/*
 * Copyright (c) 1991, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 *
 * @(#) Copyright (c) 1991, 1993, 1994 The Regents of the University of California.  All rights reserved.
 * @(#)pwd.c	8.3 (Berkeley) 4/1/94
 * $FreeBSD: src/bin/pwd/pwd.c,v 1.9.2.3 2002/06/17 11:04:22 tjr Exp $
 * $DragonFly: src/bin/pwd/pwd.c,v 1.5 2005/03/05 21:58:20 liamfoy Exp $
 */

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

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static char	*getcwd_logical(void);
static void	usage(void);

int
main(int argc, char *argv[])
{
	int physical;
	int ch;
	char *p;
	char buf[PATH_MAX];

	if (strcmp(getprogname(), "realpath") == 0) {
		if (argc != 2)
			usage();
		if ((p = realpath(argv[1], buf)) == NULL)
			err(1, "%s", argv[1]);
		printf("%s\n", p);
		exit(0);
	}

	physical = 1;
	while ((ch = getopt(argc, argv, "LP")) != -1)
		switch (ch) {
		case 'L':
			physical = 0;
			break;
		case 'P':
			physical = 1;
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (argc != 0)
		usage();

	/*
	 * If we're trying to find the logical current directory and that
	 * fails, behave as if -P was specified.
	 */
	if ((!physical && (p = getcwd_logical()) != NULL) ||
	    (p = getcwd(NULL, 0)) != NULL)
		printf("%s\n", p);
	else
		err(1, ".");

	exit(0);
}

static void
usage(void)
{
	if (strcmp(getprogname(), "realpath") == 0)
		fprintf(stderr, "usage: realpath [path]\n");
	else
		fprintf(stderr, "usage: pwd [-LP]\n");
  	exit(1);
}

static char *
getcwd_logical(void)
{
	struct stat logic, phy;
	char *pwd;

	/*
	 * Check that $PWD is an absolute logical pathname referring to
	 * the current working directory.
	 */
	if ((pwd = getenv("PWD")) != NULL && *pwd == '/') {
		if (stat(pwd, &logic) == -1 || stat(".", &phy) == -1)
			return (NULL);
		if (logic.st_dev == phy.st_dev && logic.st_ino == phy.st_ino)
			return (pwd);
	}

	errno = ENOENT;
	return (NULL);
}