locale/programs/charmap-dir.c

   1 /* Copyright (C) 2000-2023 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   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
   6    by the Free Software Foundation; version 2 of the License, or
   7    (at your option) 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, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <dirent.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <libintl.h>
  21 #include <spawn.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/stat.h>
  27
  28 #include "localedef.h"
  29 #include "charmap-dir.h"
  30
  31 /* The data type of a charmap directory being traversed.  */
  32 struct charmap_dir
  33 {
  34   DIR *dir;
  35   /* The directory pathname, ending in a slash.  */
  36   char *directory;
  37   size_t directory_len;
  38   /* Scratch area used for returning pathnames.  */
  39   char *pathname;
  40   size_t pathname_size;
  41 };
  42
  43 /* Starts a charmap directory traversal.
  44    Returns a CHARMAP_DIR, or NULL if the directory doesn't exist.  */
  45 CHARMAP_DIR *
  46 charmap_opendir (const char *directory)
  47 {
  48   struct charmap_dir *cdir;
  49   DIR *dir;
  50   size_t len;
  51   int add_slash;
  52
  53   dir = opendir (directory);
  54   if (dir == NULL)
  55     {
  56       record_error (1, errno, gettext ("\
  57 cannot read character map directory `%s'"),
  58                     directory);
  59       return NULL;
  60     }
  61
  62   cdir = (struct charmap_dir *) xmalloc (sizeof (struct charmap_dir));
  63   cdir->dir = dir;
  64
  65   len = strlen (directory);
  66   add_slash = (len == 0 || directory[len - 1] != '/');
  67   cdir->directory = (char *) xmalloc (len + add_slash + 1);
  68   memcpy (cdir->directory, directory, len);
  69   if (add_slash)
  70     cdir->directory[len] = '/';
  71   cdir->directory[len + add_slash] = '\0';
  72   cdir->directory_len = len + add_slash;
  73
  74   cdir->pathname = NULL;
  75   cdir->pathname_size = 0;
  76
  77   return cdir;
  78 }
  79
  80 /* Reads the next directory entry.
  81    Returns its charmap name, or NULL if past the last entry or upon error.
  82    The storage returned may be overwritten by a later charmap_readdir
  83    call on the same CHARMAP_DIR.  */
  84 const char *
  85 charmap_readdir (CHARMAP_DIR *cdir)
  86 {
  87   for (;;)
  88     {
  89       struct dirent64 *dirent;
  90       size_t len;
  91       size_t size;
  92       char *filename;
  93       mode_t mode;
  94
  95       dirent = readdir64 (cdir->dir);
  96       if (dirent == NULL)
  97         return NULL;
  98       if (strcmp (dirent->d_name, ".") == 0)
  99         continue;
 100       if (strcmp (dirent->d_name, "..") == 0)
 101         continue;
 102
 103       len = strlen (dirent->d_name);
 104
 105       size = cdir->directory_len + len + 1;
 106       if (size > cdir->pathname_size)
 107         {
 108           free (cdir->pathname);
 109           if (size < 2 * cdir->pathname_size)
 110             size = 2 * cdir->pathname_size;
 111           cdir->pathname = (char *) xmalloc (size);
 112           cdir->pathname_size = size;
 113         }
 114
 115       stpcpy (stpcpy (cdir->pathname, cdir->directory), dirent->d_name);
 116       filename = cdir->pathname + cdir->directory_len;
 117
 118       if (dirent->d_type != DT_UNKNOWN && dirent->d_type != DT_LNK)
 119         mode = DTTOIF (dirent->d_type);
 120       else
 121         {
 122           struct stat64 statbuf;
 123
 124           if (stat64 (cdir->pathname, &statbuf) < 0)
 125             continue;
 126
 127           mode = statbuf.st_mode;
 128         }
 129
 130       if (!S_ISREG (mode))
 131         continue;
 132
 133       /* For compressed charmaps, the canonical charmap name does not
 134          include the extension.  */
 135       if (len > 3 && memcmp (&filename[len - 3], ".gz", 3) == 0)
 136         filename[len - 3] = '\0';
 137       else if (len > 4 && memcmp (&filename[len - 4], ".bz2", 4) == 0)
 138         filename[len - 4] = '\0';
 139
 140       return filename;
 141     }
 142 }
 143
 144 /* Finishes a charmap directory traversal, and frees the resources
 145    attached to the CHARMAP_DIR.  */
 146 int
 147 charmap_closedir (CHARMAP_DIR *cdir)
 148 {
 149   DIR *dir = cdir->dir;
 150
 151   free (cdir->directory);
 152   free (cdir->pathname);
 153   free (cdir);
 154   return closedir (dir);
 155 }
 156
 157 /* Creates a subprocess decompressing the given pathname, and returns
 158    a stream reading its output (the decompressed data).  */
