gdb/gnulib/import/canonicalize-lgpl.c

   1 /* Return the canonical absolute name of a given file.
   2    Copyright (C) 1996-2016 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 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 General Public License for more details.
  14
  15    You should have received a copy of the GNU 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
  88 static void
  89 alloc_failed (void)
  90 {
  91 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  92   /* Avoid errno problem without using the malloc or realloc modules; see:
  93      http://lists.gnu.org/archive/html/bug-gnulib/2016-08/msg00025.html  */
  94   errno = ENOMEM;
  95 #endif
  96 }
  97
  98 /* Return the canonical absolute name of file NAME.  A canonical name
  99    does not contain any ".", ".." components nor any repeated path
 100    separators ('/') or symlinks.  All path components must exist.  If
 101    RESOLVED is null, the result is malloc'd; otherwise, if the
 102    canonical name is PATH_MAX chars or more, returns null with 'errno'
 103    set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
 104    returns the name in RESOLVED.  If the name cannot be resolved and
 105    RESOLVED is non-NULL, it contains the path of the first component
 106    that cannot be resolved.  If the path can be resolved, RESOLVED
 107    holds the same value as the value returned.  */
 108
 109 char *
 110 __realpath (const char *name, char *resolved)
 111 {
 112   char *rpath, *dest, *extra_buf = NULL;
 113   const char *start, *end, *rpath_limit;
 114   long int path_max;
 115   int num_links = 0;
 116   size_t prefix_len;
 117
 118   if (name == NULL)
 119     {
 120       /* As per Single Unix Specification V2 we must return an error if
 121          either parameter is a null pointer.  We extend this to allow
 122          the RESOLVED parameter to be NULL in case the we are expected to
 123          allocate the room for the return value.  */
 124       __set_errno (EINVAL);
 125       return NULL;
 126     }
 127
 128   if (name[0] == '\0')
 129     {
 130       /* As per Single Unix Specification V2 we must return an error if
 131          the name argument points to an empty string.  */
 132       __set_errno (ENOENT);
 133       return NULL;
 134     }
 135
 136 #ifdef PATH_MAX
 137   path_max = PATH_MAX;
 138 #else
 139   path_max = pathconf (name, _PC_PATH_MAX);
 140   if (path_max <= 0)
 141     path_max = 8192;
 142 #endif
 143
 144   if (resolved == NULL)
 145     {
 146       rpath = malloc (path_max);
 147       if (rpath == NULL)
 148         {
 149           alloc_failed ();
 150           return NULL;
 151         }
 152     }
 153   else
 154     rpath = resolved;
 155   rpath_limit = rpath + path_max;
 156
 157   /* This is always zero for Posix hosts, but can be 2 for MS-Windows
 158      and MS-DOS X:/foo/bar file names.  */
 159   prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
 160
 161   if (!IS_ABSOLUTE_FILE_NAME (name))
 162     {
 163       if (!__getcwd (rpath, path_max))
 164         {
 165           rpath[0] = '\0';
 166           goto error;
 167         }
 168       dest = strchr (rpath, '\0');
 169       start = name;
 170       prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
 171     }
 172   else
 173     {
 174       dest = rpath;
 175       if (prefix_len)
 176         {
 177           memcpy (rpath, name, prefix_len);
 178           dest += prefix_len;
 179         }
 180       *dest++ = '/';
 181       if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
 182         {
 183           if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
 184             *dest++ = '/';
 185           *dest = '\0';
 186         }
 187       start = name + prefix_len;
 188     }
 189
 190   for (end = start; *start; start = end)
 191     {
 192 #ifdef _LIBC
 193       struct stat64 st;
 194 #else
 195       struct stat st;
 196 #endif
 197       int n;
 198
 199       /* Skip sequence of multiple path-separators.  */
 200       while (ISSLASH (*start))
 201         ++start;
 202
 203       /* Find end of path component.  */
 204       for (end = start; *end && !ISSLASH (*end); ++end)
 205         /* Nothing.  */;
 206
 207       if (end - start == 0)
 208         break;
 209       else if (end - start == 1 && start[0] == '.')
 210         /* nothing */;
 211       else if (end - start == 2 && start[0] == '.' && start[1] == '.')
