// CAUTION: This code might crash your X session - save your data before executing this!
// It also needs uinput - run "modprobe uinput" to load it if necessary.

#include <error.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>

#include <sys/ioctl.h>

#include <linux/input.h>
#include <linux/uinput.h>


#define ERROR_IF( condition ) \
	if( condition ) \
		error_at_line( condition, errno, __FILE__, __LINE__, #condition )


static int xioctl( int fd, unsigned long int request, ... )
{
	va_list ap;
	void * arg;

	va_start( ap, request );
	arg = va_arg( ap, void * );
	va_end( ap );

	int r;
	do
		r = ioctl( fd, request, arg );
	while( -1 == r && EINTR == errno );
	return r;
}


#define sendEvent( fd, type, code, value ) \
	printf( "Sending event type=%s, code=%s, value=%d\n", #type, #code, value ); \
	fflush( stdout ); \
	sendEvent_real( fd, type, code, value );

static void sendEvent_real( int fd, __u16 type, __u16 code, __s16 value )
{
	struct input_event ev = {};
	ev.type = type;
	ev.code = code;
	ev.value = value;

	ERROR_IF( write( fd, &ev, sizeof(ev) ) != sizeof( struct input_event ) );
}


int main( int argc, char ** argv )
{
	int fd;
	ERROR_IF( (fd = open( "/dev/uinput", O_WRONLY | O_NONBLOCK )) < 0 );

	// setup device information
	struct uinput_user_dev uidev = {};
	snprintf( uidev.name, UINPUT_MAX_NAME_SIZE, "MTSlotBugInducer" );

	uidev.id.bustype = BUS_VIRTUAL;
	uidev.id.vendor  = 0x1;
	uidev.id.product = 0x1;
	uidev.id.version = 1;

	uidev.absmax[ABS_MT_POSITION_X] = 4096;
	uidev.absmax[ABS_MT_POSITION_Y] = 4096;
	uidev.absmin[ABS_MT_POSITION_X] = 0;
	uidev.absmin[ABS_MT_POSITION_Y] = 0;
	uidev.absfuzz[ABS_MT_POSITION_X] = 0;
	uidev.absflat[ABS_MT_POSITION_X] = 0;
	uidev.absfuzz[ABS_MT_POSITION_Y] = 0;
	uidev.absflat[ABS_MT_POSITION_Y] = 0;

	uidev.absmax[ABS_X] = 4096;
	uidev.absmax[ABS_Y] = 4096;
	uidev.absmin[ABS_X] = 0;
	uidev.absmin[ABS_Y] = 0;
	uidev.absfuzz[ABS_X] = 0;
	uidev.absflat[ABS_X] = 0;
	uidev.absfuzz[ABS_Y] = 0;
	uidev.absflat[ABS_Y] = 0;

	ERROR_IF( xioctl( fd, UI_SET_EVBIT, EV_SYN ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_PROPBIT, INPUT_PROP_DIRECT ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_EVBIT, EV_KEY ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_KEYBIT, BTN_TOUCH ) == -1 );

	ERROR_IF( xioctl( fd, UI_SET_EVBIT, EV_ABS ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_ABSBIT, ABS_MT_POSITION_X ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_ABSBIT, ABS_MT_POSITION_Y ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_ABSBIT, ABS_X ) == -1 );
	ERROR_IF( xioctl( fd, UI_SET_ABSBIT, ABS_Y ) == -1 );

	// create
	ERROR_IF( write( fd, &uidev, sizeof(uidev) ) != sizeof(uidev) );
	ERROR_IF( xioctl( fd, UI_DEV_CREATE ) == -1 );


	sendEvent( fd, EV_SYN, SYN_MT_REPORT, 0 );
	sendEvent( fd, EV_SYN, SYN_REPORT, 0 );

	// send random touches for a few seconds
	int j;
	for( j = 0; j < 10; j++ )
	{
		// send 32 random simultaneous touches
		int i;
		for( i = 0; i < 32; i++ )
		{
			sendEvent( fd, EV_ABS, ABS_MT_POSITION_X, rand()%4096 );
			sendEvent( fd, EV_ABS, ABS_MT_POSITION_Y, rand()%4096 );
			sendEvent( fd, EV_SYN, SYN_MT_REPORT, 0 );
		}
		sendEvent( fd, EV_SYN, SYN_REPORT, 0 );

		sleep( 1 );
	}


	// clean up
	ERROR_IF( xioctl( fd, UI_DEV_DESTROY ) == -1 );
	ERROR_IF( close( fd ) == -1 );

	return 0;
}