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1/*
2 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. The names of the authors may not be used to endorse or promote
13 * products derived from this software without specific prior written
14 * permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#if defined(LIBC_SCCS) && !defined(lint)
30static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94";
31#endif /* LIBC_SCCS and not lint */
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: src/lib/libc/stdlib/realpath.c,v 1.20 2003/05/28 08:23:01 fjoe Exp $");
34
35#include "namespace.h"
36#include <sys/param.h>
37#include <sys/stat.h>
38#include <sys/mount.h>
39
40#include <errno.h>
41#include <stdlib.h>
42#include <string.h>
43#include <unistd.h>
44#include <sys/attr.h>
45#include <sys/vnode.h>
46#include "un-namespace.h"
47
48struct attrs {
49 u_int32_t len;
50 attrreference_t name;
51 dev_t dev;
52 fsobj_type_t type;
53 fsobj_id_t id;
54 char buf[PATH_MAX];
55};
56
57#ifndef BUILDING_VARIANT
58__private_extern__ struct attrlist _rp_alist = {
59 ATTR_BIT_MAP_COUNT,
60 0,
61 ATTR_CMN_NAME | ATTR_CMN_DEVID | ATTR_CMN_OBJTYPE | ATTR_CMN_OBJID,
62 0,
63 0,
64 0,
65 0,
66};
67#else /* BUILDING_VARIANT */
68__private_extern__ struct attrlist _rp_alist;
69#endif /* BUILDING_VARIANT */
70
71extern char * __private_getcwd(char *, size_t, int);
72
73/*
74 * char *realpath(const char *path, char resolved[PATH_MAX]);
75 *
76 * Find the real name of path, by removing all ".", ".." and symlink
77 * components. Returns (resolved) on success, or (NULL) on failure,
78 * in which case the path which caused trouble is left in (resolved).
79 */
80char *
81realpath(const char *path, char resolved[PATH_MAX])
82{
83 struct attrs attrs;
84 struct stat sb;
85 char *p, *q, *s;
86 size_t left_len, resolved_len, save_resolved_len;
87 unsigned symlinks;
88 int serrno, slen, useattrs, islink;
89 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
90 dev_t dev, lastdev;
91 struct statfs sfs;
92 static dev_t rootdev;
93 static int rootdev_inited = 0;
94 ino_t inode;
95
96 if (path == NULL) {
97 errno = EINVAL;
98 return (NULL);
99 }
100#if __DARWIN_UNIX03
101 if (*path == 0) {
102 errno = ENOENT;
103 return (NULL);
104 }
105#endif /* __DARWIN_UNIX03 */
106 if (!rootdev_inited) {
107 rootdev_inited = 1;
108 if (stat("/", &sb) < 0) {
109 return (NULL);
110 }
111 rootdev = sb.st_dev;
112 }
113 serrno = errno;
114 symlinks = 0;
115 if (path[0] == '/') {
116 resolved[0] = '/';
117 resolved[1] = '\0';
118 if (path[1] == '\0') {
119 return (resolved);
120 }
121 resolved_len = 1;
122 left_len = strlcpy(left, path + 1, sizeof(left));
123 } else {
124#if !defined(VARIANT_DARWINEXTSN) && __DARWIN_UNIX03
125 /* 4447159: don't use GETPATH, so this will fail if */
126 /* if parent directories are not readable, as per POSIX */
127 if (__private_getcwd(resolved, PATH_MAX, 0) == NULL)
128#else /* VARIANT_DARWINEXTSN || !__DARWIN_UNIX03 */
129 if (__private_getcwd(resolved, PATH_MAX, 1) == NULL)
130#endif /* !VARIANT_DARWINEXTSN && __DARWIN_UNIX03 */
131 {
132 strlcpy(resolved, ".", PATH_MAX);
133 return (NULL);
134 }
135 resolved_len = strlen(resolved);
136 left_len = strlcpy(left, path, sizeof(left));
137 }
138 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
139 errno = ENAMETOOLONG;
140 return (NULL);
141 }
142 if (resolved_len > 1) {
143 if (stat(resolved, &sb) < 0) {
144 return (NULL);
145 }
146 lastdev = sb.st_dev;
147 } else
148 lastdev = rootdev;
149
150 /*
151 * Iterate over path components in `left'.
152 */
153 while (left_len != 0) {
154 /*
155 * Extract the next path component and adjust `left'
156 * and its length.
157 */
158 p = strchr(left, '/');
159 s = p ? p : left + left_len;
160 if (s - left >= sizeof(next_token)) {
161 errno = ENAMETOOLONG;
162 return (NULL);
163 }
164 memcpy(next_token, left, s - left);
165 next_token[s - left] = '\0';
166 left_len -= s - left;
167 if (p != NULL)
168 memmove(left, s + 1, left_len + 1);
169 if (resolved[resolved_len - 1] != '/') {
170 if (resolved_len + 1 >= PATH_MAX) {
171 errno = ENAMETOOLONG;
172 return (NULL);
173 }
174 resolved[resolved_len++] = '/';
175 resolved[resolved_len] = '\0';
176 }
177 if (next_token[0] == '\0')
178 continue;
179 else if (strcmp(next_token, ".") == 0)
180 continue;
181 else if (strcmp(next_token, "..") == 0) {
182 /*
183 * Strip the last path component except when we have
184 * single "/"
185 */
186 if (resolved_len > 1) {
187 resolved[resolved_len - 1] = '\0';
188 q = strrchr(resolved, '/') + 1;
189 *q = '\0';
190 resolved_len = q - resolved;
191 }
192 continue;
193 }
194
195 /*
196 * Save resolved_len, so that we can later null out
197 * the the appended next_token, and replace with the
198 * real name (matters on case-insensitive filesystems).
