/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License, Version 1.0 only

 * (the "License").  You may not use this file except in compliance

 * with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*	Copyright (c) 1988 AT&T	*/

/*	  All Rights Reserved  	*/

#pragma weak realpath = _realpath

#include "synonyms.h"

#include <sys/types.h>

#include <dirent.h>

#include <sys/param.h>

#include <limits.h>

#include <errno.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

/*

 * Canonicalize the path given in file_name, resolving away all symbolic link

 * components.  Store the result into the buffer named by resolved_name, which

 * must be long enough (MAXPATHLEN bytes will suffice).  Returns NULL

 * on failure and resolved_name on success.  On failure, to maintain

 * compatibility with the past, the contents of file_name will be copied

 * into resolved_name.

 */

char *

realpath(const char *file_name, char *resolved_name)

{

	char cwd[PATH_MAX];

	int len;

	if (file_name == NULL || resolved_name == NULL) {

		errno = EINVAL;

		return (NULL);

	}

	/*

	 * Call resolvepath() to resolve all the symlinks in file_name,

	 * eliminate embedded "." components, and collapse embedded ".."

	 * components.  We may be left with leading ".." components.

	 */

	if ((len = resolvepath(file_name, resolved_name, PATH_MAX)) < 0) {

		(void) strlcpy(resolved_name, file_name, PATH_MAX);

		return (NULL);		/* errno set by resolvepath() */

	}

	if (len >= PATH_MAX)	/* "can't happen" */

		len = PATH_MAX - 1;

	resolved_name[len] = '\0';

	if (*resolved_name == '/')	/* nothing more to do */

		return (resolved_name);

	/*

	 * Prepend the current working directory to the relative path.

	 * If the relative path is not empty (or "."), collapse all of the

	 * resulting embedded ".." components with trailing cwd components.

	 * We know that getcwd() returns a path name free of symlinks.

	 */

	if (getcwd(cwd, sizeof (cwd)) == NULL) {

		(void) strlcpy(resolved_name, file_name, PATH_MAX);

		return (NULL);		/* errno set by getcwd() */

	}

	if (len != 0 && strcmp(resolved_name, ".") != 0) {

		char *relpath = resolved_name;

		char *endcwd = cwd + strlen(cwd);

		/*

		 * Eliminate ".." components from the relative path

		 * left-to-right, components from cwd right-to-left.

		 */

		relpath[len++] = '/';

		while (len >= 3 && strncmp(relpath, "../", 3) == 0) {

			relpath += 3;

			len -= 3;

			while (*--endcwd != '/')

				continue;

		}

		if (len == 0) {

			/* the relative path was all ".." components */

			*endcwd = '\0';

		} else {

			/* there are non-null components on both sides */

			relpath[--len] = '\0';

			*endcwd++ = '/';

			if (endcwd + len >= cwd + PATH_MAX) {

				(void) strlcpy(resolved_name,

				    file_name, PATH_MAX);

				errno = ENAMETOOLONG;

				return (NULL);

			}

			(void) strcpy(endcwd, relpath);

		}

	}

	(void) strcpy(resolved_name, cwd);

	return (resolved_name);

}