/*  man.c: How to read and format man files.
    $Id: man.c,v 1.14 2008/06/28 08:09:32 gray Exp $

   Copyright (C) 1995, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 
   2007, 2008 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Originally written by Brian Fox Thu May  4 09:17:52 1995. */

#include "info.h"
#include <sys/ioctl.h>
#include "signals.h"
#if defined (HAVE_SYS_TIME_H)
#include <sys/time.h>
#endif
#if defined (HAVE_SYS_WAIT_H)
#include <sys/wait.h>
#endif

#include "tilde.h"
#include "man.h"

#if !defined (_POSIX_VERSION)
#define pid_t int
#endif

#if defined (FD_SET)
#  if defined (hpux)
#    define fd_set_cast(x) (int *)(x)
#  else
#    define fd_set_cast(x) (fd_set *)(x)
#  endif /* !hpux */
#endif /* FD_SET */

#if STRIP_DOT_EXE
static char const * const exec_extensions[] = {
  ".exe", ".com", ".bat", ".btm", ".sh", ".ksh", ".pl", ".sed", "", NULL
};
#else
static char const * const exec_extensions[] = { "", NULL };
#endif

static char *read_from_fd (int fd);
static NODE *manpage_node_of_file_buffer (FILE_BUFFER *file_buffer,
    char *pagename);
static char *get_manpage_contents (char *pagename);

NODE *
make_manpage_node (char *pagename)
{
  return info_get_node (MANPAGE_FILE_BUFFER_NAME, pagename);
}

NODE *
get_manpage_node (FILE_BUFFER *file_buffer, char *pagename)
{
  NODE *node;

  node = manpage_node_of_file_buffer (file_buffer, pagename);

  if (!node)
    {
      char *page;

      page = get_manpage_contents (pagename);

      if (page)
        {
          char header[1024];
          long oldsize, newsize;
          int hlen, plen;
	  char *old_contents = file_buffer->contents;

          sprintf (header, "\n\n%c\n%s %s,  %s %s,  %s (dir)\n\n",
                   INFO_COOKIE,
                   INFO_FILE_LABEL, file_buffer->filename,
                   INFO_NODE_LABEL, pagename,
                   INFO_UP_LABEL);
          oldsize = file_buffer->filesize;
          hlen = strlen (header);
          plen = strlen (page);
          newsize = (oldsize + hlen + plen);
          file_buffer->contents = xrealloc (file_buffer->contents, 1 + newsize);
          memcpy (file_buffer->contents + oldsize, header, hlen);
          memcpy (file_buffer->contents + oldsize + hlen, page, plen);
          file_buffer->contents[newsize] = '\0';
          file_buffer->filesize = newsize;
          file_buffer->finfo.st_size = newsize;
          build_tags_and_nodes (file_buffer);
          free (page);
	  /* We have just relocated file_buffer->contents from under
	     the feet of info_windows[] array.  Therefore, all the
	     nodes on that list which are showing man pages have their
	     contents member pointing into the blue.  Undo that harm.  */
	  if (old_contents && oldsize && old_contents != file_buffer->contents)
	    {
	      int iw;
	      INFO_WINDOW *info_win;
	      char *old_contents_end = old_contents + oldsize;

	      for (iw = 0; (info_win = info_windows[iw]); iw++)
		{
		  int in;

		  for (in = 0; in < info_win->nodes_index; in++)
		    {
		      NODE *tmp_node = info_win->nodes[in];

		      /* It really only suffices to see that node->filename
			 is "*manpages*".  But after several hours of
			 debugging this, would you blame me for being a bit
			 paranoid?  */
		      if (tmp_node && tmp_node->filename
                          && tmp_node->contents
                          && strcmp (tmp_node->filename,
				  MANPAGE_FILE_BUFFER_NAME) == 0
                          && tmp_node->contents >= old_contents
                          && tmp_node->contents + tmp_node->nodelen
                                <= old_contents_end)
			{
			  info_win->nodes[in] =
			    manpage_node_of_file_buffer (file_buffer,
                                tmp_node->nodename);
			  free (tmp_node->nodename);
			  free (tmp_node);
			}
		    }
		}
	    }
        }

