1 /* Return the canonical absolute name of a given file.
2 Copyright (C) 1996-2006 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 #include <config.h>
20
21 #include "canonicalize.h"
22
23 #include <stdlib.h>
24 #include <string.h>
25
26 #if HAVE_SYS_PARAM_H
27 # include <sys/param.h>
28 #endif
29
30 #include <sys/stat.h>
31
32 #include <unistd.h>
33
34 #include <errno.h>
35 #include <stddef.h>
36
37 #include "cycle-check.h"
38 #include "filenamecat.h"
39 #include "xalloc.h"
40 #include "xgetcwd.h"
41
42 #ifndef ELOOP
43 # define ELOOP 0
44 #endif
45 #ifndef __set_errno
46 # define __set_errno(Val) errno = (Val)
47 #endif
48
49 #include "pathmax.h"
50 #include "xreadlink.h"
51
52 #if !HAVE_CANONICALIZE_FILE_NAME
53 /* Return the canonical absolute name of file NAME. A canonical name
54 does not contain any `.', `..' components nor any repeated file name
55 separators ('/') or symlinks. All components must exist.
56 The result is malloc'd. */
57
58 char *
canonicalize_file_name(const char * name)59 canonicalize_file_name (const char *name)
60 {
61 # if HAVE_RESOLVEPATH
62
63 char *resolved, *extra_buf = NULL;
64 size_t resolved_size;
65 ssize_t resolved_len;
66
67 if (name == NULL)
68 {
69 __set_errno (EINVAL);
70 return NULL;
71 }
72
73 if (name[0] == '\0')
74 {
75 __set_errno (ENOENT);
76 return NULL;
77 }
78
79 /* All known hosts with resolvepath (e.g. Solaris 7) don't turn
80 relative names into absolute ones, so prepend the working
81 directory if the file name is not absolute. */
82 if (name[0] != '/')
83 {
84 char *wd;
85
86 if (!(wd = xgetcwd ()))
87 return NULL;
88
89 extra_buf = file_name_concat (wd, name, NULL);
90 name = extra_buf;
91 free (wd);
92 }
93
94 resolved_size = strlen (name);
95 while (1)
96 {
97 resolved_size = 2 * resolved_size + 1;
98 resolved = xmalloc (resolved_size);
99 resolved_len = resolvepath (name, resolved, resolved_size);
100 if (resolved_len < 0)
101 {
102 free (resolved);
103 free (extra_buf);
104 return NULL;
105 }
106 if (resolved_len < resolved_size)
107 break;
108 free (resolved);
109 }
110
111 free (extra_buf);
112
113 /* NUL-terminate the resulting name. */
114 resolved[resolved_len] = '\0';
115
116 return resolved;
117
118 # else
119
120 return canonicalize_filename_mode (name, CAN_EXISTING);
121
122 # endif /* !HAVE_RESOLVEPATH */
123 }
124 #endif /* !HAVE_CANONICALIZE_FILE_NAME */
125
126 /* Return the canonical absolute name of file NAME. A canonical name
127 does not contain any `.', `..' components nor any repeated file name
128 separators ('/') or symlinks. Whether components must exist
129 or not depends on canonicalize mode. The result is malloc'd. */
130
131 char *
canonicalize_filename_mode(const char * name,canonicalize_mode_t can_mode)132 canonicalize_filename_mode (const char *name, canonicalize_mode_t can_mode)
133 {
134 char *rname, *dest, *extra_buf = NULL;
135 char const *start;
136 char const *end;
137 char const *rname_limit;
138 size_t extra_len = 0;
139 struct cycle_check_state cycle_state;
140
141 if (name == NULL)
142 {
143 __set_errno (EINVAL);
144 return NULL;
145 }
146
147 if (name[0] == '\0')
148 {
149 __set_errno (ENOENT);
150 return NULL;
151 }
152
153 if (name[0] != '/')
154 {
155 rname = xgetcwd ();
156 if (!rname)
157 return NULL;
158 dest = strchr (rname, '\0');
159 if (dest - rname < PATH_MAX)
160 {
161 char *p = xrealloc (rname, PATH_MAX);
162 dest = p + (dest - rname);
163 rname = p;
164 rname_limit = rname + PATH_MAX;
165 }
166 else
167 {
168 rname_limit = dest;
169 }
170 }
171 else
172 {
173 rname = xmalloc (PATH_MAX);
174 rname_limit = rname + PATH_MAX;
175 rname[0] = '/';
176 dest = rname + 1;
177 }
178
179 cycle_check_init (&cycle_state);
180 for (start = end = name; *start; start = end)
181 {
182 /* Skip sequence of multiple file name separators. */
183 while (*start == '/')
184 ++start;
185
186 /* Find end of component. */
187 for (end = start; *end && *end != '/'; ++end)
188 /* Nothing. */;
189
190 if (end - start == 0)
191 break;
192 else if (end - start == 1 && start[0] == '.')
