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, __SYSCALL_SSLEN);
  57 }
  58
  59 static void *start(void *arg)
  60 {
  61         pthread_t self = __pthread_self();
  62         struct start_args *args = arg;
  63         sigset_t set;
  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         self->result = (void *)-1;
  70
  71         sigfillset(&set);
  72         pthread_sigmask(SIG_BLOCK, &set, 0);
  73
  74         pthread_barrier_wait(&args->b);
  75         __wait(&self->delete_timer, 0, 0, 1);
  76         __syscall(SYS_timer_delete, self->result);
  77         return 0;
  78 }
  79
  80 int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
  81 {
  82         static pthread_once_t once = PTHREAD_ONCE_INIT;
  83         pthread_t td;
  84         pthread_attr_t attr;
  85         int r;
  86         struct start_args args;
  87         struct ksigevent ksev, *ksevp=0;
  88         int timerid;
  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 *)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                 r = pthread_create(&td, &attr, start, &args);
 114                 if (r) {
 115                         errno = r;
 116                         return -1;
 117                 }
 118                 ksev.sigev_value.sival_ptr = 0;
 119                 ksev.sigev_signo = SIGTIMER;
 120                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 121                 ksev.sigev_tid = td->tid;
 122                 r = syscall(SYS_timer_create, clk, &ksev, &timerid);
 123                 pthread_barrier_wait(&args.b);
 124                 if (r < 0) {
 125                         pthread_cancel(td);
 126                         return -1;
 127                 }
 128                 td->result = (void *)timerid;
 129                 *res = td;
 130                 break;
 131         default:
 132                 errno = EINVAL;
 133                 return -1;
 134         }
 135
 136         return 0;
 137 }