Merge from vendor branch NTPD:

[dragonfly.git] / usr.bin / make / arch.c

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#)arch.c   8.2 (Berkeley) 1/2/94
 * $FreeBSD: src/usr.bin/make/arch.c,v 1.15.2.1 2001/02/13 03:13:57 will Exp $
 * $DragonFly: src/usr.bin/make/arch.c,v 1.13 2004/11/18 02:01:39 dillon Exp $
 */

/*-
 * arch.c --
 *      Functions to manipulate libraries, archives and their members.
 *
 *      Once again, cacheing/hashing comes into play in the manipulation
 * of archives. The first time an archive is referenced, all of its members'
 * headers are read and hashed and the archive closed again. All hashed
 * archives are kept on a list which is searched each time an archive member
 * is referenced.
 *
 * The interface to this module is:
 *      Arch_ParseArchive       Given an archive specification, return a list
 *                              of GNode's, one for each member in the spec.
 *                              FAILURE is returned if the specification is
 *                              invalid for some reason.
 *
 *      Arch_Touch              Alter the modification time of the archive
 *                              member described by the given node to be
 *                              the current time.
 *
 *      Arch_TouchLib           Update the modification time of the library
 *                              described by the given node. This is special
 *                              because it also updates the modification time
 *                              of the library's table of contents.
 *
 *      Arch_MTime              Find the modification time of a member of
 *                              an archive *in the archive*. The time is also
 *                              placed in the member's GNode. Returns the
 *                              modification time.
 *
 *      Arch_MemTime            Find the modification time of a member of
 *                              an archive. Called when the member doesn't
 *                              already exist. Looks in the archive for the
 *                              modification time. Returns the modification
 *                              time.
 *
 *      Arch_FindLib            Search for a library along a path. The
 *                              library name in the GNode should be in
 *                              -l<name> format.
 *
 *      Arch_LibOODate          Special function to decide if a library node
 *                              is out-of-date.
 *
 *      Arch_Init               Initialize this module.
 *
 *      Arch_End                Cleanup this module.
 */

#include    <sys/types.h>
#include    <sys/stat.h>
#include    <sys/time.h>
#include    <sys/param.h>
#include    <ctype.h>
#include    <ar.h>
#include    <utime.h>
#include    <stdio.h>
#include    <stdlib.h>
#include    "make.h"
#include    "hash.h"
#include    "dir.h"
#include    "config.h"

static Lst        archives;   /* Lst of archives we've already examined */

typedef struct Arch {
    char          *name;      /* Name of archive */
    Hash_Table    members;    /* All the members of the archive described
                               * by <name, struct ar_hdr *> key/value pairs */
    char          *fnametab;  /* Extended name table strings */
    size_t        fnamesize;  /* Size of the string table */
} Arch;

static int ArchFindArchive(void *, void *);
static void ArchFree(void *);
static struct ar_hdr *ArchStatMember(char *, char *, Boolean);
static FILE *ArchFindMember(char *, char *, struct ar_hdr *, char *);
#if defined(__svr4__) || defined(__SVR4) || defined(__ELF__)
#define SVR4ARCHIVES
static int ArchSVR4Entry(Arch *, char *, size_t, FILE *);
#endif

/*-
 *-----------------------------------------------------------------------
 * ArchFree --
 *      Free memory used by an archive
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static void
ArchFree(void *ap)
{
    Arch *a = (Arch *) ap;
    Hash_Search   search;
    Hash_Entry    *entry;

    /* Free memory from hash entries */
    for (entry = Hash_EnumFirst(&a->members, &search);
         entry != NULL;
         entry = Hash_EnumNext(&search))
        free(Hash_GetValue(entry));

    free(a->name);
    free(a->fnametab);
    Hash_DeleteTable(&a->members);
    free(a);
}



/*-
 *-----------------------------------------------------------------------
 * Arch_ParseArchive --
 *      Parse the archive specification in the given line and find/create
 *      the nodes for the specified archive members, placing their nodes
 *      on the given list, given the pointer to the start of the
 *      specification, a Lst on which to place the nodes, and a context
 *      in which to expand variables.
 *
 * Results:
 *      SUCCESS if it was a valid specification. The linePtr is updated
 *      to point to the first non-space after the archive spec. The
 *      nodes for the members are placed on the given list.
 *
 * Side Effects:
 *      Some nodes may be created. The given list is extended.
 *
 *-----------------------------------------------------------------------
 */
ReturnStatus
Arch_ParseArchive (char **linePtr, Lst nodeLst, GNode *ctxt)
{
    char            *cp;            /* Pointer into line */
    GNode           *gn;            /* New node */
    char            *libName;       /* Library-part of specification */
    char            *memName;       /* Member-part of specification */
    char            *nameBuf;       /* temporary place for node name */
    char            saveChar;       /* Ending delimiter of member-name */
    Boolean         subLibName;     /* TRUE if libName should have/had
                                     * variable substitution performed on it */

