CDE/cde/lib/tt/mini_isam/issignals.c

/*
 * CDE - Common Desktop Environment
 *
 * Copyright (c) 1993-2012, The Open Group. All rights reserved.
 *
 * These libraries and programs are free software; you can
 * redistribute them and/or modify them under the terms of the GNU
 * Lesser General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * These libraries and programs are distributed in the hope that
 * they will be useful, but WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with these libraries and programs; if not, write
 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
 * Floor, Boston, MA 02110-1301 USA
 */
/*%%  (c) Copyright 1993, 1994 Hewlett-Packard Company			 */
/*%%  (c) Copyright 1993, 1994 International Business Machines Corp.	 */
/*%%  (c) Copyright 1993, 1994 Sun Microsystems, Inc.			 */
/*%%  (c) Copyright 1993, 1994 Novell, Inc. 				 */
/*%%  $XConsortium: issignals.c /main/3 1995/10/23 11:44:41 rswiston $ 			 				 */
/*
 * Copyright (c) 1988 by Sun Microsystems, Inc.
 */

/*
 * issignals.c
 *
 * Description:
 *	Signal masking functions
 */


#include "isam_impl.h"
#include <signal.h>

/*
 * _issignal_mask() is called at the beginning of each ISAM update operation
 * to mask signals for the duration of the operation. _issignals_unmask()
 * is called at the end of the operation to restore the original signal
 * mask.
 *
 * _issignals_cntl() enables/disables this signal masking facility.
 * (the default is "mask the signals").
 *
 * The variable already_masked is used to provide more robustness: it
 * will prevent permanent signal masking due to bugs in the ISAM package.
 * The permanent masking of signals would happen if _issignals_mask()
 * were called twice in a row.
 */


static int      do_mask = 1;		    /* default value */
static int      already_masked;
static sigset_t oldmask;
static sigset_t allsignals;


/* opt, 1 will enable masking, 0 will disable masking */
int _issignals_cntl(int opt)
{
    int		oldmask = do_mask;

    do_mask = opt ? 1 : 0;

    return (oldmask);
}

void
_issignals_mask(void)
{
    if (do_mask && !already_masked) {
        (void) sigfillset(&allsignals);
        (void) sigdelset(&allsignals, SIGTRAP);
        (void) sigdelset(&allsignals, SIGSEGV);
        (void) sigdelset(&allsignals, SIGILL);
        (void) sigdelset(&allsignals, SIGBUS);
        (void) sigprocmask(SIG_SETMASK, &allsignals, &oldmask);
	already_masked = 1;
    }
}

void
_issignals_unmask(void)
{
    if (do_mask) {
	(void)sigprocmask(SIG_SETMASK, &oldmask, NULL);
	already_masked = 0;
    }
}