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)
35 static char *rcsid = "$OpenBSD: realpath.c,v 1.7 2002/05/24 21:22:37 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 * MAXSYMLINKS
49 */
50 #ifndef MAXSYMLINKS
51 #define MAXSYMLINKS 5
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 */
61 char *
62 realpath(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)strlcpy(resolved, ".", MAXPATHLEN);
73 return (NULL);
74 }
75 close(fd);
76
77 /* Convert "." -> "" to optimize away a needless lstat() and chdir() */
78 if (path[0] == '.' && path[1] == '\0')
79 path = "";
80
81 /*
82 * Find the dirname and basename from the path to be resolved.
83 * Change directory to the dirname component.
84 * lstat the basename part.
85 * if it is a symlink, read in the value and loop.
86 * if it is a directory, then change to that directory.
87 * get the current directory name and append the basename.
88 */
89 strlcpy(resolved, path, MAXPATHLEN);
90 loop:
91 q = strrchr(resolved, '/');
92 if (q != NULL) {
93 p = q + 1;
94 if (q == resolved)
95 q = "/";
96 else {
97 do {
98 --q;
99 } while (q > resolved && *q == '/');
100 q[1] = '\0';
101 q = resolved;
102 }
103 if (chdir(q) < 0)
104 goto err1;
105 } else
106 p = resolved;
107
108 /* Deal with the last component. */
109 if (*p != '\0' && lstat(p, &sb) == 0) {
110 if (S_ISLNK(sb.st_mode)) {
111 if (++symlinks > MAXSYMLINKS) {
112 serrno = ELOOP;
113 goto err1;
114 }
115 n = readlink(p, resolved, MAXPATHLEN-1);
116 if (n < 0)
117 goto err1;
118 resolved[n] = '\0';
119 goto loop;
120 }
121 if (S_ISDIR(sb.st_mode)) {
122 if (chdir(p) < 0)
123 goto err1;
124 p = "";
125 }
126 }
127
128 /*
129 * Save the last component name and get the full pathname of
130 * the current directory.
131 */
132 (void)strlcpy(wbuf, p, sizeof wbuf);
133 if (getcwd(resolved, MAXPATHLEN) == 0)
134 goto err1;
135
136 /*
137 * Join the two strings together, ensuring that the right thing
138 * happens if the last component is empty, or the dirname is root.
139 */
140 if (resolved[0] == '/' && resolved[1] == '\0')
141 rootd = 1;
142 else
143 rootd = 0;
144
145 if (*wbuf) {
146 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
147 serrno = ENAMETOOLONG;
148 goto err1;
149 }
150 if (rootd == 0)
151 (void)strcat(resolved, "/");
152 (void)strcat(resolved, wbuf);
153 }
154
155 /* Go back to where we came from. */
156 if (chdir(start) < 0) {
157 serrno = errno;
158 goto err2;
159 }
160 return (resolved);
161
162 err1: chdir(start);
163 err2: errno = serrno;
164 return (NULL);
165 }
166 #endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */
167
168 #pragma ident "%Z%%M% %I% %E% SMI"