lib/savedir.c

   1 /* savedir.c -- save the list of files in a directory in a string
   2    Copyright (C) 1990, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <sys/types.h>
  25
  26 #include <errno.h>
  27 #ifndef errno
  28 extern int errno;
  29 #endif
  30
  31 #if HAVE_DIRENT_H
  32 # include <dirent.h>
  33 #else
  34 # define dirent direct
  35 # if HAVE_SYS_NDIR_H
  36 #  include <sys/ndir.h>
  37 # endif
  38 # if HAVE_SYS_DIR_H
  39 #  include <sys/dir.h>
  40 # endif
  41 # if HAVE_NDIR_H
  42 #  include <ndir.h>
  43 # endif
  44 #endif
  45
  46 #ifdef CLOSEDIR_VOID
  47 /* Fake a return value. */
  48 # define CLOSEDIR(d) (closedir (d), 0)
  49 #else
  50 # define CLOSEDIR(d) closedir (d)
  51 #endif
  52
  53 #ifdef STDC_HEADERS
  54 # include <stdlib.h>
  55 # include <string.h>
  56 #endif
  57 #ifndef NULL
  58 # define NULL 0
  59 #endif
  60
  61 #include "savedir.h"
  62 #include "xalloc.h"
  63
  64 /* Return a freshly allocated string containing the filenames
  65    in directory DIR, separated by '\0' characters;
  66    the end is marked by two '\0' characters in a row.
  67    NAME_SIZE is the number of bytes to initially allocate
  68    for the string; it will be enlarged as needed.
  69    Use NAME_SIZE == -1 if you do not know the size.
  70    Return NULL (setting errno) if DIR cannot be opened, read, or closed.  */
  71
  72 #ifndef NAME_SIZE_DEFAULT
  73 # define NAME_SIZE_DEFAULT 512
  74 #endif
  75
  76 char *
  77 savedir (const char *dir, off_t name_size)
  78 {
  79   DIR *dirp;
  80   struct dirent *dp;
  81   char *name_space;
  82   size_t allocated = name_size; /* Overflow is checked indirectly below.  */
  83   size_t used = 0;
  84   int save_errno;
  85
  86   dirp = opendir (dir);
  87   if (dirp == NULL)
  88     return NULL;
  89
  90   /* Use the default if the size is not known.  Be sure "allocated"
  91      is at least `1' so there's room for the final NUL byte.
  92      Do not simply test name_size <= 0, because the initialization
  93      of "allocated" might have overflowed.  */
  94   if (name_size < 0 || allocated == 0)
  95     allocated = NAME_SIZE_DEFAULT;
  96
  97   name_space = xmalloc (allocated);
  98
  99   errno = 0;
 100   while ((dp = readdir (dirp)) != NULL)
 101     {
 102       /* Skip "", ".", and "..".  "" is returned by at least one buggy
 103          implementation: Solaris 2.4 readdir on NFS filesystems.  */
 104       char const *entry = dp->d_name;
 105       if (entry[entry[0] != '.' ? 0 : entry[1] != '.' ? 1 : 2] != '\0')
 106         {
 107           size_t entry_size = strlen (entry) + 1;
 108           if (used + entry_size < used)
 109             xalloc_die ();
 110           if (allocated <= used + entry_size)
 111             {
 112               do
 113                 {
 114                   if (2 * allocated < allocated)
 115                     xalloc_die ();
 116                   allocated *= 2;
 117                 }
 118               while (allocated <= used + entry_size);
 119
 120               name_space = xrealloc (name_space, allocated);
 121             }
 122           memcpy (name_space + used, entry, entry_size);
 123           used += entry_size;
 124         }
 125     }
 126   name_space[used] = '\0';
 127   save_errno = errno;
 128   if (CLOSEDIR (dirp) != 0)
 129     save_errno = errno;
 130   if (save_errno != 0)
 131     {
 132       free (name_space);
 133       errno = save_errno;
 134       return NULL;
 135     }
 136   return name_space;
 137 }