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-rw-r--r--src/lib/libc/stdlib/realpath.c212
1 files changed, 212 insertions, 0 deletions
diff --git a/src/lib/libc/stdlib/realpath.c b/src/lib/libc/stdlib/realpath.c
new file mode 100644
index 0000000000..534f48d4b4
--- /dev/null
+++ b/src/lib/libc/stdlib/realpath.c
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1/* $OpenBSD: realpath.c,v 1.15 2012/09/13 15:39:05 deraadt 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#include <sys/param.h>
31#include <sys/stat.h>
32
33#include <errno.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37
38/*
39 * char *realpath(const char *path, char resolved[PATH_MAX]);
40 *
41 * Find the real name of path, by removing all ".", ".." and symlink
42 * components. Returns (resolved) on success, or (NULL) on failure,
43 * in which case the path which caused trouble is left in (resolved).
44 */
45char *
46realpath(const char *path, char *resolved)
47{
48 struct stat sb;
49 char *p, *q, *s;
50 size_t left_len, resolved_len;
51 unsigned symlinks;
52 int serrno, slen, mem_allocated;
53 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
54
55 if (path[0] == '\0') {
56 errno = ENOENT;
57 return (NULL);
58 }
59
60 serrno = errno;
61
62 if (resolved == NULL) {
63 resolved = malloc(PATH_MAX);
64 if (resolved == NULL)
65 return (NULL);
66 mem_allocated = 1;
67 } else
68 mem_allocated = 0;
69
70 symlinks = 0;
71 if (path[0] == '/') {
72 resolved[0] = '/';
73 resolved[1] = '\0';
74 if (path[1] == '\0')
75 return (resolved);
76 resolved_len = 1;
77 left_len = strlcpy(left, path + 1, sizeof(left));
78 } else {
79 if (getcwd(resolved, PATH_MAX) == NULL) {
80 if (mem_allocated)
81 free(resolved);
82 else
83 strlcpy(resolved, ".", PATH_MAX);
84 return (NULL);
85 }
86 resolved_len = strlen(resolved);
87 left_len = strlcpy(left, path, sizeof(left));
88 }
89 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
90 errno = ENAMETOOLONG;
91 goto err;
92 }
93
94 /*
95 * Iterate over path components in `left'.
96 */
97 while (left_len != 0) {
98 /*
99 * Extract the next path component and adjust `left'
100 * and its length.
101 */
102 p = strchr(left, '/');
103 s = p ? p : left + left_len;
104 if (s - left >= sizeof(next_token)) {
105 errno = ENAMETOOLONG;
106 goto err;
107 }
108 memcpy(next_token, left, s - left);
109 next_token[s - left] = '\0';
110 left_len -= s - left;
111 if (p != NULL)
112 memmove(left, s + 1, left_len + 1);
113 if (resolved[resolved_len - 1] != '/') {
114 if (resolved_len + 1 >= PATH_MAX) {
115 errno = ENAMETOOLONG;
116 goto err;
117 }
118 resolved[resolved_len++] = '/';
119 resolved[resolved_len] = '\0';
120 }
121 if (next_token[0] == '\0')
122 continue;
123 else if (strcmp(next_token, ".") == 0)
124 continue;
125 else if (strcmp(next_token, "..") == 0) {
126 /*
127 * Strip the last path component except when we have
128 * single "/"
129 */
130 if (resolved_len > 1) {
131 resolved[resolved_len - 1] = '\0';
132 q = strrchr(resolved, '/') + 1;
133 *q = '\0';
134 resolved_len = q - resolved;
135 }
136 continue;
137 }
138
139 /*
140 * Append the next path component and lstat() it. If
141 * lstat() fails we still can return successfully if
142 * there are no more path components left.
143 */
144 resolved_len = strlcat(resolved, next_token, PATH_MAX);
145 if (resolved_len >= PATH_MAX) {
146 errno = ENAMETOOLONG;
147 goto err;
148 }
149 if (lstat(resolved, &sb) != 0) {
150 if (errno == ENOENT && p == NULL) {
151 errno = serrno;
152 return (resolved);
153 }
154 goto err;
155 }
156 if (S_ISLNK(sb.st_mode)) {
157 if (symlinks++ > MAXSYMLINKS) {
158 errno = ELOOP;
159 goto err;
160 }
161 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
162 if (slen < 0)
163 goto err;
164 symlink[slen] = '\0';
165 if (symlink[0] == '/') {
166 resolved[1] = 0;
167 resolved_len = 1;
168 } else if (resolved_len > 1) {
169 /* Strip the last path component. */
170 resolved[resolved_len - 1] = '\0';
171 q = strrchr(resolved, '/') + 1;
172 *q = '\0';
173 resolved_len = q - resolved;
174 }
175
176 /*
177 * If there are any path components left, then
178 * append them to symlink. The result is placed
179 * in `left'.
180 */
181 if (p != NULL) {
182 if (symlink[slen - 1] != '/') {
183 if (slen + 1 >= sizeof(symlink)) {
184 errno = ENAMETOOLONG;
185 goto err;
186 }
187 symlink[slen] = '/';
188 symlink[slen + 1] = 0;
189 }
190 left_len = strlcat(symlink, left, sizeof(symlink));
191 if (left_len >= sizeof(left)) {
192 errno = ENAMETOOLONG;
193 goto err;
194 }
195 }
196 left_len = strlcpy(left, symlink, sizeof(left));
197 }
198 }
199
200 /*
201 * Remove trailing slash except when the resolved pathname
202 * is a single "/".
203 */
204 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
205 resolved[resolved_len - 1] = '\0';
206 return (resolved);
207
208err:
209 if (mem_allocated)
210 free(resolved);
211 return (NULL);
212}
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