//-------------------------------------------------------------------
//	trytimer.cpp
//
//	This demo studies the effects of the 'setitimer()' function
//	on timer-related fields within the 'task_struct' structure. 
//	Requires our 'timerinfo.o' module in the current directory.
//
//	programmer: ALLAN CRUSE
//	date begun: 18 SEP 2004
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for system(), exit() 
#include <unistd.h>	// for read(), close() 
#include <signal.h>	// for signal()
#include <sys/time.h>	// for setitimer()

char filename[] = "/proc/timerinfo";

int main( int argc, char **argv )
{
	system(" /sbin/insmod timerinfo.o" );

	signal( SIGALRM, SIG_IGN );
	
	int	fd = open( filename, O_RDONLY );
	if ( fd < 0 ) { perror( filename ); exit(1); }

	char	buffer[ 1024 ] = {0};
	int	nbytes = read( fd, buffer, sizeof buffer );
	if ( nbytes < 0 ) { perror( "read" ); exit(1); }
	else	write( 1, buffer, nbytes );
	
	struct itimerval   it, oldit;

	it.it_value.tv_sec = 2;
	it.it_value.tv_usec = 0;
	it.it_interval.tv_sec = 1;
	it.it_interval.tv_usec = 0;
	setitimer( ITIMER_REAL, &it, &oldit );
	
	lseek( fd, 0, SEEK_SET );
	nbytes = read( fd, buffer, sizeof buffer );
	if ( nbytes < 0 ) { perror( "read" ); exit(1); }
	else	write( 1, buffer, nbytes );

	getchar();
	
	lseek( fd, 0, SEEK_SET );
	nbytes = read( fd, buffer, sizeof buffer );
	if ( nbytes < 0 ) { perror( "read" ); exit(1); }
	else	write( 1, buffer, nbytes );

	close( fd );
	printf( "\n" );
	system(" /sbin/rmmod timerinfo" );
}