    libName = *linePtr;

    subLibName = FALSE;

    for (cp = libName; *cp != '(' && *cp != '\0'; cp++) {
        if (*cp == '$') {
            /*
             * Variable spec, so call the Var module to parse the puppy
             * so we can safely advance beyond it...
             */
            int         length;
            Boolean     freeIt;
            char        *result;

            result=Var_Parse(cp, ctxt, TRUE, &length, &freeIt);
            if (result == var_Error) {
                return(FAILURE);
            } else {
                subLibName = TRUE;
            }

            if (freeIt) {
                free(result);
            }
            cp += length-1;
        }
    }

    *cp++ = '\0';
    if (subLibName) {
        libName = Var_Subst(NULL, libName, ctxt, TRUE);
    }


    for (;;) {
        /*
         * First skip to the start of the member's name, mark that
         * place and skip to the end of it (either white-space or
         * a close paren).
         */
        Boolean doSubst = FALSE; /* TRUE if need to substitute in memName */

        while (*cp != '\0' && *cp != ')' && isspace ((unsigned char) *cp)) {
            cp++;
        }
        memName = cp;
        while (*cp != '\0' && *cp != ')' && !isspace ((unsigned char) *cp)) {
            if (*cp == '$') {
                /*
                 * Variable spec, so call the Var module to parse the puppy
                 * so we can safely advance beyond it...
                 */
                int     length;
                Boolean freeIt;
                char    *result;

                result=Var_Parse(cp, ctxt, TRUE, &length, &freeIt);
                if (result == var_Error) {
                    return(FAILURE);
                } else {
                    doSubst = TRUE;
                }

                if (freeIt) {
                    free(result);
                }
                cp += length;
            } else {
                cp++;
            }
        }

        /*
         * If the specification ends without a closing parenthesis,
         * chances are there's something wrong (like a missing backslash),
         * so it's better to return failure than allow such things to happen
         */
        if (*cp == '\0') {
            printf("No closing parenthesis in archive specification\n");
            return (FAILURE);
        }

        /*
         * If we didn't move anywhere, we must be done
         */
        if (cp == memName) {
            break;
        }

        saveChar = *cp;
        *cp = '\0';

        /*
         * XXX: This should be taken care of intelligently by
         * SuffExpandChildren, both for the archive and the member portions.
         */
        /*
         * If member contains variables, try and substitute for them.
         * This will slow down archive specs with dynamic sources, of course,
         * since we'll be (non-)substituting them three times, but them's
         * the breaks -- we need to do this since SuffExpandChildren calls
         * us, otherwise we could assume the thing would be taken care of
         * later.
         */
        if (doSubst) {
            char    *buf;
            char    *sacrifice;
            char    *oldMemName = memName;
            size_t   sz;

            memName = Var_Subst(NULL, memName, ctxt, TRUE);

            /*
             * Now form an archive spec and recurse to deal with nested
             * variables and multi-word variable values.... The results
             * are just placed at the end of the nodeLst we're returning.
             */
            sz = strlen(memName) + strlen(libName) + 3;
            buf = sacrifice = emalloc(sz);
            snprintf(buf, sz, "%s(%s)", libName, memName);

            if (strchr(memName, '$') && strcmp(memName, oldMemName) == 0) {
                /*
                 * Must contain dynamic sources, so we can't deal with it now.
                 * Just create an ARCHV node for the thing and let
                 * SuffExpandChildren handle it...
                 */
                gn = Targ_FindNode(buf, TARG_CREATE);

                if (gn == NULL) {
                    free(buf);
                    return(FAILURE);
                } else {
                    gn->type |= OP_ARCHV;
                    (void)Lst_AtEnd(nodeLst, (void *)gn);
                }
            } else if (Arch_ParseArchive(&sacrifice, nodeLst, ctxt)!=SUCCESS) {
                /*
                 * Error in nested call -- free buffer and return FAILURE
                 * ourselves.
                 */
                free(buf);
                return(FAILURE);
            }
            /*
             * Free buffer and continue with our work.
             */
            free(buf);
        } else if (Dir_HasWildcards(memName)) {
            Lst   members = Lst_Init(FALSE);
            char  *member;
            size_t sz = MAXPATHLEN;
            size_t nsz;

            nameBuf = emalloc(sz);