193 /* nothing */;
194 else if (end - start == 2 && start[0] == '.' && start[1] == '.')
195 {
196 /* Back up to previous component, ignore if at root already. */
197 if (dest > rname + 1)
198 while ((--dest)[-1] != '/');
199 }
200 else
201 {
202 struct stat st;
203
204 if (dest[-1] != '/')
205 *dest++ = '/';
206
207 if (dest + (end - start) >= rname_limit)
208 {
209 ptrdiff_t dest_offset = dest - rname;
210 size_t new_size = rname_limit - rname;
211
212 if (end - start + 1 > PATH_MAX)
213 new_size += end - start + 1;
214 else
215 new_size += PATH_MAX;
216 rname = xrealloc (rname, new_size);
217 rname_limit = rname + new_size;
218
219 dest = rname + dest_offset;
220 }
221
222 dest = memcpy (dest, start, end - start);
223 dest += end - start;
224 *dest = '\0';
225
226 if (lstat (rname, &st) != 0)
227 {
228 if (can_mode == CAN_EXISTING)
229 goto error;
230 if (can_mode == CAN_ALL_BUT_LAST && *end)
231 goto error;
232 st.st_mode = 0;
233 }
234
235 if (S_ISLNK (st.st_mode))
236 {
237 char *buf;
238 size_t n, len;
239
240 if (cycle_check (&cycle_state, &st))
241 {
242 __set_errno (ELOOP);
243 if (can_mode == CAN_MISSING)
244 continue;
245 else
246 goto error;
247 }
248
249 buf = xreadlink (rname, st.st_size);
250 if (!buf)
251 {
252 if (can_mode == CAN_MISSING)
253 continue;
254 else
255 goto error;
256 }
257
258 n = strlen (buf);
259 len = strlen (end);
260
261 if (!extra_len)
262 {
263 extra_len =
264 ((n + len + 1) > PATH_MAX) ? (n + len + 1) : PATH_MAX;
265 extra_buf = xmalloc (extra_len);
266 }
267 else if ((n + len + 1) > extra_len)
268 {
269 extra_len = n + len + 1;
270 extra_buf = xrealloc (extra_buf, extra_len);
271 }
272
273 /* Careful here, end may be a pointer into extra_buf... */
274 memmove (&extra_buf[n], end, len + 1);
275 name = end = memcpy (extra_buf, buf, n);
276
277 if (buf[0] == '/')
278 dest = rname + 1; /* It's an absolute symlink */
279 else
280 /* Back up to previous component, ignore if at root already: */
281 if (dest > rname + 1)
282 while ((--dest)[-1] != '/');
283
284 free (buf);
285 }
286 else
287 {
288 if (!S_ISDIR (st.st_mode) && *end && (can_mode != CAN_MISSING))
289 {
290 errno = ENOTDIR;
291 goto error;
292 }
293 }
294 }
295 }
296 if (dest > rname + 1 && dest[-1] == '/')
297 --dest;
298 *dest = '\0';
299
300 free (extra_buf);
301 return rname;
302
303 error:
304 free (extra_buf);
305 free (rname);
306 return NULL;
307 }
308