usr/src/lib/libc/gen/signal.c

/*
 * Copyright (c) 1985 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)signal.c    5.3 (Berkeley) %G%";
#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);
}