1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2013 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 #ifndef _LIBC
19 /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
20 optimizes away the name == NULL test below. */
21 # define _GL_ARG_NONNULL(params)
22
23 # define _GL_USE_STDLIB_ALLOC 1
24 # include <config.h>
25 #endif
26
27 #if !HAVE_CANONICALIZE_FILE_NAME || !FUNC_REALPATH_WORKS || defined _LIBC
28
29 /* Specification. */
30 #include <stdlib.h>
31
32 #include <alloca.h>
33 #include <string.h>
34 #include <unistd.h>
35 #include <limits.h>
36 #if HAVE_SYS_PARAM_H || defined _LIBC
37 # include <sys/param.h>
38 #endif
39 #include <sys/stat.h>
40 #include <errno.h>
41 #include <stddef.h>
42
43 #ifdef _LIBC
44 # include <shlib-compat.h>
45 #else
46 # define SHLIB_COMPAT(lib, introduced, obsoleted) 0
47 # define versioned_symbol(lib, local, symbol, version) extern int dummy
48 # define compat_symbol(lib, local, symbol, version)
49 # define weak_alias(local, symbol)
50 # define __canonicalize_file_name canonicalize_file_name
51 # define __realpath realpath
52 # include "pathmax.h"
53 # include "malloca.h"
54 # include "dosname.h"
55 # if HAVE_GETCWD
56 # if IN_RELOCWRAPPER
57 /* When building the relocatable program wrapper, use the system's getcwd
58 function, not the gnulib override, otherwise we would get a link error.
59 */
60 # undef getcwd
61 # endif
62 # ifdef VMS
63 /* We want the directory in Unix syntax, not in VMS syntax. */
64 # define __getcwd(buf, max) getcwd (buf, max, 0)
65 # else
66 # define __getcwd getcwd
67 # endif
68 # else
69 # define __getcwd(buf, max) getwd (buf)
70 # endif
71 # define __readlink readlink
72 # define __set_errno(e) errno = (e)
73 # ifndef MAXSYMLINKS
74 # ifdef SYMLOOP_MAX
75 # define MAXSYMLINKS SYMLOOP_MAX
76 # else
77 # define MAXSYMLINKS 20
78 # endif
79 # endif
80 #endif
81
82 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
83 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
84 #endif
85
86 #if !FUNC_REALPATH_WORKS || defined _LIBC
87 /* Return the canonical absolute name of file NAME. A canonical name
88 does not contain any ".", ".." components nor any repeated path
89 separators ('/') or symlinks. All path components must exist. If
90 RESOLVED is null, the result is malloc'd; otherwise, if the
91 canonical name is PATH_MAX chars or more, returns null with 'errno'
92 set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
93 returns the name in RESOLVED. If the name cannot be resolved and
94 RESOLVED is non-NULL, it contains the path of the first component
95 that cannot be resolved. If the path can be resolved, RESOLVED
96 holds the same value as the value returned. */
97
98 char *
__realpath(const char * name,char * resolved)99 __realpath (const char *name, char *resolved)
100 {
101 char *rpath, *dest, *extra_buf = NULL;
102 const char *start, *end, *rpath_limit;
103 long int path_max;
104 int num_links = 0;
105 size_t prefix_len;
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 = 8192;
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 /* This is always zero for Posix hosts, but can be 2 for MS-Windows
149 and MS-DOS X:/foo/bar file names. */
150 prefix_len = FILE_SYSTEM_PREFIX_LEN (name);
151
152 if (!IS_ABSOLUTE_FILE_NAME (name))
153 {
154 if (!__getcwd (rpath, path_max))
155 {
156 rpath[0] = '\0';
157 goto error;
158 }
159 dest = strchr (rpath, '\0');
160 start = name;
161 prefix_len = FILE_SYSTEM_PREFIX_LEN (rpath);
162 }
163 else
164 {
165 dest = rpath;
166 if (prefix_len)
167 {
168 memcpy (rpath, name, prefix_len);
169 dest += prefix_len;
170 }
171 *dest++ = '/';
172 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
173 {
174 if (ISSLASH (name[1]) && !ISSLASH (name[2]) && !prefix_len)
175 *dest++ = '/';
176 *dest = '\0';
177 }
178 start = name + prefix_len;
179 }
180
181 for (end = start; *start; start = end)
182 {
183 #ifdef _LIBC
184 struct stat64 st;
185 #else
186 struct stat st;
187 #endif
188 int n;
189
190 /* Skip sequence of multiple path-separators. */
191 while (ISSLASH (*start))
192 ++start;
193
194 /* Find end of path component. */
195 for (end = start; *end && !ISSLASH (*end); ++end)
196 /* Nothing. */;
197
198 if (end - start == 0)
199 break;
200 else if (end - start == 1 && start[0] == '.')
