src/time/timer_create.c

   1 #include <time.h>
   2 #include <setjmp.h>
   3 #include "pthread_impl.h"
   4
   5 struct ksigevent {
   6         union sigval sigev_value;
   7         int sigev_signo;
   8         int sigev_notify;
   9         int sigev_tid;
  10 };
  11
  12 struct start_args {
  13         pthread_barrier_t b;
  14         struct sigevent *sev;
  15 };
  16
  17 static void dummy_0()
  18 {
  19 }
  20 weak_alias(dummy_0, __pthread_tsd_run_dtors);
  21
  22 static void cleanup_fromsig(void *p)
  23 {
  24         pthread_t self = __pthread_self();
  25         __pthread_tsd_run_dtors();
  26         self->cancel = 0;
  27         self->cancelbuf = 0;
  28         self->canceldisable = 0;
  29         self->cancelasync = 0;
  30         self->unblock_cancel = 0;
  31         __reset_tls();
  32         longjmp(p, 1);
  33 }
  34
  35 static void timer_handler(int sig, siginfo_t *si, void *ctx)
  36 {
  37 }
  38
  39 static void install_handler()
  40 {
  41         struct sigaction sa = {
  42                 .sa_sigaction = timer_handler,
  43                 .sa_flags = SA_SIGINFO | SA_RESTART
  44         };
  45         __libc_sigaction(SIGTIMER, &sa, 0);
  46 }
  47
  48 static void *start(void *arg)
  49 {
  50         pthread_t self = __pthread_self();
  51         struct start_args *args = arg;
  52         int id = self->timer_id;
  53         jmp_buf jb;
  54
  55         void (*notify)(union sigval) = args->sev->sigev_notify_function;
  56         union sigval val = args->sev->sigev_value;
  57
  58         pthread_barrier_wait(&args->b);
  59         for (;;) {
  60                 siginfo_t si;
  61                 while (sigwaitinfo(SIGTIMER_SET, &si) < 0);
  62                 if (si.si_code == SI_TIMER && !setjmp(jb)) {
  63                         pthread_cleanup_push(cleanup_fromsig, jb);
  64                         notify(val);
  65                         pthread_cleanup_pop(1);
  66                 }
  67                 if (self->timer_id < 0) break;
  68         }
  69         __syscall(SYS_timer_delete, id);
  70         return 0;
  71 }
  72
  73 int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
  74 {
  75         static pthread_once_t once = PTHREAD_ONCE_INIT;
  76         pthread_t td;
  77         pthread_attr_t attr;
  78         int r;
  79         struct start_args args;
  80         struct ksigevent ksev, *ksevp=0;
  81         int timerid;
  82         sigset_t set;
  83
  84         switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
  85         case SIGEV_NONE:
  86         case SIGEV_SIGNAL:
  87                 if (evp) {
  88                         ksev.sigev_value = evp->sigev_value;
  89                         ksev.sigev_signo = evp->sigev_signo;
  90                         ksev.sigev_notify = evp->sigev_notify;
  91                         ksev.sigev_tid = 0;
  92                         ksevp = &ksev;
  93                 }
  94                 if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
  95                         return -1;
  96                 *res = (void *)(intptr_t)timerid;
  97                 break;
  98         case SIGEV_THREAD:
  99                 pthread_once(&once, install_handler);
 100                 if (evp->sigev_notify_attributes)
 101                         attr = *evp->sigev_notify_attributes;
 102                 else
 103                         pthread_attr_init(&attr);
 104                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 105                 pthread_barrier_init(&args.b, 0, 2);
 106                 args.sev = evp;
 107
 108                 __block_app_sigs(&set);
 109                 __syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGTIMER_SET, 0, _NSIG/8);
 110                 r = pthread_create(&td, &attr, start, &args);
 111                 __restore_sigs(&set);
 112                 if (r) {
 113                         errno = r;
 114                         return -1;
 115                 }
 116
 117                 ksev.sigev_value.sival_ptr = 0;
 118                 ksev.sigev_signo = SIGTIMER;
 119                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 120                 ksev.sigev_tid = td->tid;
 121                 if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
 122                         timerid = -1;
 123                 td->timer_id = timerid;
 124                 pthread_barrier_wait(&args.b);
 125                 if (timerid < 0) return -1;
 126                 *res = (void *)(INTPTR_MIN | (uintptr_t)td>>1);
 127                 break;
 128         default:
 129                 errno = EINVAL;
 130                 return -1;
 131         }
 132
 133         return 0;
 134 }