      node = manpage_node_of_file_buffer (file_buffer, pagename);
    }

  return node;
}

FILE_BUFFER *
create_manpage_file_buffer (void)
{
  FILE_BUFFER *file_buffer = make_file_buffer ();
  file_buffer->filename = xstrdup (MANPAGE_FILE_BUFFER_NAME);
  file_buffer->fullpath = xstrdup (MANPAGE_FILE_BUFFER_NAME);
  file_buffer->finfo.st_size = 0;
  file_buffer->filesize = 0;
  file_buffer->contents = NULL;
  file_buffer->flags = (N_IsInternal | N_CannotGC | N_IsManPage);

  return file_buffer;
}

/* Scan the list of directories in PATH looking for FILENAME.  If we find
   one that is an executable file, return it as a new string.  Otherwise,
   return a NULL pointer. */
static char *
executable_file_in_path (char *filename, char *path)
{
  struct stat finfo;
  char *temp_dirname;
  int statable, dirname_index;

  dirname_index = 0;

  while ((temp_dirname = extract_colon_unit (path, &dirname_index)))
    {
      char *temp;
      char *temp_end;
      int i;

      /* Expand a leading tilde if one is present. */
      if (*temp_dirname == '~')
        {
          char *expanded_dirname;

          expanded_dirname = tilde_expand_word (temp_dirname);
          free (temp_dirname);
          temp_dirname = expanded_dirname;
        }

      temp = xmalloc (34 + strlen (temp_dirname) + strlen (filename));
      strcpy (temp, temp_dirname);
      if (!IS_SLASH (temp[(strlen (temp)) - 1]))
        strcat (temp, "/");
      strcat (temp, filename);
      temp_end = temp + strlen (temp);

      free (temp_dirname);

      /* Look for FILENAME, possibly with any of the extensions
	 in EXEC_EXTENSIONS[].  */
      for (i = 0; exec_extensions[i]; i++)
	{
	  if (exec_extensions[i][0])
	    strcpy (temp_end, exec_extensions[i]);
	  statable = (stat (temp, &finfo) == 0);

	  /* If we have found a regular executable file, then use it. */
	  if ((statable) && (S_ISREG (finfo.st_mode)) &&
	      (access (temp, X_OK) == 0))
	    return temp;
	}

      free (temp);
    }
  return NULL;
}

/* Return the full pathname of the system man page formatter. */
static char *
find_man_formatter (void)
{
  char *man_command = getenv ("INFO_MAN_COMMAND");
  return man_command ? man_command :
                       executable_file_in_path ("man", getenv ("PATH"));
}

static char *manpage_pagename = NULL;
static char *manpage_section  = NULL;

static void
get_page_and_section (char *pagename)
{
  register int i;

  if (manpage_pagename)
    free (manpage_pagename);

  if (manpage_section)
    free (manpage_section);

  manpage_pagename = NULL;
  manpage_section  = NULL;

  for (i = 0; pagename[i] != '\0' && pagename[i] != '('; i++);

  manpage_pagename = xmalloc (1 + i);
  strncpy (manpage_pagename, pagename, i);
  manpage_pagename[i] = '\0';

  if (pagename[i] == '(')
    {
      int start;

      start = i + 1;

      for (i = start; pagename[i] != '\0' && pagename[i] != ')'; i++);

      manpage_section = xmalloc (1 + (i - start));
      strncpy (manpage_section, pagename + start, (i - start));
      manpage_section[i - start] = '\0';
    }
}

#if PIPE_USE_FORK
static void
reap_children (int sig)
{
  wait (NULL);
}
#endif

static char *
get_manpage_contents (char *pagename)
{
  static char *formatter_args[4] = { NULL };
  int pipes[2];
  pid_t child;
  RETSIGTYPE (*sigsave) (int signum);
  char *formatted_page = NULL;
  int arg_index = 1;

  if (formatter_args[0] == NULL)
    formatter_args[0] = find_man_formatter ();

  if (formatter_args[0] == NULL)
    return NULL;

  get_page_and_section (pagename);

  if (manpage_section)
    formatter_args[arg_index++] = manpage_section;
  else
    formatter_args[arg_index++] = "-a";    

  formatter_args[arg_index++] = manpage_pagename;
  formatter_args[arg_index] = NULL;

  /* Open a pipe to this program, read the output, and save it away
     in FORMATTED_PAGE.  The reader end of the pipe is pipes[0]; the
     writer end is pipes[1]. */
#if PIPE_USE_FORK
  pipe (pipes);

  sigsave = signal (SIGCHLD, reap_children);

  child = fork ();
  if (child == -1)
    return NULL;

  if (child != 0)
    {
      /* In the parent, close the writing end of the pipe, and read from
         the exec'd child. */
      close (pipes[1]);
      formatted_page = read_from_fd (pipes[0]);
      close (pipes[0]);
      signal (SIGCHLD, sigsave);
    }
  else
    { /* In the child, close the read end of the pipe, make the write end
         of the pipe be stdout, and execute the man page formatter. */
      close (pipes[0]);
      freopen (NULL_DEVICE, "w", stderr);
      freopen (NULL_DEVICE, "r", stdin);
      dup2 (pipes[1], fileno (stdout));

      execv (formatter_args[0], formatter_args);

