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_1(pthread_t self)
  18 {
  19 }
  20 weak_alias(dummy_1, __pthread_tsd_run_dtors);
  21
  22 static void cleanup_fromsig(void *p)
  23 {
  24         pthread_t self = __pthread_self();
  25         __pthread_tsd_run_dtors(self);
  26         self->cancel = 0;
  27         self->cancelbuf = 0;
  28         self->canceldisable = 0;
  29         self->cancelasync = 0;
  30         self->unblock_cancel = 0;
  31         longjmp(p, 1);
  32 }
  33
  34 static void timer_handler(int sig, siginfo_t *si, void *ctx)
  35 {
  36         pthread_t self = __pthread_self();
  37         jmp_buf jb;
  38         void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  39         union sigval val = { .sival_ptr = self->start_arg };
  40
  41         if (!setjmp(jb) && si->si_code == SI_TIMER) {
  42                 pthread_cleanup_push(cleanup_fromsig, jb);
  43                 notify(val);
  44                 pthread_cleanup_pop(1);
  45         }
  46 }
  47
  48 static void install_handler()
  49 {
  50         struct sigaction sa = {
  51                 .sa_sigaction = timer_handler,
  52                 .sa_flags = SA_SIGINFO | SA_RESTART
  53         };
  54         __libc_sigaction(SIGTIMER, &sa, 0);
  55         __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  56                 SIGTIMER_SET, 0, _NSIG/8);
  57 }
  58
  59 static void *start(void *arg)
  60 {
  61         pthread_t self = __pthread_self();
  62         struct start_args *args = arg;
  63         int id;
  64
  65         /* Reuse no-longer-needed thread structure fields to avoid
  66          * needing the timer address in the signal handler. */
  67         self->start = (void *(*)(void *))args->sev->sigev_notify_function;
  68         self->start_arg = args->sev->sigev_value.sival_ptr;
  69
  70         pthread_barrier_wait(&args->b);
  71         if ((id = self->timer_id) >= 0) {
  72                 __wait(&self->timer_id, 0, id, 1);
  73                 __syscall(SYS_timer_delete, id);
  74         }
  75         return 0;
  76 }
  77
  78 int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
  79 {
  80         static pthread_once_t once = PTHREAD_ONCE_INIT;
  81         pthread_t td;
  82         pthread_attr_t attr;
  83         int r;
  84         struct start_args args;
  85         struct ksigevent ksev, *ksevp=0;
  86         int timerid;
  87         sigset_t set;
  88
  89         switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
  90         case SIGEV_NONE:
  91         case SIGEV_SIGNAL:
  92                 if (evp) {
  93                         ksev.sigev_value = evp->sigev_value;
  94                         ksev.sigev_signo = evp->sigev_signo;
  95                         ksev.sigev_notify = evp->sigev_notify;
  96                         ksev.sigev_tid = 0;
  97                         ksevp = &ksev;
  98                 }
  99                 if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
 100                         return -1;
 101                 *res = (void *)(intptr_t)timerid;
 102                 break;
 103         case SIGEV_THREAD:
 104                 pthread_once(&once, install_handler);
 105                 if (evp->sigev_notify_attributes)
 106                         attr = *evp->sigev_notify_attributes;
 107                 else
 108                         pthread_attr_init(&attr);
 109                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 110                 pthread_barrier_init(&args.b, 0, 2);
 111                 args.sev = evp;
 112
 113                 __block_app_sigs(&set);
 114                 r = pthread_create(&td, &attr, start, &args);
 115                 __restore_sigs(&set);
 116                 if (r) {
 117                         errno = r;
 118                         return -1;
 119                 }
 120
 121                 ksev.sigev_value.sival_ptr = 0;
 122                 ksev.sigev_signo = SIGTIMER;
 123                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 124                 ksev.sigev_tid = td->tid;
 125                 if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
 126                         timerid = -1;
 127                 td->timer_id = timerid;
 128                 pthread_barrier_wait(&args.b);
 129                 if (timerid < 0) return -1;
 130                 *res = (void *)(INTPTR_MIN | (uintptr_t)td>>1);
 131                 break;
 132         default:
 133                 errno = EINVAL;
 134                 return -1;
 135         }
 136
 137         return 0;
 138 }