[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.
 *
 * 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 1.6 2002/01/12 16:24:35 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, rootd, 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)strcpy(resolved, ".");
		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)strcpy(wbuf, p);
	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')
		rootd = 1;
	else
		rootd = 0;

	if (*wbuf) {
		if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
			serrno = ENAMETOOLONG;
			goto err1;
		}
		if (rootd == 0)
			(void)strcat(resolved, "/");
		(void)strcat(resolved, wbuf);
	}

	/* 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.
	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)
1656cbed	35	static char *rcsid = "$OpenBSD: realpath.c,v 1.6 2002/01/12 16:24:35 millert Exp $";
443172c4	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
c2207f11	47	/*
	48	* MAXSYMLINKS
	49	*/
	50	#ifndef MAXSYMLINKS
	51	#define MAXSYMLINKS 5
	52	#endif
	53
443172c4	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)strcpy(resolved, ".");
	73	return (NULL);
	74	}
	75	close(fd);
	76
1656cbed	77	/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
	78	if (path[0] == '.' && path[1] == '\0')
	79	path = "";
	80
443172c4	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	*/
f11065cb	89	strlcpy(resolved, path, MAXPATHLEN);
443172c4	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. */
1656cbed	109	if (*p != '\0' && lstat(p, &sb) == 0) {
443172c4	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)strcpy(wbuf, p);
	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) */