 159 static
 160 FILE *
 161 fopen_uncompressed (const char *pathname, const char *compressor)
 162 {
 163   int pfd;
 164
 165   pfd = open (pathname, O_RDONLY);
 166   if (pfd >= 0)
 167     {
 168       struct stat64 statbuf;
 169       int fd[2];
 170
 171       if (fstat64 (pfd, &statbuf) >= 0
 172           && S_ISREG (statbuf.st_mode)
 173           && pipe (fd) >= 0)
 174         {
 175           char *argv[4]
 176             = { (char *) compressor, (char *) "-d", (char *) "-c", NULL };
 177           posix_spawn_file_actions_t actions;
 178
 179           if (posix_spawn_file_actions_init (&actions) == 0)
 180             {
 181               if (posix_spawn_file_actions_adddup2 (&actions,
 182                                                     fd[1], STDOUT_FILENO) == 0
 183                   && posix_spawn_file_actions_addclose (&actions, fd[1]) == 0
 184                   && posix_spawn_file_actions_addclose (&actions, fd[0]) == 0
 185                   && posix_spawn_file_actions_adddup2 (&actions,
 186                                                        pfd, STDIN_FILENO) == 0
 187                   && posix_spawn_file_actions_addclose (&actions, pfd) == 0
 188                   && posix_spawnp (NULL, compressor, &actions, NULL,
 189                                    argv, environ) == 0)
 190                 {
 191                   posix_spawn_file_actions_destroy (&actions);
 192                   close (fd[1]);
 193                   close (pfd);
 194                   return fdopen (fd[0], "r");
 195                 }
 196               posix_spawn_file_actions_destroy (&actions);
 197             }
 198           close (fd[1]);
 199           close (fd[0]);
 200         }
 201       close (pfd);
 202     }
 203   return NULL;
 204 }
 205
 206 /* Opens a charmap for reading, given its name (not an alias name).  */
 207 FILE *
 208 charmap_open (const char *directory, const char *name)
 209 {
 210   size_t dlen = strlen (directory);
 211   int add_slash = (dlen == 0 || directory[dlen - 1] != '/');
 212   size_t nlen = strlen (name);
 213   char *pathname;
 214   char *p;
 215   FILE *stream;
 216
 217   pathname = alloca (dlen + add_slash + nlen + 5);
 218   p = stpcpy (pathname, directory);
 219   if (add_slash)
 220     *p++ = '/';
 221   p = stpcpy (p, name);
 222
 223   stream = fopen (pathname, "rm");
 224   if (stream != NULL)
 225     return stream;
 226
 227   memcpy (p, ".gz", 4);
 228   stream = fopen_uncompressed (pathname, "gzip");
 229   if (stream != NULL)
 230     return stream;
 231
 232   memcpy (p, ".bz2", 5);
 233   stream = fopen_uncompressed (pathname, "bzip2");
 234   if (stream != NULL)
 235     return stream;
 236
 237   return NULL;
 238 }
 239
 240 /* An empty alias list.  Avoids the need to return NULL from
 241    charmap_aliases.  */
 242 static char *empty[1];
 243
 244 /* Returns a NULL terminated list of alias names of a charmap.  */
 245 char **
 246 charmap_aliases (const char *directory, const char *name)
 247 {
 248   FILE *stream;
 249   char **aliases;
 250   size_t naliases;
 251
 252   stream = charmap_open (directory, name);
 253   if (stream == NULL)
 254     return empty;
 255
 256   aliases = NULL;
 257   naliases = 0;
 258
 259   while (!feof (stream))
 260     {
 261       char *alias = NULL;
 262       char junk[BUFSIZ];
 263
 264       if (fscanf (stream, " <code_set_name> %ms", &alias) == 1
 265           || fscanf (stream, "%% alias %ms", &alias) == 1)
 266         {
 267           aliases = (char **) xrealloc (aliases,
 268                                         (naliases + 2) * sizeof (char *));
 269           aliases[naliases++] = alias;
 270         }
 271
 272       /* Read the rest of the line.  */
 273       if (fgets (junk, sizeof junk, stream) != NULL)
 274         {
 275           if (strstr (junk, "CHARMAP") != NULL)
 276             /* We cannot expect more aliases from now on.  */
 277             break;
 278
 279           while (strchr (junk, '\n') == NULL
 280                  && fgets (junk, sizeof junk, stream) != NULL)
 281             continue;
 282         }
 283     }
 284
 285   fclose (stream);
 286
 287   if (naliases == 0)
 288     return empty;
 289
 290   aliases[naliases] = NULL;
 291   return aliases;
 292 }
 293
 294 /* Frees an alias list returned by charmap_aliases.  */
 295 void
 296 charmap_free_aliases (char **aliases)
 297 {
 298   if (aliases != empty)
 299     {
 300       char **p;
 301
 302       for (p = aliases; *p; p++)
 303         free (*p);
 304
 305       free (aliases);
 306     }
 307 }