp->branches != NULL)
            {
                error (0, 0, "%s: can't remove branch point %s",
                       rcs->print_path,
                       revp->version);
                goto delrev_done;
            }

            /* Doing this only for the :: syntax is for compatibility.
               See cvs.texinfo for somewhat more discussion.  */
            if (!inclusive
                && walklist (RCS_symbols (rcs), findtag, revp->version))
            {
                /* We don't print which file this happens to on the theory
                   that the caller will print the name of the file in a
                   more useful fashion (fullname not rcs->path).  */
                error (0, 0, "cannot remove revision %s because it has tags",
                       revp->version);
                goto delrev_done;
            }

            /* It's misleading to print the `deleting revision' output
               here, since we may not actually delete these revisions.
               But that's how RCS does it.  Bleah.  Someday this should be
               moved to the point where the revs are actually marked for
               deletion. -twp */
            cvs_output ("deleting revision ", 0);
            cvs_output (revp->version, 0);
            cvs_output ("\n", 1);
        }
    }

    if (rev2 == NULL)
        ;
    else if (found)
    {
        if (rev2_inclusive)
            after = xstrdup (next);
        else
            after = xstrdup (revp->version);
    }
    else if (!inclusive)
    {
        /* In the case of an empty range, for example 1.2::1.2 or
           1.2::1.3, we want to just do nothing.  */
        status = 0;
        goto delrev_done;
    }
    else
    {
        /* This looks fishy in the cases where tag1 == NULL or tag2 == NULL.
           Are those cases really impossible?  */
        assert (tag1 != NULL);
        assert (tag2 != NULL);

        error (0, 0, "%s: invalid revision range %s:%s", rcs->print_path,
               tag1, tag2);
        goto delrev_done;
    }

    if (after == NULL && before == NULL)
    {
        /* The user is trying to delete all revisions.  While an
           RCS file without revisions makes sense to RCS (e.g. the
           state after "rcs -i"), CVS has never been able to cope with
           it.  So at least for now we just make this an error.

           We don't include rcs->path in the message since "cvs admin"
           already printed "RCS file:" and the name.  */
        error (1, 0, "attempt to delete all revisions");
    }

    /* The conditionals at this point get really hairy.  Here is the
       general idea:

       IF before != NULL and after == NULL
         THEN don't check out any revisions, just delete them
       IF before == NULL and after != NULL
         THEN only check out after's revision, and use it for the new deltatext
       ELSE
         check out both revisions and diff -n them.  This could use
         RCS_exec_rcsdiff with some changes, like being able
         to suppress diagnostic messages and to direct output. */

    if (after != NULL)
    {
        char *diffbuf;
        size_t bufsize, len;

#if defined (WOE32) && !defined (__CYGWIN32__)
        /* FIXME: This is an awful kludge, but at least until I have
           time to work on it a little more and test it, I'd rather
           give a fatal error than corrupt the file.  I think that we
           need to use "-kb" and "--binary" and "rb" to get_file
           (probably can do it always, not just for binary files, if
           we are consistent between the RCS_checkout and the diff).  */
        {
            char *expand = RCS_getexpand (rcs);
            if (expand != NULL && STREQ (expand, "b"))
                error (1, 0,
                   "admin -o not implemented yet for binary on this system");
        }
#endif /* WOE32 */

        afterfile = cvs_temp_name();
        status = RCS_checkout (rcs, NULL, after, NULL, "-ko", afterfile,
                               NULL, NULL);
        if (status > 0)
            goto delrev_done;

        if (before == NULL)
        {
            /* We are deleting revisions from the head of the tree,
               so must create a new head. */
            diffbuf = NULL;
            bufsize = 0;
            get_file (afterfile, afterfile, "r", &diffbuf, &bufsize, &len);

            save_noexec = noexec;
            noexec = 0;
            if (unlink_file (afterfile) < 0)
                error (0, errno, "cannot remove %s", afterfile);
            noexec = save_noexec;

            free (afterfile);
            afterfile = NULL;

            free (rcs->head);
            rcs->head = xstrdup (after);
        }
        else
        {
            int dargc = 0;
            size_t darg_allocated = 0;
            char **dargv = NULL;

            beforefile = cvs_temp_name();
            status = RCS_checkout (rcs, NULL, before, NULL, "-ko", beforefile,
                                   NULL, NULL);
            if (status > 0)
                goto delrev_done;

            outfile = cvs_temp_name();
            run_add_arg_p (&dargc, &darg_allocated, &dargv, "-a");
            run_add_arg_p (&dargc, &darg_allocated, &dargv, "-n");
            status = diff_exec (beforefile, afterfile, NULL, NULL,
                                dargc, dargv, outfile);
            run_arg_free_p (dargc, dargv);
            free (dargv);

            if (status == 2)
            {
                /* Not sure we need this message; will diff_exec already
                   have printed an error?  */
                error (0, 0, "%s: could not diff", rcs->print_path);
                status = 1;
                goto delrev_done;
            }

            diffbuf = NULL;
            bufsize = 0;
            get_file (outfile, outfile, "r", &diffbuf, &bufsize, &len);
        }

        /* Save the new change text in after's delta node. */
        nodep = findnode (rcs->versions, after);
        revp = nodep->data;

        assert (revp->text == NULL);

        revp->text = xmalloc (sizeof (Deltatext));
        memset (revp->text, 0, sizeof (Deltatext));
        revp->text->version = xstrdup (revp->version);
        revp->text->text = diffbuf;
        revp->text->len = len;

        /* If DIFFBUF is NULL, it means that OUTFILE is empty and that
           there are no differences between the two revisions.  In that
           case, we want to force RCS_copydeltas to write an empty string
           for the new change text (leaving the text field set NULL
           means "preserve the original change text for this delta," so
           we don't want that). */
        if (revp->text->text == NULL)
            revp->text->text = xstrdup ("");
    }

    /* Walk through the revisions (again) to mark each one as
       outdated.  (FIXME: would it be safe to use the `dead' field for
       this?  Doubtful.) */
    for (next = rev1;
         next != NULL && (after == NULL || ! STREQ (next, after));
         next = revp->next)
    {
        nodep = findnode (rcs->versions, next);
        revp = nodep->data;
        revp->outdated = 1;
    }

    /* Update delta links.  If BEFORE == NULL, we're changing the
       head of the tree and don't need to update any `next' links. */
    if (before != NULL)
    {
        /* If REV1 is the first node on its branch, then BEFORE is its
           root node (on the trunk) and we have to update its branches
           list.  Otherwise, BEFORE is on the same branch as AFTER, and
           we can just change BEFORE's `next' field to point to AFTER.
           (This should be safe: since findnode manages its lists via
           the `hashnext' and `hashprev' fields, rather than `next' and
           `prev', mucking with `next' and `prev' should not corrupt the
           delta tree's internal structure.  Much. -twp) */

        if (rev1 == NULL)
            /* beforep's ->next field already should be equal to after,
               which I think is always NULL in this case.  */
            ;
        else if (STREQ (rev1, branchpoint))
        {
            nodep = findnode (rcs->versions, before);
            revp = nodep->data;
            nodep = revp->branches->list->next;
            while (nodep != revp->branches->list &&
                   ! STREQ (nodep->key, rev1))
                nodep = nodep->next;
            assert (nodep != revp->branches->list);
            if (after == NULL)
                delnode (nodep);
            else
            {
                free (nodep->key);
                nodep->key = xstrdup (after);
            }
        }
        else
        {
            nodep = findnode (rcs->versions, before);
            beforep = nodep->data;
            free (beforep->next);
            beforep->next = xstrdup (after);
        }
    }

    status = 0;

 delrev_done:
    if (rev1 != NULL)
        free (rev1);
    if (rev2 && rev2 != rev1)
        free (rev2);
    if (branchpoint != NULL)
        free (branchpoint);
    if (before != NULL)
        free (before);
    if (after != NULL)
        free (after);

    save_noexec = noexec;
    noexec = 0;
    if (beforefile != NULL)
    {
        if (unlink_file (beforefile) < 0)
            error (0, errno, "cannot remove %s", beforefile);
        free (beforefile);
    }
    if (afterfile != NULL)
    {
        if (unlink_file (afterfile) < 0)
            error (0, errno, "cannot remove %s", afterfile);
        free (afterfile);
    }
    if (outfile != NULL)
    {
        if (unlink_file (outfile) < 0)
            error (0, errno, "cannot remove %s", outfile);
        free (outfile);
    }
    noexec = save_noexec;

    return status;
}



/*
 * TRUE if there exists a symbolic tag "tag" in file.
 */
int 
RCS_exist_tag (RCSNode *rcs, char *tag)
{

    assert (rcs != NULL);

    if (findnode (RCS_symbols (rcs), tag))
    return 1;
    return 0;

