/* 
 * Copyright (C) 2004 Andrew Beekhof <andrew@beekhof.net>
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <crm_internal.h>

#ifndef _GNU_SOURCE
#  define _GNU_SOURCE
#endif

#include <stdlib.h>
#include <signal.h>
#include <errno.h>

#include <crm/crm.h>
#include <crm/common/mainloop.h>

static gboolean
crm_trigger_prepare(GSource* source, gint *timeout)
{
    crm_trigger_t *trig = (crm_trigger_t*)source;
    return trig->trigger;
}

static gboolean
crm_trigger_check(GSource* source)
{
    crm_trigger_t *trig = (crm_trigger_t*)source;
    return trig->trigger;
}

static gboolean
crm_trigger_dispatch(GSource *source, GSourceFunc callback, gpointer userdata)
{
    crm_trigger_t *trig = (crm_trigger_t*)source;
    trig->trigger = FALSE;

    if(callback) {
	return callback(trig->user_data);
    }
    return TRUE;
}

static GSourceFuncs crm_trigger_funcs = {
    crm_trigger_prepare,
    crm_trigger_check,
    crm_trigger_dispatch,
    NULL
};

static crm_trigger_t *
mainloop_setup_trigger(
    GSource *source, int priority, gboolean (*dispatch)(gpointer user_data), gpointer userdata)
{
    crm_trigger_t *trigger = NULL;
    trigger = (crm_trigger_t*) source;

    trigger->id = 0;
    trigger->trigger = FALSE;
    trigger->user_data = userdata;

    if(dispatch) {
	g_source_set_callback(source, dispatch, trigger, NULL);
    }
    
    g_source_set_priority(source, priority);
    g_source_set_can_recurse(source, FALSE);

    trigger->id = g_source_attach(source, NULL);
    return trigger;
}

crm_trigger_t *
mainloop_add_trigger(
    int priority, gboolean (*dispatch)(gpointer user_data), gpointer userdata)
{
    GSource *source = NULL;

    CRM_ASSERT(sizeof(crm_trigger_t) > sizeof(GSource));
    source = g_source_new(&crm_trigger_funcs, sizeof(crm_trigger_t));
    CRM_ASSERT(source != NULL);

    return mainloop_setup_trigger(source, priority, dispatch, userdata);
}

void 
mainloop_set_trigger(crm_trigger_t* source)
{
    source->trigger = TRUE;
}

gboolean 
mainloop_destroy_trigger(crm_trigger_t* source)
{
    source->trigger = FALSE;
    if (source->id > 0) {
	g_source_remove(source->id);
    }
    return TRUE;
}

typedef struct signal_s 
{
	crm_trigger_t trigger; /* must be first */
	void (*handler)(int sig);
	int signal;

} crm_signal_t;

static crm_signal_t *crm_signals[NSIG];

static gboolean
crm_signal_dispatch(GSource *source, GSourceFunc callback, gpointer userdata)
{
    crm_signal_t *sig = (crm_signal_t*)source;
    crm_info("Invoking handler for signal %d: %s",
	     sig->signal, strsignal(sig->signal));

    sig->trigger.trigger = FALSE;
    if(sig->handler) {
	sig->handler(sig->signal);
    }
    return TRUE;
}

static void mainloop_signal_handler(int sig) 
{
    if(sig > 0 && sig < NSIG && crm_signals[sig] != NULL) {
	mainloop_set_trigger((crm_trigger_t*)crm_signals[sig]);
    }
}

static GSourceFuncs crm_signal_funcs = {
    crm_trigger_prepare,
    crm_trigger_check,
    crm_signal_dispatch,
    NULL
};

gboolean crm_signal(int sig, void (*dispatch)(int sig)) 
{
    sigset_t mask;
    struct sigaction sa;
    struct sigaction old;    

    if(sigemptyset(&mask) < 0) {
	crm_perror(LOG_ERR, "Call to sigemptyset failed");
	return FALSE;
    }
    
    sa.sa_handler = dispatch;
    sa.sa_flags = SA_RESTART;
    sa.sa_mask = mask;
    
    if(sigaction(sig, &sa, &old) < 0) {
	crm_perror(LOG_ERR, "Could not install signal handler for signal %d", sig);
	return FALSE;
    }
    
    return TRUE;
}

gboolean
mainloop_add_signal(int sig, void (*dispatch)(int sig))
{
    GSource *source = NULL;
    int priority = G_PRIORITY_HIGH - 1;
    if(sig == SIGTERM) {
	/* TERM is higher priority than other signals,
	 *   signals are higher priority than other ipc.
	 * Yes, minus: smaller is "higher"
	 */
	priority--;
    }
    
    if(sig >= NSIG || sig < 0) {
	crm_err("Signal %d is out of range", sig);
	return FALSE;
	
    } else if(crm_signals[sig] != NULL) {
	crm_err("Signal handler for %d is already installed", sig);
	return FALSE;
    }
    
    CRM_ASSERT(sizeof(crm_signal_t) > sizeof(GSource));
    source = g_source_new(&crm_signal_funcs, sizeof(crm_signal_t));

    crm_signals[sig] = (crm_signal_t*)mainloop_setup_trigger(source, priority, NULL, NULL);
    CRM_ASSERT(crm_signals[sig] != NULL);

    crm_signals[sig]->handler = dispatch;
    crm_signals[sig]->signal = sig;

    if(crm_signal(sig, mainloop_signal_handler) == FALSE) {
	crm_signal_t *tmp = crm_signals[sig];
	crm_signals[sig] = NULL;

	mainloop_destroy_trigger((crm_trigger_t*)tmp);
	return FALSE;
    }
    
    return TRUE;
}

gboolean 
mainloop_destroy_signal(int sig)
{
    crm_signal_t *tmp = NULL;
    
    if(sig >= NSIG || sig < 0) {
	crm_err("Signal %d is out of range", sig);
	return FALSE;

    } else if(crm_signal(sig, NULL) == FALSE) {
	crm_perror(LOG_ERR, "Could not uninstall signal handler for signal %d", sig);
	return FALSE;

    } else if(crm_signals[sig] == NULL) {
	return TRUE;
    }

    tmp = crm_signals[sig];
    crm_signals[sig] = NULL;
    mainloop_destroy_trigger((crm_trigger_t*)tmp);
    return TRUE;
}