201 /* nothing */;
202 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
203 {
204 /* Back up to previous component, ignore if at root already. */
205 if (dest > rpath + prefix_len + 1)
206 for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
207 continue;
208 if (DOUBLE_SLASH_IS_DISTINCT_ROOT
209 && dest == rpath + 1 && !prefix_len
210 && ISSLASH (*dest) && !ISSLASH (dest[1]))
211 dest++;
212 }
213 else
214 {
215 size_t new_size;
216
217 if (!ISSLASH (dest[-1]))
218 *dest++ = '/';
219
220 if (dest + (end - start) >= rpath_limit)
221 {
222 ptrdiff_t dest_offset = dest - rpath;
223 char *new_rpath;
224
225 if (resolved)
226 {
227 __set_errno (ENAMETOOLONG);
228 if (dest > rpath + prefix_len + 1)
229 dest--;
230 *dest = '\0';
231 goto error;
232 }
233 new_size = rpath_limit - rpath;
234 if (end - start + 1 > path_max)
235 new_size += end - start + 1;
236 else
237 new_size += path_max;
238 new_rpath = (char *) realloc (rpath, new_size);
239 if (new_rpath == NULL)
240 {
241 /* It's easier to set errno to ENOMEM than to rely on the
242 'realloc-posix' gnulib module. */
243 errno = ENOMEM;
244 goto error;
245 }
246 rpath = new_rpath;
247 rpath_limit = rpath + new_size;
248
249 dest = rpath + dest_offset;
250 }
251
252 #ifdef _LIBC
253 dest = __mempcpy (dest, start, end - start);
254 #else
255 memcpy (dest, start, end - start);
256 dest += end - start;
257 #endif
258 *dest = '\0';
259
260 #ifdef _LIBC
261 if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
262 #else
263 if (lstat (rpath, &st) < 0)
264 #endif
265 goto error;
266
267 if (S_ISLNK (st.st_mode))
268 {
269 char *buf;
270 size_t len;
271
272 if (++num_links > MAXSYMLINKS)
273 {
274 __set_errno (ELOOP);
275 goto error;
276 }
277
278 buf = malloca (path_max);
279 if (!buf)
280 {
281 errno = ENOMEM;
282 goto error;
283 }
284
285 n = __readlink (rpath, buf, path_max - 1);
286 if (n < 0)
287 {
288 int saved_errno = errno;
289 freea (buf);
290 errno = saved_errno;
291 goto error;
292 }
293 buf[n] = '\0';
294
295 if (!extra_buf)
296 {
297 extra_buf = malloca (path_max);
298 if (!extra_buf)
299 {
300 freea (buf);
301 errno = ENOMEM;
302 goto error;
303 }
304 }
305
306 len = strlen (end);
307 if ((long int) (n + len) >= path_max)
308 {
309 freea (buf);
310 __set_errno (ENAMETOOLONG);
311 goto error;
312 }
313
314 /* Careful here, end may be a pointer into extra_buf... */
315 memmove (&extra_buf[n], end, len + 1);
316 name = end = memcpy (extra_buf, buf, n);
317
318 if (IS_ABSOLUTE_FILE_NAME (buf))
319 {
320 size_t pfxlen = FILE_SYSTEM_PREFIX_LEN (buf);
321
322 if (pfxlen)
323 memcpy (rpath, buf, pfxlen);
324 dest = rpath + pfxlen;
325 *dest++ = '/'; /* It's an absolute symlink */
326 if (DOUBLE_SLASH_IS_DISTINCT_ROOT)
327 {
328 if (ISSLASH (buf[1]) && !ISSLASH (buf[2]) && !pfxlen)
329 *dest++ = '/';
330 *dest = '\0';
331 }
332 /* Install the new prefix to be in effect hereafter. */
333 prefix_len = pfxlen;
334 }
335 else
336 {
337 /* Back up to previous component, ignore if at root
338 already: */
339 if (dest > rpath + prefix_len + 1)
340 for (--dest; dest > rpath && !ISSLASH (dest[-1]); --dest)
341 continue;
342 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1
343 && ISSLASH (*dest) && !ISSLASH (dest[1]) && !prefix_len)
344 dest++;
345 }
346 }
347 else if (!S_ISDIR (st.st_mode) && *end != '\0')
348 {
349 __set_errno (ENOTDIR);
350 goto error;
351 }
352 }
353 }
354 if (dest > rpath + prefix_len + 1 && ISSLASH (dest[-1]))
355 --dest;
356 if (DOUBLE_SLASH_IS_DISTINCT_ROOT && dest == rpath + 1 && !prefix_len
357 && ISSLASH (*dest) && !ISSLASH (dest[1]))
358 dest++;
359 *dest = '\0';
360
361 if (extra_buf)
362 freea (extra_buf);
363
364 return rpath;
365
366 error:
367 {
368 int saved_errno = errno;
369 if (extra_buf)
370 freea (extra_buf);
371 if (resolved == NULL)
372 free (rpath);
373 errno = saved_errno;
374 }
375 return NULL;
376 }
377 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3);
378 #endif /* !FUNC_REALPATH_WORKS || defined _LIBC */
379
380
381 #if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_3)
382 char *
383 attribute_compat_text_section
__old_realpath(const char * name,char * resolved)384 __old_realpath (const char *name, char *resolved)
385 {
386 if (resolved == NULL)
387 {
388 __set_errno (EINVAL);
389 return NULL;
390 }
391
392 return __realpath (name, resolved);
393 }
394 compat_symbol (libc, __old_realpath, realpath, GLIBC_2_0);
395 #endif
396
397
398 char *
__canonicalize_file_name(const char * name)399 __canonicalize_file_name (const char *name)
400 {
401 return __realpath (name, NULL);
402 }
403 weak_alias (__canonicalize_file_name, canonicalize_file_name)
404
405 #else
406
407 /* This declaration is solely to ensure that after preprocessing
408 this file is never empty. */
409 typedef int dummy;
410
411 #endif
412