}



/*
 * TRUE if RCS revision number "rev" exists.
 * This includes magic branch revisions, not found in rcs->versions, 
 * but only in rcs->symbols, requiring a list walk to find them.
 * Take advantage of list walk callback function already used by 
 * RCS_delete_revs, above.
 */
int
RCS_exist_rev (RCSNode *rcs, char *rev)
{

    assert (rcs != NULL);

    if (rcs->flags & PARTIAL)
        RCS_reparsercsfile (rcs, NULL, NULL);

    if (findnode(rcs->versions, rev) != 0)
        return 1;

    if (walklist (RCS_symbols(rcs), findtag, rev) != 0)
        return 1;

    return 0;

}




/* RCS_deltas and friends.  Processing of the deltas in RCS files.  */
struct line
{
    /* Text of this line.  Part of the same malloc'd block as the struct
       line itself (we probably should use the "struct hack" (char text[1])
       and save ourselves sizeof (char *) bytes).  Does not include \n;
       instead has_newline indicates the presence or absence of \n.  */
    char *text;
    /* Length of this line, not counting \n if has_newline is true.  */
    size_t len;
    /* Version in which it was introduced.  */
    RCSVers *vers;
    /* Nonzero if this line ends with \n.  This will always be true
       except possibly for the last line.  */
    int has_newline;
    /* Number of pointers to this struct line.  */
    int refcount;
};

struct linevector
{
    /* How many lines in use for this linevector?  */
    unsigned int nlines;
    /* How many lines allocated for this linevector?  */
    unsigned int lines_alloced;
    /* Pointer to array containing a pointer to each line.  */
    struct line **vector;
};



/* Initialize *VEC to be a linevector with no lines.  */
static void
linevector_init (struct linevector *vec)
{
    vec->lines_alloced = 0;
    vec->nlines = 0;
    vec->vector = NULL;
}



/* Given some text TEXT, add each of its lines to VEC before line POS
   (where line 0 is the first line).  The last line in TEXT may or may
   not be \n terminated.
   Set the version for each of the new lines to VERS.  This
   function returns non-zero for success.  It returns zero if the line
   number is out of range.

   Each of the lines in TEXT are copied to space which is managed with
   the linevector (and freed by linevector_free).  So the caller doesn't
   need to keep TEXT around after the call to this function.  */
static int
linevector_add (struct linevector *vec, const char *text, size_t len,
                RCSVers *vers, unsigned int pos)
{
    const char *textend;
    unsigned int i;
    unsigned int nnew;
    const char *p;
    const char *nextline_text;
    size_t nextline_len;
    int nextline_newline;
    struct line *q;

    if (len == 0)
        return 1;

    textend = text + len;

    /* Count the number of lines we will need to add.  */
    nnew = 1;
    for (p = text; p < textend; ++p)
        if (*p == '\n' && p + 1 < textend)
            ++nnew;

    /* Expand VEC->VECTOR if needed.  */
    if (vec->nlines + nnew >= vec->lines_alloced)
    {
        if (vec->lines_alloced == 0)
            vec->lines_alloced = 10;
        while (vec->nlines + nnew >= vec->lines_alloced)
            vec->lines_alloced *= 2;
        vec->vector = xnrealloc (vec->vector,
                                 vec->lines_alloced, sizeof (*vec->vector));
    }

    /* Make room for the new lines in VEC->VECTOR.  */
    for (i = vec->nlines + nnew - 1; i >= pos + nnew; --i)
        vec->vector[i] = vec->vector[i - nnew];

    if (pos > vec->nlines)
        return 0;

    /* Actually add the lines, to VEC->VECTOR.  */
    i = pos;
    nextline_text = text;
    nextline_newline = 0;
    for (p = text; p < textend; ++p)
        if (*p == '\n')
        {
            nextline_newline = 1;
            if (p + 1 == textend)
                /* If there are no characters beyond the last newline, we
                   don't consider it another line.  */
                break;
            nextline_len = p - nextline_text;
            q = xmalloc (sizeof (struct line) + nextline_len);
            q->vers = vers;
            q->text = (char *)q + sizeof (struct line);
            q->len = nextline_len;
            q->has_newline = nextline_newline;
            q->refcount = 1;
            memcpy (q->text, nextline_text, nextline_len);
            vec->vector[i++] = q;

            nextline_text = (char *)p + 1;
            nextline_newline = 0;
        }
    nextline_len = p - nextline_text;
    q = xmalloc (sizeof (struct line) + nextline_len);
    q->vers = vers;
    q->text = (char *)q + sizeof (struct line);
    q->len = nextline_len;
    q->has_newline = nextline_newline;
    q->refcount = 1;
    memcpy (q->text, nextline_text, nextline_len);
    vec->vector[i] = q;

    vec->nlines += nnew;

    return 1;
}



/* Remove NLINES lines from VEC at position POS (where line 0 is the
   first line).  */
static void
linevector_delete (struct linevector *vec, unsigned int pos,
                   unsigned int nlines)
{
    unsigned int i;
    unsigned int last;

    last = vec->nlines - nlines;
    for (i = pos; i < pos + nlines; ++i)
    {
        if (--vec->vector[i]->refcount == 0)
            free (vec->vector[i]);
    }
    for (i = pos; i < last; ++i)
        vec->vector[i] = vec->vector[i + nlines];
    vec->nlines -= nlines;
}



/* Copy FROM to TO, copying the vectors but not the lines pointed to.  */
static void
linevector_copy (struct linevector *to, struct linevector *from)
{
    unsigned int ln;

    for (ln = 0; ln < to->nlines; ++ln)
    {
        if (--to->vector[ln]->refcount == 0)
            free (to->vector[ln]);
    }
    if (from->nlines > to->lines_alloced)
    {
        if (to->lines_alloced == 0)
            to->lines_alloced = 10;
        while (from->nlines > to->lines_alloced)
            to->lines_alloced *= 2;
        to->vector = xnrealloc (to->vector,
                                to->lines_alloced,
                                sizeof (*to->vector));
    }
    memcpy (to->vector, from->vector,
            xtimes (from->nlines, sizeof (*to->vector)));
    to->nlines = from->nlines;
    for (ln = 0; ln < to->nlines; ++ln)
        ++to->vector[ln]->refcount;
}



/* Free storage associated with linevector.  */
static void
linevector_free (struct linevector *vec)
{
    unsigned int ln;

    if (vec->vector != NULL)
    {
        for (ln = 0; ln < vec->nlines; ++ln)
            if (--vec->vector[ln]->refcount == 0)
                free (vec->vector[ln]);

        free (vec->vector);
    }
}



/* Given a textual string giving the month (1-12), terminated with any
   character not recognized by atoi, return the 3 character name to
   print it with.  I do not think it is a good idea to change these
   strings based on the locale; they are standard abbreviations (for
   example in rfc822 mail messages) which should be widely understood.
   Returns a pointer into static readonly storage.  */
static const char *
month_printname (const char *month)
{
    static const char *const months[] =
      {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
    int mnum;

    mnum = atoi (month);
    if (mnum < 1 || mnum > 12)
        return "???";
    return months[mnum - 1];
}



/* Apply changes to the line vector LINES.  DIFFBUF is a buffer of
   length DIFFLEN holding the change text from an RCS file (the output
   of diff -n).  NAME is used in error messages.  The VERS field of
   any line added is set to ADDVERS.  The VERS field of any line
   deleted is set to DELVERS, unless DELVERS is NULL, in which case
   the VERS field of deleted lines is unchanged.  The function returns
   non-zero if the change text is applied successfully.  It returns
   zero if the change text does not appear to apply to LINES (e.g., a
   line number is invalid).  If the change text is improperly
   formatted (e.g., it is not the output of diff -n), the function
   calls error with a status of 1, causing the program to exit.  */
static int
apply_rcs_changes (struct linevector *lines, const char *diffbuf,
                   size_t difflen, const char *name, RCSVers *addvers,
                   RCSVers *delvers)
{
    const char *p;
    const char *q;
    int op;
    /* The RCS format throws us for a loop in that the deltafrags (if
       we define a deltafrag as an add or a delete) need to be applied
       in reverse order.  So we stick them into a linked list.  */
    struct deltafrag {
        enum {FRAG_ADD, FRAG_DELETE} type;
        unsigned long pos;
        unsigned long nlines;
        const char *new_lines;
        size_t len;
        struct deltafrag *next;
    };
    struct deltafrag *dfhead;
    struct deltafrag *df;
    int err;

    dfhead = NULL;
    for (p = diffbuf; p != NULL && p < diffbuf + difflen; )
    {
        op = *p++;
        if (op != 'a' && op != 'd')
            /* Can't just skip over the deltafrag, because the value
               of op determines the syntax.  */
            error (1, 0, "unrecognized operation '\\x%x' in %s",
                   op, name);
        df = xmalloc (sizeof (struct deltafrag));
        df->next = dfhead;
        dfhead = df;
        df->pos = strtoul (p, (char **) &q, 10);

        if (p == q)
            error (1, 0, "number expected in %s", name);
        p = q;
        if (*p++ != ' ')
            error (1, 0, "space expected in %s", name);
        df->nlines = strtoul (p, (char **) &q, 10);
        if (p == q)
            error (1, 0, "number expected in %s", name);
        p = q;
        if (*p++ != '\012')
            error (1, 0, "linefeed expected in %s", name);

        if (op == 'a')
        {
            unsigned int i;

            df->type = FRAG_ADD;
            i = df->nlines;
            /* The text we want is the number of lines specified, or
               until the end of the value, whichever comes first (it
               will be the former except in the case where we are
               adding a line which does not end in newline).  */
            for (q = p; i != 0; ++q)
                if (*q == '\n')
                    --i;
                else if (q == diffbuf + difflen)
                {
                    if (i != 1)
                        error (1, 0, "premature end of change in %s", name);
                    else
                        break;
                }

