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1 | /* Return the canonical absolute name of a given file. |
2 | Copyright (C) 1996-2003, 2005-2008 Free Software Foundation, Inc. | |
3 | This file is part of the GNU C Library. | |
4 | ||
5 | This program is free software: you can redistribute it and/or modify | |
6 | it under the terms of the GNU Lesser General Public License as published by | |
7 | the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program 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 | |
13 | GNU Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public License | |
16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
17 | ||
18 | #include <config.h> | |
19 | ||
20 | /* Avoid a clash of our rpl_realpath() function with the prototype in | |
21 | <stdlib.h> on Solaris 2.5.1. */ | |
22 | #undef realpath | |
23 | ||
24 | #if !HAVE_CANONICALIZE_FILE_NAME || defined _LIBC | |
25 | ||
26 | #include <alloca.h> | |
27 | ||
28 | /* Specification. */ | |
29 | #include "canonicalize.h" | |
30 | ||
31 | #include <stddef.h> | |
32 | #include <stdlib.h> | |
33 | #include <string.h> | |
34 | ||
35 | #if HAVE_UNISTD_H || defined _LIBC | |
36 | # include <unistd.h> | |
37 | #endif | |
38 | ||
39 | #include <limits.h> | |
40 | ||
41 | #if HAVE_SYS_PARAM_H || defined _LIBC | |
42 | # include <sys/param.h> | |
43 | #endif | |
44 | #ifndef MAXSYMLINKS | |
45 | # define MAXSYMLINKS 20 | |
46 | #endif | |
47 | ||
48 | #include <sys/stat.h> | |
49 | ||
50 | #include <errno.h> | |
51 | #ifndef _LIBC | |
52 | # define __set_errno(e) errno = (e) | |
53 | # ifndef ENAMETOOLONG | |
54 | # define ENAMETOOLONG EINVAL | |
55 | # endif | |
56 | #endif | |
57 | ||
58 | #ifdef _LIBC | |
59 | # include <shlib-compat.h> | |
60 | #else | |
61 | # define SHLIB_COMPAT(lib, introduced, obsoleted) 0 | |
62 | # define versioned_symbol(lib, local, symbol, version) | |
63 | # define compat_symbol(lib, local, symbol, version) | |
64 | # define weak_alias(local, symbol) | |
65 | # define __canonicalize_file_name canonicalize_file_name | |
66 | # define __realpath rpl_realpath | |
67 | # include "pathmax.h" | |
68 | # include "malloca.h" | |
69 | # if HAVE_GETCWD | |
70 | # ifdef VMS | |
71 | /* We want the directory in Unix syntax, not in VMS syntax. */ | |
72 | # define __getcwd(buf, max) getcwd (buf, max, 0) | |
73 | # else | |
74 | # define __getcwd getcwd | |
75 | # endif | |
76 | # else | |
77 | # define __getcwd(buf, max) getwd (buf) | |
78 | # endif | |
79 | # define __readlink readlink | |
80 | /* On systems without symbolic links, call stat() instead of lstat(). */ | |
81 | # if !defined S_ISLNK && !HAVE_READLINK | |
82 | # define lstat stat | |
83 | # endif | |
84 | #endif | |
85 | ||
86 | /* Return the canonical absolute name of file NAME. A canonical name | |
87 | does not contain any `.', `..' components nor any repeated path | |
88 | separators ('/') or symlinks. All path components must exist. If | |
89 | RESOLVED is null, the result is malloc'd; otherwise, if the | |
90 | canonical name is PATH_MAX chars or more, returns null with `errno' | |
91 | set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars, | |
92 | returns the name in RESOLVED. If the name cannot be resolved and | |
93 | RESOLVED is non-NULL, it contains the path of the first component | |
94 | that cannot be resolved. If the path can be resolved, RESOLVED | |
95 | holds the same value as the value returned. */ | |
96 | ||
97 | char * | |
98 | __realpath (const char *name, char *resolved) | |
99 | { | |
