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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $FreeBSD: src/usr.bin/cmp/regular.c,v 1.7.2.3 2001/11/21 10:47:54 dwmalone Exp $
  34  * $DragonFly: src/usr.bin/cmp/regular.c,v 1.4 2003/11/03 19:31:28 eirikn Exp $
  35  *
  36  * @(#)regular.c        8.3 (Berkeley) 4/2/94
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/mman.h>
  41 #include <sys/stat.h>
  42
  43 #include <err.h>
  44 #include <limits.h>
  45 #include <stdlib.h>
  46 #include <stdio.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49
  50 #include "extern.h"
  51
  52 static u_char *remmap(u_char *, int, off_t);
  53 #define MMAP_CHUNK (8*1024*1024)
  54
  55 #define ROUNDPAGE(i) ((i) & ~pagemask)
  56
  57 void
  58 c_regular(int fd1, const char *file1, off_t skip1, off_t len1, int fd2,
  59           const char *file2, off_t skip2, off_t len2)
  60 {
  61         u_char ch, *p1, *p2, *m1, *m2, *e1, *e2;
  62         off_t byte, length, line;
  63         int dfound;
  64         off_t pagemask, off1, off2;
  65         size_t pagesize;
  66
  67         if (skip1 > len1)
  68                 eofmsg(file1);
  69         len1 -= skip1;
  70         if (skip2 > len2)
  71                 eofmsg(file2);
  72         len2 -= skip2;
  73
  74         if (sflag && len1 != len2)
  75                 exit(DIFF_EXIT);
  76
  77         pagesize = getpagesize();
  78         pagemask = (off_t)pagesize - 1;
  79         off1 = ROUNDPAGE(skip1);
  80         off2 = ROUNDPAGE(skip2);
  81
  82         length = MIN(len1, len2);
  83
  84         if ((m1 = remmap(NULL, fd1, off1)) == NULL) {
  85                 c_special(fd1, file1, skip1, fd2, file2, skip2);
  86                 return;
  87         }
  88
  89         if ((m2 = remmap(NULL, fd2, off2)) == NULL) {
  90                 munmap(m1, MMAP_CHUNK);
  91                 c_special(fd1, file1, skip1, fd2, file2, skip2);
  92                 return;
  93         }
  94
  95         dfound = 0;
  96         e1 = m1 + MMAP_CHUNK;
  97         e2 = m2 + MMAP_CHUNK;
  98         p1 = m1 + (skip1 - off1);
  99         p2 = m2 + (skip2 - off2);
 100
 101         for (byte = line = 1; length--; ++byte) {
 102                 if ((ch = *p1) != *p2) {
 103                         if (xflag) {
 104                                 dfound = 1;
 105                                 (void)printf("%08qx %02x %02x\n", byte - 1, ch, *p2);
 106                         } else if (lflag) {
 107                                 dfound = 1;
 108                                 (void)printf("%6qd %3o %3o\n", byte, ch, *p2);
 109                         } else
 110                                 diffmsg(file1, file2, byte, line);
 111                                 /* NOTREACHED */
 112                 }
 113                 if (ch == '\n')
 114                         ++line;
 115                 if (++p1 == e1) {
 116                         off1 += MMAP_CHUNK;
 117                         if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) {
 118                                 munmap(m2, MMAP_CHUNK);
 119                                 err(ERR_EXIT, "remmap %s", file1);
 120                         }
 121                         e1 = m1 + MMAP_CHUNK;
 122                 }
 123                 if (++p2 == e2) {
 124                         off2 += MMAP_CHUNK;
 125                         if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) {
 126                                 munmap(m1, MMAP_CHUNK);
 127                                 err(ERR_EXIT, "remmap %s", file2);
 128                         }
 129                         e2 = m2 + MMAP_CHUNK;
 130                 }
 131         }
 132         munmap(m1, MMAP_CHUNK);
 133         munmap(m2, MMAP_CHUNK);
 134
 135         if (len1 != len2)
 136                 eofmsg (len1 > len2 ? file2 : file1);
 137         if (dfound)
 138                 exit(DIFF_EXIT);
 139 }
 140
 141 static u_char *
 142 remmap(u_char *mem, int fd, off_t offset)
 143 {
 144         if (mem != NULL)
 145                 munmap(mem, MMAP_CHUNK);
 146         mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset);
 147         if (mem == MAP_FAILED)
 148                 return (NULL);
 149         madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL);
 150         return (mem);
 151 }