88 lines
1.9 KiB
C
88 lines
1.9 KiB
C
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/*
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* Simple program to compare two mmap'd areas.
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*
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* Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
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* Copyright (C) 2001 O'Reilly & Associates
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*
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* The source code in this file can be freely used, adapted,
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* and redistributed in source or binary form, so long as an
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* acknowledgment appears in derived source files. The citation
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* should list that the code comes from the book "Linux Device
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* Drivers" by Alessandro Rubini and Jonathan Corbet, published
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* by O'Reilly & Associates. No warranty is attached;
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* we cannot take responsibility for errors or fitness for use.
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*
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* $Id: mapcmp.c,v 1.2 2004/03/05 17:35:41 corbet Exp $
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/errno.h>
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#include <fcntl.h>
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static char *mapdev (const char *, unsigned long, unsigned long);
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#define PAGE_SIZE 4096
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/*
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* memcmp dev1 dev2 offset pages
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*/
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int main (int argc, char **argv)
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{
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unsigned long offset, size, i;
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char *addr1, *addr2;
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/*
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* Sanity check.
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*/
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if (argc != 5)
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{
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fprintf (stderr, "Usage: mapcmp dev1 dev2 offset pages\n");
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exit (1);
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}
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/*
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* Map the two devices.
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*/
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offset = strtoul (argv[3], NULL, 16);
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size = atoi (argv[4])*PAGE_SIZE;
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printf ("Offset is 0x%lx\n", offset);
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addr1 = mapdev (argv[1], offset, size);
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addr2 = mapdev (argv[2], offset, size);
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/*
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* Do the comparison.
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*/
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printf ("Comparing...");
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fflush (stdout);
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for (i = 0; i < size; i++)
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if (*addr1++ != *addr2++)
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{
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printf ("areas differ at byte %ld\n", i);
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exit (0);
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}
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printf ("areas are identical.\n");
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exit (0);
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}
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static char *mapdev (const char *dev, unsigned long offset,
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unsigned long size)
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{
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char *addr;
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int fd = open (dev, O_RDONLY);
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if (fd < 0)
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{
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perror (dev);
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exit (1);
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}
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addr = mmap (0, size, PROT_READ, MAP_PRIVATE, fd, offset);
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if (addr == MAP_FAILED)
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{
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perror (dev);
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exit (1);
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}
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printf ("Mapped %s (%lu @ %lx) at %p\n", dev, size, offset, addr);
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return (addr);
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}
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