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: head/usr.bin/cmp/regular.c 223376 2011-06-21 20:44:06Z delphij $
  30  *
  31  * @(#)regular.c        8.3 (Berkeley) 4/2/94
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/mman.h>
  36 #include <sys/stat.h>
  37
  38 #include <err.h>
  39 #include <limits.h>
  40 #include <signal.h>
  41 #include <stdlib.h>
  42 #include <stdint.h>
  43 #include <stdio.h>
  44 #include <unistd.h>
  45
  46 #include "extern.h"
  47
  48 static u_char *remmap(u_char *, int, off_t);
  49 static void segv_handler(int);
  50 #define MMAP_CHUNK (8*1024*1024)
  51
  52 #define ROUNDPAGE(i) ((i) & ~pagemask)
  53
  54 void
  55 c_regular(int fd1, const char *file1, off_t skip1, off_t len1,
  56     int fd2, const char *file2, off_t skip2, off_t len2)
  57 {
  58         u_char ch, *p1, *p2, *m1, *m2, *e1, *e2;
  59         off_t byte, length, line;
  60         int dfound;
  61         off_t pagemask, off1, off2;
  62         size_t pagesize;
  63         struct sigaction act, oact;
  64
  65         if (skip1 > len1)
  66                 eofmsg(file1);
  67         len1 -= skip1;
  68         if (skip2 > len2)
  69                 eofmsg(file2);
  70         len2 -= skip2;
  71
  72         if (sflag && len1 != len2)
  73                 exit(DIFF_EXIT);
  74
  75         sigemptyset(&act.sa_mask);
  76         act.sa_flags = SA_NODEFER;
  77         act.sa_handler = segv_handler;
  78         if (sigaction(SIGSEGV, &act, &oact))
  79                 err(ERR_EXIT, "sigaction()");
  80
  81         pagesize = getpagesize();
  82         pagemask = (off_t)pagesize - 1;
  83         off1 = ROUNDPAGE(skip1);
  84         off2 = ROUNDPAGE(skip2);
  85
  86         length = MIN(len1, len2);
  87
  88         if ((m1 = remmap(NULL, fd1, off1)) == NULL) {
  89                 c_special(fd1, file1, skip1, fd2, file2, skip2);
  90                 return;
  91         }
  92
  93         if ((m2 = remmap(NULL, fd2, off2)) == NULL) {
  94                 munmap(m1, MMAP_CHUNK);
  95                 c_special(fd1, file1, skip1, fd2, file2, skip2);
  96                 return;
  97         }
  98
  99         dfound = 0;
 100         e1 = m1 + MMAP_CHUNK;
 101         e2 = m2 + MMAP_CHUNK;
 102         p1 = m1 + (skip1 - off1);
 103         p2 = m2 + (skip2 - off2);
 104
 105         for (byte = line = 1; length--; ++byte) {
 106                 if ((ch = *p1) != *p2) {
 107                         if (xflag) {
 108                                 dfound = 1;
 109                                 printf("%08jx %02x %02x\n",
 110                                     (intmax_t)byte - 1, ch, *p2);
 111                         } else if (lflag) {
 112                                 dfound = 1;
 113                                 printf("%6jd %3o %3o\n",
 114                                     (intmax_t)byte, ch, *p2);
 115                         } else
 116                                 diffmsg(file1, file2, byte, line);
 117                                 /* NOTREACHED */
 118                 }
 119                 if (ch == '\n')
 120                         ++line;
 121                 if (++p1 == e1) {
 122                         off1 += MMAP_CHUNK;
 123                         if ((p1 = m1 = remmap(m1, fd1, off1)) == NULL) {
 124                                 munmap(m2, MMAP_CHUNK);
 125                                 err(ERR_EXIT, "remmap %s", file1);
 126                         }
 127                         e1 = m1 + MMAP_CHUNK;
 128                 }
 129                 if (++p2 == e2) {
 130                         off2 += MMAP_CHUNK;
 131                         if ((p2 = m2 = remmap(m2, fd2, off2)) == NULL) {
 132                                 munmap(m1, MMAP_CHUNK);
 133                                 err(ERR_EXIT, "remmap %s", file2);
 134                         }
 135                         e2 = m2 + MMAP_CHUNK;
 136                 }
 137         }
 138         munmap(m1, MMAP_CHUNK);
 139         munmap(m2, MMAP_CHUNK);
 140
 141         if (sigaction(SIGSEGV, &oact, NULL))
 142                 err(ERR_EXIT, "sigaction()");
 143
 144         if (len1 != len2)
 145                 eofmsg (len1 > len2 ? file2 : file1);
 146         if (dfound)
 147                 exit(DIFF_EXIT);
 148 }
 149
 150 static u_char *
 151 remmap(u_char *mem, int fd, off_t offset)
 152 {
 153         if (mem != NULL)
 154                 munmap(mem, MMAP_CHUNK);
 155         mem = mmap(NULL, MMAP_CHUNK, PROT_READ, MAP_SHARED, fd, offset);
 156         if (mem == MAP_FAILED)
 157                 return (NULL);
 158         madvise(mem, MMAP_CHUNK, MADV_SEQUENTIAL);
 159         return (mem);
 160 }
 161
 162 static void
 163 segv_handler(int sig __unused) {
 164         static const char msg[] = "cmp: Input/output error (caught SIGSEGV)\n";
 165
 166         write(STDERR_FILENO, msg, sizeof(msg));
 167         _exit(EXIT_FAILURE);
 168 }