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_t self = __pthread_self();
   7         self->canceldisable = 1;
   8         self->cancelasync = 0;
   9         pthread_exit(PTHREAD_CANCELED);
  10 }
  11
  12 long __syscall_cp_asm(volatile void *, syscall_arg_t,
  13                       syscall_arg_t, syscall_arg_t, syscall_arg_t,
  14                       syscall_arg_t, syscall_arg_t, syscall_arg_t);
  15
  16 long __syscall_cp_c(syscall_arg_t nr,
  17                     syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
  18                     syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
  19 {
  20         pthread_t self;
  21         long r;
  22
  23         if (!libc.has_thread_pointer || (self = __pthread_self())->canceldisable)
  24                 return __syscall(nr, u, v, w, x, y, z);
  25
  26         r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
  27         if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
  28                 __cancel();
  29         return r;
  30 }
  31
  32 static void _sigaddset(sigset_t *set, int sig)
  33 {
  34         unsigned s = sig-1;
  35         set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
  36 }
  37
  38 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
  39 {
  40         pthread_t self = __pthread_self();
  41         ucontext_t *uc = ctx;
  42         const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
  43         extern const char __cp_begin[1], __cp_end[1];
  44
  45         a_barrier();
  46         if (!self->cancel || self->canceldisable) return;
  47
  48         _sigaddset(&uc->uc_sigmask, SIGCANCEL);
  49
  50         if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
  51                 self->canceldisable = 1;
  52                 pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
  53                 __cancel();
  54         }
  55
  56         __syscall(SYS_tkill, self->tid, SIGCANCEL);
  57 }
  58
  59 void __testcancel()
  60 {
  61         if (!libc.has_thread_pointer) return;
  62         pthread_t self = __pthread_self();
  63         if (self->cancel && !self->canceldisable)
  64                 __cancel();
  65 }
  66
  67 static void init_cancellation()
  68 {
  69         struct sigaction sa = {
  70                 .sa_flags = SA_SIGINFO | SA_RESTART,
  71                 .sa_sigaction = cancel_handler
  72         };
  73         sigfillset(&sa.sa_mask);
  74         __libc_sigaction(SIGCANCEL, &sa, 0);
  75 }
  76
  77 int pthread_cancel(pthread_t t)
  78 {
  79         static int init;
  80         if (!init) {
  81                 init_cancellation();
  82                 init = 1;
  83         }
  84         a_store(&t->cancel, 1);
  85         return pthread_kill(t, SIGCANCEL);
  86 }