lib/canonicalize-lgpl.c

   1 /* Return the canonical absolute name of a given file.
   2    Copyright (C) 1996-2010 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _LIBC
  19 # include <config.h>
  20 #endif
  21
  22 #if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
  23
  24 /* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
  25    optimizes away the name == NULL test below.  */
  26 #define _GL_ARG_NONNULL(params)
  27
  28 /* Specification.  */
  29 #include <stdlib.h>
  30
  31 #include <alloca.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <limits.h>
  35 #if HAVE_SYS_PARAM_H || defined _LIBC
  36 # include <sys/param.h>
  37 #endif
  38 #include <sys/stat.h>
  39 #include <errno.h>
  40 #include <stddef.h>
  41
  42 #ifdef _LIBC
  43 # include <shlib-compat.h>
  44 #else
  45 # define SHLIB_COMPAT(lib, introduced, obsoleted) 0
  46 # define versioned_symbol(lib, local, symbol, version) extern int dummy
  47 # define compat_symbol(lib, local, symbol, version)
  48 # define weak_alias(local, symbol)
  49 # define __canonicalize_file_name canonicalize_file_name
  50 # define __realpath realpath
  51 # include "pathmax.h"
  52 # include "malloca.h"
  53 # if HAVE_GETCWD
  54 #  ifdef VMS
  55     /* We want the directory in Unix syntax, not in VMS syntax.  */
  56 #   define __getcwd(buf, max) getcwd (buf, max, 0)
  57 #  else
  58 #   define __getcwd getcwd
  59 #  endif
  60 # else
  61 #  define __getcwd(buf, max) getwd (buf)
  62 # endif
  63 # define __readlink readlink
  64 # define __set_errno(e) errno = (e)
  65 # ifndef MAXSYMLINKS
  66 #  ifdef SYMLOOP_MAX
  67 #   define MAXSYMLINKS SYMLOOP_MAX
  68 #  else
  69 #   define MAXSYMLINKS 20
  70 #  endif
  71 # endif
  72 #endif
  73
  74 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
  75 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
  76 #endif
  77
  78 #if !FUNC_REALPATH_WORKS || defined _LIBC
  79 /* Return the canonical absolute name of file NAME.  A canonical name
  80    does not contain any `.', `..' components nor any repeated path
  81    separators ('/') or symlinks.  All path components must exist.  If
  82    RESOLVED is null, the result is malloc'd; otherwise, if the
  83    canonical name is PATH_MAX chars or more, returns null with `errno'
  84    set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
  85    returns the name in RESOLVED.  If the name cannot be resolved and
  86    RESOLVED is non-NULL, it contains the path of the first component
  87    that cannot be resolved.  If the path can be resolved, RESOLVED
  88    holds the same value as the value returned.  */
  89
  90 char *
  91 __realpath (const char *name, char *resolved)
  92 {
  93   char *rpath, *dest, *extra_buf = NULL;
  94   const char *start, *end, *rpath_limit;
  95   long int path_max;
  96   int num_links = 0;
  97
  98   if (name == NULL)
  99     {
 100       /* As per Single Unix Specification V2 we must return an error if
 101          either parameter is a null pointer.  We extend this to allow
 102          the RESOLVED parameter to be NULL in case the we are expected to
 103          allocate the room for the return value.  */
 104       __set_errno (EINVAL);
 105       return NULL;
 106     }
 107
 108   if (name[0] == '\0')
 109     {
 110       /* As per Single Unix Specification V2 we must return an error if
 111          the name argument points to an empty string.  */
 112       __set_errno (ENOENT);
 113       return NULL;
 114     }
 115
 116 #ifdef PATH_MAX
 117   path_max = PATH_MAX;
 118 #else
 119   path_max = pathconf (name, _PC_PATH_MAX);
 120   if (path_max <= 0)
 121     path_max = 1024;
 122 #endif
 123
 124   if (resolved == NULL)
 125     {
 126       rpath = malloc (path_max);
 127       if (rpath == NULL)
 128         {
 129           /* It's easier to set errno to ENOMEM than to rely on the
 130              'malloc-posix' gnulib module.  */
 131           errno = ENOMEM;
 132           return NULL;
 133         }
 134     }
 135   else
 136     rpath = resolved;
 137   rpath_limit = rpath + path_max;
 138
 139   if (name[0] != '/')
 140     {
 141       if (!__getcwd (rpath, path_max))
 142         {
 143           rpath[0] = '\0';
 144           goto error;
 145         }
 146       dest = strchr (rpath, '\0');
 147     }
 148   else
 149     {
 150       rpath[0] = '/';
 151       dest = rpath + 1;
 152       if (DOUBLE_SLASH_IS_DISTINCT_ROOT && name[1] == '/')
 153         *dest++ = '/';
 154     }
 155
 156   for (start = end = name; *start; start = end)
 157     {
 158 #ifdef _LIBC
 159       struct stat64 st;
 160 #else
 161       struct stat st;
 162 #endif
 163       int n;
 164
 165       /* Skip sequence of multiple path-separators.  */
 166       while (*start == '/')
 167         ++start;
 168
 169       /* Find end of path component.  */
 170       for (end = start; *end && *end != '/'; ++end)
 171         /* Nothing.  */;
 172
 173       if (end - start == 0)
 174         break;
 175       else if (end - start == 1 && start[0] == '.')
