From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Fri, 13 Oct 1995 15:29:23 -0400
From: beto@plan9.cs.su.oz.au beto@plan9.cs.su.oz.au
Subject: Panel + forks + postnote
Topicbox-Message-UUID: 2da29bc8-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19951013192923.p310uFZ5Wv6r5NeNLXsasWYGcHvN0SJTna11eb1iiLI@z>

Hi, 

I'm writing a program which uses the Panel library, 
starts new processes based on mouse actions and
after a while kills those processes, but the interface
should not died. Is this possible? Has any one tried?
Mothra uses it, put only kills subprocesses in fatal
conditions, which do not require the Panel to keep 
working.

I'm having problems after killing processes with
the panel library. It looks like there is some kind of
sincronization program, I'm not quite sure what's going on.
The error is 
	bitblt: bad slave 32 on event pipe: fd out of
	range or not open

Here is an small program with I hope will
reproduce the problem. 

Any help would be appreciated.
thanks
beto


#include <u.h>
#include <libc.h>
#include <libg.h>
#include <panel.h>
Panel *root;

void playnetwork(void);
void killall(void);

void restart(Panel *p, int buttons){
	USED(p, buttons);
	killall();
	playnetwork();
}
/*
  * To see the problem just press
  * retstart
  */
void main(void){
	rfork(RFNOTEG|RFNAMEG);
	binit(0, 0, 0);
	einit(Emouse);
	plinit(screen.ldepth);

	root=plframe(0, 0);
	pllabel(root, 0, "Playing.....");
	plbutton(root, 0, "restart", restart);

	ereshaped(screen.r);
	playnetwork();
	for(;;) plmouse(root, emouse());
}

void ereshaped(Rectangle r){
	screen.r=r;
	plpack(root, r);
	bitblt(&screen, r.min, &screen, r, Zero);
	pldraw(root, &screen);
}


/* from mothra.c */
void filter(char *cmd, int fd, int teefd){
	char cmdbuf[512];
	if(teefd!=-1) sprint(cmdbuf, "tee -a /fd/%d | %s", teefd, cmd);
	else strcpy(cmdbuf, cmd);
	bflush();
	switch(rfork(RFFDG|RFPROC|RFNOWAIT)){
	case -1:
		break;
	case 0:
		/*close(0);
		bclose();
		dup(fd, 0);
		close(fd);/**/
		execl("/bin/rc", "rc", "-c", cmdbuf, 0);
		_exits(0); 
	default:
		break;
	}
	close(teefd);
	close(fd);
}
void
playnetwork(void)
{
	filter("sleep 1000", 0,-1);
}
void 
killall(void)
{
	postnote(PNGROUP, getpid(), "kill\n");
}