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b4a555d6 | 1 | /* Return the canonical absolute name of a given file inside chroot. |
43bc8ac6 | 2 | Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2004, 2005 |
a334319f | 3 | Free Software Foundation, Inc. |
b4a555d6 UD |
4 | This file is part of the GNU C Library. |
5 | ||
43bc8ac6 UD |
6 | This program is free software; you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License version 2 as | |
8 | published by the Free Software Foundation. | |
b4a555d6 | 9 | |
43bc8ac6 | 10 | This program is distributed in the hope that it will be useful, |
b4a555d6 | 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
43bc8ac6 UD |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | GNU General Public License for more details. | |
b4a555d6 | 14 | |
43bc8ac6 UD |
15 | You should have received a copy of the GNU General Public License |
16 | along with this program; if not, write to the Free Software Foundation, | |
17 | Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
b4a555d6 UD |
18 | |
19 | #include <stdlib.h> | |
20 | #include <string.h> | |
21 | #include <unistd.h> | |
22 | #include <limits.h> | |
23 | #include <sys/param.h> | |
24 | #include <sys/stat.h> | |
25 | #include <errno.h> | |
26 | #include <stddef.h> | |
0b87a270 AJ |
27 | #include <stdint.h> |
28 | ||
a334319f | 29 | #include "ldconfig.h" |
b4a555d6 UD |
30 | |
31 | #ifndef PATH_MAX | |
32 | #define PATH_MAX 1024 | |
33 | #endif | |
34 | ||
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. */ | |
40 | ||
41 | char * | |
42 | chroot_canon (const char *chroot, const char *name) | |
43 | { | |
d1dddedf UD |
44 | char *rpath; |
45 | char *dest; | |
46 | char *extra_buf = NULL; | |
47 | char *rpath_root; | |
48 | const char *start; | |
49 | const char *end; | |
50 | const char *rpath_limit; | |
b4a555d6 UD |
51 | int num_links = 0; |
52 | size_t chroot_len = strlen (chroot); | |
53 | ||
54 | if (chroot_len < 1) | |
55 | { | |
56 | __set_errno (EINVAL); | |
57 | return NULL; | |
58 | } | |
59 | ||
60 | rpath = malloc (chroot_len + PATH_MAX); | |
f05a089d RM |
61 | if (rpath == NULL) |
62 | return NULL; | |
63 | ||
b4a555d6 UD |
64 | rpath_limit = rpath + chroot_len + PATH_MAX; |
65 | ||
66 | rpath_root = (char *) mempcpy (rpath, chroot, chroot_len) - 1; | |
67 | if (*rpath_root != '/') | |
68 | *++rpath_root = '/'; | |
69 | dest = rpath_root + 1; | |
70 | ||
71 | for (start = end = name; *start; start = end) | |
72 | { | |
73 | struct stat64 st; | |
74 | int n; | |
75 | ||
76 | /* Skip sequence of multiple path-separators. */ | |
77 | while (*start == '/') | |
78 | ++start; | |
79 | ||
80 | /* Find end of path component. */ | |
81 | for (end = start; *end && *end != '/'; ++end) | |
82 | /* Nothing. */; | |
83 | ||
84 | if (end - start == 0) | |
85 | break; | |
86 | else if (end - start == 1 && start[0] == '.') | |
87 | /* nothing */; | |
88 | else if (end - start == 2 && start[0] == '.' && start[1] == '.') | |
89 | { | |
90 | /* Back up to previous component, ignore if at root already. */ | |
91 | if (dest > rpath_root + 1) | |
92 | while ((--dest)[-1] != '/'); | |
93 | } | |
94 | else | |
95 | { | |
96 | size_t new_size; | |
97 | ||
98 | if (dest[-1] != '/') | |
99 | *dest++ = '/'; | |
100 | ||
101 | if (dest + (end - start) >= rpath_limit) | |
102 | { | |
103 | ptrdiff_t dest_offset = dest - rpath; | |
d1dddedf | 104 | char *new_rpath; |
b4a555d6 UD |
105 | |
106 | new_size = rpath_limit - rpath; | |
107 | if (end - start + 1 > PATH_MAX) | |
108 | new_size += end - start + 1; | |
109 | else | |
110 | new_size += PATH_MAX; | |
d1dddedf UD |
111 | new_rpath = (char *) realloc (rpath, new_size); |
112 | if (new_rpath == NULL) | |
f05a089d | 113 | goto error; |
d1dddedf UD |
114 | rpath = new_rpath; |
115 | rpath_limit = rpath + new_size; | |
b4a555d6 UD |
116 | |
117 | dest = rpath + dest_offset; | |
118 | } | |
119 | ||
120 | dest = mempcpy (dest, start, end - start); | |
121 | *dest = '\0'; | |
122 | ||
123 | if (lstat64 (rpath, &st) < 0) | |
124 | { | |
125 | if (*end == '\0') | |
126 | goto done; | |
127 | goto error; | |
128 | } | |
129 | ||
130 | if (S_ISLNK (st.st_mode)) | |
131 | { | |
132 | char *buf = alloca (PATH_MAX); | |
133 | size_t len; | |
134 | ||
135 | if (++num_links > MAXSYMLINKS) | |
136 | { | |
137 | __set_errno (ELOOP); | |
138 | goto error; | |
139 | } | |
140 | ||
141 | n = readlink (rpath, buf, PATH_MAX); | |
142 | if (n < 0) | |
143 | { | |
144 | if (*end == '\0') | |
145 | goto done; | |
146 | goto error; | |
147 | } | |
148 | buf[n] = '\0'; | |
149 | ||
150 | if (!extra_buf) | |
151 | extra_buf = alloca (PATH_MAX); | |
152 | ||
153 | len = strlen (end); | |
154 | if ((long int) (n + len) >= PATH_MAX) | |
155 | { | |
156 | __set_errno (ENAMETOOLONG); | |
157 | goto error; | |
158 | } | |
159 | ||
160 | /* Careful here, end may be a pointer into extra_buf... */ | |
161 | memmove (&extra_buf[n], end, len + 1); | |
162 | name = end = memcpy (extra_buf, buf, n); | |
163 | ||
164 | if (buf[0] == '/') | |
165 | dest = rpath_root + 1; /* It's an absolute symlink */ | |
166 | else | |
167 | /* Back up to previous component, ignore if at root already: */ | |
168 | if (dest > rpath_root + 1) | |
169 | while ((--dest)[-1] != '/'); | |
170 | } | |
171 | } | |
172 | } | |
173 | done: | |
174 | if (dest > rpath_root + 1 && dest[-1] == '/') | |
175 | --dest; | |
176 | *dest = '\0'; | |
177 | ||
178 | return rpath; | |
179 | ||
180 | error: | |
181 | free (rpath); | |
182 | return NULL; | |
183 | } |