      /* If we get here, we couldn't exec, so close out the pipe and
         exit. */
      close (pipes[1]);
      xexit (0);
    }
#else  /* !PIPE_USE_FORK */
  /* Cannot fork/exec, but can popen/pclose.  */
  {
    FILE *fpipe;
    char *cmdline = xmalloc (strlen (formatter_args[0])
			     + strlen (manpage_pagename)
			     + (arg_index > 2 ? strlen (manpage_section) : 0)
 			     + 3);
    int save_stderr = dup (fileno (stderr));
    int fd_err = open (NULL_DEVICE, O_WRONLY, 0666);

    if (fd_err > 2)
      dup2 (fd_err, fileno (stderr)); /* Don't print errors. */
    sprintf (cmdline, "%s %s %s", formatter_args[0], manpage_pagename,
				  arg_index > 2 ? manpage_section : "");
    fpipe = popen (cmdline, "r");
    free (cmdline);
    if (fd_err > 2)
      close (fd_err);
    dup2 (save_stderr, fileno (stderr));
    if (fpipe == 0)
      return NULL;
    formatted_page = read_from_fd (fileno (fpipe));
    if (pclose (fpipe) == -1)
      {
	if (formatted_page)
	  free (formatted_page);
	return NULL;
      }
  }
#endif /* !PIPE_USE_FORK */

  /* If we have the page, then clean it up. */
  if (formatted_page)
    clean_manpage (formatted_page);

  return formatted_page;
}

static NODE *
manpage_node_of_file_buffer (FILE_BUFFER *file_buffer, char *pagename)
{
  NODE *node = NULL;
  TAG *tag = NULL;

  if (file_buffer->contents)
    {
      register int i;

      for (i = 0; (tag = file_buffer->tags[i]); i++)
        {
          if (mbscasecmp (pagename, tag->nodename) == 0)
            break;
        }
    }

  if (tag)
    {
      node = xmalloc (sizeof (NODE));
      node->filename = file_buffer->filename;
      node->nodename = xstrdup (tag->nodename);
      node->contents = file_buffer->contents + tag->nodestart;
      node->nodelen = tag->nodelen;
      node->flags    = 0;
      node->display_pos = 0;
      node->parent   = NULL;
      node->flags = (N_HasTagsTable | N_IsManPage);
      node->contents += skip_node_separator (node->contents);
    }

  return node;
}

static char *
read_from_fd (int fd)
{
  struct timeval timeout;
  char *buffer = NULL;
  int bsize = 0;
  int bindex = 0;
  int select_result;
#if defined (FD_SET)
  fd_set read_fds;

  timeout.tv_sec = 15;
  timeout.tv_usec = 0;

  FD_ZERO (&read_fds);
  FD_SET (fd, &read_fds);

  select_result = select (fd + 1, fd_set_cast (&read_fds), 0, 0, &timeout);
#else /* !FD_SET */
  select_result = 1;
#endif /* !FD_SET */

  switch (select_result)
    {
    case 0:
    case -1:
      break;

    default:
      {
        int amount_read;
        int done = 0;

        while (!done)
          {
            while ((bindex + 1024) > (bsize))
              buffer = xrealloc (buffer, (bsize += 1024));
            buffer[bindex] = '\0';

            amount_read = read (fd, buffer + bindex, 1023);

            if (amount_read < 0)
              {
                done = 1;
              }
            else
              {
                bindex += amount_read;
                buffer[bindex] = '\0';
                if (amount_read == 0)
                  done = 1;
              }
          }
      }
    }

  if ((buffer != NULL) && (*buffer == '\0'))
    {
      free (buffer);
      buffer = NULL;
    }

  return buffer;
}

static char *reference_section_starters[] =
{
  "\nRELATED INFORMATION",
  "\nRELATED\tINFORMATION",
  "RELATED INFORMATION\n",
  "RELATED\tINFORMATION\n",
  "\nSEE ALSO",
  "\nSEE\tALSO",
  "SEE ALSO\n",
  "SEE\tALSO\n",
  NULL
};

static SEARCH_BINDING frs_binding;

static SEARCH_BINDING *
find_reference_section (NODE *node)
{
  register int i;
  long position = -1;

  frs_binding.buffer = node->contents;
  frs_binding.start = 0;
  frs_binding.end = node->nodelen;
  frs_binding.flags = S_SkipDest;

  for (i = 0; reference_section_starters[i] != NULL; i++)
    {
      position = search_forward (reference_section_starters[i], &frs_binding);
      if (position != -1)
        break;
    }

  if (position == -1)
    return NULL;

