/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma weak _signal = signal
#pragma weak _sighold = sighold
#pragma weak _sigrelse = sigrelse
#pragma weak _sigignore = sigignore
#pragma weak _sigset = sigset

#include "lint.h"
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <wait.h>

/*
 * Check for valid signal number as per SVID.
 */
#define CHECK_SIG(s, code) \
        if ((s) <= 0 || (s) >= NSIG || (s) == SIGKILL || (s) == SIGSTOP) { \
                errno = EINVAL; \
                return (code); \
        }

/*
 * Equivalent to stopdefault set in the kernel implementation (sig.c).
 */
#define STOPDEFAULT(s) \
        ((s) == SIGSTOP || (s) == SIGTSTP || (s) == SIGTTOU || (s) == SIGTTIN)


/*
 * SVr3.x signal compatibility routines. They are now
 * implemented as library routines instead of system
 * calls.
 */

void(*
signal(int sig, void(*func)(int)))(int)
{
        struct sigaction nact;
        struct sigaction oact;

        CHECK_SIG(sig, SIG_ERR);

        nact.sa_handler = func;
        nact.sa_flags = SA_RESETHAND|SA_NODEFER;
        (void) sigemptyset(&nact.sa_mask);

        /*
         * Pay special attention if sig is SIGCHLD and
         * the disposition is SIG_IGN, per sysV signal man page.
         */
        if (sig == SIGCHLD) {
                nact.sa_flags |= SA_NOCLDSTOP;
                if (func == SIG_IGN)
                        nact.sa_flags |= SA_NOCLDWAIT;
        }

        if (STOPDEFAULT(sig))
                nact.sa_flags |= SA_RESTART;

        if (sigaction(sig, &nact, &oact) < 0)
                return (SIG_ERR);

        return (oact.sa_handler);
}

int
sighold(int sig)
{
        sigset_t set;

        CHECK_SIG(sig, -1);

        /*
         * errno set on failure by either sigaddset or sigprocmask.
         */
        (void) sigemptyset(&set);
        if (sigaddset(&set, sig) < 0)
                return (-1);
        return (sigprocmask(SIG_BLOCK, &set, (sigset_t *)0));
}

int
sigrelse(int sig)
{
        sigset_t set;

        CHECK_SIG(sig, -1);

        /*
         * errno set on failure by either sigaddset or sigprocmask.
         */
        (void) sigemptyset(&set);
        if (sigaddset(&set, sig) < 0)
                return (-1);
        return (sigprocmask(SIG_UNBLOCK, &set, (sigset_t *)0));
}

int
sigignore(int sig)
{
        struct sigaction act;
        sigset_t set;

        CHECK_SIG(sig, -1);

        act.sa_handler = SIG_IGN;
        act.sa_flags = 0;
        (void) sigemptyset(&act.sa_mask);

        /*
         * Pay special attention if sig is SIGCHLD and
         * the disposition is SIG_IGN, per sysV signal man page.
         */
        if (sig == SIGCHLD) {
                act.sa_flags |= SA_NOCLDSTOP;
                act.sa_flags |= SA_NOCLDWAIT;
        }

        if (STOPDEFAULT(sig))
                act.sa_flags |= SA_RESTART;

        if (sigaction(sig, &act, (struct sigaction *)0) < 0)
                return (-1);

        (void) sigemptyset(&set);
        if (sigaddset(&set, sig) < 0)
                return (-1);
        return (sigprocmask(SIG_UNBLOCK, &set, (sigset_t *)0));
}

int
__sigpause(int sig)
{
        sigset_t set;
        int rval;

        CHECK_SIG(sig, -1);

        /*
         * sigpause() is defined to unblock the signal
         * and not block it again on return.
         * sigsuspend() restores the original signal set,
         * so we have to unblock sig overtly.
         */
        (void) sigprocmask(0, (sigset_t *)0, &set);
        if (sigdelset(&set, sig) < 0)
                return (-1);
        rval = sigsuspend(&set);
        (void) sigrelse(sig);
        return (rval);
}

void(*
sigset(int sig, void(*func)(int)))(int)
{
        struct sigaction nact;
        struct sigaction oact;
        sigset_t nset;
        sigset_t oset;
        int code;

        CHECK_SIG(sig, SIG_ERR);

        (void) sigemptyset(&nset);
        if (sigaddset(&nset, sig) < 0)
                return (SIG_ERR);

        if (func == SIG_HOLD) {
                if (sigprocmask(SIG_BLOCK, &nset, &oset) < 0)
                        return (SIG_ERR);
                if (sigaction(sig, (struct sigaction *)0, &oact) < 0)
                        return (SIG_ERR);
        } else {
                nact.sa_handler = func;
                nact.sa_flags = 0;
                (void) sigemptyset(&nact.sa_mask);
                /*
                 * Pay special attention if sig is SIGCHLD and
                 * the disposition is SIG_IGN, per sysV signal man page.
                 */
                if (sig == SIGCHLD) {
                        nact.sa_flags |= SA_NOCLDSTOP;
                        if (func == SIG_IGN)
                                nact.sa_flags |= SA_NOCLDWAIT;
                }

                if (STOPDEFAULT(sig))
                        nact.sa_flags |= SA_RESTART;

                if (sigaction(sig, &nact, &oact) < 0)
                        return (SIG_ERR);

                if (sigprocmask(SIG_UNBLOCK, &nset, &oset) < 0)
                        return (SIG_ERR);
        }

        if ((code = sigismember(&oset, sig)) < 0)
                return (SIG_ERR);
        else if (code == 1)
                return (SIG_HOLD);

        return (oact.sa_handler);
}