gnu/dist/gettext/gettext-tools/lib/canonicalize.c

   1 /* Return the canonical absolute name of a given file.
   2    Copyright (C) 1996-2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 /* Avoid a clash of our rpl_realpath() function with the prototype in
  25    <stdlib.h> on Solaris 2.5.1.  */
  26 #undef realpath
  27
  28 #if !HAVE_CANONICALIZE_FILE_NAME || defined _LIBC
  29
  30 #include <alloca.h>
  31
  32 /* Specification.  */
  33 #include "canonicalize.h"
  34
  35 #include <stddef.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #if HAVE_UNISTD_H || defined _LIBC
  40 # include <unistd.h>
  41 #endif
  42
  43 #include <limits.h>
  44
  45 #if HAVE_SYS_PARAM_H || defined _LIBC
  46 # include <sys/param.h>
  47 #endif
  48 #ifndef MAXSYMLINKS
  49 # define MAXSYMLINKS 20
  50 #endif
  51
  52 #include <sys/stat.h>
  53
  54 #include <errno.h>
  55 #ifndef _LIBC
  56 # define __set_errno(e) errno = (e)
  57 # ifndef ENAMETOOLONG
  58 #  define ENAMETOOLONG EINVAL
  59 # endif
  60 #endif
  61
  62 #ifdef _LIBC
  63 # include <shlib-compat.h>
  64 #else
  65 # define SHLIB_COMPAT(lib, introduced, obsoleted) 0
  66 # define versioned_symbol(lib, local, symbol, version)
  67 # define compat_symbol(lib, local, symbol, version)
  68 # define weak_alias(local, symbol)
  69 # define __canonicalize_file_name canonicalize_file_name
  70 # define __realpath rpl_realpath
  71 # include "pathmax.h"
  72 # include "allocsa.h"
  73 # if HAVE_GETCWD
  74 #  ifdef VMS
  75     /* We want the directory in Unix syntax, not in VMS syntax.  */
  76 #   define __getcwd(buf, max) getcwd (buf, max, 0)
  77 #  else
  78 #   define __getcwd getcwd
  79 #  endif
  80 # else
  81 #  define __getcwd(buf, max) getwd (buf)
  82 # endif
  83 # define __readlink readlink
  84   /* On systems without symbolic links, call stat() instead of lstat().  */
  85 # if !defined S_ISNLK && !HAVE_READLINK
  86 #  define lstat stat
  87 # endif
  88 #endif
  89
  90 /* Return the canonical absolute name of file NAME.  A canonical name
  91    does not contain any `.', `..' components nor any repeated path
  92    separators ('/') or symlinks.  All path components must exist.  If
  93    RESOLVED is null, the result is malloc'd; otherwise, if the
  94    canonical name is PATH_MAX chars or more, returns null with `errno'
  95    set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
  96    returns the name in RESOLVED.  If the name cannot be resolved and
  97    RESOLVED is non-NULL, it contains the path of the first component
  98    that cannot be resolved.  If the path can be resolved, RESOLVED
  99    holds the same value as the value returned.  */
 100
 101 char *
 102 __realpath (const char *name, char *resolved)
 103 {
 104   char *rpath, *dest, *extra_buf = NULL;
 105   const char *start, *end, *rpath_limit;
 106   long int path_max;
 107   int num_links = 0;
 108
 109   if (name == NULL)
 110     {
 111       /* As per Single Unix Specification V2 we must return an error if
 112          either parameter is a null pointer.  We extend this to allow
 113          the RESOLVED parameter to be NULL in case the we are expected to
 114          allocate the room for the return value.  */
 115       __set_errno (EINVAL);
 116       return NULL;
 117     }
 118
 119   if (name[0] == '\0')
 120     {
 121       /* As per Single Unix Specification V2 we must return an error if
 122          the name argument points to an empty string.  */
 123       __set_errno (ENOENT);
 124       return NULL;
 125     }
 126
 127 #ifdef PATH_MAX
 128   path_max = PATH_MAX;
 129 #else
 130   path_max = pathconf (name, _PC_PATH_MAX);
 131   if (path_max <= 0)
 132     path_max = 1024;
 133 #endif
 134
 135   if (resolved == NULL)
 136     {
 137       rpath = malloc (path_max);
 138       if (rpath == NULL)
 139         return NULL;
 140     }
 141   else
 142     rpath = resolved;
 143   rpath_limit = rpath + path_max;
 144
 145   if (name[0] != '/')
 146     {
 147       if (!__getcwd (rpath, path_max))
 148         {
 149           rpath[0] = '\0';
 150           goto error;
 151         }
 152       dest = strchr (rpath, '\0');
 153     }
 154   else
 155     {
 156       rpath[0] = '/';
 157       dest = rpath + 1;
 158     }
 159
 160   for (start = end = name; *start; start = end)
 161     {
 162 #ifdef _LIBC
 163       struct stat64 st;
 164 #else
 165       struct stat st;
 166 #endif
 167       int n;
 168
 169       /* Skip sequence of multiple path-separators.  */
 170       while (*start == '/')
 171         ++start;
 172
 173       /* Find end of path component.  */
 174       for (end = start; *end && *end != '/'; ++end)
 175         /* Nothing.  */;
 176
 177       if (end - start == 0)
 178         break;
 179       else if (end - start == 1 && start[0] == '.')
