1 /* Return the canonical absolute name of a given file inside chroot.
2 Copyright (C) 1996,1997,1998,1999,2000,2001,2004,2005,2010,2011
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published
8 by the Free Software Foundation; version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, see <http://www.gnu.org/licenses/>. */
23 #include <sys/param.h>
35 /* Return the canonical absolute name of file NAME as if chroot(CHROOT) was
36 done first. A canonical name does not contain any `.', `..' components
37 nor any repeated path separators ('/') or symlinks. All path components
38 must exist and NAME must be absolute filename. The result is malloc'd.
39 The returned name includes the CHROOT prefix. */
42 chroot_canon (const char *chroot
, const char *name
)
46 char *extra_buf
= NULL
;
50 const char *rpath_limit
;
52 size_t chroot_len
= strlen (chroot
);
60 rpath
= xmalloc (chroot_len
+ PATH_MAX
);
62 rpath_limit
= rpath
+ chroot_len
+ PATH_MAX
;
64 rpath_root
= (char *) mempcpy (rpath
, chroot
, chroot_len
) - 1;
65 if (*rpath_root
!= '/')
67 dest
= rpath_root
+ 1;
69 for (start
= end
= name
; *start
; start
= end
)
73 /* Skip sequence of multiple path-separators. */
77 /* Find end of path component. */
78 for (end
= start
; *end
&& *end
!= '/'; ++end
)
83 else if (end
- start
== 1 && start
[0] == '.')
85 else if (end
- start
== 2 && start
[0] == '.' && start
[1] == '.')
87 /* Back up to previous component, ignore if at root already. */
88 if (dest
> rpath_root
+ 1)
89 while ((--dest
)[-1] != '/');
98 if (dest
+ (end
- start
) >= rpath_limit
)
100 ptrdiff_t dest_offset
= dest
- rpath
;
103 new_size
= rpath_limit
- rpath
;
104 if (end
- start
+ 1 > PATH_MAX
)
105 new_size
+= end
- start
+ 1;
107 new_size
+= PATH_MAX
;
108 new_rpath
= (char *) xrealloc (rpath
, new_size
);
110 rpath_limit
= rpath
+ new_size
;
112 dest
= rpath
+ dest_offset
;
115 dest
= mempcpy (dest
, start
, end
- start
);
118 if (lstat64 (rpath
, &st
) < 0)
125 if (S_ISLNK (st
.st_mode
))
127 char *buf
= alloca (PATH_MAX
);
130 if (++num_links
> MAXSYMLINKS
)
136 ssize_t n
= readlink (rpath
, buf
, PATH_MAX
- 1);
146 extra_buf
= alloca (PATH_MAX
);
149 if (len
>= PATH_MAX
- n
)
151 __set_errno (ENAMETOOLONG
);
155 /* Careful here, end may be a pointer into extra_buf... */
156 memmove (&extra_buf
[n
], end
, len
+ 1);
157 name
= end
= memcpy (extra_buf
, buf
, n
);
160 dest
= rpath_root
+ 1; /* It's an absolute symlink */
162 /* Back up to previous component, ignore if at root already: */
163 if (dest
> rpath_root
+ 1)
164 while ((--dest
)[-1] != '/');
169 if (dest
> rpath_root
+ 1 && dest
[-1] == '/')