/*      $OpenBSD: regular.c,v 1.13 2021/01/09 09:58:12 otto Exp $      */
/*      $NetBSD: regular.c,v 1.2 1995/09/08 03:22:59 tls 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/mman.h>
#include <sys/stat.h>

#include <err.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "extern.h"

#define MINIMUM(a, b)   (((a) < (b)) ? (a) : (b))

void
c_regular(int fd1, char *file1, off_t skip1, off_t len1,
    int fd2, char *file2, off_t skip2, off_t len2)
{
        u_char ch, *p1, *p2;
        off_t byte, length, line;
        int dfound;

        if (skip1 > len1)
                eofmsg(file1);
        len1 -= skip1;
        if (skip2 > len2)
                eofmsg(file2);
        len2 -= skip2;

        if (sflag && len1 != len2)
                exit(1);

        length = MINIMUM(len1, len2);
        if (length > SIZE_MAX) {
        mmap_failed:
                c_special(fd1, file1, skip1, fd2, file2, skip2);
                return;
        }

        if ((p1 = mmap(NULL, (size_t)length, PROT_READ,
            MAP_PRIVATE, fd1, skip1)) == MAP_FAILED)
                goto mmap_failed;
        if ((p2 = mmap(NULL, (size_t)length, PROT_READ,
            MAP_PRIVATE, fd2, skip2)) == MAP_FAILED) {
                munmap(p1, (size_t)length);
                goto mmap_failed;
        }
        if (length) {
                madvise(p1, length, MADV_SEQUENTIAL);
                madvise(p2, length, MADV_SEQUENTIAL);
        }

        dfound = 0;
        for (byte = line = 1; length--; ++p1, ++p2, ++byte) {
                if ((ch = *p1) != *p2) {
                        if (lflag) {
                                dfound = 1;
                                (void)printf("%6lld %3o %3o\n", (long long)byte,
                                    ch, *p2);
                        } else
                                diffmsg(file1, file2, byte, line);
                                /* NOTREACHED */
                }
                if (ch == '\n')
                        ++line;
        }

        if (len1 != len2)
                eofmsg (len1 > len2 ? file2 : file1);
        if (dfound)
                exit(DIFF_EXIT);
}