[openssh.git] / 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 1.11 2004/11/30 15:12:59 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;
	char *p, *q, wbuf[MAXPATHLEN];
	int symlinks = 0;

	/* Save the starting point. */
#ifndef HAVE_FCHDIR
	char start[MAXPATHLEN];
	/* this is potentially racy but without fchdir we have no option */
	if (getcwd(start, sizeof(start)) == NULL) {
		resolved[0] = '.';
		resolved[1] = '\0';
		return (NULL);
	}
#endif
	if ((fd = open(".", O_RDONLY)) < 0) {
		resolved[0] = '.';
		resolved[1] = '\0';
		return (NULL);
	}

	/* 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.
	 */
	if (strlcpy(resolved, path, MAXPATHLEN) >= MAXPATHLEN) {
		serrno = ENAMETOOLONG;
		goto err2;
	}
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) {
				errno = ELOOP;
				goto err1;
			}
			if ((n = readlink(p, resolved, MAXPATHLEN-1)) < 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.
	 */
	if (strlcpy(wbuf, p, sizeof(wbuf)) >= sizeof(wbuf)) {
		errno = ENAMETOOLONG;
		goto err1;
	}
	if (getcwd(resolved, MAXPATHLEN) == NULL)
		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) {
			errno = ENAMETOOLONG;
			goto err1;
		}
		if (needslash) {
			if (strlcat(resolved, "/", MAXPATHLEN) >= MAXPATHLEN) {
				errno = ENAMETOOLONG;
				goto err1;
			}
		}
		if (strlcat(resolved, wbuf, MAXPATHLEN) >= MAXPATHLEN) {
			errno = ENAMETOOLONG;
			goto err1;
		}
	}

	/* Go back to where we came from. */
#ifdef HAVE_FCHDIR
	if (fchdir(fd) < 0) {
#else
	if (chdir(start) < 0) {
#endif
		serrno = errno;
		goto err2;
	}

	/* It's okay if the close fails, what's an fd more or less? */
	(void)close(fd);
	return (resolved);

