/*----------------------------------------------------------------------------*/
/* Note to Vermont Views Terminal Users.  This code was sent to us by a       */
/* Vermont Views customer, running Vermont Views on a SCO UNIX machine.	      */
/* The customer had a VV application running in the first virtual session     */
/* and while working in other virtual sessions, experienced bleed through     */
/* of the VV application running in the first virtual session.  Below is a    */
/* small program to demonstrate how to avoid this problem		      */
/*									      */
/* We do not support the code posted on the BBS by customers.   It is simply  */
/* put here to share information.  Because we did not write this code, we     */
/* can not support it.							      */
/*----------------------------------------------------------------------------*/


#include <sys/vt.h>
#include <signal.h>


main(argc,argv)
int argc;
char *argv[];
{ 	
	/* set vt structure for use with Vermont Views */ 
	static struct vt_mode vt_in = { VT_PROCESS, 0, SIGUSR1, SIGUSR2, SIGUSR1 };

	/* set vt structure to return to default operation */
	static struct vt_mode vt_out = { VT_AUTO, 0, 0, 0, 0 };
		

	/* set user signals to point to custom release / custom acquire routines */
	signal(SIGUSR1,cust_rel);
	signal(SIGUSR2,cust_acq);

	/* tell SCO virtual terminal driver that we will handle vt switches */
	ioctl(1,VT_SETMODE,&vt_in);

	vv_init();

	/* NOTE: - before terminating this program the vt driver should be reset 
	         - disallow aborts to make sure this is done 
	           (A kill -9 will still kill this program and leave the virtual
			   terminal driver in a bad state) */
	se_abortfp((ISVRP)NULLFP);


	/*

	.........main body........

	*/

	vv_exit();

	/* reset vt driver */
	ioctl(1,VT_SETMODE,&vt_out);

	/* reset signals */
	signal(SIGUSR1,SIG_DFL);
	signal(SIGUSR2,SIG_DFL);

}


/* custom release routine (called when the user wants to switch from a vt
   that is running VV to another vt) */
static void cust_rel()
{
	/* turn off signal */
	signal(SIGUSR1, SIG_IGN);

	/* disable screen writing */
	_vid_echo = OFF;

	/* force vt switch */
	ioctl(1,VT_RELDISP,1);

	/* re-establish signal */
	signal(SIGUSR1,cust_rel);

	return;
}


/* custom acquire routine (called when the user wants to switch from a vt
   to another vt running VV) */
static void cust_acq()
{
	/* turn off signal */
	signal(SIGUSR2, SIG_IGN);

	/* re-enable screen writing */
	_vid_echo = ON;

	/* force vt switch */
	ioctl(1,VT_RELDISP,VT_ACKACQ);

	/* re-establish signal */
	vs_refresh();

	/* re-establish signal */
	signal(SIGUSR2,cust_acq);

	return;
}