            /* Stash away a pointer to the text we are adding.  */
            df->new_lines = p;
            df->len = q - p;

            p = q;
        }
        else
        {
            /* Correct for the fact that line numbers in RCS files
               start with 1.  */
            --df->pos;

            assert (op == 'd');
            df->type = FRAG_DELETE;
        }
    }

    err = 0;
    for (df = dfhead; df != NULL;)
    {
        unsigned int ln;

        /* Once an error is encountered, just free the rest of the list and
         * return.
         */
        if (!err)
            switch (df->type)
            {
            case FRAG_ADD:
                if (! linevector_add (lines, df->new_lines, df->len, addvers,
                                      df->pos))
                    err = 1;
                break;
            case FRAG_DELETE:
                if (df->pos > lines->nlines
                    || df->pos + df->nlines > lines->nlines)
                    return 0;
                if (delvers != NULL)
                    for (ln = df->pos; ln < df->pos + df->nlines; ++ln)
                        lines->vector[ln]->vers = delvers;
                linevector_delete (lines, df->pos, df->nlines);
                break;
            }

        df = df->next;
        free (dfhead);
        dfhead = df;
    }

    return !err;
}



/* Apply an RCS change text to a buffer.  The function name starts
   with rcs rather than RCS because this does not take an RCSNode
   argument.  NAME is used in error messages.  TEXTBUF is the text
   buffer to change, and TEXTLEN is the size.  DIFFBUF and DIFFLEN are
   the change buffer and size.  The new buffer is returned in *RETBUF
   and *RETLEN.  The new buffer is allocated by xmalloc.

   Return 1 for success.  On failure, call error and return 0.  */
int
rcs_change_text (const char *name, char *textbuf, size_t textlen,
                 const char *diffbuf, size_t difflen, char **retbuf,
                 size_t *retlen)
{
    struct linevector lines;
    int ret;

    *retbuf = NULL;
    *retlen = 0;

    linevector_init (&lines);

    if (! linevector_add (&lines, textbuf, textlen, NULL, 0))
        error (1, 0, "cannot initialize line vector");

    if (! apply_rcs_changes (&lines, diffbuf, difflen, name, NULL, NULL))
    {
        error (0, 0, "invalid change text in %s", name);
        ret = 0;
    }
    else
    {
        char *p;
        size_t n;
        unsigned int ln;

        n = 0;
        for (ln = 0; ln < lines.nlines; ++ln)
            /* 1 for \n */
            n += lines.vector[ln]->len + 1;

        p = xmalloc (n);
        *retbuf = p;

        for (ln = 0; ln < lines.nlines; ++ln)
        {
            memcpy (p, lines.vector[ln]->text, lines.vector[ln]->len);
            p += lines.vector[ln]->len;
            if (lines.vector[ln]->has_newline)
                *p++ = '\n';
        }

        *retlen = p - *retbuf;
        assert (*retlen <= n);

        ret = 1;
    }

    linevector_free (&lines);

    return ret;
}



/* Walk the deltas in RCS to get to revision VERSION.

   If OP is RCS_ANNOTATE, then write annotations using cvs_output.

   If OP is RCS_FETCH, then put the contents of VERSION into a
   newly-malloc'd array and put a pointer to it in *TEXT.  Each line
   is \n terminated; the caller is responsible for converting text
   files if desired.  The total length is put in *LEN.

   If FP is non-NULL, it should be a file descriptor open to the file
   RCS with file position pointing to the deltas.  We close the file
   when we are done.

   If LOG is non-NULL, then *LOG is set to the log message of VERSION,
   and *LOGLEN is set to the length of the log message.

   On error, give a fatal error.  */
void
RCS_deltas (RCSNode *rcs, FILE *fp, struct rcsbuffer *rcsbuf,
            const char *version, enum rcs_delta_op op, char **text,
            size_t *len, char **log, size_t *loglen)
{
    struct rcsbuffer rcsbuf_local;
    char *branchversion;
    char *cpversion;
    char *key;
    char *value;
    size_t vallen;
    RCSVers *vers;
    RCSVers *prev_vers;
    RCSVers *trunk_vers;
    char *next;
    int ishead, isnext, isversion, onbranch;
    Node *node;
    struct linevector headlines;
    struct linevector curlines;
    struct linevector trunklines;
    int foundhead;

    assert (version);

    if (fp == NULL)
    {
        rcsbuf_cache_open (rcs, rcs->delta_pos, &fp, &rcsbuf_local);
        rcsbuf = &rcsbuf_local;
    }

   if (log) *log = NULL;

    ishead = 1;
    vers = NULL;
    prev_vers = NULL;
    trunk_vers = NULL;
    next = NULL;
    onbranch = 0;
    foundhead = 0;

    linevector_init (&curlines);
    linevector_init (&headlines);
    linevector_init (&trunklines);

    /* We set BRANCHVERSION to the version we are currently looking
       for.  Initially, this is the version on the trunk from which
       VERSION branches off.  If VERSION is not a branch, then
       BRANCHVERSION is just VERSION.  */
    branchversion = xstrdup (version);
    cpversion = strchr (branchversion, '.');
    if (cpversion != NULL)
        cpversion = strchr (cpversion + 1, '.');
    if (cpversion != NULL)
        *cpversion = '\0';

    do {
        if (! rcsbuf_getrevnum (rcsbuf, &key))
            error (1, 0, "unexpected EOF reading RCS file %s", rcs->print_path);

        if (next != NULL && ! STREQ (next, key))
        {
            /* This is not the next version we need.  It is a branch
               version which we want to ignore.  */
            isnext = 0;
            isversion = 0;
        }
        else
        {
            isnext = 1;

            /* look up the revision */
            node = findnode (rcs->versions, key);
            if (node == NULL)
                error (1, 0,
                       "mismatch in rcs file %s between deltas and deltatexts (%s)",
                       rcs->print_path, key);

            /* Stash the previous version.  */
            prev_vers = vers;

            vers = node->data;
            next = vers->next;

            /* Compare key and trunkversion now, because key points to
               storage controlled by rcsbuf_getkey.  */
            if (STREQ (branchversion, key))
                isversion = 1;
            else
                isversion = 0;
        }

        while (1)
        {
            if (! rcsbuf_getkey (rcsbuf, &key, &value))
                error (1, 0, "%s does not appear to be a valid rcs file",
                       rcs->print_path);

            if (log != NULL
                && isversion
                && STREQ (key, "log")
                && STREQ (branchversion, version))
            {
                if (*log != NULL)
                {
                    error (0, 0, "Duplicate `log' keyword in RCS file (`%s').",
                           rcs->print_path);
                    free (*log);
                }
                *log = rcsbuf_valcopy (rcsbuf, value, 0, loglen);
            }

            if (STREQ (key, "text"))
            {
                rcsbuf_valpolish (rcsbuf, value, 0, &vallen);
                if (ishead)
                {
                    if (! linevector_add (&curlines, value, vallen, NULL, 0))
                        error (1, 0, "invalid rcs file %s", rcs->print_path);

                    ishead = 0;
                }
                else if (isnext)
                {
                    if (! apply_rcs_changes (&curlines, value, vallen,
                                             rcs->path,
                                             onbranch ? vers : NULL,
                                             onbranch ? NULL : prev_vers))
                        error (1, 0, "invalid change text in %s", rcs->print_path);
                }
                break;
            }
        }

        if (isversion)
        {
            /* This is either the version we want, or it is the
               branchpoint to the version we want.  */
            if (STREQ (branchversion, version))
            {
                /* This is the version we want.  */
                linevector_copy (&headlines, &curlines);
                foundhead = 1;
                if (onbranch)
                {
                    /* We have found this version by tracking up a
                       branch.  Restore back to the lines we saved
                       when we left the trunk, and continue tracking
                       down the trunk.  */
                    onbranch = 0;
                    vers = trunk_vers;
                    next = vers->next;
                    linevector_copy (&curlines, &trunklines);
                }
            }
            else
            {
                Node *p;

                /* We need to look up the branch.  */
                onbranch = 1;

                if (numdots (branchversion) < 2)
                {
                    unsigned int ln;

                    /* We are leaving the trunk; save the current
                       lines so that we can restore them when we
                       continue tracking down the trunk.  */
                    trunk_vers = vers;
                    linevector_copy (&trunklines, &curlines);

