/*
 * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: signal.c,v 1.17 2005/06/14 23:07:20 ca Exp $")

#if SM_CONF_SETITIMER
# include <sm/time.h>
#endif /* SM_CONF_SETITIMER */
#include <errno.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <sm/clock.h>
#include <sm/signal.h>
#include <signal.h>
#include <sm/string.h>

unsigned int    volatile InCriticalSection; /* >0 if inside critical section */
int             volatile PendingSignal; /* pending signal to resend */

/*
**  SM_SIGNAL -- set a signal handler
**
**      This is essentially old BSD "signal(3)".
**
**      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
**              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
**              DOING.
*/

sigfunc_t
sm_signal(sig, handler)
        int sig;
        sigfunc_t handler;
{
# if defined(SA_RESTART) || (!defined(SYS5SIGNALS) && !defined(BSD4_3))
        struct sigaction n, o;
# endif /* defined(SA_RESTART) || (!defined(SYS5SIGNALS) && !defined(BSD4_3)) */

        /*
        **  First, try for modern signal calls
        **  and restartable syscalls
        */

# ifdef SA_RESTART
        (void) memset(&n, '\0', sizeof n);
#  if USE_SA_SIGACTION
        n.sa_sigaction = (void(*)(int, siginfo_t *, void *))(uintptr_t) handler;
        n.sa_flags = SA_RESTART|SA_SIGINFO;
#  else /* USE_SA_SIGACTION */
        n.sa_handler = handler;
        n.sa_flags = SA_RESTART;
#  endif /* USE_SA_SIGACTION */
        if (sigaction(sig, &n, &o) < 0)
                return SIG_ERR;
        return o.sa_handler;
# else /* SA_RESTART */

        /*
        **  Else check for SYS5SIGNALS or
        **  BSD4_3 signals
        */

#  if defined(SYS5SIGNALS) || defined(BSD4_3)
#   ifdef BSD4_3
        return signal(sig, handler);
#   else /* BSD4_3 */
        return sigset(sig, handler);
#   endif /* BSD4_3 */
#  else /* defined(SYS5SIGNALS) || defined(BSD4_3) */

        /*
        **  Finally, if nothing else is available,
        **  go for a default
        */

        (void) memset(&n, '\0', sizeof n);
        n.sa_handler = handler;
        if (sigaction(sig, &n, &o) < 0)
                return SIG_ERR;
        return o.sa_handler;
#  endif /* defined(SYS5SIGNALS) || defined(BSD4_3) */
# endif /* SA_RESTART */
}
/*
**  SM_BLOCKSIGNAL -- hold a signal to prevent delivery
**
**      Parameters:
**              sig -- the signal to block.
**
**      Returns:
**              1 signal was previously blocked
**              0 signal was not previously blocked
**              -1 on failure.
*/

int
sm_blocksignal(sig)
        int sig;
{
# ifdef BSD4_3
#  ifndef sigmask
#   define sigmask(s)   (1 << ((s) - 1))
#  endif /* ! sigmask */
        return (sigblock(sigmask(sig)) & sigmask(sig)) != 0;
# else /* BSD4_3 */
#  ifdef ALTOS_SYSTEM_V
        sigfunc_t handler;

        handler = sigset(sig, SIG_HOLD);
        if (handler == SIG_ERR)
                return -1;
        else
                return handler == SIG_HOLD;
#  else /* ALTOS_SYSTEM_V */
        sigset_t sset, oset;

        (void) sigemptyset(&sset);
        (void) sigaddset(&sset, sig);
        if (sigprocmask(SIG_BLOCK, &sset, &oset) < 0)
                return -1;
        else
                return sigismember(&oset, sig);
#  endif /* ALTOS_SYSTEM_V */
# endif /* BSD4_3 */
}
/*
**  SM_RELEASESIGNAL -- release a held signal
**
**      Parameters:
**              sig -- the signal to release.
**
**      Returns:
**              1 signal was previously blocked
**              0 signal was not previously blocked
**              -1 on failure.
*/

int
sm_releasesignal(sig)
        int sig;
{
# ifdef BSD4_3
        return (sigsetmask(sigblock(0) & ~sigmask(sig)) & sigmask(sig)) != 0;
# else /* BSD4_3 */
#  ifdef ALTOS_SYSTEM_V
        sigfunc_t handler;

        handler = sigset(sig, SIG_HOLD);
        if (sigrelse(sig) < 0)
                return -1;
        else
                return handler == SIG_HOLD;
#  else /* ALTOS_SYSTEM_V */
        sigset_t sset, oset;

