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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License,
* version 2 as published by the Free Software Foundation.
*
* (C) John Crispin <blogic@openwrt.org>
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
int main(int argc, char **argv)
{
uint32_t t = 0, sum = 0x55aa55aa;
int fd;
if ((argc != 2) || ((fd = open(argv[1], O_RDWR)) == -1)) {
fprintf(stderr, "Usage: %s input_file\n", *argv);
return -EINVAL;
}
lseek(fd, -4, SEEK_END);
write(fd, &t, 4);
lseek(fd, 0, SEEK_SET);
while (read(fd, &t, 4) > 0)
sum -= t;
lseek(fd, -4, SEEK_END);
write(fd, &sum, 4);
close(fd);
return 0;
}
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