2000-09-30 02:54:42 +02:00
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/* Return the canonical absolute name of a given file inside chroot.
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2011-10-29 18:24:38 +02:00
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Copyright (C) 1996,1997,1998,1999,2000,2001,2004,2005,2010,2011
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2005-12-21 23:16:34 +01:00
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Free Software Foundation, Inc.
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2000-09-30 02:54:42 +02:00
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This file is part of the GNU C Library.
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2005-12-07 06:49:17 +01:00
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This program is free software; you can redistribute it and/or modify
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2007-07-16 02:56:07 +02:00
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it under the terms of the GNU General Public License as published
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by the Free Software Foundation; version 2 of the License, or
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(at your option) any later version.
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2000-09-30 02:54:42 +02:00
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2005-12-07 06:49:17 +01:00
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This program is distributed in the hope that it will be useful,
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2000-09-30 02:54:42 +02:00
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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2005-12-07 06:49:17 +01:00
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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2000-09-30 02:54:42 +02:00
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2005-12-07 06:49:17 +01:00
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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2000-09-30 02:54:42 +02:00
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <limits.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <stddef.h>
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2000-11-15 10:41:20 +01:00
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#include <stdint.h>
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2005-12-21 23:16:34 +01:00
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#include <ldconfig.h>
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2000-09-30 02:54:42 +02:00
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#ifndef PATH_MAX
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#define PATH_MAX 1024
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#endif
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/* Return the canonical absolute name of file NAME as if chroot(CHROOT) was
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done first. A canonical name does not contain any `.', `..' components
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nor any repeated path separators ('/') or symlinks. All path components
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must exist and NAME must be absolute filename. The result is malloc'd.
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The returned name includes the CHROOT prefix. */
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char *
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chroot_canon (const char *chroot, const char *name)
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{
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2001-12-29 16:57:15 +01:00
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char *rpath;
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char *dest;
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char *extra_buf = NULL;
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char *rpath_root;
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const char *start;
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const char *end;
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const char *rpath_limit;
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2000-09-30 02:54:42 +02:00
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int num_links = 0;
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size_t chroot_len = strlen (chroot);
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if (chroot_len < 1)
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{
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__set_errno (EINVAL);
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return NULL;
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}
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2010-05-03 22:33:13 +02:00
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rpath = xmalloc (chroot_len + PATH_MAX);
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2004-06-10 04:16:08 +02:00
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2000-09-30 02:54:42 +02:00
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rpath_limit = rpath + chroot_len + PATH_MAX;
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rpath_root = (char *) mempcpy (rpath, chroot, chroot_len) - 1;
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if (*rpath_root != '/')
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*++rpath_root = '/';
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dest = rpath_root + 1;
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for (start = end = name; *start; start = end)
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{
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struct stat64 st;
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int n;
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/* Skip sequence of multiple path-separators. */
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while (*start == '/')
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++start;
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/* Find end of path component. */
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for (end = start; *end && *end != '/'; ++end)
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/* Nothing. */;
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if (end - start == 0)
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break;
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else if (end - start == 1 && start[0] == '.')
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/* nothing */;
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else if (end - start == 2 && start[0] == '.' && start[1] == '.')
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{
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/* Back up to previous component, ignore if at root already. */
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if (dest > rpath_root + 1)
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while ((--dest)[-1] != '/');
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}
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else
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{
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size_t new_size;
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if (dest[-1] != '/')
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*dest++ = '/';
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if (dest + (end - start) >= rpath_limit)
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{
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ptrdiff_t dest_offset = dest - rpath;
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2001-12-29 16:57:15 +01:00
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char *new_rpath;
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2000-09-30 02:54:42 +02:00
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new_size = rpath_limit - rpath;
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if (end - start + 1 > PATH_MAX)
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new_size += end - start + 1;
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else
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new_size += PATH_MAX;
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2010-05-03 22:33:13 +02:00
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new_rpath = (char *) xrealloc (rpath, new_size);
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2001-12-29 16:57:15 +01:00
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rpath = new_rpath;
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rpath_limit = rpath + new_size;
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2000-09-30 02:54:42 +02:00
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dest = rpath + dest_offset;
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}
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dest = mempcpy (dest, start, end - start);
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*dest = '\0';
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if (lstat64 (rpath, &st) < 0)
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{
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if (*end == '\0')
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goto done;
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goto error;
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}
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if (S_ISLNK (st.st_mode))
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{
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char *buf = alloca (PATH_MAX);
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size_t len;
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if (++num_links > MAXSYMLINKS)
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{
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__set_errno (ELOOP);
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goto error;
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}
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2011-10-29 18:24:38 +02:00
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n = readlink (rpath, buf, PATH_MAX - 1);
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2000-09-30 02:54:42 +02:00
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if (n < 0)
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{
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if (*end == '\0')
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goto done;
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goto error;
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}
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buf[n] = '\0';
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if (!extra_buf)
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extra_buf = alloca (PATH_MAX);
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len = strlen (end);
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if ((long int) (n + len) >= PATH_MAX)
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{
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__set_errno (ENAMETOOLONG);
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goto error;
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}
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/* Careful here, end may be a pointer into extra_buf... */
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memmove (&extra_buf[n], end, len + 1);
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name = end = memcpy (extra_buf, buf, n);
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if (buf[0] == '/')
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dest = rpath_root + 1; /* It's an absolute symlink */
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else
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/* Back up to previous component, ignore if at root already: */
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if (dest > rpath_root + 1)
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while ((--dest)[-1] != '/');
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}
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}
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}
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done:
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if (dest > rpath_root + 1 && dest[-1] == '/')
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--dest;
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*dest = '\0';
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return rpath;
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error:
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free (rpath);
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return NULL;
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}
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