1/*	$NetBSD$	*/
2
3/*
4 * Copyright (c) 1989, 1991, 1993, 1995
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Jan-Simon Pendry.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include <sys/cdefs.h>
36#if defined(LIBC_SCCS) && !defined(lint)
37#if 0
38static char sccsid[] = "@(#)getcwd.c	8.5 (Berkeley) 2/7/95";
39#else
40__RCSID("$NetBSD$");
41#endif
42#endif /* LIBC_SCCS and not lint */
43
44#include "namespace.h"
45#include <sys/param.h>
46#include <sys/stat.h>
47
48#include <assert.h>
49#include <errno.h>
50#include <stdlib.h>
51#include <string.h>
52#include <unistd.h>
53#include <ssp/ssp.h>
54
55#include "extern.h"
56
57#ifdef __weak_alias
58__weak_alias(getcwd,_getcwd)
59__weak_alias(_sys_getcwd,_getcwd)
60__weak_alias(realpath,_realpath)
61#endif
62
63/*
64 * char *realpath(const char *path, char *resolved);
65 *
66 * Find the real name of path, by removing all ".", ".." and symlink
67 * components.  Returns (resolved) on success, or (NULL) on failure,
68 * in which case the path which caused trouble is left in (resolved).
69 */
70char *
71realpath(const char * __restrict path, char * __restrict resolved)
72{
73	struct stat sb;
74	int idx = 0, n, nlnk = 0;
75	const char *q;
76	char *p, wbuf[2][MAXPATHLEN], *fres;
77	size_t len;
78
79	/* POSIX sez we must test for this */
80	if (path == NULL) {
81		errno = EINVAL;
82		return NULL;
83	}
84
85	if (resolved == NULL) {
86		fres = resolved = malloc(MAXPATHLEN);
87		if (resolved == NULL)
88			return NULL;
89	} else
90		fres = NULL;
91
92
93	/*
94	 * Build real path one by one with paying an attention to .,
95	 * .. and symbolic link.
96	 */
97
98	/*
99	 * `p' is where we'll put a new component with prepending
100	 * a delimiter.
101	 */
102	p = resolved;
103
104	if (*path == '\0') {
105		*p = '\0';
106		errno = ENOENT;
107		goto out;
108	}
109
110	/* If relative path, start from current working directory. */
111	if (*path != '/') {
112		/* check for resolved pointer to appease coverity */
113		if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) {
114			p[0] = '.';
115			p[1] = '\0';
116			goto out;
117		}
118		len = strlen(resolved);
119		if (len > 1)
120			p += len;
121	}
122
123loop:
124	/* Skip any slash. */
125	while (*path == '/')
126		path++;
127
128	if (*path == '\0') {
129		if (p == resolved)
130			*p++ = '/';
131		*p = '\0';
132		return resolved;
133	}
134
135	/* Find the end of this component. */
136	q = path;
137	do
138		q++;
139	while (*q != '/' && *q != '\0');
140
141	/* Test . or .. */
142	if (path[0] == '.') {
143		if (q - path == 1) {
144			path = q;
145			goto loop;
146		}
147		if (path[1] == '.' && q - path == 2) {
148			/* Trim the last component. */
149			if (p != resolved)
150				while (*--p != '/')
151					continue;
152			path = q;
153			goto loop;
154		}
155	}
156
157	/* Append this component. */
158	if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) {
159		errno = ENAMETOOLONG;
160		if (p == resolved)
161			*p++ = '/';
162		*p = '\0';
163		goto out;
164	}
165	p[0] = '/';
166	memcpy(&p[1], path,
167	    /* LINTED We know q > path. */
168	    q - path);
169	p[1 + q - path] = '\0';
170
171	/*
172	 * If this component is a symlink, toss it and prepend link
173	 * target to unresolved path.
174	 */
175	if (lstat(resolved, &sb) == -1)
176		goto out;
177
178	if (S_ISLNK(sb.st_mode)) {
179		if (nlnk++ >= MAXSYMLINKS) {
180			errno = ELOOP;
181			goto out;
182		}
183		n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1);
184		if (n < 0)
185			return (NULL);
186		if (n == 0) {
187			errno = ENOENT;
188			goto out;
189		}
190
191		/* Append unresolved path to link target and switch to it. */
192		if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) {
193			errno = ENAMETOOLONG;
194			goto out;
195		}
196		memcpy(&wbuf[idx][n], q, len + 1);
197		path = wbuf[idx];
198		idx ^= 1;
199
200		/* If absolute symlink, start from root. */
201		if (*path == '/')
202			p = resolved;
203		goto loop;
204	}
205	if (*q == '/' && !S_ISDIR(sb.st_mode)) {
206		errno = ENOTDIR;
207		goto out;
208	}
209
210	/* Advance both resolved and unresolved path. */
211	p += 1 + q - path;
212	path = q;
213	goto loop;
214out:
215	free(fres);
216	return NULL;
217}
218
219char *
220__ssp_real(getcwd)(char *pt, size_t size)
221{
222	char *npt;
223
224	/*
225	 * If a buffer is specified, the size has to be non-zero.
226	 */
227	if (pt != NULL) {
228		if (size == 0) {
229			/* __getcwd(pt, 0) results ERANGE. */
230			errno = EINVAL;
231			return (NULL);
232		}
233		if (__getcwd(pt, size) >= 0)
234			return (pt);
235		return (NULL);
236	}
237
238	/*
239	 * If no buffer specified by the user, allocate one as necessary.
240	 */
241	size = 1024 >> 1;
242	do {
243		if ((npt = realloc(pt, size <<= 1)) == NULL)
244			break;
245		pt = npt;
246		if (__getcwd(pt, size) >= 0)
247			return (pt);
248	} while (size <= MAXPATHLEN * 4 && errno == ERANGE);
249
250	free(pt);
251	return (NULL);
252}
253