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 void __reset_tls();
  23
  24 static void cleanup_fromsig(void *p)
  25 {
  26         pthread_t self = __pthread_self();
  27         __pthread_tsd_run_dtors(self);
  28         self->cancel = 0;
  29         self->cancelbuf = 0;
  30         self->canceldisable = 0;
  31         self->cancelasync = 0;
  32         self->unblock_cancel = 0;
  33         __reset_tls();
  34         longjmp(p, 1);
  35 }
  36
  37 static void timer_handler(int sig, siginfo_t *si, void *ctx)
  38 {
  39         pthread_t self = __pthread_self();
  40         jmp_buf jb;
  41         void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  42         union sigval val = { .sival_ptr = self->start_arg };
  43
  44         if (!setjmp(jb) && si->si_code == SI_TIMER) {
  45                 pthread_cleanup_push(cleanup_fromsig, jb);
  46                 notify(val);
  47                 pthread_cleanup_pop(1);
  48         }
  49 }
  50
  51 static void install_handler()
  52 {
  53         struct sigaction sa = {
  54                 .sa_sigaction = timer_handler,
  55                 .sa_flags = SA_SIGINFO | SA_RESTART
  56         };
  57         __libc_sigaction(SIGTIMER, &sa, 0);
  58 }
  59
  60 static void *start(void *arg)
  61 {
  62         pthread_t self = __pthread_self();
  63         struct start_args *args = arg;
  64         int id;
  65
  66         /* Reuse no-longer-needed thread structure fields to avoid
  67          * needing the timer address in the signal handler. */
  68         self->start = (void *(*)(void *))args->sev->sigev_notify_function;
  69         self->start_arg = args->sev->sigev_value.sival_ptr;
  70
  71         pthread_barrier_wait(&args->b);
  72         if ((id = self->timer_id) >= 0) {
  73                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  74                         SIGTIMER_SET, 0, _NSIG/8);
  75                 __wait(&self->timer_id, 0, id, 1);
  76                 __syscall(SYS_timer_delete, id);
  77         }
  78         return 0;
  79 }
  80
  81 int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
  82 {
  83         static pthread_once_t once = PTHREAD_ONCE_INIT;
  84         pthread_t td;
  85         pthread_attr_t attr;
  86         int r;
  87         struct start_args args;
  88         struct ksigevent ksev, *ksevp=0;
  89         int timerid;
  90         sigset_t set;
  91
  92         switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
  93         case SIGEV_NONE:
  94         case SIGEV_SIGNAL:
  95                 if (evp) {
  96                         ksev.sigev_value = evp->sigev_value;
  97                         ksev.sigev_signo = evp->sigev_signo;
  98                         ksev.sigev_notify = evp->sigev_notify;
  99                         ksev.sigev_tid = 0;
 100                         ksevp = &ksev;
 101                 }
 102                 if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
 103                         return -1;
 104                 *res = (void *)(intptr_t)timerid;
 105                 break;
 106         case SIGEV_THREAD:
 107                 pthread_once(&once, install_handler);
 108                 if (evp->sigev_notify_attributes)
 109                         attr = *evp->sigev_notify_attributes;
 110                 else
 111                         pthread_attr_init(&attr);
 112                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 113                 pthread_barrier_init(&args.b, 0, 2);
 114                 args.sev = evp;
 115
 116                 __block_app_sigs(&set);
 117                 r = pthread_create(&td, &attr, start, &args);
 118                 __restore_sigs(&set);
 119                 if (r) {
 120                         errno = r;
 121                         return -1;
 122                 }
 123
 124                 ksev.sigev_value.sival_ptr = 0;
 125                 ksev.sigev_signo = SIGTIMER;
 126                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 127                 ksev.sigev_tid = td->tid;
 128                 if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
 129                         timerid = -1;
 130                 td->timer_id = timerid;
 131                 pthread_barrier_wait(&args.b);
 132                 if (timerid < 0) return -1;
 133                 *res = (void *)(INTPTR_MIN | (uintptr_t)td>>1);
 134                 break;
 135         default:
 136                 errno = EINVAL;
 137                 return -1;
 138         }
 139
 140         return 0;
 141 }