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fa0bc87c | 1 | /* Return the canonical absolute name of a given file. |
2b778ceb | 2 | Copyright (C) 1996-2021 Free Software Foundation, Inc. |
a18f587d | 3 | This file is part of the GNU C Library. |
fa0bc87c | 4 | |
a18f587d | 5 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
fa0bc87c | 9 | |
a18f587d UD |
10 | The GNU C Library 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 GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
fa0bc87c | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
fa0bc87c | 18 | |
33d52792 | 19 | #include <assert.h> |
fa0bc87c RM |
20 | #include <stdlib.h> |
21 | #include <string.h> | |
22 | #include <unistd.h> | |
23 | #include <limits.h> | |
24 | #include <sys/stat.h> | |
25 | #include <errno.h> | |
e5aa91c3 | 26 | #include <stddef.h> |
fa0bc87c | 27 | |
4f75b7a0 | 28 | #include <eloop-threshold.h> |
3e0dd85b UD |
29 | #include <shlib-compat.h> |
30 | ||
394f4f17 RM |
31 | /* Return the canonical absolute name of file NAME. A canonical name |
32 | does not contain any `.', `..' components nor any repeated path | |
33 | separators ('/') or symlinks. All path components must exist. If | |
34 | RESOLVED is null, the result is malloc'd; otherwise, if the | |
35 | canonical name is PATH_MAX chars or more, returns null with `errno' | |
36 | set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars, | |
37 | returns the name in RESOLVED. If the name cannot be resolved and | |
38 | RESOLVED is non-NULL, it contains the path of the first component | |
39 | that cannot be resolved. If the path can be resolved, RESOLVED | |
40 | holds the same value as the value returned. */ | |
fa0bc87c | 41 | |
f7501ae6 UD |
42 | char * |
43 | __realpath (const char *name, char *resolved) | |
fa0bc87c | 44 | { |
394f4f17 RM |
45 | char *rpath, *dest, *extra_buf = NULL; |
46 | const char *start, *end, *rpath_limit; | |
fa0bc87c | 47 | long int path_max; |
394f4f17 | 48 | int num_links = 0; |
fa0bc87c | 49 | |
310b3460 | 50 | if (name == NULL) |
86187531 UD |
51 | { |
52 | /* As per Single Unix Specification V2 we must return an error if | |
310b3460 | 53 | either parameter is a null pointer. We extend this to allow |
49c091e5 | 54 | the RESOLVED parameter to be NULL in case the we are expected to |
310b3460 | 55 | allocate the room for the return value. */ |
86187531 UD |
56 | __set_errno (EINVAL); |
57 | return NULL; | |
58 | } | |
59 | ||
60 | if (name[0] == '\0') | |
61 | { | |
62 | /* As per Single Unix Specification V2 we must return an error if | |
63 | the name argument points to an empty string. */ | |
64 | __set_errno (ENOENT); | |
65 | return NULL; | |
66 | } | |
67 | ||
fa0bc87c | 68 | #ifdef PATH_MAX |
394f4f17 | 69 | path_max = PATH_MAX; |
fa0bc87c | 70 | #else |
dba2bdbe | 71 | path_max = __pathconf (name, _PC_PATH_MAX); |
394f4f17 RM |
72 | if (path_max <= 0) |
73 | path_max = 1024; | |
fa0bc87c | 74 | #endif |
fa0bc87c | 75 | |
92712dee RM |
76 | if (resolved == NULL) |
77 | { | |
78 | rpath = malloc (path_max); | |
79 | if (rpath == NULL) | |
80 | return NULL; | |
81 | } | |
82 | else | |
83 | rpath = resolved; | |
394f4f17 | 84 | rpath_limit = rpath + path_max; |
fa0bc87c | 85 | |
a18f587d UD |
86 | if (name[0] != '/') |
87 | { | |
2ad4fab2 | 88 | if (!__getcwd (rpath, path_max)) |
a1d84548 UD |
89 | { |
90 | rpath[0] = '\0'; | |
91 | goto error; | |
92 | } | |
e7c8359e | 93 | dest = __rawmemchr (rpath, '\0'); |
a18f587d UD |
94 | } |
95 | else | |
96 | { | |
97 | rpath[0] = '/'; | |
98 | dest = rpath + 1; | |
99 | } | |
fa0bc87c | 100 | |
394f4f17 | 101 | for (start = end = name; *start; start = end) |
fa0bc87c | 102 | { |
8edf6e0d | 103 | struct stat64 st; |
394f4f17 RM |
104 | int n; |
105 | ||
86187531 | 106 | /* Skip sequence of multiple path-separators. */ |
2ac51313 UD |
107 | while (*start == '/') |
108 | ++start; | |
394f4f17 | 109 | |
86187531 | 110 | /* Find end of path component. */ |
2ac51313 UD |
111 | for (end = start; *end && *end != '/'; ++end) |
112 | /* Nothing. */; | |
df21c858 | 113 | |
394f4f17 RM |
114 | if (end - start == 0) |
115 | break; | |
2ac51313 | 116 | else if (end - start == 1 && start[0] == '.') |
394f4f17 | 117 | /* nothing */; |
2ac51313 | 118 | else if (end - start == 2 && start[0] == '.' && start[1] == '.') |
86187531 UD |
119 | { |
