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         timer_t t;
  15 };
  16
  17 static void sighandler(int sig, siginfo_t *si, void *ctx)
  18 {
  19         int st;
  20         pthread_t self = __pthread_self();
  21         void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  22         union sigval val = { .sival_ptr = self->start_arg };
  23
  24         pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &st);
  25         notify(val);
  26         pthread_setcancelstate(st, 0);
  27 }
  28
  29 static void killtimer(void *arg)
  30 {
  31         timer_t t = arg;
  32         if (t->timerid >= 0) __syscall(SYS_timer_delete, t->timerid);
  33 }
  34
  35 static void *start(void *arg)
  36 {
  37         pthread_t self = __pthread_self();
  38         struct start_args *args = arg;
  39         struct __timer t = { .timerid = -1 };
  40
  41         /* Reuse no-longer-needed thread structure fields to avoid
  42          * needing the timer address in the signal handler. */
  43         self->start = (void *(*)(void *))args->sev->sigev_notify_function;
  44         self->start_arg = args->sev->sigev_value.sival_ptr;
  45         args->t = &t;
  46
  47         pthread_cleanup_push(killtimer, &t);
  48         pthread_barrier_wait(&args->b);
  49         pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, 0);
  50         /* Loop on async-signal-safe cancellation point */
  51         for (;;) sleep(1);
  52         pthread_cleanup_pop(1);
  53         return 0;
  54 }
  55
  56 int timer_create(clockid_t clk, struct sigevent *evp, timer_t *res)
  57 {
  58         struct sigevent sev = {
  59                 .sigev_notify = SIGEV_SIGNAL,
  60                 .sigev_signo = SIGALRM
  61         };
  62         pthread_t td;
  63         pthread_attr_t attr;
  64         int r;
  65         struct start_args args;
  66         timer_t t;
  67         struct ksigevent ksev;
  68         int timerid;
  69
  70         if (evp) sev = *evp;
  71
  72         switch (sev.sigev_notify) {
  73         case SIGEV_NONE:
  74         case SIGEV_SIGNAL:
  75                 ksev.sigev_value = evp ? sev.sigev_value
  76                         : (union sigval){.sival_ptr=t};
  77                 ksev.sigev_signo = sev.sigev_signo;
  78                 ksev.sigev_notify = sev.sigev_notify;
  79                 ksev.sigev_tid = 0;
  80                 if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
  81                         return -1;
  82                 if (!(t = calloc(1, sizeof *t))) {
  83                         syscall(SYS_timer_delete, timerid);
  84                         return -1;
  85                 }
  86                 t->timerid = timerid;
  87                 break;
  88         case SIGEV_THREAD:
  89                 if (!libc.sigtimer) libc.sigtimer = sighandler;
  90                 if (sev.sigev_notify_attributes)
  91                         attr = *sev.sigev_notify_attributes;
  92                 else
  93                         pthread_attr_init(&attr);
  94                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  95                 pthread_barrier_init(&args.b, 0, 2);
  96                 args.sev = &sev;
  97                 r = pthread_create(&td, &attr, start, &args);
  98                 if (r) {
  99                         errno = r;
 100                         return -1;
 101                 }
 102                 ksev.sigev_value.sival_ptr = 0;
 103                 ksev.sigev_signo = SIGCANCEL;
 104                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 105                 ksev.sigev_tid = td->tid;
 106                 r = syscall(SYS_timer_create, clk, &ksev, &timerid);
 107                 pthread_barrier_wait(&args.b);
 108                 t = args.t;
 109                 if (r < 0) {
 110                         pthread_cancel(td);
 111                         return -1;
 112                 }
 113                 t->timerid = timerid;
 114                 t->thread = td;
 115                 break;
 116         default:
 117                 errno = EINVAL;
 118                 return -1;
 119         }
 120
 121         *res = t;
 122         return 0;
 123 }