            Dir_Expand(memName, dirSearchPath, members);
            while (!Lst_IsEmpty(members)) {
                member = (char *)Lst_DeQueue(members);
                nsz = strlen(libName) + strlen(member) + 3; /* 3 = ()+\0 */
                if (sz < nsz) {
                        sz = nsz * 2;
                        nameBuf = erealloc(nameBuf, sz);
                }
                snprintf(nameBuf, sz, "%s(%s)", libName, member);
                free(member);
                gn = Targ_FindNode (nameBuf, TARG_CREATE);
                if (gn == NULL) {
                    free(nameBuf);
                    return (FAILURE);
                } else {
                    /*
                     * We've found the node, but have to make sure the rest of
                     * the world knows it's an archive member, without having
                     * to constantly check for parentheses, so we type the
                     * thing with the OP_ARCHV bit before we place it on the
                     * end of the provided list.
                     */
                    gn->type |= OP_ARCHV;
                    (void) Lst_AtEnd (nodeLst, (void *)gn);
                }
            }
            Lst_Destroy(members, NOFREE);
            free(nameBuf);
        } else {
            size_t sz = strlen(libName) + strlen(memName) + 3;
            nameBuf = emalloc(sz);
            snprintf(nameBuf, sz, "%s(%s)", libName, memName);
            gn = Targ_FindNode (nameBuf, TARG_CREATE);
            free(nameBuf);
            if (gn == NULL) {
                return (FAILURE);
            } else {
                /*
                 * We've found the node, but have to make sure the rest of the
                 * world knows it's an archive member, without having to
                 * constantly check for parentheses, so we type the thing with
                 * the OP_ARCHV bit before we place it on the end of the
                 * provided list.
                 */
                gn->type |= OP_ARCHV;
                (void) Lst_AtEnd (nodeLst, (void *)gn);
            }
        }
        if (doSubst) {
            free(memName);
        }

        *cp = saveChar;
    }

    /*
     * If substituted libName, free it now, since we need it no longer.
     */
    if (subLibName) {
        free(libName);
    }

    /*
     * We promised the pointer would be set up at the next non-space, so
     * we must advance cp there before setting *linePtr... (note that on
     * entrance to the loop, cp is guaranteed to point at a ')')
     */
    do {
        cp++;
    } while (*cp != '\0' && isspace ((unsigned char) *cp));

    *linePtr = cp;
    return (SUCCESS);
}

/*-
 *-----------------------------------------------------------------------
 * ArchFindArchive --
 *      See if the given archive is the one we are looking for. Called
 *      From ArchStatMember and ArchFindMember via Lst_Find with the
 *      current list element and the name we want.
 *
 * Results:
 *      0 if it is, non-zero if it isn't.
 *
 * Side Effects:
 *      None.
 *
 *-----------------------------------------------------------------------
 */
static int
ArchFindArchive (void *ar, void *archName)
{
    return (strcmp ((char *) archName, ((Arch *) ar)->name));
}

/*-
 *-----------------------------------------------------------------------
 * ArchStatMember --
 *      Locate a member of an archive, given the path of the archive and
 *      the path of the desired member, and a boolean representing whether
 *      or not the archive should be hashed (if not already hashed).
 *
 * Results:
 *      A pointer to the current struct ar_hdr structure for the member. Note
 *      That no position is returned, so this is not useful for touching
 *      archive members. This is mostly because we have no assurances that
 *      The archive will remain constant after we read all the headers, so
 *      there's not much point in remembering the position...
 *
 * Side Effects:
 *
 *-----------------------------------------------------------------------
 */
static struct ar_hdr *
ArchStatMember (char *archive, char *member, Boolean hash)
{
#define AR_MAX_NAME_LEN     (sizeof(arh.ar_name)-1)
    FILE *        arch;       /* Stream to archive */
    int           size;       /* Size of archive member */
    char          *cp;        /* Useful character pointer */
    char          magic[SARMAG];
    LstNode       ln;         /* Lst member containing archive descriptor */
    Arch          *ar;        /* Archive descriptor */
    Hash_Entry    *he;        /* Entry containing member's description */
    struct ar_hdr arh;        /* archive-member header for reading archive */
    char          memName[MAXPATHLEN];
                            /* Current member name while hashing. */

