4.3BSD-UWisc/src/lib/libc/gen/signal.c

#if defined(LIBC_RCS) && !defined(lint)
static char rcs_id[] =
	"$Header: signal.c,v 1.3 86/09/08 14:45:16 tadl Exp $";
#endif
/*
 * RCS info
 *	$Locker:  $
 */
/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)signal.c	5.2 (Berkeley) 3/9/86";
#endif LIBC_SCCS and not lint

/*
 * Almost backwards compatible signal.
 */
#include <signal.h>

int (*
signal(s, a))()
	int s, (*a)();
{
	struct sigvec osv, sv;
	static int mask[NSIG];
	static int flags[NSIG];

	sv.sv_handler = a;
	sv.sv_mask = mask[s];
	sv.sv_flags = flags[s];
	if (sigvec(s, &sv, &osv) < 0)
		return (BADSIG);
	if (sv.sv_mask != osv.sv_mask || sv.sv_flags != osv.sv_flags) {
		mask[s] = sv.sv_mask = osv.sv_mask;
		flags[s] = sv.sv_flags = osv.sv_flags;
		if (sigvec(s, &sv, 0) < 0)
			return (BADSIG);
	}
	return (osv.sv_handler);
}