                    /* Reset the version information we have
                       accumulated so far.  It only applies to the
                       changes from the head to this version.  */
                    for (ln = 0; ln < curlines.nlines; ++ln)
                        curlines.vector[ln]->vers = NULL;
                }

                /* The next version we want is the entry on
                   VERS->branches which matches this branch.  For
                   example, suppose VERSION is 1.21.4.3 and
                   BRANCHVERSION was 1.21.  Then we look for an entry
                   starting with "1.21.4" and we'll put it (probably
                   1.21.4.1) in NEXT.  We'll advance BRANCHVERSION by
                   two dots (in this example, to 1.21.4.3).  */

                if (vers->branches == NULL)
                    error (1, 0, "missing expected branches in %s",
                           rcs->print_path);
                if (!cpversion)
                    error (1, 0, "Invalid revision number in `%s'.",
                           rcs->print_path);
                *cpversion = '.';
                ++cpversion;
                cpversion = strchr (cpversion, '.');
                if (cpversion == NULL)
                    error (1, 0, "version number confusion in %s",
                           rcs->print_path);
                for (p = vers->branches->list->next;
                     p != vers->branches->list;
                     p = p->next)
                    if (strncmp (p->key, branchversion,
                                 cpversion - branchversion) == 0)
                        break;
                if (p == vers->branches->list)
                    error (1, 0, "missing expected branch in %s",
                           rcs->print_path);

                next = p->key;

                cpversion = strchr (cpversion + 1, '.');
                if (cpversion != NULL)
                    *cpversion = '\0';
            }
        }
        if (op == RCS_FETCH && foundhead)
            break;
    } while (next != NULL);

    free (branchversion);

    rcsbuf_cache (rcs, rcsbuf);

    if (! foundhead)
        error (1, 0, "could not find desired version %s in %s",
               version, rcs->print_path);

    /* Now print out or return the data we have just computed.  */
    switch (op)
    {
        case RCS_ANNOTATE:
            {
                unsigned int ln;

                for (ln = 0; ln < headlines.nlines; ++ln)
                {
                    char *buf;
                    /* Period which separates year from month in date.  */
                    char *ym;
                    /* Period which separates month from day in date.  */
                    char *md;
                    RCSVers *prvers;

                    prvers = headlines.vector[ln]->vers;
                    if (prvers == NULL)
                        prvers = vers;

                    buf = xmalloc (strlen (prvers->version) + 24);
                    sprintf (buf, "%-12s (%-8.8s ",
                             prvers->version,
                             prvers->author);
                    cvs_output (buf, 0);
                    free (buf);

                    /* Now output the date.  */
                    ym = strchr (prvers->date, '.');
                    if (ym == NULL)
                    {
                        cvs_output ("??", 0);
                        cvs_output ("-???", 0);
                        cvs_output ("-??", 0);
                    }
                    else
                    {
                        md = strchr (ym + 1, '.');
                        if (md == NULL)
                            cvs_output ("??", 0);
                        else
                            cvs_output (md + 1, 2);

                        cvs_output ("-", 1);
                        cvs_output (month_printname (ym + 1), 0);
                        cvs_output ("-", 1);
                        /* Only output the last two digits of the year.  Our output
                           lines are long enough as it is without printing the
                           century.  */
                        cvs_output (ym - 2, 2);
                    }
                    cvs_output ("): ", 0);
                    if (headlines.vector[ln]->len != 0)
                        cvs_output (headlines.vector[ln]->text,
                                    headlines.vector[ln]->len);
                    cvs_output ("\n", 1);
                }
            }
            break;
        case RCS_FETCH:
            {
                char *p;
                size_t n;
                unsigned int ln;

                assert (text != NULL);
                assert (len != NULL);

                n = 0;
                for (ln = 0; ln < headlines.nlines; ++ln)
                    /* 1 for \n */
                    n += headlines.vector[ln]->len + 1;
                p = xmalloc (n);
                *text = p;
                for (ln = 0; ln < headlines.nlines; ++ln)
                {
                    memcpy (p, headlines.vector[ln]->text,
                            headlines.vector[ln]->len);
                    p += headlines.vector[ln]->len;
                    if (headlines.vector[ln]->has_newline)
                        *p++ = '\n';
                }
                *len = p - *text;
                assert (*len <= n);
            }
            break;
    }

    linevector_free (&curlines);
    linevector_free (&headlines);
    linevector_free (&trunklines);

    return;
}



/* Read the information for a single delta from the RCS buffer RCSBUF,
   whose name is RCSFILE.  *KEYP and *VALP are either NULL, or the
   first key/value pair to read, as set by rcsbuf_getkey. Return NULL
   if there are no more deltas.  Store the key/value pair which
   terminated the read in *KEYP and *VALP.  */
static RCSVers *
getdelta (struct rcsbuffer *rcsbuf, char *rcsfile, char **keyp, char **valp)
{
    RCSVers *vnode;
    char *key, *value, *cp;
    Node *kv;

    /* Get revision number if it wasn't passed in. This uses
       rcsbuf_getkey because it doesn't croak when encountering
       unexpected input.  As a result, we have to play unholy games
       with `key' and `value'. */
    if (*keyp != NULL)
    {
        key = *keyp;
        value = *valp;
    }
    else
    {
        if (! rcsbuf_getkey (rcsbuf, &key, &value))
            error (1, 0, "%s: unexpected EOF", rcsfile);
    }

    /* Make sure that it is a revision number and not a cabbage 
       or something. */
    for (cp = key;
         (isdigit ((unsigned char) *cp) || *cp == '.') && *cp != '\0';
         cp++)
        /* do nothing */ ;
    /* Note that when comparing with RCSDATE, we are not massaging
       VALUE from the string found in the RCS file.  This is OK since
       we know exactly what to expect.  */
    if (*cp != '\0' || strncmp (RCSDATE, value, (sizeof RCSDATE) - 1) != 0)
    {
        *keyp = key;
        *valp = value;
        return NULL;
    }

    vnode = xmalloc (sizeof (RCSVers));
    memset (vnode, 0, sizeof (RCSVers));

    vnode->version = xstrdup (key);

    /* Grab the value of the date from value.  Note that we are not
       massaging VALUE from the string found in the RCS file.  */
    cp = value + (sizeof RCSDATE) - 1;  /* skip the "date" keyword */
    while (whitespace (*cp))            /* take space off front of value */
        cp++;

    vnode->date = xstrdup (cp);

    /* Get author field.  */
    if (! rcsbuf_getkey (rcsbuf, &key, &value))
    {
        error (1, 0, "unexpected end of file reading %s", rcsfile);
    }
    if (! STREQ (key, "author"))
        error (1, 0, "\
unable to parse %s; `author' not in the expected place", rcsfile);
    vnode->author = rcsbuf_valcopy (rcsbuf, value, 0, NULL);

    /* Get state field.  */
    if (! rcsbuf_getkey (rcsbuf, &key, &value))
    {
        error (1, 0, "unexpected end of file reading %s", rcsfile);
    }
    if (! STREQ (key, "state"))
        error (1, 0, "\
unable to parse %s; `state' not in the expected place", rcsfile);
    vnode->state = rcsbuf_valcopy (rcsbuf, value, 0, NULL);
    /* The value is optional, according to rcsfile(5).  */
    if (value != NULL && STREQ (value, RCSDEAD))
    {
        vnode->dead = 1;
    }

    /* Note that "branches" and "next" are in fact mandatory, according
       to doc/RCSFILES.  */

    /* fill in the branch list (if any branches exist) */
    if (! rcsbuf_getkey (rcsbuf, &key, &value))
    {
        error (1, 0, "unexpected end of file reading %s", rcsfile);
    }
    if (STREQ (key, RCSDESC))
    {
        *keyp = key;
        *valp = value;
        /* Probably could/should be a fatal error.  */
        error (0, 0, "warning: 'branches' keyword missing from %s", rcsfile);
        return vnode;
    }
    if (value != NULL)
    {
        vnode->branches = getlist ();
        /* Note that we are not massaging VALUE from the string found
           in the RCS file.  */
        do_branches (vnode->branches, value);
    }

    /* fill in the next field if there is a next revision */
    if (! rcsbuf_getkey (rcsbuf, &key, &value))
    {
        error (1, 0, "unexpected end of file reading %s", rcsfile);
    }
    if (STREQ (key, RCSDESC))
    {
        *keyp = key;
        *valp = value;
        /* Probably could/should be a fatal error.  */
        error (0, 0, "warning: 'next' keyword missing from %s", rcsfile);
        return vnode;
    }
    if (value != NULL)
        vnode->next = rcsbuf_valcopy (rcsbuf, value, 0, NULL);

    /*
     * XXX - this is where we put the symbolic link stuff???
     * (into newphrases in the deltas).
     */
    while (1)
    {
        if (! rcsbuf_getkey (rcsbuf, &key, &value))
            error (1, 0, "unexpected end of file reading %s", rcsfile);

