lib/canonicalize-lgpl.c

   1 /* Return the canonical absolute name of a given file.
   2    Copyright (C) 1996-2012 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 # define _GL_USE_STDLIB_ALLOC 1
  20 # include <config.h>
  21 #endif
  22
  23 #if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
  24
  25 /* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
  26    optimizes away the name == NULL test below.  */
  27 #define _GL_ARG_NONNULL(params)
  28
  29 /* Specification.  */
  30 #include <stdlib.h>
  31
  32 #include <alloca.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35 #include <limits.h>
  36 #if HAVE_SYS_PARAM_H || defined _LIBC
  37 # include <sys/param.h>
  38 #endif
  39 #include <sys/stat.h>
  40 #include <errno.h>
  41 #include <stddef.h>
  42
  43 #ifdef _LIBC
  44 # include <shlib-compat.h>
  45 #else
  46 # define SHLIB_COMPAT(lib, introduced, obsoleted) 0
  47 # define versioned_symbol(lib, local, symbol, version) extern int dummy
  48 # define compat_symbol(lib, local, symbol, version)
  49 # define weak_alias(local, symbol)
  50 # define __canonicalize_file_name canonicalize_file_name
  51 # define __realpath realpath
  52 # include "pathmax.h"
  53 # include "malloca.h"
  54 # if HAVE_GETCWD
  55 #  if IN_RELOCWRAPPER
  56     /* When building the relocatable program wrapper, use the system's getcwd
  57        function, not the gnulib override, otherwise we would get a link error.
  58      */
  59 #   undef getcwd
  60 #  endif
  61 #  ifdef VMS
  62     /* We want the directory in Unix syntax, not in VMS syntax.  */
  63 #   define __getcwd(buf, max) getcwd (buf, max, 0)
  64 #  else
  65 #   define __getcwd getcwd
  66 #  endif
  67 # else
  68 #  define __getcwd(buf, max) getwd (buf)
  69 # endif
  70 # define __readlink readlink
  71 # define __set_errno(e) errno = (e)
  72 # ifndef MAXSYMLINKS
  73 #  ifdef SYMLOOP_MAX
  74 #   define MAXSYMLINKS SYMLOOP_MAX
  75 #  else
  76 #   define MAXSYMLINKS 20
  77 #  endif
  78 # endif
  79 #endif
  80
  81 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
  82 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
  83 #endif
  84
  85 #if !FUNC_REALPATH_WORKS || defined _LIBC
  86 /* Return the canonical absolute name of file NAME.  A canonical name
  87    does not contain any ".", ".." components nor any repeated path
  88    separators ('/') or symlinks.  All path components must exist.  If
  89    RESOLVED is null, the result is malloc'd; otherwise, if the
  90    canonical name is PATH_MAX chars or more, returns null with 'errno'
  91    set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
  92    returns the name in RESOLVED.  If the name cannot be resolved and
  93    RESOLVED is non-NULL, it contains the path of the first component
  94    that cannot be resolved.  If the path can be resolved, RESOLVED
  95    holds the same value as the value returned.  */
  96
  97 char *
  98 __realpath (const char *name, char *resolved)
  99 {
 100   char *rpath, *dest, *extra_buf = NULL;
 101   const char *start, *end, *rpath_limit;
 102   long int path_max;
 103   int num_links = 0;
 104
 105   if (name == NULL)
 106     {
 107       /* As per Single Unix Specification V2 we must return an error if
 108          either parameter is a null pointer.  We extend this to allow
 109          the RESOLVED parameter to be NULL in case the we are expected to
 110          allocate the room for the return value.  */
 111       __set_errno (EINVAL);
 112       return NULL;
 113     }
 114
 115   if (name[0] == '\0')
 116     {
 117       /* As per Single Unix Specification V2 we must return an error if
 118          the name argument points to an empty string.  */
 119       __set_errno (ENOENT);
 120       return NULL;
 121     }
 122
 123 #ifdef PATH_MAX
 124   path_max = PATH_MAX;
 125 #else
 126   path_max = pathconf (name, _PC_PATH_MAX);
 127   if (path_max <= 0)
 128     path_max = 8192;
 129 #endif
 130
 131   if (resolved == NULL)
 132     {
 133       rpath = malloc (path_max);
 134       if (rpath == NULL)
 135         {
 136           /* It's easier to set errno to ENOMEM than to rely on the
 137              'malloc-posix' gnulib module.  */
 138           errno = ENOMEM;
 139           return NULL;
 140         }
 141     }
 142   else
 143     rpath = resolved;
 144   rpath_limit = rpath + path_max;
 145
 146   if (name[0] != '/')
 147     {
 148       if (!__getcwd (rpath, path_max))
 149         {
 150           rpath[0] = '\0';
 151           goto error;
 152         }
 153       dest = strchr (rpath, '\0');
 154     }
 155   else
 156     {
 157       rpath[0] = '/';
 158       dest = rpath + 1;
 159       if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
 160         {
 161           if (name[1] == '/' && name[2] != '/')
 162             *dest++ = '/';
 163           *dest = '\0';
 164         }
 165     }
 166
 167   for (start = end = name; *start; start = end)
 168     {
 169 #ifdef _LIBC
 170       struct stat64 st;
 171 #else
 172       struct stat st;
 173 #endif
 174       int n;
 175
 176       /* Skip sequence of multiple path-separators.  */
 177       while (*start == '/')
 178         ++start;
 179
 180       /* Find end of path component.  */
 181       for (end = start; *end && *end != '/'; ++end)
 182         /* Nothing.  */;
 183
 184       if (end - start == 0)
 185         break;
 186       else if (end - start == 1 && start[0] == '.')
