src/time/timer_create.c

   1 #include <time.h>
   2 #include "pthread_impl.h"
   3
   4 struct ksigevent {
   5         union sigval sigev_value;
   6         int sigev_signo;
   7         int sigev_notify;
   8         int sigev_tid;
   9 };
  10
  11 struct start_args {
  12         pthread_barrier_t b;
  13         struct sigevent *sev;
  14         timer_t t;
  15 };
  16
  17 static void sighandler(int sig, siginfo_t *si, void *ctx)
  18 {
  19         int st;
  20         timer_t t = si->si_value.sival_ptr;
  21         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &st);
  22         t->notify(t->val);
  23         pthread_setcancelstate(st, 0);
  24 }
  25
  26 static void killtimer(void *arg)
  27 {
  28         timer_t t = arg;
  29         if (t->timerid >= 0) __syscall(SYS_timer_delete, t->timerid);
  30 }
  31
  32 static void *start(void *arg)
  33 {
  34         struct start_args *args = arg;
  35         struct __timer t = {
  36                 .notify = args->sev->sigev_notify_function,
  37                 .val = args->sev->sigev_value,
  38         };
  39
  40         args->t = &t;
  41
  42         pthread_barrier_wait(&args->b);
  43
  44         pthread_cleanup_push(killtimer, &t);
  45         pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, 0);
  46         /* Loop on async-signal-safe cancellation point */
  47         for (;;) sleep(1);
  48         pthread_cleanup_pop(1);
  49         return 0;
  50 }
  51
  52 int timer_create(clockid_t clk, struct sigevent *evp, timer_t *res)
  53 {
  54         struct sigevent sev = {
  55                 .sigev_notify = SIGEV_SIGNAL,
  56                 .sigev_signo = SIGALRM
  57         };
  58         pthread_t td;
  59         pthread_attr_t attr;
  60         int r;
  61         struct start_args args;
  62         timer_t t;
  63         struct ksigevent ksev;
  64
  65         if (evp) sev = *evp;
  66
  67         switch (sev.sigev_notify) {
  68         case SIGEV_NONE:
  69         case SIGEV_SIGNAL:
  70                 if (!(t = calloc(1, sizeof *t)))
  71                         return -1;
  72                 ksev.sigev_value = evp ? sev.sigev_value
  73                         : (union sigval){.sival_ptr=t};
  74                 ksev.sigev_signo = sev.sigev_signo;
  75                 ksev.sigev_notify = sev.sigev_notify;
  76                 ksev.sigev_tid = 0;
  77                 break;
  78         case SIGEV_THREAD:
  79                 if (sev.sigev_notify_attributes)
  80                         attr = *sev.sigev_notify_attributes;
  81                 else
  82                         pthread_attr_init(&attr);
  83                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  84                 pthread_barrier_init(&args.b, 0, 2);
  85                 args.sev = &sev;
  86                 r = pthread_create(&td, &attr, start, &args);
  87                 if (r) {
  88                         errno = r;
  89                         return -1;
  90                 }
  91                 pthread_barrier_wait(&args.b);
  92                 t = args.t;
  93                 t->thread = td;
  94                 ksev.sigev_value.sival_ptr = t;
  95                 ksev.sigev_signo = SIGCANCEL;
  96                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
  97                 ksev.sigev_tid = td->tid;
  98                 if (!libc.sigtimer) libc.sigtimer = sighandler;
  99                 break;
 100         }
 101
 102         t->timerid = -1;
 103         if (syscall(SYS_timer_create, clk, &ksev, &t->timerid) < 0) {
 104                 timer_delete(t);
 105                 return -1;
 106         }
 107
 108         *res = t;
 109         return 0;
 110 }