1 /*
2 * Please, don't add this file to libcommon because timers requires
3 * -lrt on systems with old libc (and probably also -lpthread for static
4 * build).
5 */
6 #include <time.h>
7 #include <signal.h>
8 #include <sys/time.h>
9
10 #include "c.h"
11 #include "timer.h"
12
13 /*
14 * Note the timeout is used for the first signal, then the signal is send
15 * repeatedly in interval ~1% of the original timeout to avoid race in signal
16 * handling -- for example you want to use timer to define timeout for a
17 * syscall:
18 *
19 * setup_timer()
20 * syscall()
21 * cancel_timer()
22 *
23 * if the timeout is too short than it's possible that the signal is delivered
24 * before application enter the syscall function. For this reason timer send
25 * the signal repeatedly.
26 *
27 * The applications need to ensure that they can tolerate multiple signal
28 * deliveries.
29 */
30 #ifdef HAVE_TIMER_CREATE
setup_timer(struct ul_timer * timer,struct itimerval * timeout,void (* timeout_handler)(int,siginfo_t *,void *))31 int setup_timer(struct ul_timer *timer,
32 struct itimerval *timeout,
33 void (*timeout_handler)(int, siginfo_t *, void *))
34 {
35 time_t sec = timeout->it_value.tv_sec;
36 long usec = timeout->it_value.tv_usec;
37 struct sigaction sig_a;
38 static struct sigevent sig_e = {
39 .sigev_notify = SIGEV_SIGNAL,
40 .sigev_signo = SIGALRM
41 };
42 struct itimerspec val = {
43 .it_value.tv_sec = sec,
44 .it_value.tv_nsec = usec * 1000,
45 .it_interval.tv_sec = sec / 100,
46 .it_interval.tv_nsec = (sec ? sec % 100 : 1) * 10*1000*1000
47 };
48
49 if (sigemptyset(&sig_a.sa_mask))
50 return 1;
51
52 sig_a.sa_flags = SA_SIGINFO;
53 sig_a.sa_sigaction = timeout_handler;
54
55 if (sigaction(SIGALRM, &sig_a, NULL))
56 return 1;
57 if (timer_create(CLOCK_MONOTONIC, &sig_e, &timer->t_id))
58 return 1;
59 if (timer_settime(timer->t_id, 0, &val, NULL))
60 return 1;
61 return 0;
62 }
cancel_timer(struct ul_timer * timer)63 void cancel_timer(struct ul_timer *timer)
64 {
65 timer_delete(timer->t_id);
66 }
67
68 #else /* !HAVE_TIMER_CREATE */
69
setup_timer(struct ul_timer * timer,struct itimerval * timeout,void (* timeout_handler)(int,siginfo_t *,void *))70 int setup_timer(struct ul_timer *timer,
71 struct itimerval *timeout,
72 void (*timeout_handler)(int, siginfo_t *, void *))
73 {
74 struct sigaction sa;
75
76 memset(&sa, 0, sizeof sa);
77 memset(timer, 0, sizeof(*timer));
78
79 sa.sa_flags = SA_SIGINFO | SA_RESETHAND;
80 sa.sa_sigaction = timeout_handler;
81
82 if (sigaction(SIGALRM, &sa, &timer->old_sa))
83 return 1;
84 if (setitimer(ITIMER_REAL, timeout, &timer->old_timer) != 0)
85 return 1;
86 return 0;
87 }
88
cancel_timer(struct ul_timer * timer)89 void cancel_timer(struct ul_timer *timer)
90 {
91 setitimer(ITIMER_REAL, &timer->old_timer, NULL);
92 sigaction(SIGALRM, &timer->old_sa, NULL);
93
94 }
95 #endif /* !HAVE_TIMER_CREATE */
96