[openssh.git] / openbsd-compat / realpath.c

/*	$OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */
/*
 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the authors may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */

#include "includes.h"

#if !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH)

#include <sys/param.h>
#include <sys/stat.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/*
 * char *realpath(const char *path, char resolved[PATH_MAX]);
 *
 * Find the real name of path, by removing all ".", ".." and symlink
 * components.  Returns (resolved) on success, or (NULL) on failure,
 * in which case the path which caused trouble is left in (resolved).
 */
char *
realpath(const char *path, char resolved[PATH_MAX])
{
	struct stat sb;
	char *p, *q, *s;
	size_t left_len, resolved_len;
	unsigned symlinks;
	int serrno, slen;
	char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];

	serrno = errno;
	symlinks = 0;
	if (path[0] == '/') {
		resolved[0] = '/';
		resolved[1] = '\0';
		if (path[1] == '\0')
			return (resolved);
		resolved_len = 1;
		left_len = strlcpy(left, path + 1, sizeof(left));
	} else {
		if (getcwd(resolved, PATH_MAX) == NULL) {
			strlcpy(resolved, ".", PATH_MAX);
			return (NULL);
		}
		resolved_len = strlen(resolved);
		left_len = strlcpy(left, path, sizeof(left));
	}
	if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
		errno = ENAMETOOLONG;
		return (NULL);
	}

	/*
	 * Iterate over path components in `left'.
	 */
	while (left_len != 0) {
		/*
		 * Extract the next path component and adjust `left'
		 * and its length.
		 */
		p = strchr(left, '/');
		s = p ? p : left + left_len;
		if (s - left >= sizeof(next_token)) {
			errno = ENAMETOOLONG;
			return (NULL);
		}
		memcpy(next_token, left, s - left);
		next_token[s - left] = '\0';
		left_len -= s - left;
		if (p != NULL)
			memmove(left, s + 1, left_len + 1);
		if (resolved[resolved_len - 1] != '/') {
			if (resolved_len + 1 >= PATH_MAX) {
				errno = ENAMETOOLONG;
				return (NULL);
			}
			resolved[resolved_len++] = '/';
			resolved[resolved_len] = '\0';
		}
		if (next_token[0] == '\0')
			continue;
		else if (strcmp(next_token, ".") == 0)
			continue;
		else if (strcmp(next_token, "..") == 0) {
			/*
			 * Strip the last path component except when we have
			 * single "/"
			 */
			if (resolved_len > 1) {
				resolved[resolved_len - 1] = '\0';
				q = strrchr(resolved, '/') + 1;
				*q = '\0';
				resolved_len = q - resolved;
			}
			continue;
		}

		/*
		 * Append the next path component and lstat() it. If
		 * lstat() fails we still can return successfully if
		 * there are no more path components left.
		 */
		resolved_len = strlcat(resolved, next_token, PATH_MAX);
		if (resolved_len >= PATH_MAX) {
			errno = ENAMETOOLONG;
			return (NULL);
		}
		if (lstat(resolved, &sb) != 0) {
			if (errno == ENOENT && p == NULL) {
				errno = serrno;
				return (resolved);
			}
			return (NULL);
		}
		if (S_ISLNK(sb.st_mode)) {
			if (symlinks++ > MAXSYMLINKS) {
				errno = ELOOP;
				return (NULL);
			}
			slen = readlink(resolved, symlink, sizeof(symlink) - 1);
			if (slen < 0)
				return (NULL);
			symlink[slen] = '\0';
			if (symlink[0] == '/') {
				resolved[1] = 0;
				resolved_len = 1;
			} else if (resolved_len > 1) {
				/* Strip the last path component. */
				resolved[resolved_len - 1] = '\0';
				q = strrchr(resolved, '/') + 1;
				*q = '\0';
				resolved_len = q - resolved;
			}

			/*
			 * If there are any path components left, then
			 * append them to symlink. The result is placed
			 * in `left'.
			 */
			if (p != NULL) {
				if (symlink[slen - 1] != '/') {
					if (slen + 1 >= sizeof(symlink)) {
						errno = ENAMETOOLONG;
						return (NULL);
					}
					symlink[slen] = '/';
					symlink[slen + 1] = 0;
				}
				left_len = strlcat(symlink, left, sizeof(left));
				if (left_len >= sizeof(left)) {
					errno = ENAMETOOLONG;
					return (NULL);
				}
			}
			left_len = strlcpy(left, symlink, sizeof(left));
		}
	}

