/*      $NetBSD: cmp.c,v 1.21 2021/03/20 14:27:47 cheusov Exp $ */

/*
 * Copyright (c) 1987, 1990, 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/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1987, 1990, 1993, 1994\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)cmp.c       8.3 (Berkeley) 4/2/94";
#else
__RCSID("$NetBSD: cmp.c,v 1.21 2021/03/20 14:27:47 cheusov Exp $");
#endif
#endif /* not lint */

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

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

#include "extern.h"

int     lflag, sflag;

__dead static void usage(void);

int
main(int argc, char *argv[])
{
        struct stat sb1, sb2;
        off_t skip1 = 0, skip2 = 0;
        int ch, fd1, fd2, special;
        const char *file1, *file2;

        setlocale(LC_ALL, "");

        special = 0;
        while ((ch = getopt(argc, argv, "cls")) != -1)
                switch (ch) {
                case 'c':
                        special = 1;    /* careful!  Don't use mmap() */
                        break;
                case 'l':               /* print all differences */
                        lflag = 1;
                        break;
                case 's':               /* silent run */
                        sflag = 1;
                        break;
                case '?':
                default:
                        usage();
                }
        argv += optind;
        argc -= optind;

        if (lflag && sflag)
                errx(ERR_EXIT, "only one of -l and -s may be specified");

        if (argc < 2 || argc > 4)
                usage();

        /* Backward compatibility -- handle "-" meaning stdin. */
        if (strcmp(file1 = argv[0], "-") == 0) {
                special = 1;
                fd1 = 0;
                file1 = "stdin";
        }
        else if ((fd1 = open(file1, O_RDONLY, 0)) < 0) {
                if (!sflag)
                        warn("%s", file1);
                exit(ERR_EXIT);
        }
        if (strcmp(file2 = argv[1], "-") == 0) {
                if (special)
                        errx(ERR_EXIT,
                                "standard input may only be specified once");
                special = 1;
                fd2 = 0;
                file2 = "stdin";
        }
        else if ((fd2 = open(file2, O_RDONLY, 0)) < 0) {
                if (!sflag)
                        warn("%s", file2);
                exit(ERR_EXIT);
        }

        if (argc > 2) {
                char *ep;

                errno = 0;
                skip1 = (off_t)strtoll(argv[2], &ep, 0);
                if (errno || ep == argv[2])
                        usage();

                if (argc == 4) {
                        skip2 = (off_t)strtoll(argv[3], &ep, 0);
                        if (errno || ep == argv[3])
                                usage();
                }
        }

        if (!special) {
                if (fstat(fd1, &sb1))
                        err(ERR_EXIT, "%s", file1);
                if (!S_ISREG(sb1.st_mode))
                        special = 1;
                else {
                        if (fstat(fd2, &sb2))
                                err(ERR_EXIT, "%s", file2);
                        if (!S_ISREG(sb2.st_mode))
                                special = 1;
                }
        }

        if (special)
                c_special(fd1, file1, skip1, fd2, file2, skip2);
        else
                c_regular(fd1, file1, skip1, sb1.st_size,
                    fd2, file2, skip2, sb2.st_size);
        exit(0);
}

static void
usage(void)
{

        (void)fprintf(stderr,
            "Usage: %s [-c] [-l | -s] file1 file2 [skip1 [skip2]]\n",
            getprogname());
        exit(ERR_EXIT);
}