120 | /* Back up to previous component, ignore if at root already. */ | |
121 | if (dest > rpath + 1) | |
122 | while ((--dest)[-1] != '/'); | |
123 | } | |
124 | else | |
fa0bc87c | 125 | { |
394f4f17 | 126 | size_t new_size; |
fa0bc87c | 127 | |
394f4f17 RM |
128 | if (dest[-1] != '/') |
129 | *dest++ = '/'; | |
130 | ||
131 | if (dest + (end - start) >= rpath_limit) | |
fa0bc87c | 132 | { |
2ac51313 | 133 | ptrdiff_t dest_offset = dest - rpath; |
d1dddedf | 134 | char *new_rpath; |
2ac51313 | 135 | |
394f4f17 | 136 | if (resolved) |
fa0bc87c | 137 | { |
c4029823 | 138 | __set_errno (ENAMETOOLONG); |
a1d84548 UD |
139 | if (dest > rpath + 1) |
140 | dest--; | |
141 | *dest = '\0'; | |
394f4f17 | 142 | goto error; |
fa0bc87c | 143 | } |
394f4f17 RM |
144 | new_size = rpath_limit - rpath; |
145 | if (end - start + 1 > path_max) | |
146 | new_size += end - start + 1; | |
147 | else | |
148 | new_size += path_max; | |
d1dddedf UD |
149 | new_rpath = (char *) realloc (rpath, new_size); |
150 | if (new_rpath == NULL) | |
151 | goto error; | |
152 | rpath = new_rpath; | |
394f4f17 | 153 | rpath_limit = rpath + new_size; |
2ac51313 UD |
154 | |
155 | dest = rpath + dest_offset; | |
fa0bc87c | 156 | } |
fa0bc87c | 157 | |
86187531 | 158 | dest = __mempcpy (dest, start, end - start); |
394f4f17 | 159 | *dest = '\0'; |
df21c858 | 160 | |
04986243 | 161 | if (__lstat64 (rpath, &st) < 0) |
394f4f17 | 162 | goto error; |
fa0bc87c | 163 | |
394f4f17 | 164 | if (S_ISLNK (st.st_mode)) |
fa0bc87c | 165 | { |
f65fd747 | 166 | char *buf = __alloca (path_max); |
40a55d20 | 167 | size_t len; |
fa0bc87c | 168 | |
4f75b7a0 | 169 | if (++num_links > __eloop_threshold ()) |
394f4f17 | 170 | { |
c4029823 | 171 | __set_errno (ELOOP); |
394f4f17 RM |
172 | goto error; |
173 | } | |
fa0bc87c | 174 | |
104426b6 | 175 | n = __readlink (rpath, buf, path_max - 1); |
394f4f17 RM |
176 | if (n < 0) |
177 | goto error; | |
178 | buf[n] = '\0'; | |
fa0bc87c | 179 | |
394f4f17 RM |
180 | if (!extra_buf) |
181 | extra_buf = __alloca (path_max); | |
fa0bc87c | 182 | |
40a55d20 | 183 | len = strlen (end); |
5460617d | 184 | if (path_max - n <= len) |
394f4f17 | 185 | { |
c4029823 | 186 | __set_errno (ENAMETOOLONG); |
394f4f17 RM |
187 | goto error; |
188 | } | |
fa0bc87c | 189 | |
40a55d20 | 190 | /* Careful here, end may be a pointer into extra_buf... */ |
86187531 | 191 | memmove (&extra_buf[n], end, len + 1); |
2ac51313 | 192 | name = end = memcpy (extra_buf, buf, n); |
394f4f17 RM |
193 | |
194 | if (buf[0] == '/') | |
40a55d20 | 195 | dest = rpath + 1; /* It's an absolute symlink */ |
394f4f17 | 196 | else |
40a55d20 | 197 | /* Back up to previous component, ignore if at root already: */ |
394f4f17 RM |
198 | if (dest > rpath + 1) |
199 | while ((--dest)[-1] != '/'); | |
200 | } | |
0f888d8e UD |
201 | else if (!S_ISDIR (st.st_mode) && *end != '\0') |
202 | { | |
203 | __set_errno (ENOTDIR); | |
204 | goto error; | |
205 | } | |
394f4f17 RM |
206 | } |
207 | } | |
208 | if (dest > rpath + 1 && dest[-1] == '/') | |
209 | --dest; | |
210 | *dest = '\0'; | |
f65fd747 | 211 | |
33d52792 | 212 | assert (resolved == NULL || resolved == rpath); |
d3a4681c | 213 | return rpath; |
394f4f17 RM |
214 | |
215 | error: | |
33d52792 UD |
216 | assert (resolved == NULL || resolved == rpath); |
217 | if (resolved == NULL) | |
394f4f17 RM |
218 | free (rpath); |
219 | return NULL; | |
fa0bc87c | 220 | } |
8ed3b643 | 221 | libc_hidden_def (__realpath) |
3e0dd85b UD |
222 | versioned_symbol (libc, __realpath, realpath, GLIBC_2_3); |
223 | ||
224 | ||
225 | #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3) | |
226 | char * | |
4a381a81 | 227 | attribute_compat_text_section |
3e0dd85b UD |
228 | __old_realpath (const char *name, char *resolved) |
229 | { | |
230 | if (resolved == NULL) | |
231 | { | |
232 | __set_errno (EINVAL); | |
233 | return NULL; | |
234 | } | |
235 | ||
236 | return __realpath (name, resolved); | |
237 | } | |
238 | compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0); | |
239 | #endif | |
fa0bc87c | 240 | |
a18f587d | 241 | |
fa0bc87c | 242 | char * |
2ad4fab2 | 243 | __canonicalize_file_name (const char *name) |
fa0bc87c | 244 | { |
f7501ae6 | 245 | return __realpath (name, NULL); |
fa0bc87c | 246 | } |
2ad4fab2 | 247 | weak_alias (__canonicalize_file_name, canonicalize_file_name) |