	/*
	 * Remove trailing slash except when the resolved pathname
	 * is a single "/".
	 */
	if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
		resolved[resolved_len - 1] = '\0';
	return (resolved);
}
#endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */
Commit	Line	Data
7dea820a	1	/* $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */
443172c4	2	/*
1a9ecc62	3	* Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
443172c4	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.
1a9ecc62	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.
443172c4	16	*
1a9ecc62	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
443172c4	18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
443172c4	19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1a9ecc62	20	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
443172c4	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
f6d4fb87	30	/* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */
f6d4fb87	31
443172c4	32	#include "includes.h"
	33
	34	#if !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH)
	35
443172c4	36	#include <sys/param.h>
	37	#include <sys/stat.h>
	38
	39	#include <errno.h>
443172c4	40	#include <stdlib.h>
	41	#include <string.h>
	42	#include <unistd.h>
	43
c2207f11	44	/*
1a9ecc62	45	* char realpath(const char path, char resolved[PATH_MAX]);
443172c4	46	*
	47	* Find the real name of path, by removing all ".", ".." and symlink
	48	* components. Returns (resolved) on success, or (NULL) on failure,
	49	* in which case the path which caused trouble is left in (resolved).
	50	*/
	51	char *
1a9ecc62	52	realpath(const char *path, char resolved[PATH_MAX])
443172c4	53	{
443172c4	54	struct stat sb;
1a9ecc62	55	char p, q, *s;
	56	size_t left_len, resolved_len;
	57	unsigned symlinks;
	58	int serrno, slen;
	59	char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
	60
	61	serrno = errno;
	62	symlinks = 0;
	63	if (path[0] == '/') {
	64	resolved[0] = '/';
667abcc6	65	resolved[1] = '\0';
1a9ecc62	66	if (path[1] == '\0')
	67	return (resolved);
	68	resolved_len = 1;
	69	left_len = strlcpy(left, path + 1, sizeof(left));
	70	} else {
	71	if (getcwd(resolved, PATH_MAX) == NULL) {
	72	strlcpy(resolved, ".", PATH_MAX);
	73	return (NULL);
	74	}
	75	resolved_len = strlen(resolved);
	76	left_len = strlcpy(left, path, sizeof(left));
667abcc6	77	}
1a9ecc62	78	if (left_len >= sizeof(left) \|\| resolved_len >= PATH_MAX) {
1a9ecc62	79	errno = ENAMETOOLONG;
443172c4	80	return (NULL);
443172c4	81	}
443172c4	82
443172c4	83	/*
1a9ecc62	84	* Iterate over path components in `left'.
443172c4	85	*/
1a9ecc62	86	while (left_len != 0) {
	87	/*
	88	* Extract the next path component and adjust `left'
	89	* and its length.
	90	*/
	91	p = strchr(left, '/');
	92	s = p ? p : left + left_len;
	93	if (s - left >= sizeof(next_token)) {
	94	errno = ENAMETOOLONG;
	95	return (NULL);
443172c4	96	}
1a9ecc62	97	memcpy(next_token, left, s - left);
	98	next_token[s - left] = '\0';
	99	left_len -= s - left;
	100	if (p != NULL)
	101	memmove(left, s + 1, left_len + 1);
	102	if (resolved[resolved_len - 1] != '/') {
	103	if (resolved_len + 1 >= PATH_MAX) {
	104	errno = ENAMETOOLONG;
	105	return (NULL);
443172c4	106	}
1a9ecc62	107	resolved[resolved_len++] = '/';
1a9ecc62	108	resolved[resolved_len] = '\0';
443172c4	109	}
1a9ecc62	110	if (next_token[0] == '\0')
	111	continue;
	112	else if (strcmp(next_token, ".") == 0)
	113	continue;
	114	else if (strcmp(next_token, "..") == 0) {
	115	/*
	116	* Strip the last path component except when we have
	117	* single "/"
	118	*/
	119	if (resolved_len > 1) {
	120	resolved[resolved_len - 1] = '\0';
	121	q = strrchr(resolved, '/') + 1;
	122	*q = '\0';
	123	resolved_len = q - resolved;
	124	}
	125	continue;
443172c4	126	}
443172c4	127
1a9ecc62	128	/*
	129	* Append the next path component and lstat() it. If
	130	* lstat() fails we still can return successfully if
	131	* there are no more path components left.
	132	*/
	133	resolved_len = strlcat(resolved, next_token, PATH_MAX);
	134	if (resolved_len >= PATH_MAX) {
667abcc6	135	errno = ENAMETOOLONG;
1a9ecc62	136	return (NULL);
667abcc6	137	}
1a9ecc62	138	if (lstat(resolved, &sb) != 0) {
	139	if (errno == ENOENT && p == NULL) {
	140	errno = serrno;
	141	return (resolved);
667abcc6	142	}
1a9ecc62	143	return (NULL);
667abcc6	144	}
1a9ecc62	145	if (S_ISLNK(sb.st_mode)) {
	146	if (symlinks++ > MAXSYMLINKS) {
	147	errno = ELOOP;
	148	return (NULL);
	149	}
	150	slen = readlink(resolved, symlink, sizeof(symlink) - 1);
	151	if (slen < 0)
	152	return (NULL);
	153	symlink[slen] = '\0';
	154	if (symlink[0] == '/') {
	155	resolved[1] = 0;
	156	resolved_len = 1;
	157	} else if (resolved_len > 1) {
	158	/* Strip the last path component. */
	159	resolved[resolved_len - 1] = '\0';
	160	q = strrchr(resolved, '/') + 1;
	161	*q = '\0';
	162	resolved_len = q - resolved;
	163	}
443172c4	164
1a9ecc62	165	/*
	166	* If there are any path components left, then
	167	* append them to symlink. The result is placed
	168	* in `left'.
	169	*/
	170	if (p != NULL) {
	171	if (symlink[slen - 1] != '/') {
	172	if (slen + 1 >= sizeof(symlink)) {
	173	errno = ENAMETOOLONG;
	174	return (NULL);
	175	}
	176	symlink[slen] = '/';
	177	symlink[slen + 1] = 0;
	178	}
	179	left_len = strlcat(symlink, left, sizeof(left));
	180	if (left_len >= sizeof(left)) {
	181	errno = ENAMETOOLONG;
	182	return (NULL);
	183	}
	184	}
	185	left_len = strlcpy(left, symlink, sizeof(left));
	186	}
443172c4	187	}
667abcc6	188
1a9ecc62	189	/*
	190	* Remove trailing slash except when the resolved pathname
	191	* is a single "/".
	192	*/
	193	if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
	194	resolved[resolved_len - 1] = '\0';
443172c4	195	return (resolved);
443172c4	196	}
443172c4	197	#endif /* !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH) */