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-rw-r--r--src/lib/libc/stdlib/realpath.c190
1 files changed, 190 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..4cb847b313
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+++ b/src/lib/libc/stdlib/realpath.c
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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#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[PATH_MAX])
47{
48 struct stat sb;
49 char *p, *q, *s;
50 size_t left_len, resolved_len;
51 unsigned symlinks;
52 int serrno, slen;
53 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
54
55 serrno = errno;
56 symlinks = 0;
57 if (path[0] == '/') {
58 resolved[0] = '/';
59 resolved[1] = '\0';
60 if (path[1] == '\0')
61 return (resolved);
62 resolved_len = 1;
63 left_len = strlcpy(left, path + 1, sizeof(left));
64 } else {
65 if (getcwd(resolved, PATH_MAX) == NULL) {
66 strlcpy(resolved, ".", PATH_MAX);
67 return (NULL);
68 }
69 resolved_len = strlen(resolved);
70 left_len = strlcpy(left, path, sizeof(left));
71 }
72 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
73 errno = ENAMETOOLONG;
74 return (NULL);
75 }
76
77 /*
78 * Iterate over path components in `left'.
79 */
80 while (left_len != 0) {
81 /*
82 * Extract the next path component and adjust `left'
83 * and its length.
84 */
85 p = strchr(left, '/');
86 s = p ? p : left + left_len;
87 if (s - left >= sizeof(next_token)) {
88 errno = ENAMETOOLONG;
89 return (NULL);
90 }
91 memcpy(next_token, left, s - left);
92 next_token[s - left] = '\0';
93 left_len -= s - left;
94 if (p != NULL)
95 memmove(left, s + 1, left_len + 1);
96 if (resolved[resolved_len - 1] != '/') {
97 if (resolved_len + 1 >= PATH_MAX) {
98 errno = ENAMETOOLONG;
99 return (NULL);
100 }
101 resolved[resolved_len++] = '/';
102 resolved[resolved_len] = '\0';
103 }
104 if (next_token[0] == '\0')
105 continue;
106 else if (strcmp(next_token, ".") == 0)
107 continue;
108 else if (strcmp(next_token, "..") == 0) {
109 /*
110 * Strip the last path component except when we have
111 * single "/"
112 */
113 if (resolved_len > 1) {
114 resolved[resolved_len - 1] = '\0';
115 q = strrchr(resolved, '/') + 1;
116 *q = '\0';
117 resolved_len = q - resolved;
118 }
119 continue;
120 }
121
122 /*
123 * Append the next path component and lstat() it. If
124 * lstat() fails we still can return successfully if
125 * there are no more path components left.
126 */
127 resolved_len = strlcat(resolved, next_token, PATH_MAX);
128 if (resolved_len >= PATH_MAX) {
129 errno = ENAMETOOLONG;
130 return (NULL);
131 }
132 if (lstat(resolved, &sb) != 0) {
133 if (errno == ENOENT && p == NULL) {
134 errno = serrno;
135 return (resolved);
136 }
137 return (NULL);
138 }
139 if (S_ISLNK(sb.st_mode)) {
140 if (symlinks++ > MAXSYMLINKS) {
141 errno = ELOOP;
142 return (NULL);
143 }
144 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
145 if (slen < 0)
146 return (NULL);
147 symlink[slen] = '\0';
148 if (symlink[0] == '/') {
149 resolved[1] = 0;
150 resolved_len = 1;
151 } else if (resolved_len > 1) {
152 /* Strip the last path component. */
153 resolved[resolved_len - 1] = '\0';
154 q = strrchr(resolved, '/') + 1;
155 *q = '\0';
156 resolved_len = q - resolved;
157 }
158
159 /*
160 * If there are any path components left, then
161 * append them to symlink. The result is placed
162 * in `left'.
163 */
164 if (p != NULL) {
165 if (symlink[slen - 1] != '/') {
166 if (slen + 1 >= sizeof(symlink)) {
167 errno = ENAMETOOLONG;
168 return (NULL);
169 }
170 symlink[slen] = '/';
171 symlink[slen + 1] = 0;
172 }
173 left_len = strlcat(symlink, left, sizeof(left));
174 if (left_len >= sizeof(left)) {
175 errno = ENAMETOOLONG;
176 return (NULL);
177 }
178 }
179 left_len = strlcpy(left, symlink, sizeof(left));
180 }
181 }
182
183 /*
184 * Remove trailing slash except when the resolved pathname
185 * is a single "/".
186 */
187 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
188 resolved[resolved_len - 1] = '\0';
189 return (resolved);
190}
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