1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2003, 2005-2007 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 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 General Public License for more details.
14
15 You should have received a copy of the GNU 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_ISNLK && !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 *
__realpath(const char * name,char * resolved)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);
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 *
__old_realpath(const char * name,char * resolved)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 *
__canonicalize_file_name(const char * name)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
363