#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>

int	main(int ac, char **av) {
    	int	fd = open(av[1], O_RDWR) ;
	char	s[6] ;
	int	i ;

	if (fd == -1) {
	    perror("open()") ; 
	    return -1 ;
	}

	if (lseek(fd, 0x2131, 0) == -1) {
	    perror("lseek()") ;
	    return -1 ;
	}

	if (read(fd, s, sizeof(s)) != sizeof(s)) {
	    perror("read()") ;
	    return -1 ;
	}

	for (i = 0; i < sizeof(s); i ++) printf("%.2x ", (unsigned char)s[i]) ;
	printf("\n") ;

	if (lseek(fd, 0x2131, 0) == -1) {
	    perror("lseek()") ;
	    return -1 ;
	}

	if (write(fd, "\x90\x90\x90\x90\x90\x90", 6) != 6) {
	    perror("write()") ;
	    return -1 ;
	}

	return 0 ;
}