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Commit | Line | Data |
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b4a555d6 | 1 | /* Return the canonical absolute name of a given file inside chroot. |
8f480b4b RM |
2 | Copyright (C) 1996,1997,1998,1999,2000,2001,2004,2005 |
3 | Free Software Foundation, Inc. | |
b4a555d6 UD |
4 | This file is part of the GNU C Library. |
5 | ||
43bc8ac6 | 6 | This program is free software; you can redistribute it and/or modify |
2e2efe65 RM |
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. | |
b4a555d6 | 10 | |
43bc8ac6 | 11 | This program is distributed in the hope that it will be useful, |
b4a555d6 | 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
43bc8ac6 UD |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | GNU General Public License for more details. | |
b4a555d6 | 15 | |
43bc8ac6 UD |
16 | You should have received a copy of the GNU General Public License |
17 | along with this program; if not, write to the Free Software Foundation, | |
18 | Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
b4a555d6 UD |
19 | |
20 | #include <stdlib.h> | |
21 | #include <string.h> | |
22 | #include <unistd.h> | |
23 | #include <limits.h> | |
24 | #include <sys/param.h> | |
25 | #include <sys/stat.h> | |
26 | #include <errno.h> | |
27 | #include <stddef.h> | |
0b87a270 AJ |
28 | #include <stdint.h> |
29 | ||
8f480b4b | 30 | #include <ldconfig.h> |
b4a555d6 UD |
31 | |
32 | #ifndef PATH_MAX | |
33 | #define PATH_MAX 1024 | |
34 | #endif | |
35 | ||
36 | /* Return the canonical absolute name of file NAME as if chroot(CHROOT) was | |
37 | done first. A canonical name does not contain any `.', `..' components | |
38 | nor any repeated path separators ('/') or symlinks. All path components | |
39 | must exist and NAME must be absolute filename. The result is malloc'd. | |
40 | The returned name includes the CHROOT prefix. */ | |
41 | ||
42 | char * | |
43 | chroot_canon (const char *chroot, const char *name) | |
44 | { | |
d1dddedf UD |
45 | char *rpath; |
46 | char *dest; | |
47 | char *extra_buf = NULL; | |
48 | char *rpath_root; | |
49 | const char *start; | |
50 | const char *end; | |
51 | const char *rpath_limit; | |
b4a555d6 UD |
52 | int num_links = 0; |
53 | size_t chroot_len = strlen (chroot); | |
54 | ||
55 | if (chroot_len < 1) | |
56 | { | |
57 | __set_errno (EINVAL); | |
58 | return NULL; | |
59 | } | |
60 | ||
61 | rpath = malloc (chroot_len + PATH_MAX); | |
f05a089d RM |
62 | if (rpath == NULL) |
63 | return NULL; | |
64 | ||
b4a555d6 UD |
65 | rpath_limit = rpath + chroot_len + PATH_MAX; |
66 | ||
67 | rpath_root = (char *) mempcpy (rpath, chroot, chroot_len) - 1; | |
68 | if (*rpath_root != '/') | |
69 | *++rpath_root = '/'; | |
70 | dest = rpath_root + 1; | |
71 | ||
72 | for (start = end = name; *start; start = end) | |
73 | { | |
74 | struct stat64 st; | |
75 | int n; | |
76 | ||
77 | /* Skip sequence of multiple path-separators. */ | |
78 | while (*start == '/') | |
79 | ++start; | |
80 | ||
81 | /* Find end of path component. */ | |
82 | for (end = start; *end && *end != '/'; ++end) | |
83 | /* Nothing. */; | |
84 | ||
85 | if (end - start == 0) | |
86 | break; | |
87 | else if (end - start == 1 && start[0] == '.') | |
88 | /* nothing */; | |
89 | else if (end - start == 2 && start[0] == '.' && start[1] == '.') | |
90 | { | |
91 | /* Back up to previous component, ignore if at root already. */ | |
92 | if (dest > rpath_root + 1) | |
93 | while ((--dest)[-1] != '/'); | |
94 | } | |
95 | else | |
96 | { | |
97 | size_t new_size; | |
98 | ||
99 | if (dest[-1] != '/') | |
100 | *dest++ = '/'; | |
101 | ||
102 | if (dest + (end - start) >= rpath_limit) | |
103 | { | |
104 | ptrdiff_t dest_offset = dest - rpath; | |
d1dddedf | 105 | char *new_rpath; |
b4a555d6 UD |
106 | |
107 | new_size = rpath_limit - rpath; | |
108 | if (end - start + 1 > PATH_MAX) | |
109 | new_size += end - start + 1; | |
110 | else | |
111 | new_size += PATH_MAX; | |
d1dddedf UD |
112 | new_rpath = (char *) realloc (rpath, new_size); |
113 | if (new_rpath == NULL) | |
f05a089d | 114 | goto error; |
d1dddedf UD |
115 | rpath = new_rpath; |
116 | rpath_limit = rpath + new_size; | |
b4a555d6 UD |
117 | |
118 | dest = rpath + dest_offset; | |
119 | } | |
120 | ||
121 | dest = mempcpy (dest, start, end - start); | |
122 | *dest = '\0'; | |
123 | ||
124 | if (lstat64 (rpath, &st) < 0) | |
125 | { | |
126 | if (*end == '\0') | |
127 | goto done; | |
128 | goto error; | |
129 | } | |
130 | ||
131 | if (S_ISLNK (st.st_mode)) | |
132 | { | |
133 | char *buf = alloca (PATH_MAX); | |
134 | size_t len; | |
135 | ||
136 | if (++num_links > MAXSYMLINKS) | |
137 | { | |
138 | __set_errno (ELOOP); | |
139 | goto error; | |
140 | } | |
141 | ||
142 | n = readlink (rpath, buf, PATH_MAX); | |
143 | if (n < 0) | |
144 | { | |
145 | if (*end == '\0') | |
146 | goto done; | |
147 | goto error; | |
148 | } | |
149 | buf[n] = '\0'; | |
150 | ||
151 | if (!extra_buf) | |
152 | extra_buf = alloca (PATH_MAX); | |
153 | ||
154 | len = strlen (end); | |
155 | if ((long int) (n + len) >= PATH_MAX) | |
156 | { | |
157 | __set_errno (ENAMETOOLONG); | |
158 | goto error; | |
159 | } | |
160 | ||
161 | /* Careful here, end may be a pointer into extra_buf... */ | |
162 | memmove (&extra_buf[n], end, len + 1); | |
163 | name = end = memcpy (extra_buf, buf, n); | |
164 | ||
165 | if (buf[0] == '/') | |
166 | dest = rpath_root + 1; /* It's an absolute symlink */ | |
167 | else | |
168 | /* Back up to previous component, ignore if at root already: */ | |
169 | if (dest > rpath_root + 1) | |
170 | while ((--dest)[-1] != '/'); | |
171 | } | |
172 | } | |
173 | } | |
174 | done: | |
175 | if (dest > rpath_root + 1 && dest[-1] == '/') | |
176 | --dest; | |
177 | *dest = '\0'; | |
178 | ||
179 | return rpath; | |
180 | ||
181 | error: | |
182 | free (rpath); | |
183 | return NULL; | |
184 | } |