lib/canonicalize-lgpl.c

   1 /* Return the canonical absolute name of a given file.
   2    Copyright (C) 1996-2014 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 /* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
  20    optimizes away the name == NULL test below.  */
  21 # define _GL_ARG_NONNULL(params)
  22
  23 # define _GL_USE_STDLIB_ALLOC 1
  24 # include <config.h>
  25 #endif
  26
  27 #if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
  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 # include "dosname.h"
  55 # if HAVE_GETCWD
  56 #  if IN_RELOCWRAPPER
  57     /* When building the relocatable program wrapper, use the system's getcwd
  58        function, not the gnulib override, otherwise we would get a link error.
  59      */
  60 #   undef getcwd
  61 #  endif
  62 #  ifdef VMS
  63     /* We want the directory in Unix syntax, not in VMS syntax.  */
  64 #   define __getcwd(buf, max) getcwd (buf, max, 0)
  65 #  else
  66 #   define __getcwd getcwd
  67 #  endif
  68 # else
  69 #  define __getcwd(buf, max) getwd (buf)
  70 # endif
  71 # define __readlink readlink
  72 # define __set_errno(e) errno = (e)
  73 # ifndef MAXSYMLINKS
  74 #  ifdef SYMLOOP_MAX
  75 #   define MAXSYMLINKS SYMLOOP_MAX
  76 #  else
  77 #   define MAXSYMLINKS 20
  78 #  endif
  79 # endif
  80 #endif
  81
  82 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
  83 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
  84 #endif
  85
  86 #if !FUNC_REALPATH_WORKS || defined _LIBC
  87 /* Return the canonical absolute name of file NAME.  A canonical name
  88    does not contain any ".", ".." components nor any repeated path
  89    separators ('/') or symlinks.  All path components must exist.  If
  90    RESOLVED is null, the result is malloc'd; otherwise, if the
  91    canonical name is PATH_MAX chars or more, returns null with 'errno'
  92    set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
  93    returns the name in RESOLVED.  If the name cannot be resolved and
  94    RESOLVED is non-NULL, it contains the path of the first component
  95    that cannot be resolved.  If the path can be resolved, RESOLVED
  96    holds the same value as the value returned.  */
  97
  98 char *
  99 __realpath (const char *name, char *resolved)
 100 {
 101   char *rpath, *dest, *extra_buf = NULL;
 102   const char *start, *end, *rpath_limit;
 103   long int path_max;
 104   int num_links = 0;
 105   size_t prefix_len;
 106
 107   if (name == NULL)
 108     {
 109       /* As per Single Unix Specification V2 we must return an error if
 110          either parameter is a null pointer.  We extend this to allow
 111          the RESOLVED parameter to be NULL in case the we are expected to
 112          allocate the room for the return value.  */
 113       __set_errno (EINVAL);
 114       return NULL;
 115     }
 116
 117   if (name[0] == '\0')
 118     {
 119       /* As per Single Unix Specification V2 we must return an error if
 120          the name argument points to an empty string.  */
 121       __set_errno (ENOENT);
 122       return NULL;
 123     }
 124
 125 #ifdef PATH_MAX
 126   path_max = PATH_MAX;
 127 #else
 128   path_max = pathconf (name, _PC_PATH_MAX);
 129   if (path_max <= 0)
 130     path_max = 8192;
 131 #endif
 132
 133   if (resolved == NULL)
 134     {
 135       rpath = malloc (path_max);
 136       if (rpath == NULL)
 137         {
 138           /* It's easier to set errno to ENOMEM than to rely on the
 139              'malloc-posix' gnulib module.  */
 140           errno = ENOMEM;
 141           return NULL;
 142         }
 143     }
 144   else
 145     rpath = resolved;
 146   rpath_limit = rpath + path_max;
 147
 148   /* This is always zero for Posix hosts, but can be 2 for MS-Windows
 149      and MS-DOS X:/foo/bar file names.  */
 150   prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
 151
 152   if (!IS_ABSOLUTE_FILE_NAME (name))
 153     {
 154       if (!__getcwd (rpath, path_max))
 155         {
 156           rpath[0] = '\0';
 157           goto error;
 158         }
 159       dest = strchr (rpath, '\0');
 160       start = name;
 161       prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
 162     }
 163   else
 164     {
 165       dest = rpath;
 166       if (prefix_len)
 167         {
 168           memcpy (rpath, name, prefix_len);
 169           dest += prefix_len;
 170         }
 171       *dest++ = '/';
 172       if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
 173         {
 174           if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
 175             *dest++ = '/';
 176           *dest = '\0';
 177         }
 178       start = name + prefix_len;
 179     }
 180
 181   for (end = start; *start; start = end)
 182     {
 183 #ifdef _LIBC
 184       struct stat64 st;
 185 #else
 186       struct stat st;
 187 #endif
 188       int n;
 189
 190       /* Skip sequence of multiple path-separators.  */
 191       while (ISSLASH (*start))
 192         ++start;
 193
 194       /* Find end of path component.  */
 195       for (end = start; *end && !ISSLASH (*end); ++end)
 196         /* Nothing.  */;
 197
 198       if (end - start == 0)
 199         break;
 200       else if (end - start == 1 && start[0] == '.')
 201         /* nothing */;
 202       else if (end - start == 2 && start[0] == '.' && start[1] == '.')
