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util-linux/lib/timer.c

95 lines
2.3 KiB

/*
* Please, don't add this file to libcommon because timers requires
* -lrt on systems with old libc (and probably also -lpthread for static
* build).
*/
#include <time.h>
#include <signal.h>
#include <sys/time.h>
#include "c.h"
#include "timer.h"
/*
* Note the timeout is used for the first signal, then the signal is send
* repeatedly in interval ~1% of the original timeout to avoid race in signal
* handling -- for example you want to use timer to define timeout for a
* syscall:
*
* setup_timer()
* syscall()
* cancel_timer()
*
* if the timeout is too short than it's possible that the signal is delivered
* before application enter the syscall function. For this reason timer send
* the signal repeatedly.
*
* The applications need to ensure that they can tolerate multiple signal
* deliveries.
*/
#ifdef HAVE_TIMER_CREATE
int setup_timer(struct ul_timer *timer,
struct itimerval *timeout,
void (*timeout_handler)(int, siginfo_t *, void *))
{
time_t sec = timeout->it_value.tv_sec;
long usec = timeout->it_value.tv_usec;
struct sigaction sig_a;
static struct sigevent sig_e = {
.sigev_notify = SIGEV_SIGNAL,
.sigev_signo = SIGALRM
};
struct itimerspec val = {
.it_value.tv_sec = sec,
.it_value.tv_nsec = usec * 1000,
.it_interval.tv_sec = sec / 100,
.it_interval.tv_nsec = (sec ? sec % 100 : 1) * 10*1000*1000
};
if (sigemptyset(&sig_a.sa_mask))
return 1;
sig_a.sa_flags = SA_SIGINFO;
sig_a.sa_sigaction = timeout_handler;
if (sigaction(SIGALRM, &sig_a, NULL))
return 1;
if (timer_create(CLOCK_MONOTONIC, &sig_e, &timer->t_id))
return 1;
if (timer_settime(timer->t_id, 0, &val, NULL))
return 1;
return 0;
}
void cancel_timer(struct ul_timer *timer)
{
timer_delete(timer->t_id);
}
#else /* !HAVE_TIMER_CREATE */
int setup_timer(struct ul_timer *timer,
struct itimerval *timeout,
void (*timeout_handler)(int, siginfo_t *, void *))
{
struct sigaction sa;
memset(&sa, 0, sizeof sa);
memset(timer, 0, sizeof(*timer));
sa.sa_flags = SA_SIGINFO | SA_RESETHAND;
sa.sa_sigaction = timeout_handler;
if (sigaction(SIGALRM, &sa, &timer->old_sa))
return 1;
if (setitimer(ITIMER_REAL, timeout, &timer->old_timer) != 0)
return 1;
return 0;
}
void cancel_timer(struct ul_timer *timer)
{
setitimer(ITIMER_REAL, &timer->old_timer, NULL);
sigaction(SIGALRM, &timer->old_sa, NULL);
}
#endif /* !HAVE_TIMER_CREATE */