    /*
     * Because of space constraints and similar things, files are archived
     * using their final path components, not the entire thing, so we need
     * to point 'member' to the final component, if there is one, to make
     * the comparisons easier...
     */
    cp = strrchr (member, '/');
    if ((cp != NULL) && (strcmp(member, RANLIBMAG) != 0))
        member = cp + 1;

    ln = Lst_Find (archives, (void *) archive, ArchFindArchive);
    if (ln != NULL) {
        ar = (Arch *) Lst_Datum (ln);

        he = Hash_FindEntry (&ar->members, member);

        if (he != NULL) {
            return ((struct ar_hdr *) Hash_GetValue (he));
        } else {
            /* Try truncated name */
            char copy[AR_MAX_NAME_LEN+1];
            size_t len = strlen (member);

            if (len > AR_MAX_NAME_LEN) {
                len = AR_MAX_NAME_LEN;
                strncpy(copy, member, AR_MAX_NAME_LEN);
                copy[AR_MAX_NAME_LEN] = '\0';
            }
            if ((he = Hash_FindEntry (&ar->members, copy)) != NULL)
                return ((struct ar_hdr *) Hash_GetValue (he));
            return (NULL);
        }
    }

    if (!hash) {
        /*
         * Caller doesn't want the thing hashed, just use ArchFindMember
         * to read the header for the member out and close down the stream
         * again. Since the archive is not to be hashed, we assume there's
         * no need to allocate extra room for the header we're returning,
         * so just declare it static.
         */
         static struct ar_hdr   sarh;

         arch = ArchFindMember(archive, member, &sarh, "r");

        if (arch == NULL) {
            return (NULL);
        } else {
            fclose(arch);
            return (&sarh);
        }
    }

    /*
     * We don't have this archive on the list yet, so we want to find out
     * everything that's in it and cache it so we can get at it quickly.
     */
    arch = fopen (archive, "r");
    if (arch == NULL) {
        return (NULL);
    }

    /*
     * We use the ARMAG string to make sure this is an archive we
     * can handle...
     */
    if ((fread (magic, SARMAG, 1, arch) != 1) ||
        (strncmp (magic, ARMAG, SARMAG) != 0)) {
            fclose (arch);
            return (NULL);
    }

    ar = (Arch *)emalloc (sizeof (Arch));
    ar->name = estrdup (archive);
    ar->fnametab = NULL;
    ar->fnamesize = 0;
    Hash_InitTable (&ar->members, -1);
    memName[AR_MAX_NAME_LEN] = '\0';

    while (fread ((char *)&arh, sizeof (struct ar_hdr), 1, arch) == 1) {
        if (strncmp ( arh.ar_fmag, ARFMAG, sizeof (arh.ar_fmag)) != 0) {
            /*
             * The header is bogus, so the archive is bad
             * and there's no way we can recover...
             */
            goto badarch;
        } else {
            /*
             * We need to advance the stream's pointer to the start of the
             * next header. Files are padded with newlines to an even-byte
             * boundary, so we need to extract the size of the file from the
             * 'size' field of the header and round it up during the seek.
             */
            arh.ar_size[sizeof(arh.ar_size)-1] = '\0';
            size = (int) strtol(arh.ar_size, NULL, 10);

            (void) strncpy (memName, arh.ar_name, sizeof(arh.ar_name));
            for (cp = &memName[AR_MAX_NAME_LEN]; *cp == ' '; cp--) {
                continue;
            }
            cp[1] = '\0';

#ifdef SVR4ARCHIVES
            /*
             * svr4 names are slash terminated. Also svr4 extended AR format.
             */
            if (memName[0] == '/') {
                /*
                 * svr4 magic mode; handle it
                 */
                switch (ArchSVR4Entry(ar, memName, size, arch)) {
                case -1:  /* Invalid data */
                    goto badarch;
                case 0:   /* List of files entry */
                    continue;
                default:  /* Got the entry */
                    break;
                }
            }
            else {
                if (cp[0] == '/')
                    cp[0] = '\0';
            }
#endif

#ifdef AR_EFMT1
            /*
             * BSD 4.4 extended AR format: #1/<namelen>, with name as the
             * first <namelen> bytes of the file
             */
            if (strncmp(memName, AR_EFMT1, sizeof(AR_EFMT1) - 1) == 0 &&
                isdigit(memName[sizeof(AR_EFMT1) - 1])) {

                unsigned int elen = atoi(&memName[sizeof(AR_EFMT1)-1]);

                if (elen > MAXPATHLEN)
                        goto badarch;
                if (fread (memName, elen, 1, arch) != 1)
                        goto badarch;
                memName[elen] = '\0';
                fseek (arch, -elen, SEEK_CUR);
                /* XXX Multiple levels may be asked for, make this conditional
                 * on one, and use DEBUGF.
                 */
                if (DEBUG(ARCH) || DEBUG(MAKE)) {
                    fprintf(stderr, "ArchStat: Extended format entry for %s\n", memName);
                }
            }
#endif

            he = Hash_CreateEntry (&ar->members, memName, NULL);
            Hash_SetValue (he, (void *)emalloc (sizeof (struct ar_hdr)));
            memcpy (Hash_GetValue (he), &arh,
                sizeof (struct ar_hdr));
        }
        fseek (arch, (size + 1) & ~1, SEEK_CUR);
    }

    fclose (arch);