 187         /* nothing */;
 188       else if (end - start == 2 && start[0] == '.' && start[1] == '.')
 189         {
 190           /* Back up to previous component, ignore if at root already.  */
 191           if (dest > rpath + 1)
 192             while ((--dest)[-1] != '/');
 193           if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 194               && *dest == '/' && dest[1] != '/')
 195             dest++;
 196         }
 197       else
 198         {
 199           size_t new_size;
 200
 201           if (dest[-1] != '/')
 202             *dest++ = '/';
 203
 204           if (dest + (end - start) >= rpath_limit)
 205             {
 206               ptrdiff_t dest_offset = dest - rpath;
 207               char *new_rpath;
 208
 209               if (resolved)
 210                 {
 211                   __set_errno (ENAMETOOLONG);
 212                   if (dest > rpath + 1)
 213                     dest--;
 214                   *dest = '\0';
 215                   goto error;
 216                 }
 217               new_size = rpath_limit - rpath;
 218               if (end - start + 1 > path_max)
 219                 new_size += end - start + 1;
 220               else
 221                 new_size += path_max;
 222               new_rpath = (char *) realloc (rpath, new_size);
 223               if (new_rpath == NULL)
 224                 {
 225                   /* It's easier to set errno to ENOMEM than to rely on the
 226                      'realloc-posix' gnulib module.  */
 227                   errno = ENOMEM;
 228                   goto error;
 229                 }
 230               rpath = new_rpath;
 231               rpath_limit = rpath + new_size;
 232
 233               dest = rpath + dest_offset;
 234             }
 235
 236 #ifdef _LIBC
 237           dest = __mempcpy (dest, start, end - start);
 238 #else
 239           memcpy (dest, start, end - start);
 240           dest += end - start;
 241 #endif
 242           *dest = '\0';
 243
 244 #ifdef _LIBC
 245           if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
 246 #else
 247           if (lstat (rpath, &st) < 0)
 248 #endif
 249             goto error;
 250
 251           if (S_ISLNK (st.st_mode))
 252             {
 253               char *buf;
 254               size_t len;
 255
 256               if (++num_links > MAXSYMLINKS)
 257                 {
 258                   __set_errno (ELOOP);
 259                   goto error;
 260                 }
 261
 262               buf = malloca (path_max);
 263               if (!buf)
 264                 {
 265                   errno = ENOMEM;
 266                   goto error;
 267                 }
 268
 269               n = __readlink (rpath, buf, path_max - 1);
 270               if (n < 0)
 271                 {
 272                   int saved_errno = errno;
 273                   freea (buf);
 274                   errno = saved_errno;
 275                   goto error;
 276                 }
 277               buf[n] = '\0';
 278
 279               if (!extra_buf)
 280                 {
 281                   extra_buf = malloca (path_max);
 282                   if (!extra_buf)
 283                     {
 284                       freea (buf);
 285                       errno = ENOMEM;
 286                       goto error;
 287                     }
 288                 }
 289
 290               len = strlen (end);
 291               if ((long int) (n + len) >= path_max)
 292                 {
 293                   freea (buf);
 294                   __set_errno (ENAMETOOLONG);
 295                   goto error;
 296                 }
 297
 298               /* Careful here, end may be a pointer into extra_buf... */
 299               memmove (&extra_buf[n], end, len + 1);
 300               name = end = memcpy (extra_buf, buf, n);
 301
 302               if (buf[0] == '/')
 303                 {
 304                   dest = rpath + 1;     /* It's an absolute symlink */
 305                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
 306                     {
 307                       if (buf[1] == '/' && buf[2] != '/')
 308                         *dest++ = '/';
 309                       *dest = '\0';
 310                     }
 311                 }
 312               else
 313                 {
 314                   /* Back up to previous component, ignore if at root
 315                      already: */
 316                   if (dest > rpath + 1)
 317                     while ((--dest)[-1] != '/');
 318                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 319                       && *dest == '/' && dest[1] != '/')
 320                     dest++;
 321                 }
 322             }
 323           else if (!S_ISDIR (st.st_mode) && *end != '\0')
 324             {
 325               __set_errno (ENOTDIR);
 326               goto error;
 327             }
 328         }
 329     }
 330   if (dest > rpath + 1 && dest[-1] == '/')
 331     --dest;
 332   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 333       && *dest == '/' && dest[1] != '/')
 334     dest++;
 335   *dest = '\0';
 336
 337   if (extra_buf)
 338     freea (extra_buf);
 339
 340   return rpath;
 341
 342 error:
 343   {
 344     int saved_errno = errno;
 345     if (extra_buf)
 346       freea (extra_buf);
 347     if (resolved == NULL)
 348       free (rpath);
 349     errno = saved_errno;
 350   }
 351   return NULL;
 352 }
 353 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
 354 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
 355
 356
 357 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
 358 char *
 359 attribute_compat_text_section
 360 __old_realpath (const char *name, char *resolved)
 361 {
 362   if (resolved == NULL)
 363     {
 364       __set_errno (EINVAL);
 365       return NULL;
 366     }
 367
 368   return __realpath (name, resolved);
 369 }
 370 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
 371 #endif
 372
 373
 374 char *
 375 __canonicalize_file_name (const char *name)
 376 {
 377   return __realpath (name, NULL);
 378 }
 379 weak_alias (__canonicalize_file_name, canonicalize_file_name)
 380
 381 #else
 382
 383 /* This declaration is solely to ensure that after preprocessing
 384    this file is never empty.  */
 385 typedef int dummy;
 386
 387 #endif