        /* The `desc' keyword is the end of the deltas. */
        if (strcmp (key, RCSDESC) == 0)
            break;

#ifdef PRESERVE_PERMISSIONS_SUPPORT

        /* The `hardlinks' value is a group of words, which must
           be parsed separately and added as a list to vnode->hardlinks. */
        if (strcmp (key, "hardlinks") == 0)
        {
            char *word;

            vnode->hardlinks = getlist();
            while ((word = rcsbuf_valword (rcsbuf, &value)) != NULL)
            {
                Node *n = getnode();
                n->key = word;
                addnode (vnode->hardlinks, n);
            }
            continue;
        }
#endif

        /* Enable use of repositories created by certain obsolete
           versions of CVS.  This code should remain indefinately;
           there is no procedure for converting old repositories, and
           checking for it is harmless.  */
        if (STREQ (key, RCSDEAD))
        {
            vnode->dead = 1;
            if (vnode->state != NULL)
                free (vnode->state);
            vnode->state = xstrdup (RCSDEAD);
            continue;
        }
        /* if we have a new revision number, we're done with this delta */
        for (cp = key;
             (isdigit ((unsigned char) *cp) || *cp == '.') && *cp != '\0';
             cp++)
            /* do nothing */ ;
        /* Note that when comparing with RCSDATE, we are not massaging
           VALUE from the string found in the RCS file.  This is OK
           since we know exactly what to expect.  */
        if (*cp == '\0' && strncmp (RCSDATE, value, strlen (RCSDATE)) == 0)
            break;

        /* At this point, key and value represent a user-defined field
           in the delta node. */
        if (vnode->other_delta == NULL)
            vnode->other_delta = getlist ();
        kv = getnode ();
        kv->type = rcsbuf_valcmp (rcsbuf) ? RCSCMPFLD : RCSFIELD;
        kv->key = xstrdup (key);
        kv->data = rcsbuf_valcopy (rcsbuf, value, kv->type == RCSFIELD, NULL);
        if (addnode (vnode->other_delta, kv) != 0)
        {
            /* Complaining about duplicate keys in newphrases seems
               questionable, in that we don't know what they mean and
               doc/RCSFILES has no prohibition on several newphrases
               with the same key.  But we can't store more than one as
               long as we store them in a List *.  */
            error (0, 0, "warning: duplicate key `%s' in RCS file `%s'",
                   key, rcsfile);
            freenode (kv);
        }
    }

    /* Return the key which caused us to fail back to the caller.  */
    *keyp = key;
    *valp = value;

    return vnode;
}



static void
freedeltatext (Deltatext *d)
{
    if (d->version != NULL)
        free (d->version);
    if (d->log != NULL)
        free (d->log);
    if (d->text != NULL)
        free (d->text);
    if (d->other != NULL)
        dellist (&d->other);
    free (d);
}

static Deltatext *
RCS_getdeltatext (RCSNode *rcs, FILE *fp, struct rcsbuffer *rcsbuf)
{
    char *num;
    char *key, *value;
    Node *p;
    Deltatext *d;

    /* Get the revision number. */
    if (! rcsbuf_getrevnum (rcsbuf, &num))
    {
        /* If num == NULL, it means we reached EOF naturally.  That's
           fine. */
        if (num == NULL)
            return NULL;
        else
            error (1, 0, "%s: unexpected EOF", rcs->print_path);
    }

    p = findnode (rcs->versions, num);
    if (p == NULL)
        error (1, 0, "mismatch in rcs file %s between deltas and deltatexts (%s)",
               rcs->print_path, num);

    d = xmalloc (sizeof (Deltatext));
    d->version = xstrdup (num);

    /* Get the log message. */
    if (! rcsbuf_getkey (rcsbuf, &key, &value))
        error (1, 0, "%s, delta %s: unexpected EOF", rcs->print_path, num);
    if (! STREQ (key, "log"))
        error (1, 0, "%s, delta %s: expected `log', got `%s'",
               rcs->print_path, num, key);
    d->log = rcsbuf_valcopy (rcsbuf, value, 0, NULL);

    /* Get random newphrases. */
    d->other = getlist();
    while (1)
    {
        if (! rcsbuf_getkey (rcsbuf, &key, &value))
            error (1, 0, "%s, delta %s: unexpected EOF", rcs->print_path, num);

        if (STREQ (key, "text"))
            break;

        p = getnode();
        p->type = rcsbuf_valcmp (rcsbuf) ? RCSCMPFLD : RCSFIELD;
        p->key = xstrdup (key);
        p->data = rcsbuf_valcopy (rcsbuf, value, p->type == RCSFIELD, NULL);
        if (addnode (d->other, p) < 0)
        {
            error (0, 0, "warning: %s, delta %s: duplicate field `%s'",
                   rcs->print_path, num, key);
        }
    }

    /* Get the change text. We already know that this key is `text'. */
    d->text = rcsbuf_valcopy (rcsbuf, value, 0, &d->len);

    return d;
}



/* RCS output functions, for writing RCS format files from RCSNode
   structures.

   For most of this work, RCS 5.7 uses an `aprintf' function which aborts
   program upon error.  Instead, these functions check the output status
   of the stream right before closing it, and aborts if an error condition
   is found.  The RCS solution is probably the better one: it produces
   more overhead, but will produce a clearer diagnostic in the case of
   catastrophic error.  In either case, however, the repository will probably
   not get corrupted. */
static int
putsymbol_proc (Node *symnode, void *fparg)
{
    FILE *fp = fparg;

    /* A fiddly optimization: this code used to just call fprintf, but
       in an old repository with hundreds of tags this can get called
       hundreds of thousands of times when doing a cvs tag.  Since
       tagging is a relatively common operation, and using putc and
       fputs is just as comprehensible, the change is worthwhile.  */
    putc ('\n', fp);
    putc ('\t', fp);
    fputs (symnode->key, fp);
    putc (':', fp);
    fputs (symnode->data, fp);
    return 0;
}



/* putlock_proc is like putsymbol_proc, but key and data are reversed. */
static int
putlock_proc (Node *symnode, void *fp)
{
    return fprintf (fp, "\n\t%s:%s", (char *)symnode->data, symnode->key);
}



static int
putrcsfield_proc (Node *node, void *vfp)
{
    FILE *fp = vfp;

    /* Some magic keys used internally by CVS start with `;'. Skip them. */
    if (node->key[0] == ';')
        return 0;

    fprintf (fp, "\n%s\t", node->key);
    if (node->data != NULL)
    {
        /* If the field's value contains evil characters,
           it must be stringified. */
        /* FIXME: This does not quite get it right.  "7jk8f" is not a valid
           value for a value in a newpharse, according to doc/RCSFILES,
           because digits are not valid in an "id".  We might do OK by
           always writing strings (enclosed in @@).  Would be nice to
           explicitly mention this one way or another in doc/RCSFILES.
           A case where we are wrong in a much more clear-cut way is that
           we let through non-graphic characters such as whitespace and
           control characters.  */

        if (node->type == RCSCMPFLD || strpbrk (node->data, "$,.:;@") == NULL)
            fputs (node->data, fp);
        else
        {
            putc ('@', fp);
            expand_at_signs (node->data, (off_t) strlen (node->data), fp);
            putc ('@', fp);
        }
    }

    /* desc, log and text fields should not be terminated with semicolon;
       all other fields should be. */
    if (! STREQ (node->key, "desc") &&
        ! STREQ (node->key, "log") &&
        ! STREQ (node->key, "text"))
    {
        putc (';', fp);
    }
    return 0;
}



#ifdef PRESERVE_PERMISSIONS_SUPPORT

/* Save a filename in a `hardlinks' RCS field.  NODE->KEY will contain
   a full pathname, but currently only basenames are stored in the RCS
   node.  Assume that the filename includes nasty characters and
   @-escape it. */

static int
puthardlink_proc (node, vfp)
    Node *node;
    void *vfp;
{
    FILE *fp = vfp;
    char *basename = strrchr (node->key, '/');

    if (basename == NULL)
        basename = node->key;
    else
        ++basename;

    putc ('\t', fp);
    putc ('@', fp);
    (void) expand_at_signs (basename, strlen (basename), fp);
    putc ('@', fp);

    return 0;
}

#endif /* PRESERVE_PERMISSIONS_SUPPORT */



/* Output the admin node for RCS into stream FP. */
static void
RCS_putadmin (RCSNode *rcs, FILE *fp)
{
    fprintf (fp, "%s\t%s;\n", RCSHEAD, rcs->head ? rcs->head : "");
    if (rcs->branch)
        fprintf (fp, "%s\t%s;\n", RCSBRANCH, rcs->branch);

    fputs ("access", fp);
    if (rcs->access)
    {
        char *p, *s;
        s = xstrdup (rcs->access);
        for (p = strtok (s, " \n\t"); p != NULL; p = strtok (NULL, " \n\t"))
            fprintf (fp, "\n\t%s", p);
        free (s);
    }
    fputs (";\n", fp);