    (void) Lst_AtEnd (archives, (void *) ar);

    /*
     * Now that the archive has been read and cached, we can look into
     * the hash table to find the desired member's header.
     */
    he = Hash_FindEntry (&ar->members, member);

    if (he != NULL) {
        return ((struct ar_hdr *) Hash_GetValue (he));
    } else {
        return (NULL);
    }

badarch:
    fclose (arch);
    Hash_DeleteTable (&ar->members);
    free(ar->fnametab);
    free (ar);
    return (NULL);
}

#ifdef SVR4ARCHIVES
/*-
 *-----------------------------------------------------------------------
 * ArchSVR4Entry --
 *      Parse an SVR4 style entry that begins with a slash.
 *      If it is "//", then load the table of filenames
 *      If it is "/<offset>", then try to substitute the long file name
 *      from offset of a table previously read.
 *
 * Results:
 *      -1: Bad data in archive
 *       0: A table was loaded from the file
 *       1: Name was successfully substituted from table
 *       2: Name was not successfully substituted from table
 *
 * Side Effects:
 *      If a table is read, the file pointer is moved to the next archive
 *      member
 *
 *-----------------------------------------------------------------------
 */
static int
ArchSVR4Entry(Arch *ar, char *name, size_t size, FILE *arch)
{
#define ARLONGNAMES1 "//"
#define ARLONGNAMES2 "/ARFILENAMES"
    size_t entry;
    char *ptr, *eptr;

    if (strncmp(name, ARLONGNAMES1, sizeof(ARLONGNAMES1) - 1) == 0 ||
        strncmp(name, ARLONGNAMES2, sizeof(ARLONGNAMES2) - 1) == 0) {

        if (ar->fnametab != NULL) {
            DEBUGF(ARCH, ("Attempted to redefine an SVR4 name table\n"));
            return -1;
        }

        /*
         * This is a table of archive names, so we build one for
         * ourselves
         */
        ar->fnametab = emalloc(size);
        ar->fnamesize = size;

        if (fread(ar->fnametab, size, 1, arch) != 1) {
            DEBUGF(ARCH, ("Reading an SVR4 name table failed\n"));
            return -1;
        }
        eptr = ar->fnametab + size;
        for (entry = 0, ptr = ar->fnametab; ptr < eptr; ptr++)
            switch (*ptr) {
            case '/':
                entry++;
                *ptr = '\0';
                break;

            case '\n':
                break;

            default:
                break;
            }
        DEBUGF(ARCH, ("Found svr4 archive name table with %zu entries\n", entry));
        return 0;
    }

    if (name[1] == ' ' || name[1] == '\0')
        return 2;

    entry = (size_t) strtol(&name[1], &eptr, 0);
    if ((*eptr != ' ' && *eptr != '\0') || eptr == &name[1]) {
        DEBUGF(ARCH, ("Could not parse SVR4 name %s\n", name));
        return 2;
    }
    if (entry >= ar->fnamesize) {
        DEBUGF(ARCH, ("SVR4 entry offset %s is greater than %zu\n",
                name, ar->fnamesize));
        return 2;
    }

    DEBUGF(ARCH, ("Replaced %s with %s\n", name, &ar->fnametab[entry]));

    (void) strncpy(name, &ar->fnametab[entry], MAXPATHLEN);
    name[MAXPATHLEN - 1] = '\0';
    return 1;
}
#endif


/*-
 *-----------------------------------------------------------------------
 * ArchFindMember --
 *      Locate a member of an archive, given the path of the archive and
 *      the path of the desired member. If the archive is to be modified,
 *      the mode should be "r+", if not, it should be "r".  arhPtr is a
 *      poitner to the header structure to fill in.
 *
 * Results:
 *      An FILE *, opened for reading and writing, positioned at the
 *      start of the member's struct ar_hdr, or NULL if the member was
 *      nonexistent. The current struct ar_hdr for member.
 *
 * Side Effects:
 *      The passed struct ar_hdr structure is filled in.
 *
 *-----------------------------------------------------------------------
 */
static FILE *
ArchFindMember (char *archive, char *member, struct ar_hdr *arhPtr, char *mode)
{
    FILE *        arch;       /* Stream to archive */
    int           size;       /* Size of archive member */
    char          *cp;        /* Useful character pointer */
    char          magic[SARMAG];
    size_t        len, tlen;

    arch = fopen (archive, mode);
    if (arch == NULL) {
        return (NULL);
    }

