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(1);
  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,
  55                 SIGTIMER_SET, 0, __SYSCALL_SSLEN);
  56 }
  57
  58 static void *start(void *arg)
  59 {
  60         pthread_t self = __pthread_self();
  61         struct start_args *args = arg;
  62         sigset_t set;
  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         self->result = (void *)-1;
  69
  70         sigfillset(&set);
  71         pthread_sigmask(SIG_BLOCK, &set, 0);
  72
  73         pthread_barrier_wait(&args->b);
  74         __wait(&self->delete_timer, 0, 0, 1);
  75         __syscall(SYS_timer_delete, self->result);
  76         return 0;
  77 }
  78
  79 int timer_create(clockid_t clk, struct sigevent *evp, timer_t *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
  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 *)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                 r = pthread_create(&td, &attr, start, &args);
 113                 if (r) {
 114                         errno = r;
 115                         return -1;
 116                 }
 117                 ksev.sigev_value.sival_ptr = 0;
 118                 ksev.sigev_signo = SIGTIMER;
 119                 ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
 120                 ksev.sigev_tid = td->tid;
 121                 r = syscall(SYS_timer_create, clk, &ksev, &timerid);
 122                 pthread_barrier_wait(&args.b);
 123                 if (r < 0) {
 124                         pthread_cancel(td);
 125                         return -1;
 126                 }
 127                 td->result = (void *)timerid;
 128                 *res = td;
 129                 break;
 130         default:
 131                 errno = EINVAL;
 132                 return -1;
 133         }
 134
 135         return 0;
 136 }