    fputs (RCSSYMBOLS, fp);
    /* If we haven't had to convert the symbols to a list yet, don't
       force a conversion now; just write out the string.  */
    if (rcs->symbols == NULL && rcs->symbols_data != NULL)
    {
        fputs ("\n\t", fp);
        fputs (rcs->symbols_data, fp);
    }
    else
        walklist (RCS_symbols (rcs), putsymbol_proc, fp);
    fputs (";\n", fp);

    fputs ("locks", fp);
    if (rcs->locks_data)
        fprintf (fp, "\t%s", rcs->locks_data);
    else if (rcs->locks)
        walklist (rcs->locks, putlock_proc, fp);
    if (rcs->strict_locks)
        fprintf (fp, "; strict");
    fputs (";\n", fp);

    if (rcs->comment)
    {
        fprintf (fp, "comment\t@");
        expand_at_signs (rcs->comment, (off_t) strlen (rcs->comment), fp);
        fputs ("@;\n", fp);
    }
    if (rcs->expand && ! STREQ (rcs->expand, "kv"))
        fprintf (fp, "%s\t@%s@;\n", RCSEXPAND, rcs->expand);

    walklist (rcs->other, putrcsfield_proc, fp);

    putc ('\n', fp);
}



static void
putdelta (RCSVers *vers, FILE *fp)
{
    Node *bp, *start;

    /* Skip if no revision was supplied, or if it is outdated (cvs admin -o) */
    if (vers == NULL || vers->outdated)
        return;

    fprintf (fp, "\n%s\n%s\t%s;\t%s %s;\t%s %s;\nbranches",
             vers->version,
             RCSDATE, vers->date,
             "author", vers->author,
             "state", vers->state ? vers->state : "");

    if (vers->branches != NULL)
    {
        start = vers->branches->list;
        for (bp = start->next; bp != start; bp = bp->next)
            fprintf (fp, "\n\t%s", bp->key);
    }

    fprintf (fp, ";\nnext\t%s;", vers->next ? vers->next : "");

    walklist (vers->other_delta, putrcsfield_proc, fp);

#ifdef PRESERVE_PERMISSIONS_SUPPORT
    if (vers->hardlinks)
    {
        fprintf (fp, "\nhardlinks");
        walklist (vers->hardlinks, puthardlink_proc, fp);
        putc (';', fp);
    }
#endif
    putc ('\n', fp);
}



static void
RCS_putdtree (RCSNode *rcs, char *rev, FILE *fp)
{
    RCSVers *versp;
    Node *p, *branch;

    /* Previously, this function used a recursive implementation, but
       if the trunk has a huge number of revisions and the program
       stack is not big, a stack overflow could occur, so this
       nonrecursive version was developed to be more safe. */
    Node *branchlist, *onebranch;
    List *branches;
    List *onebranchlist;

    if (rev == NULL)
        return;

    branches = getlist();

    for (; rev != NULL;)
    {
        /* Find the delta node for this revision. */
        p = findnode (rcs->versions, rev);
        if (p == NULL)
        {
            error (1, 0,
                   "error parsing repository file %s, file may be corrupt.", 
                   rcs->path);
        }
 
        versp = p->data;

        /* Print the delta node and go for its `next' node.  This
           prints the trunk. If there are any branches printed on this
           revision, mark we have some. */
        putdelta (versp, fp);
        /* Store branch information into branch list so to write its
           trunk afterwards */
        if (versp->branches != NULL)
        {
            branch = getnode();
            branch->data = versp->branches;

            addnode(branches, branch);
        }

        rev = versp->next;
    }

    /* If there are any branches printed on this revision,
       print those trunks as well. */
    branchlist = branches->list;
    for (branch = branchlist->next;
         branch != branchlist;
         branch = branch->next)
    {
        onebranchlist = (List *)(branch->data);
        onebranch = onebranchlist->list;
        for (p = onebranch->next; p != onebranch; p = p->next)
            RCS_putdtree (rcs, p->key, fp);

        branch->data = NULL; /* so to prevent its freeing on dellist */
    }

    dellist(&branches);
}



static void
RCS_putdesc (RCSNode *rcs, FILE *fp)
{
    fprintf (fp, "\n\n%s\n@", RCSDESC);
    if (rcs->desc != NULL)
    {
        off_t len = (off_t) strlen (rcs->desc);
        if (len > 0)
        {
            expand_at_signs (rcs->desc, len, fp);
            if (rcs->desc[len-1] != '\n')
                putc ('\n', fp);
        }
    }
    fputs ("@\n", fp);
}



static void
putdeltatext (FILE *fp, Deltatext *d)
{
    fprintf (fp, "\n\n%s\nlog\n@", d->version);
    if (d->log != NULL)
    {
        int loglen = strlen (d->log);
        expand_at_signs (d->log, (off_t) loglen, fp);
        if (d->log[loglen-1] != '\n')
            putc ('\n', fp);
    }
    putc ('@', fp);

    walklist (d->other, putrcsfield_proc, fp);

    fputs ("\ntext\n@", fp);
    if (d->text != NULL)
        expand_at_signs (d->text, (off_t) d->len, fp);
    fputs ("@\n", fp);
}



/* TODO: the whole mechanism for updating deltas is kludgey... more
   sensible would be to supply all the necessary info in a `newdeltatext'
   field for RCSVers nodes. -twp */

/* Copy delta text nodes from FIN to FOUT.  If NEWDTEXT is non-NULL, it
   is a new delta text node, and should be added to the tree at the
   node whose revision number is INSERTPT.  (Note that trunk nodes are
   written in decreasing order, and branch nodes are written in
   increasing order.) */
static void
RCS_copydeltas (RCSNode *rcs, FILE *fin, struct rcsbuffer *rcsbufin,
                FILE *fout, Deltatext *newdtext, char *insertpt)
{
    int actions;
    RCSVers *dadmin;
    Node *np;
    int insertbefore, found;
    char *bufrest;
    int nls;
    size_t buflen;
#ifndef HAVE_MMAP
    char buf[8192];
    int got;
#endif

    /* Count the number of versions for which we have to do some
       special operation.  */
    actions = walklist (rcs->versions, count_delta_actions, NULL);

    /* Make a note of whether NEWDTEXT should be inserted
       before or after its INSERTPT. */
    insertbefore = (newdtext != NULL && numdots (newdtext->version) == 1);

    while (actions != 0 || newdtext != NULL)
    {
        Deltatext *dtext;

        dtext = RCS_getdeltatext (rcs, fin, rcsbufin);

        /* We shouldn't hit EOF here, because that would imply that
           some action was not taken, or that we could not insert
           NEWDTEXT.  */
        if (dtext == NULL)
            error (1, 0, "internal error: EOF too early in RCS_copydeltas");

        found = (insertpt != NULL && STREQ (dtext->version, insertpt));
        if (found && insertbefore)
        {
            putdeltatext (fout, newdtext);
            newdtext = NULL;
            insertpt = NULL;
        }

        np = findnode (rcs->versions, dtext->version);
        dadmin = np->data;

        /* If this revision has been outdated, just skip it. */
        if (dadmin->outdated)
        {
            freedeltatext (dtext);
            --actions;
            continue;
        }
           
        /* Update the change text for this delta.  New change text
           data may come from cvs admin -m, cvs admin -o, or cvs ci. */
        if (dadmin->text != NULL)
        {
            if (dadmin->text->log != NULL || dadmin->text->text != NULL)
                --actions;
            if (dadmin->text->log != NULL)
            {
                free (dtext->log);
                dtext->log = dadmin->text->log;
                dadmin->text->log = NULL;
            }
            if (dadmin->text->text != NULL)
            {
                free (dtext->text);
                dtext->text = dadmin->text->text;
                dtext->len = dadmin->text->len;
                dadmin->text->text = NULL;
            }
        }
        putdeltatext (fout, dtext);
        freedeltatext (dtext);

        if (found && !insertbefore)
        {
            putdeltatext (fout, newdtext);
            newdtext = NULL;
            insertpt = NULL;
        }
    }

    /* Copy the rest of the file directly, without bothering to
       interpret it.  The caller will handle error checking by calling
       ferror.

