/*      $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);
}