path: root/calendar/alarm.c

/*
 * Alarm handling for the GNOME Calendar.
 *
 * (C) 1998 the Free Software Foundation
 *
 * Author: Miguel de Icaza (miguel@kernel.org)
 */
#include <config.h>
#include <time.h>
#include <gnome.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/time.h>
#include "alarm.h"

/* The pipes used to notify about an alarm */
int alarm_pipes [2];

/* The list of pending alarms */
static GList *alarms;

static void *head_alarm;

typedef struct {
    time_t        activation_time;
    AlarmFunction fn;
    void          *closure;
} AlarmRecord;

/*
 * SIGALRM handler.  Notifies the callback about the alarm
 */
static void
alarm_activate ()
{
    char c = 0;

    write (alarm_pipes [1], &c, 1);
}

static void
alarm_ready (void *closure, int fd, GdkInputCondition cond)
{
    AlarmRecord *ar = head_alarm;
    char c;

    if (read (alarm_pipes [0], &c, 1) != 1)
        return;

    if (ar == NULL){
        g_warning ("Empty events.  This should not happen\n");
        return;
    }
    (*ar->fn)(ar->activation_time, ar->closure);
    alarms = g_list_remove (alarms, head_alarm);
    if (alarms)
        head_alarm = alarms->data;
    else
        head_alarm = NULL;
    g_free (ar);
}

static int
alarm_compare_by_time (gconstpointer a, gconstpointer b)
{
    const AlarmRecord *ara = a;
    const AlarmRecord *arb = b;
    time_t diff;
    
    diff = ara->activation_time - arb->activation_time;
    return (diff < 0) ? -1 : (diff > 0) ? 1 : 0;
}

void
alarm_add (time_t alarm_time, AlarmFunction fn, void *closure)
{
    time_t now = time (NULL);
    AlarmRecord *ar;

    /* If it already expired, do not add it */
    if (alarm_time < now)
        return;
    
    ar = g_new0 (AlarmRecord, 1);
    ar->activation_time = alarm_time;
    ar->fn = fn;
    ar->closure = closure;

    alarms = g_list_insert_sorted (alarms, ar, alarm_compare_by_time);

    /* If first alarm is not the previous first alarm, reschedule SIGALRM */
    if (head_alarm != alarms->data){
        struct itimerval itimer;
        int v;
        
        /* Set the timer to disable upon activation */
        itimer.it_interval.tv_sec = 0;
        itimer.it_interval.tv_usec = 0;
        itimer.it_value.tv_sec = alarm_time - now;
        itimer.it_value.tv_usec = 0;
        v = setitimer (ITIMER_REAL, &itimer, NULL);
        head_alarm = alarms->data;
    }
}

int 
alarm_kill (void *closure_key)
{
    GList *p;

    for (p = alarms; p; p = p->next){
        AlarmRecord *ar = p->data;
        
        if (ar->closure == closure_key){
            alarms = g_list_remove (alarms, p->data);
            if (alarms)
                head_alarm = alarms->data;
            else
                head_alarm = NULL;
            return 1;
        }
    }
    return 0;
}

void
alarm_init (void)
{
    struct sigaction sa;
    int flags;
    
    pipe (alarm_pipes);
    
    /* set non blocking mode */
    fcntl (alarm_pipes [0], F_GETFL, &flags);
    fcntl (alarm_pipes [0], F_SETFL, flags | O_NONBLOCK);
    gdk_input_add (alarm_pipes [0], GDK_INPUT_READ, alarm_ready, 0);

    /* Setup the signal handler */
    sa.sa_handler = alarm_activate;
    sigemptyset (&sa.sa_mask);
    sa.sa_flags   = SA_RESTART;
    sigaction (SIGALRM, &sa, NULL);
}