ssignal.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static	char	*sccsid = "@(#)ssignal.c	4.1	(ULTRIX)	7/3/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1985, 1988 by			*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/*
 *	Modification History
 *
 * 001	Jon Reeves, 1988-Aug-09
 *	Increase maximum signal to 'NSIG' for X/Open compliance
 */
/*	@(#)ssignal.c	1.2	*/
/*LINTLIBRARY*/
/*
 *	ssignal, gsignal: software signals
 */
#include <signal.h>

/* Highest allowable user signal number */
#define MAXSIG NSIG

/* Lowest allowable signal number (lowest user number is always 1) */
#define MINSIG (-4)

/* Table of signal values */
static int (*sigs[MAXSIG-MINSIG+1])();

int
(*ssignal(sig, fn))()
register int sig, (*fn)();
{
	register int (*savefn)();

	if(sig >= MINSIG && sig <= MAXSIG) {
		savefn = sigs[sig-MINSIG];
		sigs[sig-MINSIG] = fn;
	} else
		savefn = (int(*)())SIG_DFL;	/* DAG */

	return(savefn);
}

int
gsignal(sig)
register int sig;
{
	register int (*sigfn)();

	if(sig < MINSIG || sig > MAXSIG ||
				(sigfn = sigs[sig-MINSIG]) == (int(*)())SIG_DFL)	/* DAG */
		return(0);
	else if(sigfn == (int(*)())SIG_IGN)	/* DAG */
		return(1);
	else {
		sigs[sig-MINSIG] = (int(*)())SIG_DFL;	/* DAG */
		return((*sigfn)(sig));
	}
}