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From: tas@mtuxo.UUCP (t.skrobala)
Newsgroups: net.micro.amiga,comp.sys.amiga
Subject: Capturing ^C
Message-ID: <2210@mtuxo.UUCP>
Date: Thu, 6-Nov-86 08:37:56 EST
Article-I.D.: mtuxo.2210
Posted: Thu Nov  6 08:37:56 1986
Date-Received: Fri, 7-Nov-86 22:44:05 EST
Distribution: na
Organization: AT&T Information Systems Labs, Holmdel NJ
Lines: 75
Xref: watmath net.micro.amiga:5751 comp.sys.amiga:1

...Throw me a line...

Is there a way to capture ^C signals on Amiga in a manner analagous to
UNIX signal()?  I'd like to be able to abort recalcitrant programs with
^C, but do some cleanup before exiting.  Thus I'd like a function to be
called when ^C is typed.  My reading of the ROM Kernel Manual suggests
that SigExcept() is the key, but, in the example below, my onintr()
function only gets called once (with d0 set to 0), when SetExcept() is
called, and never thereafter; ^C's are ignored.  If I explicitly call
signal(task, SIGBREAKF_CTRL_C), onintr() *does* get called.  If I don't
call SetExcept(), ^C produces an immediate exit (after I hit RETURN to
satisfy the read()).

I know that it's possible to check for ^C with SetSignal() after
every read(), but I'm hoping that there's a less burdensome way
to detect the exception.

I am using Manx Aztec C with 1.1 Amiga software.

Thanks,
Tom Skrobala AT&T Information Systems  ihnp4!ariel!tas

--------------------------------------------------------------

#include <exec/types.h>
#include <exec/tasks.h>
#include <libraries/dos.h>
#include <stdio.h>
#include <functions.h>

long exceptID ;
long hadIntr ;

#asm
	public	_onintr
_onintr:
	or.l d0,_exceptID
	add.l #1,_hadIntr
	rts
#endasm

extern onintr() ;


main()
{
	struct Task	*task ;
	long		oldSignals ;
	char		buf[10] ;
	int		n ;

	exceptID = 0 ;
	hadIntr = 0 ;

	task = FindTask( NULL ) ;
	printf( "task=0x%lx\n", task ) ;

	task->tc_ExceptCode = (APTR)onintr ;
	oldSignals = SetExcept( SIGBREAKF_CTRL_C, SIGBREAKF_CTRL_C ) ;

	while( n = read( 0, buf, 10 ), buf[0] != 'x' )
	{
		if( exceptID || hadIntr )
		{
			printf( "received %ld signal(s) 0x%lx\n",
				hadIntr, exceptID ) ;
			exceptID = 0 ;
			hadIntr = 0 ;
		}
		printf( "received n=%d, %c\n", n, buf[0] ) ;
		if( n < 0 )
			printf( "received err=%ld\n", IoErr() ) ;
	}
	printf( "out of loop\n" ) ;
}