nsz Git - musl/blob - src/thread/cancel_impl.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, syscall_arg_t, syscall_arg_t,
  13                       syscall_arg_t, syscall_arg_t, syscall_arg_t, syscall_arg_t);
  14
  15 long (__syscall_cp)(syscall_arg_t nr, syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
  16                     syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
  17 {
  18         pthread_t self;
  19         long r;
  20
  21         if (!libc.main_thread || (self = __pthread_self())->canceldisable)
  22                 return __syscall(nr, u, v, w, x, y, z);
  23
  24         r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
  25         if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable)
  26                 __cancel();
  27         return r;
  28 }
  29
  30 static void _sigaddset(sigset_t *set, int sig)
  31 {
  32         unsigned s = sig-1;
  33         set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
  34 }
  35
  36 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
  37 {
  38         pthread_t self = __pthread_self();
  39         ucontext_t *uc = ctx;
  40         const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
  41         extern const char __cp_begin[1], __cp_end[1];
  42
  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_tgkill, self->pid, self->tid, SIGCANCEL);
  54 }
  55
  56 void __testcancel()
  57 {
  58         pthread_t self = pthread_self();
  59         if (self->cancel && !self->canceldisable)
  60                 __cancel();
  61 }
  62
  63 static void init_cancellation()
  64 {
  65         struct sigaction sa = {
  66                 .sa_flags = SA_SIGINFO | SA_RESTART,
  67                 .sa_sigaction = cancel_handler
  68         };
  69         sigfillset(&sa.sa_mask);
  70         __libc_sigaction(SIGCANCEL, &sa, 0);
  71 }
  72
  73 int pthread_cancel(pthread_t t)
  74 {
  75         static int init;
  76         if (!init) {
  77                 init_cancellation();
  78                 init = 1;
  79         }
  80         a_store(&t->cancel, 1);
  81         return pthread_kill(t, SIGCANCEL);
  82 }