/*
	counter-file.c -- print the counter value in a file.
*/
#include <stdio.h>

static void load_counter();
static void save_counter();

int counter = 0;

main( int argc, char *argv[], char *envp[] )
{
	load_counter();
	printf("%d -> ",counter );
	counter = counter + 1 ;
	printf("%d\n",counter );
	save_counter();
}

#include <unistd.h>	/* pread() */
#include <fcntl.h>	/* open() */
#include <stdlib.h>	/* exit() */

#define FILENAME "counter.data"

static void
load_counter()
{
    int fd ;
    	fd = open(FILENAME,O_RDWR|O_CREAT,0666);
	if( fd < 0 )
	{
	    perror(FILENAME);
	    exit(1);
	}
	read( fd, &counter, sizeof(counter) );
	close( fd );
}

static void
save_counter()
{
    int fd ;
    	fd = open(FILENAME,O_RDWR|O_CREAT,0666);
	if( fd < 0 )
	{
	    perror(FILENAME);
	    exit(1);
	}
	write( fd, &counter, sizeof(counter) );
	close( fd );
}