 203         {
 204           /* Back up to previous component, ignore if at root already.  */
 205           if (dest > rpath + prefix_len + 1)
 206             for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
 207               continue;
 208           if (DOUBLE_SLASH_IS_DISTINCT_ROOT
 209               && dest == rpath + 1 && !prefix_len
 210               && ISSLASH (*dest) && !ISSLASH (dest[1]))
 211             dest++;
 212         }
 213       else
 214         {
 215           size_t new_size;
 216
 217           if (!ISSLASH (dest[-1]))
 218             *dest++ = '/';
 219
 220           if (dest + (end - start) >= rpath_limit)
 221             {
 222               ptrdiff_t dest_offset = dest - rpath;
 223               char *new_rpath;
 224
 225               if (resolved)
 226                 {
 227                   __set_errno (ENAMETOOLONG);
 228                   if (dest > rpath + prefix_len + 1)
 229                     dest--;
 230                   *dest = '\0';
 231                   goto error;
 232                 }
 233               new_size = rpath_limit - rpath;
 234               if (end - start + 1 > path_max)
 235                 new_size += end - start + 1;
 236               else
 237                 new_size += path_max;
 238               new_rpath = (char *) realloc (rpath, new_size);
 239               if (new_rpath == NULL)
 240                 {
 241                   /* It's easier to set errno to ENOMEM than to rely on the
 242                      'realloc-posix' gnulib module.  */
 243                   errno = ENOMEM;
 244                   goto error;
 245                 }
 246               rpath = new_rpath;
 247               rpath_limit = rpath + new_size;
 248
 249               dest = rpath + dest_offset;
 250             }
 251
 252 #ifdef _LIBC
 253           dest = __mempcpy (dest, start, end - start);
 254 #else
 255           memcpy (dest, start, end - start);
 256           dest += end - start;
 257 #endif
 258           *dest = '\0';
 259
 260 #ifdef _LIBC
 261           if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
 262 #else
 263           if (lstat (rpath, &st) < 0)
 264 #endif
 265             goto error;
 266
 267           if (S_ISLNK (st.st_mode))
 268             {
 269               char *buf;
 270               size_t len;
 271
 272               if (++num_links > MAXSYMLINKS)
 273                 {
 274                   __set_errno (ELOOP);
 275                   goto error;
 276                 }
 277
 278               buf = malloca (path_max);
 279               if (!buf)
 280                 {
 281                   errno = ENOMEM;
 282                   goto error;
 283                 }
 284
 285               n = __readlink (rpath, buf, path_max - 1);
 286               if (n < 0)
 287                 {
 288                   int saved_errno = errno;
 289                   freea (buf);
 290                   errno = saved_errno;
 291                   goto error;
 292                 }
 293               buf[n] = '\0';
 294
 295               if (!extra_buf)
 296                 {
 297                   extra_buf = malloca (path_max);
 298                   if (!extra_buf)
 299                     {
 300                       freea (buf);
 301                       errno = ENOMEM;
 302                       goto error;
 303                     }
 304                 }
 305
 306               len = strlen (end);
 307               if ((long int) (n + len) >= path_max)
 308                 {
 309                   freea (buf);
 310                   __set_errno (ENAMETOOLONG);
 311                   goto error;
 312                 }
 313
 314               /* Careful here, end may be a pointer into extra_buf... */
 315               memmove (&extra_buf[n], end, len + 1);
 316               name = end = memcpy (extra_buf, buf, n);
 317
 318               if (IS_ABSOLUTE_FILE_NAME (buf))
 319                 {
 320                   size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
 321
 322                   if (pfxlen)
 323                     memcpy (rpath, buf, pfxlen);
 324                   dest = rpath + pfxlen;
 325                   *dest++ = '/'; /* It's an absolute symlink */
 326                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
 327                     {
 328                       if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
 329                         *dest++ = '/';
 330                       *dest = '\0';
 331                     }
 332                   /* Install the new prefix to be in effect hereafter.  */
 333                   prefix_len = pfxlen;
 334                 }
 335               else
 336                 {
 337                   /* Back up to previous component, ignore if at root
 338                      already: */
 339                   if (dest > rpath + prefix_len + 1)
 340                     for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
 341                       continue;
 342                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 343                       && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
 344                     dest++;
 345                 }
 346             }
 347           else if (!S_ISDIR (st.st_mode) && *end != '\0')
 348             {
 349               __set_errno (ENOTDIR);
 350               goto error;
 351             }
 352         }
 353     }
 354   if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
 355     --dest;
 356   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
 357       && ISSLASH (*dest) && !ISSLASH (dest[1]))
 358     dest++;
 359   *dest = '\0';
 360
 361   if (extra_buf)
 362     freea (extra_buf);
 363
 364   return rpath;
 365
 366 error:
 367   {
 368     int saved_errno = errno;
 369     if (extra_buf)
 370       freea (extra_buf);
 371     if (resolved == NULL)
 372       free (rpath);
 373     errno = saved_errno;
 374   }
 375   return NULL;
 376 }
 377 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
 378 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
 379
 380
 381 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
 382 char *
 383 attribute_compat_text_section
 384 __old_realpath (const char *name, char *resolved)
 385 {
 386   if (resolved == NULL)
 387     {
 388       __set_errno (EINVAL);
 389       return NULL;
 390     }
 391
 392   return __realpath (name, resolved);
 393 }
 394 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
 395 #endif
 396
 397
 398 char *
 399 __canonicalize_file_name (const char *name)
 400 {
 401   return __realpath (name, NULL);
 402 }
 403 weak_alias (__canonicalize_file_name, canonicalize_file_name)
 404
 405 #else
 406
 407 /* This declaration is solely to ensure that after preprocessing
 408    this file is never empty.  */
 409 typedef int dummy;
 410
 411 #endif