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

/* OPENBSD ORIGINAL: lib/libc/stdlib/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)
			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
12408a1b	1	/* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */
12408a1b	2
3c0ef626	3	/*
	4	* Copyright (c) 1994
	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.
0fff78ff	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.
3c0ef626	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 "includes.h"
	36
	37	#if !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH)
	38
	39	#if defined(LIBC_SCCS) && !defined(lint)
0fff78ff	40	static char *rcsid = "$OpenBSD: realpath.c,v 1.10 2003/08/01 21:04:59 millert Exp $";
3c0ef626	41	#endif /* LIBC_SCCS and not lint */
	42
	43	#include <sys/param.h>
	44	#include <sys/stat.h>
	45
	46	#include <errno.h>
	47	#include <fcntl.h>
	48	#include <stdlib.h>
	49	#include <string.h>
	50	#include <unistd.h>
	51
	52	/*
	53	* MAXSYMLINKS
	54	*/
	55	#ifndef MAXSYMLINKS
	56	#define MAXSYMLINKS 5
	57	#endif
	58
	59	/*
	60	* char realpath(const char path, char resolved_path[MAXPATHLEN]);
	61	*
	62	* Find the real name of path, by removing all ".", ".." and symlink
	63	* components. Returns (resolved) on success, or (NULL) on failure,
	64	* in which case the path which caused trouble is left in (resolved).
	65	*/
	66	char *
	67	realpath(const char path, char resolved)
	68	{
	69	struct stat sb;
0fff78ff	70	int fd, n, needslash, serrno = 0;
3c0ef626	71	char p, q, wbuf[MAXPATHLEN], start[MAXPATHLEN];
	72	int symlinks = 0;
	73
	74	/* Save the starting point. */
	75	getcwd(start,MAXPATHLEN);
	76	if ((fd = open(".", O_RDONLY)) < 0) {
41b2f314	77	(void)strlcpy(resolved, ".", MAXPATHLEN);
3c0ef626	78	return (NULL);
	79	}
	80	close(fd);
	81
e9a17296	82	/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
	83	if (path[0] == '.' && path[1] == '\0')
	84	path = "";
	85
3c0ef626	86	/*
	87	* Find the dirname and basename from the path to be resolved.
	88	* Change directory to the dirname component.
	89	* lstat the basename part.
	90	* if it is a symlink, read in the value and loop.
	91	* if it is a directory, then change to that directory.
	92	* get the current directory name and append the basename.
	93	*/
	94	strlcpy(resolved, path, MAXPATHLEN);
	95	loop:
	96	q = strrchr(resolved, '/');
	97	if (q != NULL) {
	98	p = q + 1;
	99	if (q == resolved)
	100	q = "/";
	101	else {
	102	do {
	103	--q;
	104	} while (q > resolved && *q == '/');
	105	q[1] = '\0';
	106	q = resolved;
	107	}
	108	if (chdir(q) < 0)
	109	goto err1;
	110	} else
	111	p = resolved;
	112
	113	/* Deal with the last component. */
e9a17296	114	if (*p != '\0' && lstat(p, &sb) == 0) {
3c0ef626	115	if (S_ISLNK(sb.st_mode)) {
	116	if (++symlinks > MAXSYMLINKS) {
	117	serrno = ELOOP;
	118	goto err1;
	119	}
	120	n = readlink(p, resolved, MAXPATHLEN-1);
	121	if (n < 0)
	122	goto err1;
	123	resolved[n] = '\0';
	124	goto loop;
	125	}
	126	if (S_ISDIR(sb.st_mode)) {
	127	if (chdir(p) < 0)
	128	goto err1;
	129	p = "";
	130	}
	131	}
	132
	133	/*
	134	* Save the last component name and get the full pathname of
	135	* the current directory.
	136	*/
41b2f314	137	(void)strlcpy(wbuf, p, sizeof wbuf);
3c0ef626	138	if (getcwd(resolved, MAXPATHLEN) == 0)
	139	goto err1;
	140
	141	/*
	142	* Join the two strings together, ensuring that the right thing
	143	* happens if the last component is empty, or the dirname is root.
	144	*/
	145	if (resolved[0] == '/' && resolved[1] == '\0')
0fff78ff	146	needslash = 0;
3c0ef626	147	else
0fff78ff	148	needslash = 1;
3c0ef626	149
3c0ef626	150	if (*wbuf) {
0fff78ff	151	if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) {
3c0ef626	152	serrno = ENAMETOOLONG;
	153	goto err1;
	154	}
12408a1b	155	if (needslash)
0fff78ff	156	strlcat(resolved, "/", MAXPATHLEN);
0fff78ff	157	strlcat(resolved, wbuf, MAXPATHLEN);
3c0ef626	158	}
	159
	160	/* Go back to where we came from. */
	161	if (chdir(start) < 0) {
	162	serrno = errno;
	163	goto err2;
	164	}
	165	return (resolved);
	166
	167	err1: chdir(start);
	168	err2: errno = serrno;
	169	return (NULL);
	170	}
	171	#endif /* !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH) */