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->cp_sp = 0;
   7         self->canceldisable = 1;
   8         self->cancelasync = 0;
   9         pthread_exit(PTHREAD_CANCELED);
  10 }
  11
  12 long __syscall_cp_asm(volatile void *, long, long, long, long, long, long, long);
  13
  14 long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
  15 {
  16         pthread_t self;
  17         uintptr_t old_sp, old_ip;
  18         long r;
  19
  20         if (!libc.lock || (self = __pthread_self())->canceldisable)
  21                 return __syscall(nr, u, v, w, x, y, z);
  22
  23         old_sp = self->cp_sp;
  24         old_ip = self->cp_ip;
  25         self->cp_sp = 0;
  26         self->cp_ip = 0;
  27         r = __syscall_cp_asm(&self->cp_sp, nr, u, v, w, x, y, z);
  28         self->cp_ip = old_ip;
  29         self->cp_sp = old_sp;
  30         if (r == -EINTR && self->cancel) __cancel();
  31         return r;
  32 }
  33
  34 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
  35 {
  36         pthread_t self = __pthread_self();
  37         ucontext_t *uc = ctx;
  38         uintptr_t sp = ((uintptr_t *)&uc->uc_mcontext)[CANCEL_REG_SP];
  39         uintptr_t ip = ((uintptr_t *)&uc->uc_mcontext)[CANCEL_REG_IP];
  40
  41         if (!self->cancel || self->canceldisable) return;
  42
  43         sigaddset(&uc->uc_sigmask, SIGCANCEL);
  44
  45         if (self->cancelasync || sp == self->cp_sp && ip <= self->cp_ip) {
  46                 self->canceldisable = 1;
  47                 pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
  48                 __cancel();
  49         }
  50
  51         if (self->cp_sp)
  52                 __syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
  53 }
  54
  55 static void testcancel()
  56 {
  57         pthread_t self = __pthread_self();
  58         if (self->cancel && !self->canceldisable)
  59                 __cancel();
  60 }
  61
  62 static void init_cancellation()
  63 {
  64         struct sigaction sa = {
  65                 .sa_flags = SA_SIGINFO | SA_RESTART,
  66                 .sa_sigaction = cancel_handler
  67         };
  68         sigfillset(&sa.sa_mask);
  69         __libc_sigaction(SIGCANCEL, &sa, 0);
  70         libc.testcancel = testcancel;
  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 }