       We just wrote a newline to the file, either in putdeltatext or
       in the caller.  However, we may not have read the corresponding
       newline from the file, because rcsbuf_getkey returns as soon as
       it finds the end of the '@' string for the desc or text key.
       Therefore, we may read three newlines when we should really
       only write two, and we check for that case here.  This is not
       an semantically important issue; we only do it to make our RCS
       files look traditional.  */

    nls = 3;

    rcsbuf_get_buffered (rcsbufin, &bufrest, &buflen);
    if (buflen > 0)
    {
        if (bufrest[0] != '\n'
            || strncmp (bufrest, "\n\n\n", buflen < 3 ? buflen : 3) != 0)
        {
            nls = 0;
        }
        else
        {
            if (buflen < 3)
                nls -= buflen;
            else
            {
                ++bufrest;
                --buflen;
                nls = 0;
            }
        }

        fwrite (bufrest, 1, buflen, fout);
    }
#ifndef HAVE_MMAP
    /* This bit isn't necessary when using mmap since the entire file
     * will already be available via the RCS buffer.  Besides, the
     * mmap code doesn't always keep the file pointer up to date, so
     * this adds some data twice.
     */
    while ((got = fread (buf, 1, sizeof buf, fin)) != 0)
    {
        if (nls > 0
            && got >= nls
            && buf[0] == '\n'
            && strncmp (buf, "\n\n\n", nls) == 0)
        {
            fwrite (buf + 1, 1, got - 1, fout);
        }
        else
        {
            fwrite (buf, 1, got, fout);
        }

        nls = 0;
    }
#endif /* HAVE_MMAP */
}



/* A helper procedure for RCS_copydeltas.  This is called via walklist
   to count the number of RCS revisions for which some special action
   is required.  */
static int
count_delta_actions (Node *np, void *ignore)
{
    RCSVers *dadmin = np->data;

    if (dadmin->outdated)
        return 1;

    if (dadmin->text != NULL
        && (dadmin->text->log != NULL || dadmin->text->text != NULL))
    {
        return 1;
    }

    return 0;
}



/*
 * Clean up temporary files.
 *
 * NOTES
 *   This function needs to be reentrant since a call to exit() can cause a
 *   call to this function, which can then be interrupted by a signal, which
 *   can cause a second call to this function.
 *
 * RETURNS
 *   Nothing.
 */
static void
rcs_cleanup (void)
{
    TRACE (TRACE_FUNCTION, "rcs_cleanup()");

    /* FIXME: Do not perform buffered I/O from an interrupt handler like
     * this (via error).  However, I'm leaving the error-calling code there
     * in the hope that on the rare occasion the error call is actually made
     * (e.g., a fluky I/O error or permissions problem prevents the deletion
     * of a just-created file) reentrancy won't be an issue.
     */

    /* We don't want to be interrupted during calls which set globals to NULL,
     * but we know that by the time we reach this function, interrupts have
     * already been blocked.
     */
    if (rcs_lockfile != NULL)
    {
        /* Use a tmp var since any of these functions could call exit, causing
         * us to be called a second time.
         */
        char *tmp = rcs_lockfile;
        rcs_lockfile = NULL;
        if (rcs_lockfd >= 0)
        {
            if (close (rcs_lockfd) != 0)
                error (0, errno, "error closing lock file %s", tmp);
            rcs_lockfd = -1;
        }

        /* Note that the checks for existence_error are because we can be
         * called from a signal handler, so we don't know whether the
         * files got created.
         */
        if (unlink_file (tmp) < 0
            && !existence_error (errno))
            error (0, errno, "cannot remove %s", tmp);
    }
}



/* RCS_internal_lockfile and RCS_internal_unlockfile perform RCS-style
   locking on the specified RCSFILE: for a file called `foo,v', open
   for writing a file called `,foo,'.

   Note that we what do here is quite different from what RCS does.
   RCS creates the ,foo, file before it reads the RCS file (if it
   knows that it will be writing later), so that it actually serves as
   a lock.  We don't; instead we rely on CVS writelocks.  This means
   that if someone is running RCS on the file at the same time they
   are running CVS on it, they might lose (we read the file,
   then RCS writes it, then we write it, clobbering the
   changes made by RCS).  I believe the current sentiment about this
   is "well, don't do that".

   A concern has been expressed about whether adopting the RCS
   strategy would slow us down.  I don't think so, since we need to
   write the ,foo, file anyway (unless perhaps if O_EXCL is slower or
   something).

   These do not perform quite the same function as the RCS -l option
   for locking files: they are intended to prevent competing RCS
   processes from stomping all over each other's laundry.  Hence,
   they are `internal' locking functions.

   If there is an error, give a fatal error; if we return we always
   return a non-NULL value.  */
static FILE *
rcs_internal_lockfile (char *rcsfile)
{
    struct stat rstat;
    FILE *fp;
    static int first_call = 1;

    if (first_call)
    {
        first_call = 0;
        /* Clean up if we get a signal or exit.  */
        cleanup_register (rcs_cleanup);
    }

    /* Get the lock file name: `,file,' for RCS file `file,v'. */
    assert (rcs_lockfile == NULL);
    assert (rcs_lockfd < 0);
    rcs_lockfile = rcs_lockfilename (rcsfile);

    /* Use the existing RCS file mode, or read-only if this is a new
       file.  (Really, this is a lie -- if this is a new file,
       RCS_checkin uses the permissions from the working copy.  For
       actually creating the file, we use 0444 as a safe default mode.) */
    if (stat (rcsfile, &rstat) < 0)
    {
        if (existence_error (errno))
            rstat.st_mode = S_IRUSR | S_IRGRP | S_IROTH;
        else
            error (1, errno, "cannot stat %s", rcsfile);
    }

    /* Try to open exclusively.  POSIX.1 guarantees that O_EXCL|O_CREAT
       guarantees an exclusive open.  According to the RCS source, with
       NFS v2 we must also throw in O_TRUNC and use an open mask that makes
       the file unwriteable.  For extensive justification, see the comments for
       rcswriteopen() in rcsedit.c, in RCS 5.7.  This is kind of pointless
       in the CVS case; see comment at the start of this file concerning
       general ,foo, file strategy.

       There is some sentiment that with NFSv3 and such, that one can
       rely on O_EXCL these days.  This might be true for unix (I
       don't really know), but I am still pretty skeptical in the case
       of the non-unix systems.  */
    rcs_lockfd = open (rcs_lockfile,
                       OPEN_BINARY | O_WRONLY | O_CREAT | O_EXCL | O_TRUNC,
                       S_IRUSR | S_IRGRP | S_IROTH);

    if (rcs_lockfd < 0)
    {
        error (1, errno, "could not open lock file `%s'", rcs_lockfile);
    }

    /* Force the file permissions, and return a stream object. */
    /* Because we change the modes later, we don't worry about
       this in the non-HAVE_FCHMOD case.  */
#ifdef HAVE_FCHMOD
    if (fchmod (rcs_lockfd, rstat.st_mode) < 0)
        error (1, errno, "cannot change mode for %s", rcs_lockfile);
#endif
    fp = fdopen (rcs_lockfd, FOPEN_BINARY_WRITE);
    if (fp == NULL)
        error (1, errno, "cannot fdopen %s", rcs_lockfile);

    return fp;
}



static void
rcs_internal_unlockfile (FILE *fp, char *rcsfile)
{
    assert (rcs_lockfile != NULL);
    assert (rcs_lockfd >= 0);

    /* Abort if we could not write everything successfully to LOCKFILE.
       This is not a great error-handling mechanism, but should prevent
       corrupting the repository. */

    if (ferror (fp))
        /* Using errno here may well be misleanding since the most recent
           call that set errno may not have anything whatsoever to do with
           the error that set the flag, but it's better than nothing.  The
           real solution is to check each call to fprintf rather than waiting
           until the end like this.  */
        error (1, errno, "error writing to lock file %s", rcs_lockfile);

    /* Flush and sync the file, or the user may be told the commit completed,
     * while a server crash/power failure could still cause the data to be
     * lost.
     *
     * Invoking rename(",<file>," , "<file>,v") on Linux and almost all UNIXs
     * only flushes the inode for the target file to disk, it does not
     * guarantee flush of the kernel buffers allocated for the ,<file>,.
     * Depending upon the load on the machine, the Linux kernel's flush daemon
     * process may not flush for a while.  In the meantime the CVS transaction
     * could have been declared committed to the end CVS user (CVS process has
     * returned the final "OK").  If the machine crashes prior to syncing the
     * changes to disk, the committed transaction can be lost.
     */
    if (fflush (fp) != 0)
        error (1, errno, "error flushing file `%s' to kernel buffers",
               rcs_lockfile);
#ifdef HAVE_FSYNC
    if (fsync (rcs_lockfd) < 0)
        error (1, errno, "error fsyncing file `%s'", rcs_lockfile);
#endif

    if (fclose (fp) == EOF)
        error (1, errno, "error closing lock file %s", rcs_lockfile);
    rcs_lockfd = -1;

    rename_file (rcs_lockfile, rcsfile);

    {
        /* Use a temporary to make sure there's no interval
           (after rcs_lockfile has been freed but before it's set to NULL)
           during which the signal handler's use of rcs_lockfile would
           reference freed memory.  */
        char *tmp = rcs_lockfile;
        rcs_lockfile = NULL;
        free (tmp);
    }
}



static char *
rcs_lockfilename (const char *rcsfile)
{
    char *lockfile, *lockp;
    const char *rcsbase, *rcsp, *rcsend;
    int rcslen;

