1 /* $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */
2 /*
3 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The names of the authors may not be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 /* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */
31
32 #include "includes.h"
33
34 #if !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH)
35
36 #include <sys/param.h>
37 #include <sys/stat.h>
38
39 #include <errno.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 /*
45 * char *realpath(const char *path, char resolved[PATH_MAX]);
46 *
47 * Find the real name of path, by removing all ".", ".." and symlink
48 * components. Returns (resolved) on success, or (NULL) on failure,
49 * in which case the path which caused trouble is left in (resolved).
50 */
51 char *
realpath(const char * path,char resolved[PATH_MAX])52 realpath(const char *path, char resolved[PATH_MAX])
53 {
54 struct stat sb;
55 char *p, *q, *s;
56 size_t left_len, resolved_len;
57 unsigned symlinks;
58 int serrno, slen;
59 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
60
61 serrno = errno;
62 symlinks = 0;
63 if (path[0] == '/') {
64 resolved[0] = '/';
65 resolved[1] = '\0';
66 if (path[1] == '\0')
67 return (resolved);
68 resolved_len = 1;
69 left_len = strlcpy(left, path + 1, sizeof(left));
70 } else {
71 if (getcwd(resolved, PATH_MAX) == NULL) {
72 strlcpy(resolved, ".", PATH_MAX);
73 return (NULL);
74 }
75 resolved_len = strlen(resolved);
76 left_len = strlcpy(left, path, sizeof(left));
77 }
78 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
79 errno = ENAMETOOLONG;
80 return (NULL);
81 }
82
83 /*
84 * Iterate over path components in `left'.
85 */
86 while (left_len != 0) {
87 /*
88 * Extract the next path component and adjust `left'
89 * and its length.
90 */
91 p = strchr(left, '/');
92 s = p ? p : left + left_len;
93 if (s - left >= sizeof(next_token)) {
94 errno = ENAMETOOLONG;
95 return (NULL);
96 }
97 memcpy(next_token, left, s - left);
98 next_token[s - left] = '\0';
99 left_len -= s - left;
100 if (p != NULL)
101 memmove(left, s + 1, left_len + 1);
102 if (resolved[resolved_len - 1] != '/') {
103 if (resolved_len + 1 >= PATH_MAX) {
104 errno = ENAMETOOLONG;
105 return (NULL);
106 }
107 resolved[resolved_len++] = '/';
108 resolved[resolved_len] = '\0';
109 }
110 if (next_token[0] == '\0')
111 continue;
112 else if (strcmp(next_token, ".") == 0)
113 continue;
114 else if (strcmp(next_token, "..") == 0) {
115 /*
116 * Strip the last path component except when we have
117 * single "/"
118 */
119 if (resolved_len > 1) {
120 resolved[resolved_len - 1] = '\0';
121 q = strrchr(resolved, '/') + 1;
122 *q = '\0';
123 resolved_len = q - resolved;
124 }
125 continue;
126 }
127
128 /*
129 * Append the next path component and lstat() it. If
130 * lstat() fails we still can return successfully if
131 * there are no more path components left.
132 */
133 resolved_len = strlcat(resolved, next_token, PATH_MAX);
134 if (resolved_len >= PATH_MAX) {
135 errno = ENAMETOOLONG;
136 return (NULL);
137 }
138 if (lstat(resolved, &sb) != 0) {
139 if (errno == ENOENT && p == NULL) {
140 errno = serrno;
141 return (resolved);
142 }
143 return (NULL);
144 }
145 if (S_ISLNK(sb.st_mode)) {
146 if (symlinks++ > MAXSYMLINKS) {
147 errno = ELOOP;
148 return (NULL);
149 }
150 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
151 if (slen < 0)
152 return (NULL);
153 symlink[slen] = '\0';
154 if (symlink[0] == '/') {
155 resolved[1] = 0;
156 resolved_len = 1;
157 } else if (resolved_len > 1) {
158 /* Strip the last path component. */
159 resolved[resolved_len - 1] = '\0';
160 q = strrchr(resolved, '/') + 1;
161 *q = '\0';
162 resolved_len = q - resolved;
163 }
164
165 /*
166 * If there are any path components left, then
167 * append them to symlink. The result is placed
168 * in `left'.
169 */
170 if (p != NULL) {
171 if (symlink[slen - 1] != '/') {
172 if (slen + 1 >= sizeof(symlink)) {
173 errno = ENAMETOOLONG;
174 return (NULL);
175 }
176 symlink[slen] = '/';
177 symlink[slen + 1] = 0;
178 }
179 left_len = strlcat(symlink, left, sizeof(left));
180 if (left_len >= sizeof(left)) {
181 errno = ENAMETOOLONG;
182 return (NULL);
183 }
184 }
185 left_len = strlcpy(left, symlink, sizeof(left));
186 }
187 }
188
189 /*
190 * Remove trailing slash except when the resolved pathname
191 * is a single "/".
192 */
193 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
194 resolved[resolved_len - 1] = '\0';
195 return (resolved);
196 }
197 #endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */
198