err1:	serrno = errno;
#ifdef HAVE_FCHDIR
	(void)fchdir(fd);
#else
	chdir(start);
#endif
err2:	(void)close(fd);
	errno = serrno;
	return (NULL);
}
#endif /* !defined(HAVE_REALPATH) || defined(BROKEN_REALPATH) */
Commit	Line	Data
d74671e4	1	/* OPENBSD ORIGINAL: lib/libc/stdlib/realpath.c */
d74671e4	2
443172c4	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.
3e67f7df	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.
443172c4	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)
667abcc6	40	static char *rcsid = "$OpenBSD: realpath.c,v 1.11 2004/11/30 15:12:59 millert Exp $";
443172c4	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
c2207f11	52	/*
	53	* MAXSYMLINKS
	54	*/
	55	#ifndef MAXSYMLINKS
	56	#define MAXSYMLINKS 5
	57	#endif
	58
443172c4	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;
667abcc6	70	int fd, n, needslash, serrno;
667abcc6	71	char p, q, wbuf[MAXPATHLEN];
443172c4	72	int symlinks = 0;
	73
	74	/* Save the starting point. */
667abcc6	75	#ifndef HAVE_FCHDIR
	76	char start[MAXPATHLEN];
	77	/* this is potentially racy but without fchdir we have no option */
	78	if (getcwd(start, sizeof(start)) == NULL) {
	79	resolved[0] = '.';
	80	resolved[1] = '\0';
	81	return (NULL);
	82	}
	83	#endif
443172c4	84	if ((fd = open(".", O_RDONLY)) < 0) {
667abcc6	85	resolved[0] = '.';
667abcc6	86	resolved[1] = '\0';
443172c4	87	return (NULL);
443172c4	88	}
443172c4	89
1656cbed	90	/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
	91	if (path[0] == '.' && path[1] == '\0')
	92	path = "";
	93
443172c4	94	/*
	95	* Find the dirname and basename from the path to be resolved.
	96	* Change directory to the dirname component.
	97	* lstat the basename part.
	98	* if it is a symlink, read in the value and loop.
	99	* if it is a directory, then change to that directory.
	100	* get the current directory name and append the basename.
	101	*/
667abcc6	102	if (strlcpy(resolved, path, MAXPATHLEN) >= MAXPATHLEN) {
	103	serrno = ENAMETOOLONG;
	104	goto err2;
	105	}
443172c4	106	loop:
	107	q = strrchr(resolved, '/');
	108	if (q != NULL) {
	109	p = q + 1;
	110	if (q == resolved)
	111	q = "/";
	112	else {
	113	do {
	114	--q;
	115	} while (q > resolved && *q == '/');
	116	q[1] = '\0';
	117	q = resolved;
	118	}
	119	if (chdir(q) < 0)
	120	goto err1;
	121	} else
	122	p = resolved;
	123
	124	/* Deal with the last component. */
1656cbed	125	if (*p != '\0' && lstat(p, &sb) == 0) {
443172c4	126	if (S_ISLNK(sb.st_mode)) {
443172c4	127	if (++symlinks > MAXSYMLINKS) {
667abcc6	128	errno = ELOOP;
443172c4	129	goto err1;
443172c4	130	}
667abcc6	131	if ((n = readlink(p, resolved, MAXPATHLEN-1)) < 0)
443172c4	132	goto err1;
	133	resolved[n] = '\0';
	134	goto loop;
	135	}
	136	if (S_ISDIR(sb.st_mode)) {
	137	if (chdir(p) < 0)
	138	goto err1;
	139	p = "";
	140	}
	141	}
	142
	143	/*
	144	* Save the last component name and get the full pathname of
	145	* the current directory.
	146	*/
667abcc6	147	if (strlcpy(wbuf, p, sizeof(wbuf)) >= sizeof(wbuf)) {
	148	errno = ENAMETOOLONG;
	149	goto err1;
	150	}
	151	if (getcwd(resolved, MAXPATHLEN) == NULL)
443172c4	152	goto err1;
	153
	154	/*
	155	* Join the two strings together, ensuring that the right thing
	156	* happens if the last component is empty, or the dirname is root.
	157	*/
	158	if (resolved[0] == '/' && resolved[1] == '\0')
510a42ce	159	needslash = 0;
443172c4	160	else
510a42ce	161	needslash = 1;
443172c4	162
443172c4	163	if (*wbuf) {
510a42ce	164	if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) {
667abcc6	165	errno = ENAMETOOLONG;
	166	goto err1;
	167	}
	168	if (needslash) {
	169	if (strlcat(resolved, "/", MAXPATHLEN) >= MAXPATHLEN) {
	170	errno = ENAMETOOLONG;
	171	goto err1;
	172	}
	173	}
	174	if (strlcat(resolved, wbuf, MAXPATHLEN) >= MAXPATHLEN) {
	175	errno = ENAMETOOLONG;
443172c4	176	goto err1;
443172c4	177	}
443172c4	178	}
	179
	180	/* Go back to where we came from. */
667abcc6	181	#ifdef HAVE_FCHDIR
	182	if (fchdir(fd) < 0) {
	183	#else
443172c4	184	if (chdir(start) < 0) {
667abcc6	185	#endif
443172c4	186	serrno = errno;
	187	goto err2;
	188	}
667abcc6	189
	190	/* It's okay if the close fails, what's an fd more or less? */
	191	(void)close(fd);
443172c4	192	return (resolved);
443172c4	193
667abcc6	194	err1: serrno = errno;
	195	#ifdef HAVE_FCHDIR
	196	(void)fchdir(fd);
	197	#else
	198	chdir(start);
	199	#endif
	200	err2: (void)close(fd);
	201	errno = serrno;
443172c4	202	return (NULL);
	203	}
	204	#endif /* !defined(HAVE_REALPATH) \|\| defined(BROKEN_REALPATH) */