    /*
     * We use the ARMAG string to make sure this is an archive we
     * can handle...
     */
    if ((fread (magic, SARMAG, 1, arch) != 1) ||
        (strncmp (magic, ARMAG, SARMAG) != 0)) {
            fclose (arch);
            return (NULL);
    }

    /*
     * Because of space constraints and similar things, files are archived
     * using their final path components, not the entire thing, so we need
     * to point 'member' to the final component, if there is one, to make
     * the comparisons easier...
     */
    cp = strrchr (member, '/');
    if ((cp != NULL) && (strcmp(member, RANLIBMAG) != 0)) {
        member = cp + 1;
    }
    len = tlen = strlen (member);
    if (len > sizeof (arhPtr->ar_name)) {
        tlen = sizeof (arhPtr->ar_name);
    }

    while (fread ((char *)arhPtr, sizeof (struct ar_hdr), 1, arch) == 1) {
        if (strncmp(arhPtr->ar_fmag, ARFMAG, sizeof (arhPtr->ar_fmag) ) != 0) {
             /*
              * The header is bogus, so the archive is bad
              * and there's no way we can recover...
              */
             fclose (arch);
             return (NULL);
        } else if (strncmp (member, arhPtr->ar_name, tlen) == 0) {
            /*
             * If the member's name doesn't take up the entire 'name' field,
             * we have to be careful of matching prefixes. Names are space-
             * padded to the right, so if the character in 'name' at the end
             * of the matched string is anything but a space, this isn't the
             * member we sought.
             */
            if (tlen != sizeof(arhPtr->ar_name) && arhPtr->ar_name[tlen] != ' '){
                goto skip;
            } else {
                /*
                 * To make life easier, we reposition the file at the start
                 * of the header we just read before we return the stream.
                 * In a more general situation, it might be better to leave
                 * the file at the actual member, rather than its header, but
                 * not here...
                 */
                fseek (arch, -sizeof(struct ar_hdr), SEEK_CUR);
                return (arch);
            }
        } else
#ifdef AR_EFMT1
                /*
                 * BSD 4.4 extended AR format: #1/<namelen>, with name as the
                 * first <namelen> bytes of the file
                 */
            if (strncmp(arhPtr->ar_name, AR_EFMT1,
                                        sizeof(AR_EFMT1) - 1) == 0 &&
                isdigit(arhPtr->ar_name[sizeof(AR_EFMT1) - 1])) {

                unsigned int elen = atoi(&arhPtr->ar_name[sizeof(AR_EFMT1)-1]);
                char ename[MAXPATHLEN];

                if (elen > MAXPATHLEN) {
                        fclose (arch);
                        return NULL;
                }
                if (fread (ename, elen, 1, arch) != 1) {
                        fclose (arch);
                        return NULL;
                }
                ename[elen] = '\0';
                /*
                 * XXX choose one.
                 */
                if (DEBUG(ARCH) || DEBUG(MAKE)) {
                    printf("ArchFind: Extended format entry for %s\n", ename);
                }
                if (strncmp(ename, member, len) == 0) {
                        /* Found as extended name */
                        fseek (arch, -sizeof(struct ar_hdr) - elen, SEEK_CUR);
                        return (arch);
                }
                fseek (arch, -elen, SEEK_CUR);
                goto skip;
        } else
#endif
        {
skip:
            /*
             * This isn't the member we're after, so we need to advance the
             * stream's pointer to the start of the next header. Files are
             * padded with newlines to an even-byte boundary, so we need to
             * extract the size of the file from the 'size' field of the
             * header and round it up during the seek.
             */
            arhPtr->ar_size[sizeof(arhPtr->ar_size)-1] = '\0';
            size = (int) strtol(arhPtr->ar_size, NULL, 10);
            fseek (arch, (size + 1) & ~1, SEEK_CUR);
        }
    }

    /*
     * We've looked everywhere, but the member is not to be found. Close the
     * archive and return NULL -- an error.
     */
    fclose (arch);
    return (NULL);
}

