1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2005 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; see the file COPYING.
16 If not, write to the Free Software Foundation,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
18
19 #ifdef HAVE_CONFIG_H
20 # include <config.h>
21 #endif
22
23 #include "canonicalize.h"
24
25 #ifdef STDC_HEADERS
26 # include <stdlib.h>
27 #else
28 void free ();
29 #endif
30
31 #if defined STDC_HEADERS || defined HAVE_STRING_H
32 # include <string.h>
33 #else
34 # include <strings.h>
35 #endif
36
37 #if HAVE_SYS_PARAM_H
38 # include <sys/param.h>
39 #endif
40
41 #include <sys/stat.h>
42
43 #if HAVE_UNISTD_H
44 # include <unistd.h>
45 #endif
46
47 #include <errno.h>
48 #include <stddef.h>
49
50 #include "cycle-check.h"
51 #include "filenamecat.h"
52 #include "stat-macros.h"
53 #include "xalloc.h"
54 #include "xgetcwd.h"
55
56 #ifndef __set_errno
57 # define __set_errno(Val) errno = (Val)
58 #endif
59
60 #include "pathmax.h"
61 #include "xreadlink.h"
62
63 #if !HAVE_CANONICALIZE_FILE_NAME
64 /* Return the canonical absolute name of file NAME. A canonical name
65 does not contain any `.', `..' components nor any repeated file name
66 separators ('/') or symlinks. All components must exist.
67 The result is malloc'd. */
68
69 char *
canonicalize_file_name(const char * name)70 canonicalize_file_name (const char *name)
71 {
72 # if HAVE_RESOLVEPATH
73
74 char *resolved, *extra_buf = NULL;
75 size_t resolved_size;
76 ssize_t resolved_len;
77
78 if (name == NULL)
79 {
80 __set_errno (EINVAL);
81 return NULL;
82 }
83
84 if (name[0] == '\0')
85 {
86 __set_errno (ENOENT);
87 return NULL;
88 }
89
90 /* All known hosts with resolvepath (e.g. Solaris 7) don't turn
91 relative names into absolute ones, so prepend the working
92 directory if the file name is not absolute. */
93 if (name[0] != '/')
94 {
95 char *wd;
96
97 if (!(wd = xgetcwd ()))
98 return NULL;
99
100 extra_buf = file_name_concat (wd, name, NULL);
101 name = extra_buf;
102 free (wd);
103 }
104
105 resolved_size = strlen (name);
106 while (1)
107 {
108 resolved_size = 2 * resolved_size + 1;
109 resolved = xmalloc (resolved_size);
110 resolved_len = resolvepath (name, resolved, resolved_size);
111 if (resolved_len < 0)
112 {
113 free (resolved);
114 free (extra_buf);
115 return NULL;
116 }
117 if (resolved_len < resolved_size)
118 break;
119 free (resolved);
120 }
121
122 free (extra_buf);
123
124 /* NUL-terminate the resulting name. */
125 resolved[resolved_len] = '\0';
126
127 return resolved;
128
129 # else
130
131 return canonicalize_filename_mode (name, CAN_EXISTING);
132
133 # endif /* !HAVE_RESOLVEPATH */
134 }
135 #endif /* !HAVE_CANONICALIZE_FILE_NAME */
136
137 /* Return the canonical absolute name of file NAME. A canonical name
138 does not contain any `.', `..' components nor any repeated file name
139 separators ('/') or symlinks. Whether components must exist
140 or not depends on canonicalize mode. The result is malloc'd. */
141
142 char *
canonicalize_filename_mode(const char * name,canonicalize_mode_t can_mode)143 canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode)
144 {
145 char *rname, *dest, *extra_buf = NULL;
146 char const *start;
147 char const *end;
148 char const *rname_limit;
149 size_t extra_len = 0;
150 struct cycle_check_state cycle_state;
151
152 if (name == NULL)
153 {
154 __set_errno (EINVAL);
155 return NULL;
156 }
157
158 if (name[0] == '\0')
159 {
160 __set_errno (ENOENT);
161 return NULL;
162 }
163
164 if (name[0] != '/')
165 {
166 rname = xgetcwd ();
167 if (!rname)
168 return NULL;
169 dest = strchr (rname, '\0');
170 if (dest - rname < PATH_MAX)
171 {
172 char *p = xrealloc (rname, PATH_MAX);
173 dest = p + (dest - rname);
174 rname = p;
175 rname_limit = rname + PATH_MAX;
176 }
177 else
178 {
179 rname_limit = dest;
180 }
181 }
182 else
183 {
184 rname = xmalloc (PATH_MAX);
185 rname_limit = rname + PATH_MAX;
186 rname[0] = '/';
187 dest = rname + 1;
188 }
189
190 cycle_check_init (&cycle_state);
191 for (start = end = name; *start; start = end)
192 {
193 /* Skip sequence of multiple file name separators. */
194 while (*start == '/')
195 ++start;
196
197 /* Find end of component. */
198 for (end = start; *end && *end != '/'; ++end)
199 /* Nothing. */;
200
201 if (end - start == 0)
202 break;
203 else if (end - start == 1 && start[0] == '.')