 176         /* nothing */;
 177       else if (end - start == 2 && start[0] == '.' && start[1] == '.')
 178         {
 179           /* Back up to previous component, ignore if at root already.  */
 180           if (dest > rpath + 1)
 181             while ((--dest)[-1] != '/');
 182           if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 183               && *dest == '/')
 184             dest++;
 185         }
 186       else
 187         {
 188           size_t new_size;
 189
 190           if (dest[-1] != '/')
 191             *dest++ = '/';
 192
 193           if (dest + (end - start) >= rpath_limit)
 194             {
 195               ptrdiff_t dest_offset = dest - rpath;
 196               char *new_rpath;
 197
 198               if (resolved)
 199                 {
 200                   __set_errno (ENAMETOOLONG);
 201                   if (dest > rpath + 1)
 202                     dest--;
 203                   *dest = '\0';
 204                   goto error;
 205                 }
 206               new_size = rpath_limit - rpath;
 207               if (end - start + 1 > path_max)
 208                 new_size += end - start + 1;
 209               else
 210                 new_size += path_max;
 211               new_rpath = (char *) realloc (rpath, new_size);
 212               if (new_rpath == NULL)
 213                 {
 214                   /* It's easier to set errno to ENOMEM than to rely on the
 215                      'realloc-posix' gnulib module.  */
 216                   errno = ENOMEM;
 217                   goto error;
 218                 }
 219               rpath = new_rpath;
 220               rpath_limit = rpath + new_size;
 221
 222               dest = rpath + dest_offset;
 223             }
 224
 225 #ifdef _LIBC
 226           dest = __mempcpy (dest, start, end - start);
 227 #else
 228           memcpy (dest, start, end - start);
 229           dest += end - start;
 230 #endif
 231           *dest = '\0';
 232
 233 #ifdef _LIBC
 234           if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
 235 #else
 236           if (lstat (rpath, &st) < 0)
 237 #endif
 238             goto error;
 239
 240           if (S_ISLNK (st.st_mode))
 241             {
 242               char *buf;
 243               size_t len;
 244
 245               if (++num_links > MAXSYMLINKS)
 246                 {
 247                   __set_errno (ELOOP);
 248                   goto error;
 249                 }
 250
 251               buf = malloca (path_max);
 252               if (!buf)
 253                 {
 254                   errno = ENOMEM;
 255                   goto error;
 256                 }
 257
 258               n = __readlink (rpath, buf, path_max - 1);
 259               if (n < 0)
 260                 {
 261                   int saved_errno = errno;
 262                   freea (buf);
 263                   errno = saved_errno;
 264                   goto error;
 265                 }
 266               buf[n] = '\0';
 267
 268               if (!extra_buf)
 269                 {
 270                   extra_buf = malloca (path_max);
 271                   if (!extra_buf)
 272                     {
 273                       freea (buf);
 274                       errno = ENOMEM;
 275                       goto error;
 276                     }
 277                 }
 278
 279               len = strlen (end);
 280               if ((long int) (n + len) >= path_max)
 281                 {
 282                   freea (buf);
 283                   __set_errno (ENAMETOOLONG);
 284                   goto error;
 285                 }
 286
 287               /* Careful here, end may be a pointer into extra_buf... */
 288               memmove (&extra_buf[n], end, len + 1);
 289               name = end = memcpy (extra_buf, buf, n);
 290
 291               if (buf[0] == '/')
 292                 {
 293                   dest = rpath + 1;     /* It's an absolute symlink */
 294                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && buf[1] == '/')
 295                     *dest++ = '/';
 296                 }
 297               else
 298                 {
 299                   /* Back up to previous component, ignore if at root
 300                      already: */
 301                   if (dest > rpath + 1)
 302                     while ((--dest)[-1] != '/');
 303                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 304                       && *dest == '/')
 305                     dest++;
 306                 }
 307             }
 308           else if (!S_ISDIR (st.st_mode) && *end != '\0')
 309             {
 310               __set_errno (ENOTDIR);
 311               goto error;
 312             }
 313         }
 314     }
 315   if (dest > rpath + 1 && dest[-1] == '/')
 316     --dest;
 317   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && *dest == '/')
 318     dest++;
 319   *dest = '\0';
 320
 321   if (extra_buf)
 322     freea (extra_buf);
 323
 324   return rpath;
 325
 326 error:
 327   {
 328     int saved_errno = errno;
 329     if (extra_buf)
 330       freea (extra_buf);
 331     if (resolved == NULL)
 332       free (rpath);
 333     errno = saved_errno;
 334   }
 335   return NULL;
 336 }
 337 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
 338 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
 339
 340
 341 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
 342 char *
 343 attribute_compat_text_section
 344 __old_realpath (const char *name, char *resolved)
 345 {
 346   if (resolved == NULL)
 347     {
 348       __set_errno (EINVAL);
 349       return NULL;
 350     }
 351
 352   return __realpath (name, resolved);
 353 }
 354 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
 355 #endif
 356
 357
 358 char *
 359 __canonicalize_file_name (const char *name)
 360 {
 361   return __realpath (name, NULL);
 362 }
 363 weak_alias (__canonicalize_file_name, canonicalize_file_name)
 364
 365 #else
 366
 367 /* This declaration is solely to ensure that after preprocessing
 368    this file is never empty.  */
 369 typedef int dummy;
 370
 371 #endif