signal.cxx

ecos实时嵌入式操作系统

    // the one supplied.
    sigset_t old = self->sigmask;
    self->sigmask = *set;

    // Loop until a signal gets delivered
    while( !cyg_deliver_signals() )
        signal_sigwait.wait();

    self->sigmask = old;
    
    signal_mutex.unlock();
    
    SIGNAL_RETURN(EINTR);
}
    

// -------------------------------------------------------------------------
// Wait for a signal in set to arrive
// Implement this as a variant on sigtimedwait().

externC int sigwait  (const sigset_t *set, int *sig)
{
    SIGNAL_ENTRY();

    siginfo_t info;
    
    int ret = sigtimedwait( set, &info, NULL );

    if( ret == -1 )
        SIGNAL_RETURN(errno);

    *sig = ret;
    
    SIGNAL_RETURN(0);
}

// -------------------------------------------------------------------------
// Do the same as sigwait() except return a siginfo_t object too.
// Implement this as a variant on sigtimedwait().

externC int sigwaitinfo  (const sigset_t *set, siginfo_t *info)
{
    SIGNAL_ENTRY();

    int ret = sigtimedwait( set, info, NULL );
    
    SIGNAL_RETURN_VALUE(ret);
}

// -------------------------------------------------------------------------
// Wait either for a signal in the given set to become pending, or
// for the timeout to expire. If timeout is NULL, wait for ever.

externC int sigtimedwait  (const sigset_t *set, siginfo_t *info,
                           const struct timespec *timeout)
{
    SIGNAL_ENTRY();

    // check for cancellation first.
    pthread_testcancel();

    int err = 0;
    cyg_tick_count ticks;

    if( timeout == NULL ) ticks = 0;
    else ticks = cyg_timespec_to_ticks( timeout ) +
             Cyg_Clock::real_time_clock->current_value();

    pthread_info *self = pthread_self_info();
    
    signal_mutex.lock();

    sigset_t todo;

    // Wait for a signal in the set to become pending
    while( (todo = (*set & (sig_pending | self->sigpending))) == 0 )
    {
        // If timeout is not NULL, do a timed wait on the
        // sigwait condition variable. If it is NULL - wait
        // until we are woken.
        if( timeout )
        {
            if( ticks == 0 || !signal_sigwait.wait(ticks) )
            {
                // If the timeout is actually zero, or we have waited and
                // timed out, then we must quit with an error.
                err = EAGAIN;
                break;
            }
        }
        else {
            if ( !signal_sigwait.wait() ) {
                // check we weren't woken up forcibly (e.g. to be cancelled)
                // if so, pretend it's an error
                err = EAGAIN;
                break;
            }
        }
        
        // Special case check for SIGALRM since the fact SIGALRM is masked
        // would have prevented it being set pending in the alarm handler.
        check_sigalarm();

        cyg_posix_timer_asr(self);
    }

    if( err == 0 )
    {
        // There is a signal in the set that is pending: deliver
        // it. todo contains a mask of all the signals that could be
        // delivered now, but we only want to deliver one of them.

        int signo = 0;

        // Select the lowest numbered signal from the todo mask
        HAL_LSBIT_INDEX( signo, todo );

        signal_state *ss = &sigstate[signo];
        sigset_t sigbit = 1L<<signo;

        if( (ss->sa.sa_flags & SA_SIGINFO) && (ss->pending != NULL) )
        {
            // If the SA_SIGINFO bit is set, then there
            // will be a signal_info object queued on the
            // pending field.

            signal_info *si = ss->pending->next;
            *info = si->si;

            // Remove the head signal_info object from the
            // circular list. 
            if( ss->pending == si )
                ss->pending = NULL;
            else
                ss->pending->next = si->next;
                
            si->next = siginfo_next;
            siginfo_next = si;
                
        }
        else
        {
            // Not a queued signal, or there is no signal_info object
            // on the pending queue: fill in info structure with
            // default values.
            info->si_signo           = signo;
            info->si_code            = SI_USER;
            info->si_value.sival_int = 0;
        }

        // Clear the bit from the pending masks. If the pending
        // queue is not empty, leave the bits set, otherwise clear
        // them.
        
        if( ss->pending == NULL )
        {
            // Clear the bit in both masks regardless of which
            // one it actually came from. This is cheaper than
            // trying to find out.
            sig_pending &= ~sigbit;
            self->sigpending &= ~sigbit;
        }

        // all done
    }
    
    signal_mutex.unlock();

    pthread_testcancel();

    if (err)
        SIGNAL_RETURN(err);
    else
        SIGNAL_RETURN_VALUE( info->si_signo );
}

//==========================================================================
// alarm, pause and sleep

// -------------------------------------------------------------------------
// Generate SIGALRM after some number of seconds

externC unsigned int alarm( unsigned int seconds )
{
    int res = 0;
    struct timespec tv;
    cyg_tick_count trigger, interval;

    SIGNAL_ENTRY();

    signal_mutex.lock();

    if( sigalrm_armed )
    {
        sigalrm_alarm.disable();

        sigalrm_alarm.get_times( &trigger, &interval );

