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

/*
 * Copyright (c) 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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)

#if defined(LIBC_SCCS) && !defined(lint)
static char *rcsid = "$OpenBSD: realpath.c,v 1.10 2003/08/01 21:04:59 millert Exp $";
#endif /* LIBC_SCCS and not lint */

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

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

/*
 * MAXSYMLINKS
 */
#ifndef MAXSYMLINKS
#define MAXSYMLINKS 5
#endif

/*
 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
 *
 * 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)
{
	struct stat sb;
	int fd, n, needslash, serrno = 0;
	char *p, *q, wbuf[MAXPATHLEN], start[MAXPATHLEN];
	int symlinks = 0;

	/* Save the starting point. */
	getcwd(start,MAXPATHLEN);	
	if ((fd = open(".", O_RDONLY)) < 0) {
		(void)strlcpy(resolved, ".", MAXPATHLEN);
		return (NULL);
	}
	close(fd);

	/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
	if (path[0] == '.' && path[1] == '\0')
		path = "";

	/*
	 * Find the dirname and basename from the path to be resolved.
	 * Change directory to the dirname component.
	 * lstat the basename part.
	 *     if it is a symlink, read in the value and loop.
	 *     if it is a directory, then change to that directory.
	 * get the current directory name and append the basename.
	 */
	strlcpy(resolved, path, MAXPATHLEN);
loop:
	q = strrchr(resolved, '/');
	if (q != NULL) {
		p = q + 1;
		if (q == resolved)
			q = "/";
		else {
			do {
				--q;
			} while (q > resolved && *q == '/');
			q[1] = '\0';
			q = resolved;
		}
		if (chdir(q) < 0)
			goto err1;
	} else
		p = resolved;

	/* Deal with the last component. */
	if (*p != '\0' && lstat(p, &sb) == 0) {
		if (S_ISLNK(sb.st_mode)) {
			if (++symlinks > MAXSYMLINKS) {
				serrno = ELOOP;
				goto err1;
			}
			n = readlink(p, resolved, MAXPATHLEN-1);
			if (n < 0)
				goto err1;
			resolved[n] = '\0';
			goto loop;
		}
		if (S_ISDIR(sb.st_mode)) {
			if (chdir(p) < 0)
				goto err1;
			p = "";
		}
	}

	/*
	 * Save the last component name and get the full pathname of
	 * the current directory.
	 */
	(void)strlcpy(wbuf, p, sizeof wbuf);
	if (getcwd(resolved, MAXPATHLEN) == 0)
		goto err1;

	/*
	 * Join the two strings together, ensuring that the right thing
	 * happens if the last component is empty, or the dirname is root.
	 */
	if (resolved[0] == '/' && resolved[1] == '\0')
		needslash = 0;
	else
		needslash = 1;

	if (*wbuf) {
		if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) {
			serrno = ENAMETOOLONG;
			goto err1;
		}
		if (needslash == 0)
			strlcat(resolved, "/", MAXPATHLEN);
		strlcat(resolved, wbuf, MAXPATHLEN);
	}

	/* Go back to where we came from. */
	if (chdir(start) < 0) {
		serrno = errno;
		goto err2;
	}
	return (resolved);