100 | char *rpath, *dest, *extra_buf = NULL; | |
101 | const char *start, *end, *rpath_limit; | |
102 | long int path_max; | |
103 | #if HAVE_READLINK | |
104 | int num_links = 0; | |
105 | #endif | |
106 | ||
107 | if (name == NULL) | |
108 | { | |
109 | /* As per Single Unix Specification V2 we must return an error if | |
110 | either parameter is a null pointer. We extend this to allow | |
111 | the RESOLVED parameter to be NULL in case the we are expected to | |
112 | allocate the room for the return value. */ | |
113 | __set_errno (EINVAL); | |
114 | return NULL; | |
115 | } | |
116 | ||
117 | if (name[0] == '\0') | |
118 | { | |
119 | /* As per Single Unix Specification V2 we must return an error if | |
120 | the name argument points to an empty string. */ | |
121 | __set_errno (ENOENT); | |
122 | return NULL; | |
123 | } | |
124 | ||
125 | #ifdef PATH_MAX | |
126 | path_max = PATH_MAX; | |
127 | #else | |
128 | path_max = pathconf (name, _PC_PATH_MAX); | |
129 | if (path_max <= 0) | |
130 | path_max = 1024; | |
131 | #endif | |
132 | ||
133 | if (resolved == NULL) | |
134 | { | |
135 | rpath = malloc (path_max); | |
136 | if (rpath == NULL) | |
137 | { | |
138 | /* It's easier to set errno to ENOMEM than to rely on the | |
139 | 'malloc-posix' gnulib module. */ | |
140 | errno = ENOMEM; | |
141 | return NULL; | |
142 | } | |
143 | } | |
144 | else | |
145 | rpath = resolved; | |
146 | rpath_limit = rpath + path_max; | |
147 | ||
148 | if (name[0] != '/') | |
149 | { | |
150 | if (!__getcwd (rpath, path_max)) | |
151 | { | |
152 | rpath[0] = '\0'; | |
153 | goto error; | |
154 | } | |
155 | dest = strchr (rpath, '\0'); | |
156 | } | |
157 | else | |
158 | { | |
159 | rpath[0] = '/'; | |
160 | dest = rpath + 1; | |
161 | } | |
162 | ||
163 | for (start = end = name; *start; start = end) | |
164 | { | |
165 | #ifdef _LIBC | |
166 | struct stat64 st; | |
167 | #else | |
168 | struct stat st; | |
169 | #endif | |
170 | ||
171 | /* Skip sequence of multiple path-separators. */ | |
172 | while (*start == '/') | |
173 | ++start; | |
174 | ||
175 | /* Find end of path component. */ | |
176 | for (end = start; *end && *end != '/'; ++end) | |
177 | /* Nothing. */; | |
178 | ||
179 | if (end - start == 0) | |
180 | break; | |
181 | else if (end - start == 1 && start[0] == '.') | |
182 | /* nothing */; | |
183 | else if (end - start == 2 && start[0] == '.' && start[1] == '.') | |
184 | { | |
185 | /* Back up to previous component, ignore if at root already. */ | |
186 | if (dest > rpath + 1) | |
187 | while ((--dest)[-1] != '/'); | |
188 | } | |
189 | else | |
190 | { | |
191 | size_t new_size; | |
192 | ||
193 | if (dest[-1] != '/') | |
194 | *dest++ = '/'; | |
195 | ||
196 | if (dest + (end - start) >= rpath_limit) | |
197 | { | |
198 | ptrdiff_t dest_offset = dest - rpath; | |
199 | char *new_rpath; | |
200 | ||
201 | if (resolved) | |
202 | { | |
203 | __set_errno (ENAMETOOLONG); | |
204 | if (dest > rpath + 1) | |
205 | dest--; | |
206 | *dest = '\0'; | |
207 | goto error; | |
208 | } | |
209 | new_size = rpath_limit - rpath; | |
210 | if (end - start + 1 > path_max) | |
211 | new_size += end - start + 1; | |
212 | else | |
213 | new_size += path_max; | |
214 | new_rpath = (char *) realloc (rpath, new_size); | |
215 | if (new_rpath == NULL) | |
216 | { | |
217 | /* It's easier to set errno to ENOMEM than to rely on the | |
218 | 'realloc-posix' gnulib module. */ | |
219 | errno = ENOMEM; | |
220 | goto error; | |
221 | } | |
222 | rpath = new_rpath; | |
223 | rpath_limit = rpath + new_size; | |