 180         /* nothing */;
 181       else if (end - start == 2 && start[0] == '.' && start[1] == '.')
 182         {
 183           /* Back up to previous component, ignore if at root already.  */
 184           if (dest > rpath + 1)
 185             while ((--dest)[-1] != '/');
 186         }
 187       else
 188         {
 189           size_t new_size;
 190
 191           if (dest[-1] != '/')
 192             *dest++ = '/';
 193
 194           if (dest + (end - start) >= rpath_limit)
 195             {
 196               ptrdiff_t dest_offset = dest - rpath;
 197               char *new_rpath;
 198
 199               if (resolved)
 200                 {
 201                   __set_errno (ENAMETOOLONG);
 202                   if (dest > rpath + 1)
 203                     dest--;
 204                   *dest = '\0';
 205                   goto error;
 206                 }
 207               new_size = rpath_limit - rpath;
 208               if (end - start + 1 > path_max)
 209                 new_size += end - start + 1;
 210               else
 211                 new_size += path_max;
 212               new_rpath = (char *) realloc (rpath, new_size);
 213               if (new_rpath == NULL)
 214                 goto error;
 215               rpath = new_rpath;
 216               rpath_limit = rpath + new_size;
 217
 218               dest = rpath + dest_offset;
 219             }
 220
 221 #ifdef _LIBC
 222           dest = __mempcpy (dest, start, end - start);
 223 #else
 224           memcpy (dest, start, end - start);
 225           dest += end - start;
 226 #endif
 227           *dest = '\0';
 228
 229 #ifdef _LIBC
 230           if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
 231 #else
 232           if (lstat (rpath, &st) < 0)
 233 #endif
 234             goto error;
 235
 236 #ifdef S_ISLNK
 237           if (S_ISLNK (st.st_mode))
 238             {
 239               char *buf;
 240               size_t len;
 241
 242               if (++num_links > MAXSYMLINKS)
 243                 {
 244                   __set_errno (ELOOP);
 245                   goto error;
 246                 }
 247
 248               buf = allocsa (path_max);
 249               if (!buf)
 250                 {
 251                   errno = ENOMEM;
 252                   goto error;
 253                 }
 254
 255               n = __readlink (rpath, buf, path_max);
 256               if (n < 0)
 257                 {
 258                   int saved_errno = errno;
 259                   freesa (buf);
 260                   errno = saved_errno;
 261                   goto error;
 262                 }
 263               buf[n] = '\0';
 264
 265               if (!extra_buf)
 266                 {
 267                   extra_buf = allocsa (path_max);
 268                   if (!extra_buf)
 269                     {
 270                       freesa (buf);
 271                       errno = ENOMEM;
 272                       goto error;
 273                     }
 274                 }
 275
 276               len = strlen (end);
 277               if ((long int) (n + len) >= path_max)
 278                 {
 279                   freesa (buf);
 280                   __set_errno (ENAMETOOLONG);
 281                   goto error;
 282                 }
 283
 284               /* Careful here, end may be a pointer into extra_buf... */
 285               memmove (&extra_buf[n], end, len + 1);
 286               name = end = memcpy (extra_buf, buf, n);
 287
 288               if (buf[0] == '/')
 289                 dest = rpath + 1;       /* It's an absolute symlink */
 290               else
 291                 /* Back up to previous component, ignore if at root already: */
 292                 if (dest > rpath + 1)
 293                   while ((--dest)[-1] != '/');
 294             }
 295 #endif
 296         }
 297     }
 298   if (dest > rpath + 1 && dest[-1] == '/')
 299     --dest;
 300   *dest = '\0';
 301
 302   if (extra_buf)
 303     freesa (extra_buf);
 304
 305   return resolved ? memcpy (resolved, rpath, dest - rpath + 1) : rpath;
 306
 307 error:
 308   {
 309     int saved_errno = errno;
 310     if (extra_buf)
 311       freesa (extra_buf);
 312     if (resolved)
 313       strcpy (resolved, rpath);
 314     else
 315       free (rpath);
 316     errno = saved_errno;
 317   }
 318   return NULL;
 319 }
 320 #ifdef _LIBC
 321 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
 322 #endif
 323
 324
 325 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
 326 char *
 327 __old_realpath (const char *name, char *resolved)
 328 {
 329   if (resolved == NULL)
 330     {
 331       __set_errno (EINVAL);
 332       return NULL;
 333     }
 334
 335   return __realpath (name, resolved);
 336 }
 337 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
 338 #endif
 339
 340
 341 char *
 342 __canonicalize_file_name (const char *name)
 343 {
 344   return __realpath (name, NULL);
 345 }
 346 weak_alias (__canonicalize_file_name, canonicalize_file_name)
 347
 348 #else
 349
 350 /* This declaration is solely to ensure that after preprocessing
 351    this file is never empty.  */
 352 typedef int dummy;
 353
 354 #endif