  /* We found the start of the reference section, and point is right after
     the string which starts it.  The text from here to the next header
     (or end of buffer) contains the only references in this manpage. */
  frs_binding.start = position;

  for (i = frs_binding.start; i < frs_binding.end - 2; i++)
    {
      if ((frs_binding.buffer[i] == '\n') &&
          (!whitespace (frs_binding.buffer[i + 1])))
        {
          frs_binding.end = i;
          break;
        }
    }

  return &frs_binding;
}

REFERENCE **
xrefs_of_manpage (NODE *node)
{
  SEARCH_BINDING *reference_section;
  REFERENCE **refs = NULL;
  int refs_index = 0;
  int refs_slots = 0;
  long position;

  reference_section = find_reference_section (node);

  if (reference_section == NULL)
    return NULL;

  /* Grovel the reference section building a list of references found there.
     A reference is alphabetic characters followed by non-whitespace text
     within parenthesis. */
  reference_section->flags = 0;

  while ((position = search_forward ("(", reference_section)) != -1)
    {
      register int start, end;

      for (start = position; start > reference_section->start; start--)
        if (whitespace (reference_section->buffer[start]))
          break;

      start++;

      for (end = position; end < reference_section->end; end++)
        {
          if (whitespace (reference_section->buffer[end]))
            {
              end = start;
              break;
            }

          if (reference_section->buffer[end] == ')')
            {
              end++;
              break;
            }
        }

      if (end != start)
        {
          REFERENCE *entry;
          int len = end - start;

          entry = xmalloc (sizeof (REFERENCE));
          entry->label = xmalloc (1 + len);
          strncpy (entry->label, (reference_section->buffer) + start, len);
          entry->label[len] = '\0';
          entry->filename = xstrdup (node->filename);
          entry->nodename = xstrdup (entry->label);
          entry->start = start;
          entry->end = end;

          add_pointer_to_array
            (entry, refs_index, refs, refs_slots, 10, REFERENCE *);
        }

      reference_section->start = position + 1;
    }

  return refs;
}

long
locate_manpage_xref (NODE *node, long int start, int dir)
{
  REFERENCE **refs;
  long position = -1;

  refs = xrefs_of_manpage (node);

  if (refs)
    {
      register int i, count;
      REFERENCE *entry;

      for (i = 0; refs[i]; i++);
      count = i;

      if (dir > 0)
        {
          for (i = 0; (entry = refs[i]); i++)
            if (entry->start > start)
              {
                position = entry->start;
                break;
              }
        }
      else
        {
          for (i = count - 1; i > -1; i--)
            {
              entry = refs[i];

              if (entry->start < start)
                {
                  position = entry->start;
                  break;
                }
            }
        }

      info_free_references (refs);
    }
  return position;
}

/* This one was a little tricky.  The binding buffer that is passed in has
   a START and END value of 0 -- strlen (window-line-containing-point).
   The BUFFER is a pointer to the start of that line. */
REFERENCE **
manpage_xrefs_in_binding (NODE *node, SEARCH_BINDING *binding)
{
  register int i;
  REFERENCE **all_refs = xrefs_of_manpage (node);
  REFERENCE **brefs = NULL;
  REFERENCE *entry;
  int brefs_index = 0;
  int brefs_slots = 0;
  int start, end;

  if (!all_refs)
    return NULL;

  start = binding->start + (binding->buffer - node->contents);
  end = binding->end + (binding->buffer - node->contents);

  for (i = 0; (entry = all_refs[i]); i++)
    {
      if ((entry->start > start) && (entry->end < end))
        {
          add_pointer_to_array
            (entry, brefs_index, brefs, brefs_slots, 10, REFERENCE *);
        }
      else
        {
          maybe_free (entry->label);
          maybe_free (entry->filename);
          maybe_free (entry->nodename);
          free (entry);
        }
    }

  free (all_refs);
  return brefs;
}