nsz Git - musl/blob - 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 };
  15
  16 static void sighandler(int sig, siginfo_t *si, void *ctx)
  17 {
  18         int st;
  19         pthread_t self = __pthread_self();
  20         void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  21         union sigval val = { .sival_ptr = self->start_arg };
  22
  23         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &st);
  24         notify(val);
  25         pthread_setcancelstate(st, 0);
  26 }
  27
  28 static void *start(void *arg)
  29 {
  30         pthread_t self = __pthread_self();
  31         struct start_args *args = arg;
  32
  33         /* Reuse no-longer-needed thread structure fields to avoid
  34          * needing the timer address in the signal handler. */
  35         self->start = (void *(*)(void *))args->sev->sigev_notify_function;
  36         self->start_arg = args->sev->sigev_value.sival_ptr;
  37         self->result = (void *)-1;
  38
  39         pthread_barrier_wait(&args->b);
  40         pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, 0);
  41         /* Loop on async-signal-safe cancellation point */
  42         for (;;) sleep(1);
  43         return 0;
  44 }
  45
  46 int timer_create(clockid_t clk, struct sigevent *evp, timer_t *res)
  47 {
  48         struct sigevent sev = {
  49                 .sigev_notify = SIGEV_SIGNAL,
  50                 .sigev_signo = SIGALRM
  51         };
  52         pthread_t td;
  53         pthread_attr_t attr;
  54         int r;
  55         struct start_args args;
  56         timer_t t;
  57         struct ksigevent ksev;
  58         int timerid;
  59
  60         if (evp) sev = *evp;
  61
  62         switch (sev.sigev_notify) {
  63         case SIGEV_NONE:
  64         case SIGEV_SIGNAL:
  65                 ksev.sigev_value = evp ? sev.sigev_value
  66                         : (union sigval){.sival_ptr=t};
  67                 ksev.sigev_signo = sev.sigev_signo;
  68                 ksev.sigev_notify = sev.sigev_notify;
  69                 ksev.sigev_tid = 0;
  70                 if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
  71                         return -1;
  72                 *res = (void *)(2*timerid+1);
  73                 break;
  74         case SIGEV_THREAD:
  75                 if (!libc.sigtimer) libc.sigtimer = sighandler;
  76                 if (sev.sigev_notify_attributes)
  77                         attr = *sev.sigev_notify_attributes;
  78                 else
  79                         pthread_attr_init(&attr);
  80                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  81                 pthread_barrier_init(&args.b, 0, 2);
  82                 args.sev = &sev;
  83                 r = pthread_create(&td, &attr, start, &args);
  84                 if (r) {
  85                         errno = r;
  86                         return -1;
  87                 }
  88                 ksev.sigev_value.sival_ptr = 0;
  89                 ksev.sigev_signo = SIGCANCEL;
  90                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
  91                 ksev.sigev_tid = td->tid;
  92                 r = syscall(SYS_timer_create, clk, &ksev, &timerid);
  93                 pthread_barrier_wait(&args.b);
  94                 if (r < 0) {
  95                         pthread_cancel(td);
  96                         return -1;
  97                 }
  98                 td->result = (void *)timerid;
  99                 *res = td;
 100                 break;
 101         default:
 102                 errno = EINVAL;
 103                 return -1;
 104         }
 105
 106         return 0;
 107 }