/*      $NetBSD: regular.c,v 1.26 2025/01/12 06:38:21 simonb 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/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)regular.c   8.3 (Berkeley) 4/2/94";
#else
__RCSID("$NetBSD: regular.c,v 1.26 2025/01/12 06:38:21 simonb Exp $");
#endif
#endif /* not lint */

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

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

#include "extern.h"

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

       if (skip1 > len1)
               eofmsg(file1, len1 + 1, 0);
       len1 -= skip1;
       if (skip2 > len2)
               eofmsg(file2, len2 + 1, 0);
       len2 -= skip2;

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

       byte = line = 1;
       dfound = 0;
       length = MIN(len1, len2);
       for (blk_sz = 1024 * 1024; length != 0; length -= blk_sz) {
               if ((uintmax_t)blk_sz > (uintmax_t)length)
                       blk_sz = length;
               p1 = mmap(NULL, blk_sz, PROT_READ, MAP_FILE|MAP_SHARED,
                   fd1, skip1);
               if (p1 == MAP_FAILED)
                       goto mmap_failed;

               p2 = mmap(NULL, blk_sz, PROT_READ, MAP_FILE|MAP_SHARED,
                   fd2, skip2);
               if (p2 == MAP_FAILED) {
                       munmap(p1, blk_sz);
                       goto mmap_failed;
               }

               blk_cnt = blk_sz;
               if ((lflag || sflag) && (memcmp(p1, p2, blk_sz) == 0)) {
                       /*
                        * If the two blocks are the same and we are
                        * using the -l or -s flags, we don't need to
                        * count lines.  There is nothing else to do
                        * except advance the pointers for munmap()
                        * below.
                        */
                       p1 += blk_sz;
                       p2 += blk_sz;
               } else {
                       for (; blk_cnt--; ++p1, ++p2, ++byte) {
                               if ((ch = *p1) != *p2) {
                                       if (!lflag) {
                                               diffmsg(file1, file2, byte, line);
                                               /* NOTREACHED */
                                       }
                                       dfound = 1;
                                       (void)printf("%6lld %3o %3o\n",
                                           (long long)byte, ch, *p2);
                               }
                               if (ch == '\n')
                                       ++line;
                       }
               }
               munmap(p1 - blk_sz, blk_sz);
               munmap(p2 - blk_sz, blk_sz);
               skip1 += blk_sz;
               skip2 += blk_sz;
       }

       if (len1 != len2)
               eofmsg(len1 > len2 ? file2 : file1, byte, line);
       if (dfound)
               exit(DIFF_EXIT);
       return;

mmap_failed:
       c_special(fd1, file1, skip1, fd2, file2, skip2);
}