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         pthread_t self = __pthread_self();
  38         jmp_buf jb;
  39         void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  40         union sigval val = { .sival_ptr = self->start_arg };
  41
  42         if (!setjmp(jb) && si->si_code == SI_TIMER) {
  43                 pthread_cleanup_push(cleanup_fromsig, jb);
  44                 notify(val);
  45                 pthread_cleanup_pop(1);
  46         }
  47 }
  48
  49 static void install_handler()
  50 {
  51         struct sigaction sa = {
  52                 .sa_sigaction = timer_handler,
  53                 .sa_flags = SA_SIGINFO | SA_RESTART
  54         };
  55         __libc_sigaction(SIGTIMER, &sa, 0);
  56 }
  57
  58 static void *start(void *arg)
  59 {
  60         pthread_t self = __pthread_self();
  61         struct start_args *args = arg;
  62         int id;
  63
  64         /* Reuse no-longer-needed thread structure fields to avoid
  65          * needing the timer address in the signal handler. */
  66         self->start = (void *(*)(void *))args->sev->sigev_notify_function;
  67         self->start_arg = args->sev->sigev_value.sival_ptr;
  68
  69         pthread_barrier_wait(&args->b);
  70         if ((id = self->timer_id) >= 0) {
  71                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  72                         SIGTIMER_SET, 0, _NSIG/8);
  73                 __wait(&self->timer_id, 0, id, 1);
  74                 __syscall(SYS_timer_delete, id);
  75         }
  76         return 0;
  77 }
  78
  79 int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
  80 {
  81         static pthread_once_t once = PTHREAD_ONCE_INIT;
  82         pthread_t td;
  83         pthread_attr_t attr;
  84         int r;
  85         struct start_args args;
  86         struct ksigevent ksev, *ksevp=0;
  87         int timerid;
  88         sigset_t set;
  89
  90         switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
  91         case SIGEV_NONE:
  92         case SIGEV_SIGNAL:
  93                 if (evp) {
  94                         ksev.sigev_value = evp->sigev_value;
  95                         ksev.sigev_signo = evp->sigev_signo;
  96                         ksev.sigev_notify = evp->sigev_notify;
  97                         ksev.sigev_tid = 0;
  98                         ksevp = &ksev;
  99                 }
 100                 if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
 101                         return -1;
 102                 *res = (void *)(intptr_t)timerid;
 103                 break;
 104         case SIGEV_THREAD:
 105                 pthread_once(&once, install_handler);
 106                 if (evp->sigev_notify_attributes)
 107                         attr = *evp->sigev_notify_attributes;
 108                 else
 109                         pthread_attr_init(&attr);
 110                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 111                 pthread_barrier_init(&args.b, 0, 2);
 112                 args.sev = evp;
 113
 114                 __block_app_sigs(&set);
 115                 r = pthread_create(&td, &attr, start, &args);
 116                 __restore_sigs(&set);
 117                 if (r) {
 118                         errno = r;
 119                         return -1;
 120                 }
 121
 122                 ksev.sigev_value.sival_ptr = 0;
 123                 ksev.sigev_signo = SIGTIMER;
 124                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 125                 ksev.sigev_tid = td->tid;
 126                 if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
 127                         timerid = -1;
 128                 td->timer_id = timerid;
 129                 pthread_barrier_wait(&args.b);
 130                 if (timerid < 0) return -1;
 131                 *res = (void *)(INTPTR_MIN | (uintptr_t)td>>1);
 132                 break;
 133         default:
 134                 errno = EINVAL;
 135                 return -1;
 136         }
 137
 138         return 0;
 139 }