/*-
 *-----------------------------------------------------------------------
 * Arch_Touch --
 *      Touch a member of an archive.
 *
 * Results:
 *      The 'time' field of the member's header is updated.
 *
 * Side Effects:
 *      The modification time of the entire archive is also changed.
 *      For a library, this could necessitate the re-ranlib'ing of the
 *      whole thing.
 *
 *-----------------------------------------------------------------------
 */
void
Arch_Touch (GNode *gn)
{
    FILE *        arch;   /* Stream open to archive, positioned properly */
    struct ar_hdr arh;    /* Current header describing member */
    char *p1, *p2;

    arch = ArchFindMember(Var_Value (ARCHIVE, gn, &p1),
                          Var_Value (TARGET, gn, &p2),
                          &arh, "r+");
    free(p1);
    free(p2);
    snprintf(arh.ar_date, sizeof(arh.ar_date), "%-12ld", (long) now);

    if (arch != NULL) {
        (void)fwrite ((char *)&arh, sizeof (struct ar_hdr), 1, arch);
        fclose (arch);
    }
}

/*-
 *-----------------------------------------------------------------------
 * Arch_TouchLib --
 *      Given a node which represents a library, touch the thing, making
 *      sure that the table of contents also is touched.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      Both the modification time of the library and of the RANLIBMAG
 *      member are set to 'now'.
 *
 *-----------------------------------------------------------------------
 */
void
Arch_TouchLib (GNode *gn)
{
#ifdef RANLIBMAG
    FILE *          arch;       /* Stream open to archive */
    struct ar_hdr   arh;        /* Header describing table of contents */
    struct utimbuf  times;      /* Times for utime() call */

    arch = ArchFindMember (gn->path, RANLIBMAG, &arh, "r+");
    snprintf(arh.ar_date, sizeof(arh.ar_date), "%-12ld", (long) now);

    if (arch != NULL) {
        (void)fwrite ((char *)&arh, sizeof (struct ar_hdr), 1, arch);
        fclose (arch);

        times.actime = times.modtime = now;
        utime(gn->path, &times);
    }
#endif
}

/*-
 *-----------------------------------------------------------------------
 * Arch_MTime --
 *      Return the modification time of a member of an archive, given its
 *      name.
 *
 * Results:
 *      The modification time (seconds).
 *
 * Side Effects:
 *      The mtime field of the given node is filled in with the value
 *      returned by the function.
 *
 *-----------------------------------------------------------------------
 */
int
Arch_MTime(GNode *gn)
{
    struct ar_hdr *arhPtr;    /* Header of desired member */
    int           modTime;    /* Modification time as an integer */
    char *p1, *p2;

    arhPtr = ArchStatMember (Var_Value (ARCHIVE, gn, &p1),
                             Var_Value (TARGET, gn, &p2),
                             TRUE);
    free(p1);
    free(p2);

    if (arhPtr != NULL) {
        modTime = (int) strtol(arhPtr->ar_date, NULL, 10);
    } else {
        modTime = 0;
    }

    gn->mtime = modTime;
    return (modTime);
}

/*-
 *-----------------------------------------------------------------------
 * Arch_MemMTime --
 *      Given a non-existent archive member's node, get its modification
 *      time from its archived form, if it exists.
 *
 * Results:
 *      The modification time.
 *
 * Side Effects:
 *      The mtime field is filled in.
 *
 *-----------------------------------------------------------------------
 */
int
Arch_MemMTime (GNode *gn)
{
    LstNode       ln;
    GNode         *pgn;
    char          *nameStart,
                  *nameEnd;

    if (Lst_Open (gn->parents) != SUCCESS) {
        gn->mtime = 0;
        return (0);
    }
    while ((ln = Lst_Next (gn->parents)) != NULL) {
        pgn = (GNode *) Lst_Datum (ln);

        if (pgn->type & OP_ARCHV) {
            /*
             * If the parent is an archive specification and is being made
             * and its member's name matches the name of the node we were
             * given, record the modification time of the parent in the
             * child. We keep searching its parents in case some other
             * parent requires this child to exist...
             */
            nameStart = strchr (pgn->name, '(') + 1;
            nameEnd = strchr (nameStart, ')');

            if (pgn->make &&
                strncmp(nameStart, gn->name, nameEnd - nameStart) == 0) {
                                     gn->mtime = Arch_MTime(pgn);
            }
        } else if (pgn->make) {
            /*
             * Something which isn't a library depends on the existence of
             * this target, so it needs to exist.
             */
            gn->mtime = 0;
            break;
        }
    }

