src/time/timer_create.c

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