        (void) sigemptyset(&sset);
        (void) sigaddset(&sset, sig);
        if (sigprocmask(SIG_UNBLOCK, &sset, &oset) < 0)
                return -1;
        else
                return sigismember(&oset, sig);
#  endif /* ALTOS_SYSTEM_V */
# endif /* BSD4_3 */
}
/*
**  PEND_SIGNAL -- Add a signal to the pending signal list
**
**      Parameters:
**              sig -- signal to add
**
**      Returns:
**              none.
**
**      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
**              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
**              DOING.
*/

void
pend_signal(sig)
        int sig;
{
        int sigbit;
        int save_errno = errno;
#if SM_CONF_SETITIMER
        struct itimerval clr;
#endif /* SM_CONF_SETITIMER */

        /*
        **  Don't want to interrupt something critical, hence delay
        **  the alarm for one second.  Hopefully, by then we
        **  will be out of the critical section.  If not, then
        **  we will just delay again.  The events to be run will
        **  still all be run, maybe just a little bit late.
        */

        switch (sig)
        {
          case SIGHUP:
                sigbit = PEND_SIGHUP;
                break;

          case SIGINT:
                sigbit = PEND_SIGINT;
                break;

          case SIGTERM:
                sigbit = PEND_SIGTERM;
                break;

          case SIGUSR1:
                sigbit = PEND_SIGUSR1;
                break;

          case SIGALRM:
                /* don't have to pend these */
                sigbit = 0;
                break;

          default:
                /* If we get here, we are in trouble */
                abort();

                /* NOTREACHED */
                /* shut up stupid compiler warning on HP-UX 11 */
                sigbit = 0;
                break;
        }

        if (sigbit != 0)
                PendingSignal |= sigbit;
        (void) sm_signal(SIGALRM, sm_tick);
#if SM_CONF_SETITIMER
        clr.it_interval.tv_sec = 0;
        clr.it_interval.tv_usec = 0;
        clr.it_value.tv_sec = 1;
        clr.it_value.tv_usec = 0;
        (void) setitimer(ITIMER_REAL, &clr, NULL);
#else /* SM_CONF_SETITIMER */
        (void) alarm(1);
#endif /* SM_CONF_SETITIMER */
        errno = save_errno;
}
/*
**  SM_ALLSIGNALS -- act on all signals
**
**      Parameters:
**              block -- whether to block or release all signals.
**
**      Returns:
**              none.
*/

void
sm_allsignals(block)
        bool block;
{
# ifdef BSD4_3
#  ifndef sigmask
#   define sigmask(s)   (1 << ((s) - 1))
#  endif /* ! sigmask */
        if (block)
        {
                int mask = 0;

                mask |= sigmask(SIGALRM);
                mask |= sigmask(SIGCHLD);
                mask |= sigmask(SIGHUP);
                mask |= sigmask(SIGINT);
                mask |= sigmask(SIGTERM);
                mask |= sigmask(SIGUSR1);

                (void) sigblock(mask);
        }
        else
                sigsetmask(0);
# else /* BSD4_3 */
#  ifdef ALTOS_SYSTEM_V
        if (block)
        {
                (void) sigset(SIGALRM, SIG_HOLD);
                (void) sigset(SIGCHLD, SIG_HOLD);
                (void) sigset(SIGHUP, SIG_HOLD);
                (void) sigset(SIGINT, SIG_HOLD);
                (void) sigset(SIGTERM, SIG_HOLD);
                (void) sigset(SIGUSR1, SIG_HOLD);
        }
        else
        {
                (void) sigset(SIGALRM, SIG_DFL);
                (void) sigset(SIGCHLD, SIG_DFL);
                (void) sigset(SIGHUP, SIG_DFL);
                (void) sigset(SIGINT, SIG_DFL);
                (void) sigset(SIGTERM, SIG_DFL);
                (void) sigset(SIGUSR1, SIG_DFL);
        }
#  else /* ALTOS_SYSTEM_V */
        sigset_t sset;

        (void) sigemptyset(&sset);
        (void) sigaddset(&sset, SIGALRM);
        (void) sigaddset(&sset, SIGCHLD);
        (void) sigaddset(&sset, SIGHUP);
        (void) sigaddset(&sset, SIGINT);
        (void) sigaddset(&sset, SIGTERM);
        (void) sigaddset(&sset, SIGUSR1);
        (void) sigprocmask(block ? SIG_BLOCK : SIG_UNBLOCK, &sset, NULL);
#  endif /* ALTOS_SYSTEM_V */
# endif /* BSD4_3 */
}
/*
**  SM_SIGNAL_NOOP -- A signal no-op function
**
**      Parameters:
**              sig -- signal received
**
**      Returns:
**              SIGFUNC_RETURN
*/

/* ARGSUSED */
SIGFUNC_DECL
sm_signal_noop(sig)
        int sig;
{
        int save_errno = errno;

        FIX_SYSV_SIGNAL(sig, sm_signal_noop);
        errno = save_errno;
        return SIGFUNC_RETURN;
}