root/maint/gnulib/lib/savedir.c

/* */

DEFINITIONS

1. direntry_cmp_name
2. direntry_cmp_inode
3. streamsavedir
4. savedir

   1 /* savedir.c -- save the list of files in a directory in a string
   2 
   3    Copyright (C) 1990, 1997-2001, 2003-2006, 2009-2021 Free Software
   4    Foundation, Inc.
   5 
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10 
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15 
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18 
  19 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
  20 
  21 #include <config.h>
  22 
  23 #include "savedir.h"
  24 
  25 #include <sys/types.h>
  26 
  27 #include <errno.h>
  28 
  29 #include "dirent--.h"
  30 #ifndef _D_EXACT_NAMLEN
  31 # define _D_EXACT_NAMLEN(dp)    strlen ((dp)->d_name)
  32 #endif
  33 
  34 #include <stddef.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 
  38 #include "xalloc.h"
  39 
  40 typedef struct
  41 {
  42   char *name;
  43 #if D_INO_IN_DIRENT
  44   ino_t ino;
  45 #endif
  46 } direntry_t;
  47 
  48 /* Compare the names of two directory entries */
  49 
  50 static int
  51 direntry_cmp_name (void const *a, void const *b)
     /*  */
  52 {
  53   direntry_t const *dea = a;
  54   direntry_t const *deb = b;
  55 
  56   return strcmp (dea->name, deb->name);
  57 }
  58 
  59 #if D_INO_IN_DIRENT
  60 /* Compare the inode numbers of two directory entries */
  61 
  62 static int
  63 direntry_cmp_inode (void const *a, void const *b)
     /*  */
  64 {
  65   direntry_t const *dea = a;
  66   direntry_t const *deb = b;
  67 
  68   return _GL_CMP (dea->ino, deb->ino);
  69 }
  70 #endif
  71 
  72 typedef int (*comparison_function) (void const *, void const *);
  73 
  74 static comparison_function const comparison_function_table[] =
  75   {
  76     0,
  77     direntry_cmp_name
  78 #if D_INO_IN_DIRENT
  79     , direntry_cmp_inode
  80 #endif
  81   };
  82 
  83 /* Return a freshly allocated string containing the file names
  84    in directory DIRP, separated by '\0' characters;
  85    the end is marked by two '\0' characters in a row.
  86    Returned values are sorted according to OPTION.
  87    Return NULL (setting errno) if DIRP cannot be read.
  88    If DIRP is NULL, return NULL without affecting errno.  */
  89 
  90 char *
  91 streamsavedir (DIR *dirp, enum savedir_option option)
     /*  */
  92 {
  93   char *name_space = NULL;
  94   idx_t allocated = 0;
  95   direntry_t *entries = NULL;
  96   idx_t entries_allocated = 0;
  97   idx_t entries_used = 0;
  98   idx_t used = 0;
  99   comparison_function cmp = comparison_function_table[option];
 100 
 101   if (dirp == NULL)
 102     return NULL;
 103 
 104   for (;;)
 105     {
 106       struct dirent const *dp;
 107       char const *entry;
 108 
 109       errno = 0;
 110       dp = readdir (dirp);
 111       if (! dp)
 112         break;
 113 
 114       /* Skip "", ".", and "..".  "" is returned by at least one buggy
 115          implementation: Solaris 2.4 readdir on NFS file systems.  */
 116       entry = dp->d_name;
 117       if (entry[entry[0] != '.' ? 0 : entry[1] != '.' ? 1 : 2] != '\0')
 118         {
 119           idx_t entry_size = _D_EXACT_NAMLEN (dp) + 1;
 120           if (cmp)
 121             {
 122               if (entries_allocated == entries_used)
 123                 entries = xpalloc (entries, &entries_allocated, 1, -1,
 124                                    sizeof *entries);
 125               entries[entries_used].name = xstrdup (entry);
 126 #if D_INO_IN_DIRENT
 127               entries[entries_used].ino = dp->d_ino;
 128 #endif
 129               entries_used++;
 130             }
 131           else
 132             {
 133               if (allocated - used <= entry_size)
 134                 name_space = xpalloc (name_space, &allocated,
 135                                       entry_size - (allocated - used),
 136                                       IDX_MAX - 1, sizeof *name_space);
 137               memcpy (name_space + used, entry, entry_size);
 138             }
 139           used += entry_size;
 140         }
 141     }
 142 
 143   if (errno != 0)
 144     {
 145       free (entries);
 146       free (name_space);
 147       return NULL;
 148     }
 149 
 150   if (cmp)
 151     {
 152       if (entries_used)
 153         qsort (entries, entries_used, sizeof *entries, cmp);
 154       name_space = ximalloc (used + 1);
 155       used = 0;
 156       for (idx_t i = 0; i < entries_used; i++)
 157         {
 158           char *dest = name_space + used;
 159           used += stpcpy (dest, entries[i].name) - dest + 1;
 160           free (entries[i].name);
 161         }
 162       free (entries);
 163     }
 164   else if (used == allocated)
 165     name_space = xirealloc (name_space, used + 1);
 166 
 167   name_space[used] = '\0';
 168   return name_space;
 169 }
 170 
 171 /* Return a freshly allocated string containing the file names
 172    in directory DIR, separated by '\0' characters;
 173    the end is marked by two '\0' characters in a row.
 174    Return NULL (setting errno) if DIR cannot be opened, read, or closed.  */
 175 
 176 char *
 177 savedir (char const *dir, enum savedir_option option)
     /*  */
 178 {
 179   DIR *dirp = opendir (dir);
 180   if (! dirp)
 181     return NULL;
 182   else
 183     {
 184       char *name_space = streamsavedir (dirp, option);
 185       if (closedir (dirp) != 0)
 186         {
 187           free (name_space);
 188           return NULL;
 189         }
 190       return name_space;
 191     }
 192 }

/* */