err1:	chdir(start);
err2:	errno = serrno;
	return (NULL);
}
#endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */
Commit	Line	Data
443172c4	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.
3e67f7df	16	* 3. Neither the name of the University nor the names of its contributors
	17	* may be used to endorse or promote products derived from this software
	18	* without specific prior written permission.
443172c4	19	*
	20	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	* SUCH DAMAGE.
	31	*/
	32
	33	#include "includes.h"
	34
	35	#if !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH)
	36
	37	#if defined(LIBC_SCCS) && !defined(lint)
510a42ce	38	static char *rcsid = "$OpenBSD: realpath.c,v 1.10 2003/08/01 21:04:59 millert Exp $";
443172c4	39	#endif /* LIBC_SCCS and not lint */
	40
	41	#include <sys/param.h>
	42	#include <sys/stat.h>
	43
	44	#include <errno.h>
	45	#include <fcntl.h>
	46	#include <stdlib.h>
	47	#include <string.h>
	48	#include <unistd.h>
	49
c2207f11	50	/*
	51	* MAXSYMLINKS
	52	*/
	53	#ifndef MAXSYMLINKS
	54	#define MAXSYMLINKS 5
	55	#endif
	56
443172c4	57	/*
	58	* char realpath(const char path, char resolved_path[MAXPATHLEN]);
	59	*
	60	* Find the real name of path, by removing all ".", ".." and symlink
	61	* components. Returns (resolved) on success, or (NULL) on failure,
	62	* in which case the path which caused trouble is left in (resolved).
	63	*/
	64	char *
	65	realpath(const char path, char resolved)
	66	{
	67	struct stat sb;
510a42ce	68	int fd, n, needslash, serrno = 0;
443172c4	69	char p, q, wbuf[MAXPATHLEN], start[MAXPATHLEN];
	70	int symlinks = 0;
	71
	72	/* Save the starting point. */
	73	getcwd(start,MAXPATHLEN);
	74	if ((fd = open(".", O_RDONLY)) < 0) {
0b832146	75	(void)strlcpy(resolved, ".", MAXPATHLEN);
443172c4	76	return (NULL);
	77	}
	78	close(fd);
	79
1656cbed	80	/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
	81	if (path[0] == '.' && path[1] == '\0')
	82	path = "";
	83
443172c4	84	/*
	85	* Find the dirname and basename from the path to be resolved.
	86	* Change directory to the dirname component.
	87	* lstat the basename part.
	88	* if it is a symlink, read in the value and loop.
	89	* if it is a directory, then change to that directory.
	90	* get the current directory name and append the basename.
	91	*/
f11065cb	92	strlcpy(resolved, path, MAXPATHLEN);
443172c4	93	loop:
	94	q = strrchr(resolved, '/');
	95	if (q != NULL) {
	96	p = q + 1;
	97	if (q == resolved)
	98	q = "/";
	99	else {
	100	do {
	101	--q;
	102	} while (q > resolved && *q == '/');
	103	q[1] = '\0';
	104	q = resolved;
	105	}
	106	if (chdir(q) < 0)
	107	goto err1;
	108	} else
	109	p = resolved;
	110
	111	/* Deal with the last component. */
1656cbed	112	if (*p != '\0' && lstat(p, &sb) == 0) {
443172c4	113	if (S_ISLNK(sb.st_mode)) {
	114	if (++symlinks > MAXSYMLINKS) {
	115	serrno = ELOOP;
	116	goto err1;
	117	}
	118	n = readlink(p, resolved, MAXPATHLEN-1);
	119	if (n < 0)
	120	goto err1;
	121	resolved[n] = '\0';
	122	goto loop;
	123	}
	124	if (S_ISDIR(sb.st_mode)) {
	125	if (chdir(p) < 0)
	126	goto err1;
	127	p = "";
	128	}
	129	}
	130
	131	/*
	132	* Save the last component name and get the full pathname of
	133	* the current directory.
	134	*/
0b832146	135	(void)strlcpy(wbuf, p, sizeof wbuf);
443172c4	136	if (getcwd(resolved, MAXPATHLEN) == 0)
	137	goto err1;
	138
	139	/*
	140	* Join the two strings together, ensuring that the right thing
	141	* happens if the last component is empty, or the dirname is root.
	142	*/
	143	if (resolved[0] == '/' && resolved[1] == '\0')
510a42ce	144	needslash = 0;
443172c4	145	else
510a42ce	146	needslash = 1;
443172c4	147
443172c4	148	if (*wbuf) {
510a42ce	149	if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) {
443172c4	150	serrno = ENAMETOOLONG;
	151	goto err1;
	152	}
510a42ce	153	if (needslash == 0)
f123055b	154	strlcat(resolved, "/", MAXPATHLEN);
f123055b	155	strlcat(resolved, wbuf, MAXPATHLEN);
443172c4	156	}
	157
	158	/* Go back to where we came from. */
	159	if (chdir(start) < 0) {
	160	serrno = errno;
	161	goto err2;
	162	}
	163	return (resolved);
	164
	165	err1: chdir(start);
	166	err2: errno = serrno;
	167	return (NULL);
	168	}
	169	#endif /* !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH) */