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-rw-r--r--bsd-realpath.c163
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1/*
2 * Copyright (c) 1994
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 "includes.h"
31
32#if !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH)
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char *rcsid = "$OpenBSD: realpath..c,v 1.4 1998/05/18 09:55:19 deraadt Exp $";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/param.h>
39#include <sys/stat.h>
40
41#include <errno.h>
42#include <fcntl.h>
43#include <stdlib.h>
44#include <string.h>
45#include <unistd.h>
46
47/*
48 * S_ISLNK compatibility
49 */
50#ifndef S_ISLNK
51#define S_ISLNK(m) ((m & 0170000) == 0120000)
52#endif
53
54/*
55 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
56 *
57 * Find the real name of path, by removing all ".", ".." and symlink
58 * components. Returns (resolved) on success, or (NULL) on failure,
59 * in which case the path which caused trouble is left in (resolved).
60 */
61char *
62realpath(const char *path, char *resolved)
63{
64 struct stat sb;
65 int fd, n, rootd, serrno = 0;
66 char *p, *q, wbuf[MAXPATHLEN], start[MAXPATHLEN];
67 int symlinks = 0;
68
69 /* Save the starting point. */
70 getcwd(start,MAXPATHLEN);
71 if ((fd = open(".", O_RDONLY)) < 0) {
72 (void)strcpy(resolved, ".");
73 return (NULL);
74 }
75 close(fd);
76
77 /*
78 * Find the dirname and basename from the path to be resolved.
79 * Change directory to the dirname component.
80 * lstat the basename part.
81 * if it is a symlink, read in the value and loop.
82 * if it is a directory, then change to that directory.
83 * get the current directory name and append the basename.
84 */
85 (void)strncpy(resolved, path, MAXPATHLEN - 1);
86 resolved[MAXPATHLEN - 1] = '\0';
87loop:
88 q = strrchr(resolved, '/');
89 if (q != NULL) {
90 p = q + 1;
91 if (q == resolved)
92 q = "/";
93 else {
94 do {
95 --q;
96 } while (q > resolved && *q == '/');
97 q[1] = '\0';
98 q = resolved;
99 }
100 if (chdir(q) < 0)
101 goto err1;
102 } else
103 p = resolved;
104
105 /* Deal with the last component. */
106 if (lstat(p, &sb) == 0) {
107 if (S_ISLNK(sb.st_mode)) {
108 if (++symlinks > MAXSYMLINKS) {
109 serrno = ELOOP;
110 goto err1;
111 }
112 n = readlink(p, resolved, MAXPATHLEN-1);
113 if (n < 0)
114 goto err1;
115 resolved[n] = '\0';
116 goto loop;
117 }
118 if (S_ISDIR(sb.st_mode)) {
119 if (chdir(p) < 0)
120 goto err1;
121 p = "";
122 }
123 }
124
125 /*
126 * Save the last component name and get the full pathname of
127 * the current directory.
128 */
129 (void)strcpy(wbuf, p);
130 if (getcwd(resolved, MAXPATHLEN) == 0)
131 goto err1;
132
133 /*
134 * Join the two strings together, ensuring that the right thing
135 * happens if the last component is empty, or the dirname is root.
136 */
137 if (resolved[0] == '/' && resolved[1] == '\0')
138 rootd = 1;
139 else
140 rootd = 0;
141
142 if (*wbuf) {
143 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
144 serrno = ENAMETOOLONG;
145 goto err1;
146 }
147 if (rootd == 0)
148 (void)strcat(resolved, "/");
149 (void)strcat(resolved, wbuf);
150 }
151
152 /* Go back to where we came from. */
153 if (chdir(start) < 0) {
154 serrno = errno;
155 goto err2;
156 }
157 return (resolved);
158
159err1: chdir(start);
160err2: errno = serrno;
161 return (NULL);
162}
163#endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */