src/time/timer_create.c

   1 #include <time.h>
   2 #include "pthread_impl.h"
   3
   4 struct ksigevent {
   5         union sigval sigev_value;
   6         int sigev_signo;
   7         int sigev_notify;
   8         int sigev_tid;
   9 };
  10
  11 struct start_args {
  12         pthread_barrier_t b;
  13         struct sigevent *sev;
  14 };
  15
  16 static void dummy_1(pthread_t self)
  17 {
  18 }
  19 weak_alias(dummy_1, __pthread_tsd_run_dtors);
  20
  21 static void cleanup_fromsig(void *p)
  22 {
  23         pthread_t self = __pthread_self();
  24         __pthread_tsd_run_dtors(self);
  25         self->cancel = 0;
  26         self->cancelbuf = 0;
  27         self->canceldisable = 0;
  28         self->cancelasync = 0;
  29         self->unblock_cancel = 0;
  30         longjmp(p, 1);
  31 }
  32
  33 static void timer_handler(int sig, siginfo_t *si, void *ctx)
  34 {
  35         pthread_t self = __pthread_self();
  36         jmp_buf jb;
  37         void (*notify)(union sigval) = (void (*)(union sigval))self->start;
  38         union sigval val = { .sival_ptr = self->start_arg };
  39
  40         if (!setjmp(jb) && si->si_code == SI_TIMER) {
  41                 pthread_cleanup_push(cleanup_fromsig, jb);
  42                 notify(val);
  43                 pthread_cleanup_pop(0);
  44         }
  45 }
  46
  47 static void install_handler()
  48 {
  49         struct sigaction sa = {
  50                 .sa_sigaction = timer_handler,
  51                 .sa_flags = SA_SIGINFO | SA_RESTART
  52         };
  53         __libc_sigaction(SIGTIMER, &sa, 0);
  54         __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGTIMER_SET, 0, 8);
  55 }
  56
  57 static void *start(void *arg)
  58 {
  59         pthread_t self = __pthread_self();
  60         struct start_args *args = arg;
  61
  62         /* Reuse no-longer-needed thread structure fields to avoid
  63          * needing the timer address in the signal handler. */
  64         self->start = (void *(*)(void *))args->sev->sigev_notify_function;
  65         self->start_arg = args->sev->sigev_value.sival_ptr;
  66         self->result = (void *)-1;
  67
  68         pthread_barrier_wait(&args->b);
  69         __wait(&self->delete_timer, 0, 0, 1);
  70         __syscall(SYS_timer_delete, self->result);
  71         return 0;
  72 }
  73
  74 int timer_create(clockid_t clk, struct sigevent *evp, timer_t *res)
  75 {
  76         static pthread_once_t once = PTHREAD_ONCE_INIT;
  77         pthread_t td;
  78         pthread_attr_t attr;
  79         int r;
  80         struct start_args args;
  81         struct ksigevent ksev, *ksevp=0;
  82         int timerid;
  83
  84         switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
  85         case SIGEV_NONE:
  86         case SIGEV_SIGNAL:
  87                 if (evp) {
  88                         ksev.sigev_value = evp->sigev_value;
  89                         ksev.sigev_signo = evp->sigev_signo;
  90                         ksev.sigev_notify = evp->sigev_notify;
  91                         ksev.sigev_tid = 0;
  92                         ksevp = &ksev;
  93                 }
  94                 if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
  95                         return -1;
  96                 *res = (void *)timerid;
  97                 break;
  98         case SIGEV_THREAD:
  99                 pthread_once(&once, install_handler);
 100                 if (evp->sigev_notify_attributes)
 101                         attr = *evp->sigev_notify_attributes;
 102                 else
 103                         pthread_attr_init(&attr);
 104                 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 105                 pthread_barrier_init(&args.b, 0, 2);
 106                 args.sev = evp;
 107                 r = pthread_create(&td, &attr, start, &args);
 108                 if (r) {
 109                         errno = r;
 110                         return -1;
 111                 }
 112                 ksev.sigev_value.sival_ptr = 0;
 113                 ksev.sigev_signo = SIGTIMER;
 114                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 115                 ksev.sigev_tid = td->tid;
 116                 r = syscall(SYS_timer_create, clk, &ksev, &timerid);
 117                 pthread_barrier_wait(&args.b);
 118                 if (r < 0) {
 119                         pthread_cancel(td);
 120                         return -1;
 121                 }
 122                 td->result = (void *)timerid;
 123                 *res = td;
 124                 break;
 125         default:
 126                 errno = EINVAL;
 127                 return -1;
 128         }
 129
 130         return 0;
 131 }