224 | ||
225 | dest = rpath + dest_offset; | |
226 | } | |
227 | ||
228 | #ifdef _LIBC | |
229 | dest = __mempcpy (dest, start, end - start); | |
230 | #else | |
231 | memcpy (dest, start, end - start); | |
232 | dest += end - start; | |
233 | #endif | |
234 | *dest = '\0'; | |
235 | ||
236 | #ifdef _LIBC | |
237 | if (__lxstat64 (_STAT_VER, rpath, &st) < 0) | |
238 | #else | |
239 | if (lstat (rpath, &st) < 0) | |
240 | #endif | |
241 | goto error; | |
242 | ||
243 | #if HAVE_READLINK | |
244 | if (S_ISLNK (st.st_mode)) | |
245 | { | |
246 | char *buf; | |
247 | size_t len; | |
248 | int n; | |
249 | ||
250 | if (++num_links > MAXSYMLINKS) | |
251 | { | |
252 | __set_errno (ELOOP); | |
253 | goto error; | |
254 | } | |
255 | ||
256 | buf = malloca (path_max); | |
257 | if (!buf) | |
258 | { | |
259 | errno = ENOMEM; | |
260 | goto error; | |
261 | } | |
262 | ||
263 | n = __readlink (rpath, buf, path_max - 1); | |
264 | if (n < 0) | |
265 | { | |
266 | int saved_errno = errno; | |
267 | freea (buf); | |
268 | errno = saved_errno; | |
269 | goto error; | |
270 | } | |
271 | buf[n] = '\0'; | |
272 | ||
273 | if (!extra_buf) | |
274 | { | |
275 | extra_buf = malloca (path_max); | |
276 | if (!extra_buf) | |
277 | { | |
278 | freea (buf); | |
279 | errno = ENOMEM; | |
280 | goto error; | |
281 | } | |
282 | } | |
283 | ||
284 | len = strlen (end); | |
285 | if ((long int) (n + len) >= path_max) | |
286 | { | |
287 | freea (buf); | |
288 | __set_errno (ENAMETOOLONG); | |
289 | goto error; | |
290 | } | |
291 | ||
292 | /* Careful here, end may be a pointer into extra_buf... */ | |
293 | memmove (&extra_buf[n], end, len + 1); | |
294 | name = end = memcpy (extra_buf, buf, n); | |
295 | ||
296 | if (buf[0] == '/') | |
297 | dest = rpath + 1; /* It's an absolute symlink */ | |
298 | else | |
299 | /* Back up to previous component, ignore if at root already: */ | |
300 | if (dest > rpath + 1) | |
301 | while ((--dest)[-1] != '/'); | |
302 | } | |
303 | #endif | |
304 | } | |
305 | } | |
306 | if (dest > rpath + 1 && dest[-1] == '/') | |
307 | --dest; | |
308 | *dest = '\0'; | |
309 | ||
310 | if (extra_buf) | |
311 | freea (extra_buf); | |
312 | ||
313 | return resolved ? memcpy (resolved, rpath, dest - rpath + 1) : rpath; | |
314 | ||
315 | error: | |
316 | { | |
317 | int saved_errno = errno; | |
318 | if (extra_buf) | |
319 | freea (extra_buf); | |
320 | if (resolved) | |
321 | strcpy (resolved, rpath); | |
322 | else | |
323 | free (rpath); | |
324 | errno = saved_errno; | |
325 | } | |
326 | return NULL; | |
327 | } | |
328 | #ifdef _LIBC | |
329 | versioned_symbol (libc, __realpath, realpath, GLIBC_2_3); | |
330 | #endif | |
331 | ||
332 | ||
333 | #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3) | |
334 | char * | |
335 | __old_realpath (const char *name, char *resolved) | |
336 | { | |
337 | if (resolved == NULL) | |
338 | { | |
339 | __set_errno (EINVAL); | |
340 | return NULL; | |
341 | } | |
342 | ||
343 | return __realpath (name, resolved); | |
344 | } | |
345 | compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0); | |
346 | #endif | |
347 | ||
348 | ||
349 | char * | |
350 | __canonicalize_file_name (const char *name) | |
351 | { | |
352 | return __realpath (name, NULL); | |
353 | } | |
354 | weak_alias (__canonicalize_file_name, canonicalize_file_name) | |
355 | ||
356 | #else | |
357 | ||
358 | /* This declaration is solely to ensure that after preprocessing | |
359 | this file is never empty. */ | |
360 | typedef int dummy; | |
361 | ||
362 | #endif |