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

   1 #include "pthread_impl.h"
   2 #include "syscall.h"
   3
   4 void __cancel()
   5 {
   6         pthread_exit(PTHREAD_CANCELED);
   7 }
   8
   9 long __syscall_cp_asm(volatile void *, syscall_arg_t,
  10                       syscall_arg_t, syscall_arg_t, syscall_arg_t,
  11                       syscall_arg_t, syscall_arg_t, syscall_arg_t);
  12
  13 long __syscall_cp_c(syscall_arg_t nr,
  14                     syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
  15                     syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
  16 {
  17         pthread_t self;
  18         long r;
  19
  20         if (!libc.has_thread_pointer || (self = __pthread_self())->canceldisable)
  21                 return __syscall(nr, u, v, w, x, y, z);
  22
  23         r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
  24         if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
  25                 __cancel();
  26         return r;
  27 }
  28
  29 static void _sigaddset(sigset_t *set, int sig)
  30 {
  31         unsigned s = sig-1;
  32         set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
  33 }
  34
  35 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
  36 {
  37         pthread_t self = __pthread_self();
  38         ucontext_t *uc = ctx;
  39         const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
  40         extern const char __cp_begin[1], __cp_end[1];
  41
  42         a_barrier();
  43         if (!self->cancel || self->canceldisable) return;
  44
  45         _sigaddset(&uc->uc_sigmask, SIGCANCEL);
  46
  47         if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
  48                 self->canceldisable = 1;
  49                 pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
  50                 __cancel();
  51         }
  52
  53         __syscall(SYS_tkill, self->tid, SIGCANCEL);
  54 }
  55
  56 void __testcancel()
  57 {
  58         if (!libc.has_thread_pointer) return;
  59         pthread_t self = __pthread_self();
  60         if (self->cancel && !self->canceldisable)
  61                 __cancel();
  62 }
  63
  64 static void init_cancellation()
  65 {
  66         struct sigaction sa = {
  67                 .sa_flags = SA_SIGINFO | SA_RESTART,
  68                 .sa_sigaction = cancel_handler
  69         };
  70         sigfillset(&sa.sa_mask);
  71         __libc_sigaction(SIGCANCEL, &sa, 0);
  72 }
  73
  74 int pthread_cancel(pthread_t t)
  75 {
  76         static int init;
  77         if (!init) {
  78                 init_cancellation();
  79                 init = 1;
  80         }
  81         a_store(&t->cancel, 1);
  82         return pthread_kill(t, SIGCANCEL);
  83 }