 212         {
 213           /* Back up to previous component, ignore if at root already.  */
 214           if (dest > rpath + prefix_len + 1)
 215             for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
 216               continue;
 217           if (DOUBLE_SLASH_IS_DISTINCT_ROOT
 218               && dest == rpath + 1 && !prefix_len
 219               && ISSLASH (*dest) && !ISSLASH (dest[1]))
 220             dest++;
 221         }
 222       else
 223         {
 224           size_t new_size;
 225
 226           if (!ISSLASH (dest[-1]))
 227             *dest++ = '/';
 228
 229           if (dest + (end - start) >= rpath_limit)
 230             {
 231               ptrdiff_t dest_offset = dest - rpath;
 232               char *new_rpath;
 233
 234               if (resolved)
 235                 {
 236                   __set_errno (ENAMETOOLONG);
 237                   if (dest > rpath + prefix_len + 1)
 238                     dest--;
 239                   *dest = '\0';
 240                   goto error;
 241                 }
 242               new_size = rpath_limit - rpath;
 243               if (end - start + 1 > path_max)
 244                 new_size += end - start + 1;
 245               else
 246                 new_size += path_max;
 247               new_rpath = (char *) realloc (rpath, new_size);
 248               if (new_rpath == NULL)
 249                 {
 250                   alloc_failed ();
 251                   goto error;
 252                 }
 253               rpath = new_rpath;
 254               rpath_limit = rpath + new_size;
 255
 256               dest = rpath + dest_offset;
 257             }
 258
 259 #ifdef _LIBC
 260           dest = __mempcpy (dest, start, end - start);
 261 #else
 262           memcpy (dest, start, end - start);
 263           dest += end - start;
 264 #endif
 265           *dest = '\0';
 266
 267 #ifdef _LIBC
 268           if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
 269 #else
 270           if (lstat (rpath, &st) < 0)
 271 #endif
 272             goto error;
 273
 274           if (S_ISLNK (st.st_mode))
 275             {
 276               char *buf;
 277               size_t len;
 278
 279               if (++num_links > MAXSYMLINKS)
 280                 {
 281                   __set_errno (ELOOP);
 282                   goto error;
 283                 }
 284
 285               buf = malloca (path_max);
 286               if (!buf)
 287                 {
 288                   __set_errno (ENOMEM);
 289                   goto error;
 290                 }
 291
 292               n = __readlink (rpath, buf, path_max - 1);
 293               if (n < 0)
 294                 {
 295                   int saved_errno = errno;
 296                   freea (buf);
 297                   __set_errno (saved_errno);
 298                   goto error;
 299                 }
 300               buf[n] = '\0';
 301
 302               if (!extra_buf)
 303                 {
 304                   extra_buf = malloca (path_max);
 305                   if (!extra_buf)
 306                     {
 307                       freea (buf);
 308                       __set_errno (ENOMEM);
 309                       goto error;
 310                     }
 311                 }
 312
 313               len = strlen (end);
 314               if ((long int) (n + len) >= path_max)
 315                 {
 316                   freea (buf);
 317                   __set_errno (ENAMETOOLONG);
 318                   goto error;
 319                 }
 320
 321               /* Careful here, end may be a pointer into extra_buf... */
 322               memmove (&extra_buf[n], end, len + 1);
 323               name = end = memcpy (extra_buf, buf, n);
 324
 325               if (IS_ABSOLUTE_FILE_NAME (buf))
 326                 {
 327                   size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
 328
 329                   if (pfxlen)
 330                     memcpy (rpath, buf, pfxlen);
 331                   dest = rpath + pfxlen;
 332                   *dest++ = '/'; /* It's an absolute symlink */
 333                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
 334                     {
 335                       if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
 336                         *dest++ = '/';
 337                       *dest = '\0';
 338                     }
 339                   /* Install the new prefix to be in effect hereafter.  */
 340                   prefix_len = pfxlen;
 341                 }
 342               else
 343                 {
 344                   /* Back up to previous component, ignore if at root
 345                      already: */
 346                   if (dest > rpath + prefix_len + 1)
 347                     for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
 348                       continue;
 349                   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
 350                       && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
 351                     dest++;
 352                 }
 353             }
 354           else if (!S_ISDIR (st.st_mode) && *end != '\0')
 355             {
 356               __set_errno (ENOTDIR);
 357               goto error;
 358             }
 359         }
 360     }
 361   if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
 362     --dest;
 363   if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
 364       && ISSLASH (*dest) && !ISSLASH (dest[1]))
 365     dest++;
 366   *dest = '\0';
 367
 368   if (extra_buf)
 369     freea (extra_buf);
 370
 371   return rpath;
 372
 373 error:
 374   {
 375     int saved_errno = errno;
 376     if (extra_buf)
 377       freea (extra_buf);
 378     if (resolved == NULL)
 379       free (rpath);
 380     __set_errno (saved_errno);
 381   }
 382   return NULL;
 383 }
 384 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
 385 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
 386
 387
 388 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
 389 char *
 390 attribute_compat_text_section
 391 __old_realpath (const char *name, char *resolved)
 392 {
 393   if (resolved == NULL)
 394     {
 395       __set_errno (EINVAL);
 396       return NULL;
 397     }
 398
 399   return __realpath (name, resolved);
 400 }
 401 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
 402 #endif
 403
 404
 405 char *
 406 __canonicalize_file_name (const char *name)
 407 {
 408   return __realpath (name, NULL);
 409 }
 410 weak_alias (__canonicalize_file_name, canonicalize_file_name)
 411
 412 #else
 413
 414 /* This declaration is solely to ensure that after preprocessing
 415    this file is never empty.  */
 416 typedef int dummy;
 417
 418 #endif