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-rw-r--r--src/lib/libc/stdlib/realpath.c214
1 files changed, 214 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..e0f9b123b3
--- /dev/null
+++ b/src/lib/libc/stdlib/realpath.c
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1/* $OpenBSD: realpath.c,v 1.16 2013/04/05 12:59:54 kurt 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/* A slightly modified copy of this file exists in libexec/ld.so */
39
40/*
41 * char *realpath(const char *path, char resolved[PATH_MAX]);
42 *
43 * Find the real name of path, by removing all ".", ".." and symlink
44 * components. Returns (resolved) on success, or (NULL) on failure,
45 * in which case the path which caused trouble is left in (resolved).
46 */
47char *
48realpath(const char *path, char *resolved)
49{
50 struct stat sb;
51 char *p, *q, *s;
52 size_t left_len, resolved_len;
53 unsigned symlinks;
54 int serrno, slen, mem_allocated;
55 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
56
57 if (path[0] == '\0') {
58 errno = ENOENT;
59 return (NULL);
60 }
61
62 serrno = errno;
63
64 if (resolved == NULL) {
65 resolved = malloc(PATH_MAX);
66 if (resolved == NULL)
67 return (NULL);
68 mem_allocated = 1;
69 } else
70 mem_allocated = 0;
71
72 symlinks = 0;
73 if (path[0] == '/') {
74 resolved[0] = '/';
75 resolved[1] = '\0';
76 if (path[1] == '\0')
77 return (resolved);
78 resolved_len = 1;
79 left_len = strlcpy(left, path + 1, sizeof(left));
80 } else {
81 if (getcwd(resolved, PATH_MAX) == NULL) {
82 if (mem_allocated)
83 free(resolved);
84 else
85 strlcpy(resolved, ".", PATH_MAX);
86 return (NULL);
87 }
88 resolved_len = strlen(resolved);
89 left_len = strlcpy(left, path, sizeof(left));
90 }
91 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
92 errno = ENAMETOOLONG;
93 goto err;
94 }
95
96 /*
97 * Iterate over path components in `left'.
98 */
99 while (left_len != 0) {
100 /*
101 * Extract the next path component and adjust `left'
102 * and its length.
103 */
104 p = strchr(left, '/');
105 s = p ? p : left + left_len;
106 if (s - left >= sizeof(next_token)) {
107 errno = ENAMETOOLONG;
108 goto err;
109 }
110 memcpy(next_token, left, s - left);
111 next_token[s - left] = '\0';
112 left_len -= s - left;
113 if (p != NULL)
114 memmove(left, s + 1, left_len + 1);
115 if (resolved[resolved_len - 1] != '/') {
116 if (resolved_len + 1 >= PATH_MAX) {
117 errno = ENAMETOOLONG;
118 goto err;
119 }
120 resolved[resolved_len++] = '/';
121 resolved[resolved_len] = '\0';
122 }
123 if (next_token[0] == '\0')
124 continue;
125 else if (strcmp(next_token, ".") == 0)
126 continue;
127 else if (strcmp(next_token, "..") == 0) {
128 /*
129 * Strip the last path component except when we have
130 * single "/"
131 */
132 if (resolved_len > 1) {
133 resolved[resolved_len - 1] = '\0';
134 q = strrchr(resolved, '/') + 1;
135 *q = '\0';
136 resolved_len = q - resolved;
137 }
138 continue;
139 }
140
141 /*
142 * Append the next path component and lstat() it. If
143 * lstat() fails we still can return successfully if
144 * there are no more path components left.
145 */
146 resolved_len = strlcat(resolved, next_token, PATH_MAX);
147 if (resolved_len >= PATH_MAX) {
148 errno = ENAMETOOLONG;
149 goto err;
150 }
151 if (lstat(resolved, &sb) != 0) {
152 if (errno == ENOENT && p == NULL) {
153 errno = serrno;
154 return (resolved);
155 }
156 goto err;
157 }
158 if (S_ISLNK(sb.st_mode)) {
159 if (symlinks++ > MAXSYMLINKS) {
160 errno = ELOOP;
161 goto err;
162 }
163 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
164 if (slen < 0)
165 goto err;
166 symlink[slen] = '\0';
167 if (symlink[0] == '/') {
168 resolved[1] = 0;
169 resolved_len = 1;
170 } else if (resolved_len > 1) {
171 /* Strip the last path component. */
172 resolved[resolved_len - 1] = '\0';
173 q = strrchr(resolved, '/') + 1;
174 *q = '\0';
175 resolved_len = q - resolved;
176 }
177
178 /*
179 * If there are any path components left, then
180 * append them to symlink. The result is placed
181 * in `left'.
182 */
183 if (p != NULL) {
184 if (symlink[slen - 1] != '/') {
185 if (slen + 1 >= sizeof(symlink)) {
186 errno = ENAMETOOLONG;
187 goto err;
188 }
189 symlink[slen] = '/';
190 symlink[slen + 1] = 0;
191 }
192 left_len = strlcat(symlink, left, sizeof(symlink));
193 if (left_len >= sizeof(left)) {
194 errno = ENAMETOOLONG;
195 goto err;
196 }
197 }
198 left_len = strlcpy(left, symlink, sizeof(left));
199 }
200 }
201
202 /*
203 * Remove trailing slash except when the resolved pathname
204 * is a single "/".
205 */
206 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
207 resolved[resolved_len - 1] = '\0';
208 return (resolved);
209
210err:
211 if (mem_allocated)
212 free(resolved);
213 return (NULL);
214}
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