usr.bin/cmp/regular.c

   1 /*-
   2  * Copyright (c) 1991, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD: src/usr.bin/cmp/regular.c,v 1.7.2.3 2001/11/21 10:47:54 dwmalone Exp $
  30  * $DragonFly: src/usr.bin/cmp/regular.c,v 1.4 2003/11/03 19:31:28 eirikn Exp $
  31  *
  32  * @(#)regular.c        8.3 (Berkeley) 4/2/94
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/mman.h>
  37 #include <sys/stat.h>
  38
  39 #include <err.h>
  40 #include <limits.h>
  41 #include <stdlib.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45
  46 #include "extern.h"
  47
  48 static u_char *remmap(u_char *, int, off_t);
  49 #define MMAP_CHUNK (8*1024*1024)
  50
  51 #define ROUNDPAGE(i) ((i) & ~pagemask)
  52
  53 void
  54 c_regular(int fd1, const char *file1, off_t skip1, off_t len1, int fd2,
  55           const char *file2, off_t skip2, off_t len2)
  56 {
  57         u_char ch, *p1, *p2, *m1, *m2, *e1, *e2;
  58         off_t byte, length, line;
  59         int dfound;
  60         off_t pagemask, off1, off2;
  61         size_t pagesize;
  62
  63         if (skip1 > len1)
  64                 eofmsg(file1);
  65         len1 -= skip1;
  66         if (skip2 > len2)
  67                 eofmsg(file2);
  68         len2 -= skip2;
  69
  70         if (sflag && len1 != len2)
  71                 exit(DIFF_EXIT);
  72
  73         pagesize = getpagesize();
  74         pagemask = (off_t)pagesize - 1;
  75         off1 = ROUNDPAGE(skip1);
  76         off2 = ROUNDPAGE(skip2);
  77
  78         length = MIN(len1, len2);
  79
  80         if ((m1 = remmap(NULL, fd1, off1)) == NULL) {
  81                 c_special(fd1, file1, skip1, fd2, file2, skip2);
  82                 return;
  83         }
  84
  85         if ((m2 = remmap(NULL, fd2, off2)) == NULL) {
  86                 munmap(m1, MMAP_CHUNK);
  87                 c_special(fd1, file1, skip1, fd2, file2, skip2);
  88                 return;
  89         }
  90
  91         dfound = 0;
  92         e1 = m1 + MMAP_CHUNK;
  93         e2 = m2 + MMAP_CHUNK;
  94         p1 = m1 + (skip1 - off1);
  95         p2 = m2 + (skip2 - off2);
  96
  97         for (byte = line = 1; length--; ++byte) {
  98                 if ((ch = *p1) != *p2) {
  99                         if (xflag) {
 100                                 dfound = 1;
 101                                 printf("%08jx %02x %02x\n",
 102                                        (intmax_t)byte - 1, ch, *p2);
 103                         } else if (lflag) {
 104                                 dfound = 1;
 105                                 printf("%6jd %3o %3o\n",
 106                                        (intmax_t)byte, ch, *p2);
 107                         } else {
 108                                 diffmsg(file1, file2, byte, line);
 109                                 /* NOTREACHED */
 110                         }
 111                 }
 112                 if (ch == '\n')
 113                         ++line;
 114                 if (++p1 == e1) {
 115                         off1 += MMAP_CHUNK;
 116                         if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) {
 117                                 munmap(m2, MMAP_CHUNK);
 118                                 err(ERR_EXIT, "remmap %s", file1);
 119                         }
 120                         e1 = m1 + MMAP_CHUNK;
 121                 }
 122                 if (++p2 == e2) {
 123                         off2 += MMAP_CHUNK;
 124                         if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) {
 125                                 munmap(m1, MMAP_CHUNK);
 126                                 err(ERR_EXIT, "remmap %s", file2);
 127                         }
 128                         e2 = m2 + MMAP_CHUNK;
 129                 }
 130         }
 131         munmap(m1, MMAP_CHUNK);
 132         munmap(m2, MMAP_CHUNK);
 133
 134         if (len1 != len2)
 135                 eofmsg (len1 > len2 ? file2 : file1);
 136         if (dfound)
 137                 exit(DIFF_EXIT);
 138 }
 139
 140 static u_char *
 141 remmap(u_char *mem, int fd, off_t offset)
 142 {
 143         if (mem != NULL)
 144                 munmap(mem, MMAP_CHUNK);
 145         mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset);
 146         if (mem == MAP_FAILED)
 147                 return (NULL);
 148         madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL);
 149         return (mem);
 150 }