        // Convert trigger time back to interval
        trigger -= Cyg_Clock::real_time_clock->current_value();
        
        cyg_ticks_to_timespec( trigger, &tv );

        res = tv.tv_sec;
        
        sigalrm_armed = false;
    }

    if( seconds != 0 )
    {
        // Here we know that the sigalrm_alarm is unarmed, set it up
        // to trigger in the required number of seconds.

        tv.tv_sec = seconds;
        tv.tv_nsec = 0;

        trigger = cyg_timespec_to_ticks( &tv );

        // Convert trigger interval to absolute time
        trigger += Cyg_Clock::real_time_clock->current_value();
        
        sigalrm_alarm.initialize( trigger, 0 );

        sigalrm_armed = true;
    }
    
    signal_mutex.unlock();

    CYG_REPORT_RETVAL(res);
    
    return res;
}

// -------------------------------------------------------------------------
// Wait for a signal to be delivered.

externC int pause( void )
{
    SIGNAL_ENTRY();

    signal_mutex.lock();

    // Check for any pending signals that can be delivered and
    // if there are none, wait for a signal to be generated
    if( !cyg_deliver_signals() )
        signal_sigwait.wait();

    // Now check again for some signals to deliver
    cyg_deliver_signals();
    
    signal_mutex.unlock();
    
    SIGNAL_RETURN(EINTR);
}

//==========================================================================
// Signal sets

// -------------------------------------------------------------------------
// Clear all signals from set.

externC int sigemptyset  (sigset_t *set)
{
    SIGNAL_ENTRY();

    *set = 0;
    
    SIGNAL_RETURN(0);
}
    

// -------------------------------------------------------------------------
// Set all signals in set.

externC int sigfillset  (sigset_t *set)
{
    SIGNAL_ENTRY();

    *set = ~0;
    
    SIGNAL_RETURN(0);
}
    

// -------------------------------------------------------------------------
// Add signo to set.

externC int sigaddset  (sigset_t *set, int signo)
{
    SIGNAL_ENTRY();

    int err = 0;
    
    if( !SIGNAL_VALID(signo) )
        err = EINVAL;
    else *set |= 1<<signo;
    
    SIGNAL_RETURN(err);
}
    

// -------------------------------------------------------------------------
// Remove signo from set.

externC int sigdelset  (sigset_t *set, int signo)
{
    SIGNAL_ENTRY();

    int err = 0;
    
    if( !SIGNAL_VALID(signo) )
        err = EINVAL;
    else *set &= ~(1<<signo);
    
    SIGNAL_RETURN(err);
}
    

// -------------------------------------------------------------------------
// Test whether signo is in set

externC int sigismember  (const sigset_t *set, int signo)
{
    SIGNAL_ENTRY();

    int ret = 0;
    
    if( !SIGNAL_VALID(signo) )
        SIGNAL_RETURN(EINVAL);

    if( *set & (1<<signo) ) ret = 1;

    CYG_REPORT_RETVAL( ret );
    return ret;
}

//==========================================================================
// ISO C compatibility functions

// -------------------------------------------------------------------------
// Installs a new signal handler for the specified signal, and returns
// the old handler

externC sa_sighandler_t signal(int sig, sa_sighandler_t handler)
{
    SIGNAL_ENTRY();

    int err;
    sa_sighandler_t ret;
    struct sigaction new_action;
    struct sigaction old_action;

    sigemptyset( &new_action.sa_mask );
    new_action.sa_flags = 0;
    new_action.sa_handler = handler;

    err = sigaction( sig, &new_action, &old_action );

    if( err < 0 )
        ret = SIG_ERR;
    else ret = old_action.sa_handler;
    
    CYG_REPORT_RETVAL( ret );
    return ret;    
}

// -------------------------------------------------------------------------
// raise() - ISO C 7.7.2 //
//
// Raises the signal, which will cause the current signal handler for
// that signal to be called

externC int raise(int sig)
{
    return kill( 0, sig );
}

// -------------------------------------------------------------------------
// siglongjmp()
// Restores signal mask and longjumps.

__externC void siglongjmp( sigjmp_buf env, int val )
{
    CYG_REPORT_FUNCNAME( "siglongjmp" );
    CYG_REPORT_FUNCARG2( "&env=%08x, val=%d", &env, val );

    // ISO C says that if we are passed val == 0, then we change it to 1
    if( val == 0 )
        val = 1;

    if( env[0].__savemask )
        pthread_sigmask( SIG_SETMASK, &env[0].__sigsavemask, NULL );
    
    HAL_REORDER_BARRIER(); // prevent any chance of optimisation re-ordering
    hal_longjmp( env[0].__jmp_buf, val );
    HAL_REORDER_BARRIER(); // prevent any chance of optimisation re-ordering

#ifdef CYGDBG_USE_ASSERTS
    CYG_ASSERT( 0, "siglongjmp should not have reached this point!" );
#else
    for (;;)
        CYG_EMPTY_STATEMENT;
#endif
    
}

#endif // ifdef CYGPKG_POSIX_SIGNALS

// -------------------------------------------------------------------------
// EOF signal.cxx