199 */
200 save_resolved_len = resolved_len;
201
202 /*
203 * Append the next path component and lstat() it. If
204 * lstat() fails we still can return successfully if
205 * there are no more path components left.
206 */
207 resolved_len = strlcat(resolved, next_token, PATH_MAX);
208 if (resolved_len >= PATH_MAX) {
209 errno = ENAMETOOLONG;
210 return (NULL);
211 }
212 if (getattrlist(resolved, &_rp_alist, &attrs, sizeof(attrs), FSOPT_NOFOLLOW) == 0) {
213 useattrs = 1;
214 islink = (attrs.type == VLNK);
215 dev = attrs.dev;
216 inode = attrs.id.fid_objno;
217 } else if (errno == ENOTSUP || errno == EINVAL) {
218 if ((useattrs = lstat(resolved, &sb)) == 0) {
219 islink = S_ISLNK(sb.st_mode);
220 dev = sb.st_dev;
221 inode = sb.st_ino;
222 }
223 } else
224 useattrs = -1;
225 if (useattrs < 0) {
226#if !__DARWIN_UNIX03
227 if (errno == ENOENT && p == NULL) {
228 errno = serrno;
229 return (resolved);
230 }
231#endif /* !__DARWIN_UNIX03 */
232 return (NULL);
233 }
234 if (dev != lastdev) {
235 /*
236 * We have crossed a mountpoint. For volumes like UDF
237 * the getattrlist name may not match the actual
238 * mountpoint, so we just copy the mountpoint directly.
239 * (3703138). However, the mountpoint may not be
240 * accessible, as when chroot-ed, so check first.
241 * There may be a file on the chroot-ed volume with
242 * the same name as the mountpoint, so compare device
243 * and inode numbers.
244 */
245 lastdev = dev;
246 if (statfs(resolved, &sfs) == 0 && lstat(sfs.f_mntonname, &sb) == 0 && dev == sb.st_dev && inode == sb.st_ino) {
247 /*
248 * However, it's possible that the mountpoint
249 * path matches, even though it isn't the real
250 * path in the chroot-ed environment, so check
251 * that each component of the mountpoint
252 * is a directory (and not a symlink)
253 */
254 char temp[MNAMELEN];
255 char *cp;
256 int ok = 1;
257
258 strcpy(temp, sfs.f_mntonname);
259 for(;;) {
260 if ((cp = strrchr(temp, '/')) == NULL) {
261 ok = 0;
262 break;
263 }
264 if (cp <= temp)
265 break;
266 *cp = 0;
267 if (lstat(temp, &sb) < 0 || (sb.st_mode & S_IFMT) != S_IFDIR) {
268 ok = 0;
269 break;
270 }
271 }
272 if (ok) {
273 resolved_len = strlcpy(resolved, sfs.f_mntonname, PATH_MAX);
274 continue;
275 }
276 }
277 /* if we fail, use the other methods. */
278 }
279 if (islink) {
280 if (symlinks++ > MAXSYMLINKS) {
281 errno = ELOOP;
282 return (NULL);
283 }
284 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
285 if (slen < 0) {
286 return (NULL);
287 }
288 symlink[slen] = '\0';
289 if (symlink[0] == '/') {
290 resolved[1] = 0;
291 resolved_len = 1;
292 lastdev = rootdev;
293 } else if (resolved_len > 1) {
294 /* Strip the last path component. */
295 resolved[resolved_len - 1] = '\0';
296 q = strrchr(resolved, '/') + 1;
297 *q = '\0';
298 resolved_len = q - resolved;
299 }
300
301 /*
302 * If there are any path components left, then
303 * append them to symlink. The result is placed
304 * in `left'.
305 */
306 if (p != NULL) {
307 if (symlink[slen - 1] != '/') {
308 if (slen + 1 >= sizeof(symlink)) {
309 errno = ENAMETOOLONG;
310 return (NULL);
311 }
312 symlink[slen] = '/';
313 symlink[slen + 1] = 0;
314 }
315 left_len = strlcat(symlink, left, sizeof(left));
316 if (left_len >= sizeof(left)) {
317 errno = ENAMETOOLONG;
318 return (NULL);
319 }
320 }
321 left_len = strlcpy(left, symlink, sizeof(left));
322 } else if (useattrs) {
323 /*
324 * attrs already has the real name.
325 */
326
327 resolved[save_resolved_len] = '\0';
328 resolved_len = strlcat(resolved, (const char *)&attrs.name + attrs.name.attr_dataoffset, PATH_MAX);
329 if (resolved_len >= PATH_MAX) {
330 errno = ENAMETOOLONG;
331 return (NULL);
332 }
333 }
334 /*
335 * For the case of useattrs == 0, we could scan the directory
336 * and try to match the inode. There are many problems with
337 * this: (1) the directory may not be readable, (2) for multiple
338 * hard links, we would find the first, but not necessarily
339 * the one specified in the path, (3) we can't try to do
340 * a case-insensitive search to match the right one in (2),
341 * because the underlying filesystem may do things like
342 * decompose composed characters. For most cases, doing
343 * nothing is the right thing when useattrs == 0, so we punt
344 * for now.
345 */
346 }
347
348 /*
349 * Remove trailing slash except when the resolved pathname
350 * is a single "/".
351 */
352 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
353 resolved[resolved_len - 1] = '\0';
354 return (resolved);
355}