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

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

/*
 * 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.
 */

#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
d74671e4	1	/* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */
d74671e4	2
443172c4	3	/*
1a9ecc62	4	* Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
443172c4	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	* 1. Redistributions of source code must retain the above copyright
	10	* notice, this list of conditions and the following disclaimer.
	11	* 2. Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
1a9ecc62	14	* 3. The names of the authors may not be used to endorse or promote
	15	* products derived from this software without specific prior written
	16	* permission.
443172c4	17	*
1a9ecc62	18	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
443172c4	19	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
443172c4	20	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1a9ecc62	21	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
443172c4	22	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	23	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	24	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	25	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	26	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	27	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	28	* SUCH DAMAGE.
	29	*/
	30
	31	#include "includes.h"
	32
	33	#if !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH)
	34
443172c4	35	#include <sys/param.h>
	36	#include <sys/stat.h>
	37
	38	#include <errno.h>
443172c4	39	#include <stdlib.h>
	40	#include <string.h>
	41	#include <unistd.h>
	42
c2207f11	43	/*
1a9ecc62	44	* char realpath(const char path, char resolved[PATH_MAX]);
443172c4	45	*
	46	* Find the real name of path, by removing all ".", ".." and symlink
	47	* components. Returns (resolved) on success, or (NULL) on failure,
	48	* in which case the path which caused trouble is left in (resolved).
	49	*/
	50	char *
1a9ecc62	51	realpath(const char *path, char resolved[PATH_MAX])
443172c4	52	{
443172c4	53	struct stat sb;
1a9ecc62	54	char p, q, *s;
	55	size_t left_len, resolved_len;
	56	unsigned symlinks;
	57	int serrno, slen;
	58	char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
	59
	60	serrno = errno;
	61	symlinks = 0;
	62	if (path[0] == '/') {
	63	resolved[0] = '/';
667abcc6	64	resolved[1] = '\0';
1a9ecc62	65	if (path[1] == '\0')
	66	return (resolved);
	67	resolved_len = 1;
	68	left_len = strlcpy(left, path + 1, sizeof(left));
	69	} else {
	70	if (getcwd(resolved, PATH_MAX) == NULL) {
	71	strlcpy(resolved, ".", PATH_MAX);
	72	return (NULL);
	73	}
	74	resolved_len = strlen(resolved);
	75	left_len = strlcpy(left, path, sizeof(left));
667abcc6	76	}
1a9ecc62	77	if (left_len >= sizeof(left) \|\| resolved_len >= PATH_MAX) {
1a9ecc62	78	errno = ENAMETOOLONG;
443172c4	79	return (NULL);
443172c4	80	}
443172c4	81
443172c4	82	/*
1a9ecc62	83	* Iterate over path components in `left'.
443172c4	84	*/
1a9ecc62	85	while (left_len != 0) {
	86	/*
	87	* Extract the next path component and adjust `left'
	88	* and its length.
	89	*/
	90	p = strchr(left, '/');
	91	s = p ? p : left + left_len;
	92	if (s - left >= sizeof(next_token)) {
	93	errno = ENAMETOOLONG;
	94	return (NULL);
443172c4	95	}
1a9ecc62	96	memcpy(next_token, left, s - left);
	97	next_token[s - left] = '\0';
	98	left_len -= s - left;
	99	if (p != NULL)
	100	memmove(left, s + 1, left_len + 1);
	101	if (resolved[resolved_len - 1] != '/') {
	102	if (resolved_len + 1 >= PATH_MAX) {
	103	errno = ENAMETOOLONG;
	104	return (NULL);
443172c4	105	}
1a9ecc62	106	resolved[resolved_len++] = '/';
1a9ecc62	107	resolved[resolved_len] = '\0';
443172c4	108	}
1a9ecc62	109	if (next_token[0] == '\0')
	110	continue;
	111	else if (strcmp(next_token, ".") == 0)
	112	continue;
	113	else if (strcmp(next_token, "..") == 0) {
	114	/*
	115	* Strip the last path component except when we have
	116	* single "/"
	117	*/
	118	if (resolved_len > 1) {
	119	resolved[resolved_len - 1] = '\0';
	120	q = strrchr(resolved, '/') + 1;
	121	*q = '\0';
	122	resolved_len = q - resolved;
	123	}
	124	continue;
443172c4	125	}
443172c4	126
1a9ecc62	127	/*
	128	* Append the next path component and lstat() it. If
	129	* lstat() fails we still can return successfully if
	130	* there are no more path components left.
	131	*/
	132	resolved_len = strlcat(resolved, next_token, PATH_MAX);
	133	if (resolved_len >= PATH_MAX) {
667abcc6	134	errno = ENAMETOOLONG;
1a9ecc62	135	return (NULL);
667abcc6	136	}
1a9ecc62	137	if (lstat(resolved, &sb) != 0) {
	138	if (errno == ENOENT && p == NULL) {
	139	errno = serrno;
	140	return (resolved);
667abcc6	141	}
1a9ecc62	142	return (NULL);
667abcc6	143	}
1a9ecc62	144	if (S_ISLNK(sb.st_mode)) {
	145	if (symlinks++ > MAXSYMLINKS) {
	146	errno = ELOOP;
	147	return (NULL);
	148	}
	149	slen = readlink(resolved, symlink, sizeof(symlink) - 1);
	150	if (slen < 0)
	151	return (NULL);
	152	symlink[slen] = '\0';
	153	if (symlink[0] == '/') {
	154	resolved[1] = 0;
	155	resolved_len = 1;
	156	} else if (resolved_len > 1) {
	157	/* Strip the last path component. */
	158	resolved[resolved_len - 1] = '\0';
	159	q = strrchr(resolved, '/') + 1;
	160	*q = '\0';
	161	resolved_len = q - resolved;
	162	}
443172c4	163
1a9ecc62	164	/*
	165	* If there are any path components left, then
	166	* append them to symlink. The result is placed
	167	* in `left'.
	168	*/
	169	if (p != NULL) {
	170	if (symlink[slen - 1] != '/') {
	171	if (slen + 1 >= sizeof(symlink)) {
	172	errno = ENAMETOOLONG;
	173	return (NULL);
	174	}
	175	symlink[slen] = '/';
	176	symlink[slen + 1] = 0;
	177	}
	178	left_len = strlcat(symlink, left, sizeof(left));
	179	if (left_len >= sizeof(left)) {
	180	errno = ENAMETOOLONG;
	181	return (NULL);
	182	}
	183	}
	184	left_len = strlcpy(left, symlink, sizeof(left));
	185	}
443172c4	186	}
667abcc6	187
1a9ecc62	188	/*
	189	* Remove trailing slash except when the resolved pathname
	190	* is a single "/".
	191	*/
	192	if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
	193	resolved[resolved_len - 1] = '\0';
443172c4	194	return (resolved);
443172c4	195	}
443172c4	196	#endif /* !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH) */