/*      $OpenBSD: pwd.c,v 1.14 2015/10/09 01:37:06 deraadt Exp $        */
/*      $NetBSD: pwd.c,v 1.22 2011/08/29 14:51:19 joerg Exp $   */

/*
 * 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. 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 <sys/stat.h>

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

extern char *__progname;
static char *getcwd_logical(void);
__dead static void usage(void);

int
main(int argc, char *argv[])
{
        int ch, lFlag = 0;
        const char *p;

        if (pledge("stdio rpath", NULL) == -1)
                err(1, "pledge");

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

        if (argc != 0)
                usage();

        if (lFlag)
                p = getcwd_logical();
        else
                p = NULL;
        if (p == NULL)
                p = getcwd(NULL, 0);

        if (p == NULL)
                err(EXIT_FAILURE, NULL);

        puts(p);

        exit(EXIT_SUCCESS);
}

static char *
getcwd_logical(void)
{
        char *pwd, *p;
        struct stat s_pwd, s_dot;

        /* Check $PWD -- if it's right, it's fast. */
        pwd = getenv("PWD");
        if (pwd == NULL)
                return NULL;
        if (pwd[0] != '/')
                return NULL;

        /* check for . or .. components, including trailing ones */
        for (p = pwd; *p != '\0'; p++)
                if (p[0] == '/' && p[1] == '.') {
                        if (p[2] == '.')
                                p++;
                        if (p[2] == '\0' || p[2] == '/')
                                return NULL;
                }

        if (stat(pwd, &s_pwd) == -1 || stat(".", &s_dot) == -1)
                return NULL;
        if (s_pwd.st_dev != s_dot.st_dev || s_pwd.st_ino != s_dot.st_ino)
                return NULL;
        return pwd;
}

static void
usage(void)
{
        fprintf(stderr, "usage: %s [-LP]\n", __progname);
        exit(EXIT_FAILURE);
}