    /* Create the lockfile name. */
    rcslen = strlen (rcsfile);
    lockfile = xmalloc (rcslen + 10);
    rcsbase = last_component (rcsfile);
    rcsend = rcsfile + rcslen - sizeof(RCSEXT);
    for (lockp = lockfile, rcsp = rcsfile; rcsp < rcsbase; ++rcsp)
        *lockp++ = *rcsp;
    *lockp++ = ',';
    while (rcsp <= rcsend)
        *lockp++ = *rcsp++;
    *lockp++ = ',';
    *lockp = '\0';

    return lockfile;
}



/* Rewrite an RCS file.  The basic idea here is that the caller should
   first call RCS_reparsercsfile, then munge the data structures as
   desired (via RCS_delete_revs, RCS_settag, &c), then call RCS_rewrite.  */
void
RCS_rewrite (RCSNode *rcs, Deltatext *newdtext, char *insertpt)
{
    FILE *fin, *fout;
    struct rcsbuffer rcsbufin;

    if (noexec)
        return;

    /* Make sure we're operating on an actual file and not a symlink.  */
    resolve_symlink (&(rcs->path));

    fout = rcs_internal_lockfile (rcs->path);

    RCS_putadmin (rcs, fout);
    RCS_putdtree (rcs, rcs->head, fout);
    RCS_putdesc (rcs, fout);

    /* Open the original RCS file and seek to the first delta text. */
    rcsbuf_cache_open (rcs, rcs->delta_pos, &fin, &rcsbufin);

    /* Update delta_pos to the current position in the output file.
       Do NOT move these statements: they must be done after fin has
       been positioned at the old delta_pos, but before any delta
       texts have been written to fout.
     */
    rcs->delta_pos = ftello (fout);
    if (rcs->delta_pos == -1)
        error (1, errno, "cannot ftello in RCS file %s", rcs->path);

    RCS_copydeltas (rcs, fin, &rcsbufin, fout, newdtext, insertpt);

    /* We don't want to call rcsbuf_cache here, since we're about to
       delete the file.  */
    rcsbuf_close (&rcsbufin);
    if (ferror (fin))
        /* The only case in which using errno here would be meaningful
           is if we happen to have left errno unmolested since the call
           which produced the error (e.g. fread).  That is pretty
           fragile even if it happens to sometimes be true.  The real
           solution is to make sure that all the code which reads
           from fin checks for errors itself (some does, some doesn't).  */
        error (0, 0, "warning: ferror set while rewriting RCS file `%s'", rcs->path);
    if (fclose (fin) < 0)
        error (0, errno, "warning: closing RCS file `%s'", rcs->path);

    rcs_internal_unlockfile (fout, rcs->path);
}



/* Abandon changes to an RCS file. */
void
RCS_abandon (RCSNode *rcs)
{
    free_rcsnode_contents (rcs);
    rcs->symbols_data = NULL;
    rcs->expand = NULL;
    rcs->access = NULL;
    rcs->locks_data = NULL;
    rcs->comment = NULL;
    rcs->desc = NULL;
    rcs->flags |= PARTIAL;
}



/*
 * For a given file with full pathname PATH and revision number REV,
 * produce a file label suitable for passing to diff.  The default
 * file label as used by RCS 5.7 looks like this:
 *
 *      FILENAME <tab> YYYY/MM/DD <sp> HH:MM:SS <tab> REVNUM
 *
 * The date and time used are the revision's last checkin date and time.
 * If REV is NULL, use the working copy's mtime instead.
 *
 * /dev/null is not statted but assumed to have been created on the Epoch.
 * At least using the POSIX.2 definition of patch, this should cause creation
 * of files on platforms such as Windoze where the null IO device isn't named
 * /dev/null to be parsed by patch properly.
 */
char *
make_file_label (const char *path, const char *rev, RCSNode *rcs)
{
    char datebuf[MAXDATELEN + 1];
    char *label;

    if (rev)
    {
        char date[MAXDATELEN + 1];
        /* revs cannot be attached to /dev/null ... duh. */
        assert (strcmp(DEVNULL, path));
        RCS_getrevtime (rcs, rev, datebuf, 0);
        (void) date_to_internet (date, datebuf);
        label = Xasprintf ("-L%s\t%s\t%s", path, date, rev);
    }
    else
    {
        struct stat sb;
        struct tm *wm;

        if (strcmp(DEVNULL, path))
        {
            const char *file = last_component (path);
            if (stat (file, &sb) < 0)
                /* Assume that if the stat fails,then the later read for the
                 * diff will too.
                 */
                error (1, errno, "could not get info for `%s'", path);
            wm = gmtime (&sb.st_mtime);
        }
        else
        {
            time_t t = 0;
            wm = gmtime(&t);
        }

        (void) tm_to_internet (datebuf, wm);
        label = Xasprintf ("-L%s\t%s", path, datebuf);
    }
    return label;
}



/*
 * Set up a local/custom RCS keyword for expansion.
 *
 * INPUTS
 *   infopath           Path to file being parsed, for error messages.
 *   ln                 Line number of INFOPATH being processed, for error
 *                      messages.
 *   keywords_in
 *   arg
 *
 * OUTPUTS
 *   keywords_in
 */
void
RCS_setlocalid (const char *infopath, unsigned int ln,
                void **keywords_in, const char *arg)
{
    char *copy, *next, *key, *s;
    struct rcs_keyword *keywords;
    enum keyword save_expandto;

    if (!*keywords_in)
        *keywords_in = new_keywords ();
    keywords = *keywords_in;

    copy = xstrdup (arg);
    next = copy;
    key = strtok (next, "=");

    /*
     * Validate key
     */
    for (s = key; *s != '\0'; s++)
    {
        if (! isalpha ((unsigned char) *s))
        {
            if (!parse_error (infopath, ln))
                    error (0, 0,
"%s [%u]: LocalKeyword ignored: Bad character `%c' in key `%s'",
                           primary_root_inverse_translate (infopath),
                           ln, *s, key);
            free (copy);
            return;
        }
    }

    save_expandto = keywords[KEYWORD_LOCALID].expandto;

    /* options? */
    while ((key = strtok (NULL, ",")) != NULL) {
        if (!strcmp(key, keywords[KEYWORD_ID].string))
            keywords[KEYWORD_LOCALID].expandto = KEYWORD_ID;
        else if (!strcmp(key, keywords[KEYWORD_HEADER].string))
            keywords[KEYWORD_LOCALID].expandto = KEYWORD_HEADER;
        else if (!strcmp(key, keywords[KEYWORD_CVSHEADER].string))
            keywords[KEYWORD_LOCALID].expandto = KEYWORD_CVSHEADER;
        else
        {
            keywords[KEYWORD_LOCALID].expandto = save_expandto;
            if (!parse_error (infopath, ln))
                error (0, 0,
"%s [%u]: LocalKeyword ignored: Unknown LocalId mode: `%s'",
                       primary_root_inverse_translate (infopath),
                       ln, key);
            free (copy);
            return;
        }
    }

    keywords[KEYWORD_LOCALID].string = xstrdup (next);
    keywords[KEYWORD_LOCALID].len = strlen (next);
    keywords[KEYWORD_LOCALID].expandit = 1;

    free (copy);
}



void
RCS_setincexc (void **keywords_in, const char *arg)
{
    char *key;
    char *copy, *next;
    bool include = false;
    struct rcs_keyword *keyword;
    struct rcs_keyword *keywords;

    if (!*keywords_in)
        *keywords_in = new_keywords ();
    keywords = *keywords_in;

    copy = xstrdup(arg);
    next = copy;
    switch (*next++) {
        case 'e':
            include = false;
            break;
        case 'i':
            include = true;
            break;
        default:
            free(copy);
            return;
    }

    if (include)
        for (keyword = keywords; keyword->string != NULL; keyword++)
        {
            keyword->expandit = false;
        }

    key = strtok(next, ",");
    while (key) {
        for (keyword = keywords; keyword->string != NULL; keyword++) {
            if (strcmp (keyword->string, key) == 0)
                keyword->expandit = include;
        }
        key = strtok(NULL, ",");
    }
    free(copy);
    return;
}



#define ATTIC "/" CVSATTIC
static char *
getfullCVSname(char *CVSname, char **pathstore)
{
    if (current_parsed_root->directory) {
        int rootlen;
        char *c = NULL;
        int alen = sizeof(ATTIC) - 1;

        *pathstore = xstrdup(CVSname);
        if ((c = strrchr(*pathstore, '/')) != NULL) {
            if (c - *pathstore >= alen) {
                if (!strncmp(c - alen, ATTIC, alen)) {
                    while (*c != '\0') {
                        *(c - alen) = *c;
                        c++;
                    }
                    *(c - alen) = '\0';
                }
            }
        }

        rootlen = strlen(current_parsed_root->directory);
        if (!strncmp(*pathstore, current_parsed_root->directory, rootlen) &&
            (*pathstore)[rootlen] == '/')
            CVSname = (*pathstore + rootlen + 1);
        else
            CVSname = (*pathstore);
    }
    return CVSname;
}