204 /* nothing */;
205 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
206 {
207 /* Back up to previous component, ignore if at root already. */
208 if (dest > rname + 1)
209 while ((--dest)[-1] != '/');
210 }
211 else
212 {
213 struct stat st;
214
215 if (dest[-1] != '/')
216 *dest++ = '/';
217
218 if (dest + (end - start) >= rname_limit)
219 {
220 ptrdiff_t dest_offset = dest - rname;
221 size_t new_size = rname_limit - rname;
222
223 if (end - start + 1 > PATH_MAX)
224 new_size += end - start + 1;
225 else
226 new_size += PATH_MAX;
227 rname = xrealloc (rname, new_size);
228 rname_limit = rname + new_size;
229
230 dest = rname + dest_offset;
231 }
232
233 dest = memcpy (dest, start, end - start);
234 dest += end - start;
235 *dest = '\0';
236
237 if (lstat (rname, &st) != 0)
238 {
239 if (can_mode == CAN_EXISTING)
240 goto error;
241 if (can_mode == CAN_ALL_BUT_LAST && *end)
242 goto error;
243 st.st_mode = 0;
244 }
245
246 if (S_ISLNK (st.st_mode))
247 {
248 char *buf;
249 size_t n, len;
250
251 if (cycle_check (&cycle_state, &st))
252 {
253 __set_errno (ELOOP);
254 if (can_mode == CAN_MISSING)
255 continue;
256 else
257 goto error;
258 }
259
260 buf = xreadlink (rname, st.st_size);
261 if (!buf)
262 {
263 if (can_mode == CAN_MISSING)
264 continue;
265 else
266 goto error;
267 }
268
269 n = strlen (buf);
270 len = strlen (end);
271
272 if (!extra_len)
273 {
274 extra_len =
275 ((n + len + 1) > PATH_MAX) ? (n + len + 1) : PATH_MAX;
276 extra_buf = xmalloc (extra_len);
277 }
278 else if ((n + len + 1) > extra_len)
279 {
280 extra_len = n + len + 1;
281 extra_buf = xrealloc (extra_buf, extra_len);
282 }
283
284 /* Careful here, end may be a pointer into extra_buf... */
285 memmove (&extra_buf[n], end, len + 1);
286 name = end = memcpy (extra_buf, buf, n);
287
288 if (buf[0] == '/')
289 dest = rname + 1; /* It's an absolute symlink */
290 else
291 /* Back up to previous component, ignore if at root already: */
292 if (dest > rname + 1)
293 while ((--dest)[-1] != '/');
294
295 free (buf);
296 }
297 else
298 {
299 if (!S_ISDIR (st.st_mode) && *end && (can_mode != CAN_MISSING))
300 {
301 errno = ENOTDIR;
302 goto error;
303 }
304 }
305 }
306 }
307 if (dest > rname + 1 && dest[-1] == '/')
308 --dest;
309 *dest = '\0';
310
311 free (extra_buf);
312 return rname;
313
314 error:
315 free (extra_buf);
316 free (rname);
317 return NULL;
318 }
319