nsz Git - musl/blob - src/thread/cancel_impl.c

   1 #include "pthread_impl.h"
   2
   3 void __cancel()
   4 {
   5         pthread_t self = __pthread_self();
   6         self->canceldisable = 1;
   7         self->cancelasync = 0;
   8         pthread_exit(PTHREAD_CANCELED);
   9 }
  10
  11 long __syscall_cp_asm(volatile void *, long, long, long, long, long, long, long);
  12
  13 long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
  14 {
  15         pthread_t self;
  16         long r;
  17
  18         if (!libc.main_thread || (self = __pthread_self())->canceldisable)
  19                 return __syscall(nr, u, v, w, x, y, z);
  20
  21         r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
  22         if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
  23                 __cancel();
  24         return r;
  25 }
  26
  27 static void _sigaddset(sigset_t *set, int sig)
  28 {
  29         unsigned s = sig-1;
  30         set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
  31 }
  32
  33 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
  34 {
  35         pthread_t self = __pthread_self();
  36         ucontext_t *uc = ctx;
  37         const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
  38         extern const char __cp_begin[1], __cp_end[1];
  39
  40         if (!self->cancel || self->canceldisable) return;
  41
  42         _sigaddset(&uc->uc_sigmask, SIGCANCEL);
  43
  44         if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
  45                 self->canceldisable = 1;
  46                 pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
  47                 __cancel();
  48         }
  49
  50         __syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
  51 }
  52
  53 void __testcancel()
  54 {
  55         pthread_t self = pthread_self();
  56         if (self->cancel && !self->canceldisable)
  57                 __cancel();
  58 }
  59
  60 static void init_cancellation()
  61 {
  62         struct sigaction sa = {
  63                 .sa_flags = SA_SIGINFO | SA_RESTART,
  64                 .sa_sigaction = cancel_handler
  65         };
  66         sigfillset(&sa.sa_mask);
  67         __libc_sigaction(SIGCANCEL, &sa, 0);
  68 }
  69
  70 int pthread_cancel(pthread_t t)
  71 {
  72         static int init;
  73         if (!init) {
  74                 init_cancellation();
  75                 init = 1;
  76         }
  77         a_store(&t->cancel, 1);
  78         return pthread_kill(t, SIGCANCEL);
  79 }