    Lst_Close (gn->parents);

    return (gn->mtime);
}

/*-
 *-----------------------------------------------------------------------
 * Arch_FindLib --
 *      Search for a named library along the given search path.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      The node's 'path' field is set to the found path (including the
 *      actual file name, not -l...). If the system can handle the -L
 *      flag when linking (or we cannot find the library), we assume that
 *      the user has placed the .LIBRARIES variable in the final linking
 *      command (or the linker will know where to find it) and set the
 *      TARGET variable for this node to be the node's name. Otherwise,
 *      we set the TARGET variable to be the full path of the library,
 *      as returned by Dir_FindFile.
 *
 *-----------------------------------------------------------------------
 */
void
Arch_FindLib (GNode *gn, Lst path)
{
    char            *libName;   /* file name for archive */
    size_t          sz;

    sz = strlen(gn->name) + 4;
    libName = (char *)emalloc(sz);
    snprintf(libName, sz, "lib%s.a", &gn->name[2]);

    gn->path = Dir_FindFile (libName, path);

    free (libName);

#ifdef LIBRARIES
    Var_Set (TARGET, gn->name, gn);
#else
    Var_Set (TARGET, gn->path == NULL ? gn->name : gn->path, gn);
#endif /* LIBRARIES */
}

/*-
 *-----------------------------------------------------------------------
 * Arch_LibOODate --
 *      Decide if a node with the OP_LIB attribute is out-of-date. Called
 *      from Make_OODate to make its life easier, with the library's
 *      graph node.
 *
 *      There are several ways for a library to be out-of-date that are
 *      not available to ordinary files. In addition, there are ways
 *      that are open to regular files that are not available to
 *      libraries. A library that is only used as a source is never
 *      considered out-of-date by itself. This does not preclude the
 *      library's modification time from making its parent be out-of-date.
 *      A library will be considered out-of-date for any of these reasons,
 *      given that it is a target on a dependency line somewhere:
 *          Its modification time is less than that of one of its
 *                sources (gn->mtime < gn->cmtime).
 *          Its modification time is greater than the time at which the
 *                make began (i.e. it's been modified in the course
 *                of the make, probably by archiving).
 *          The modification time of one of its sources is greater than
 *                the one of its RANLIBMAG member (i.e. its table of contents
 *                is out-of-date). We don't compare of the archive time
 *                vs. TOC time because they can be too close. In my
 *                opinion we should not bother with the TOC at all since
 *                this is used by 'ar' rules that affect the data contents
 *                of the archive, not by ranlib rules, which affect the
 *                TOC.
 *
 * Results:
 *      TRUE if the library is out-of-date. FALSE otherwise.
 *
 * Side Effects:
 *      The library will be hashed if it hasn't been already.
 *
 *-----------------------------------------------------------------------
 */
Boolean
Arch_LibOODate (GNode *gn)
{
    Boolean       oodate;

    if (OP_NOP(gn->type) && Lst_IsEmpty(gn->children)) {
        oodate = FALSE;
    } else if ((gn->mtime > now) || (gn->mtime < gn->cmtime)) {
        oodate = TRUE;
    } else {
#ifdef RANLIBMAG
        struct ar_hdr   *arhPtr;    /* Header for __.SYMDEF */
        int             modTimeTOC; /* The table-of-contents's mod time */

        arhPtr = ArchStatMember (gn->path, RANLIBMAG, FALSE);

        if (arhPtr != NULL) {
            modTimeTOC = (int) strtol(arhPtr->ar_date, NULL, 10);

            /* XXX choose one. */
            if (DEBUG(ARCH) || DEBUG(MAKE)) {
                printf("%s modified %s...", RANLIBMAG, Targ_FmtTime(modTimeTOC));
            }
            oodate = (gn->cmtime > modTimeTOC);
        } else {
            /*
             * A library w/o a table of contents is out-of-date
             */
            if (DEBUG(ARCH) || DEBUG(MAKE)) {
                printf("No t.o.c....");
            }
            oodate = TRUE;
        }
#else
        oodate = (gn->mtime == 0); /* out-of-date if not present */
#endif
    }
    return (oodate);
}

/*-
 *-----------------------------------------------------------------------
 * Arch_Init --
 *      Initialize things for this module.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      The 'archives' list is initialized.
 *
 *-----------------------------------------------------------------------
 */
void
Arch_Init (void)
{
    archives = Lst_Init (FALSE);
}



/*-
 *-----------------------------------------------------------------------
 * Arch_End --
 *      Cleanup things for this module.
 *
 * Results:
 *      None.
 *
 * Side Effects:
 *      The 'archives' list is freed
 *
 *-----------------------------------------------------------------------
 */
void
Arch_End (void)
{
    Lst_Destroy(archives, ArchFree);
}