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         uintptr_t old_sp, old_ip;
  17         long r;
  18
  19         if (!libc.lock || (self = __pthread_self())->canceldisable)
  20                 return __syscall(nr, u, v, w, x, y, z);
  21
  22         old_sp = self->cp_sp;
  23         old_ip = self->cp_ip;
  24         self->cp_sp = 0;
  25         self->cp_ip = 0;
  26         r = __syscall_cp_asm(&self->cp_sp, nr, u, v, w, x, y, z);
  27         self->cp_sp = old_sp;
  28         self->cp_ip = old_ip;
  29         if (r == -EINTR && self->cancel) __cancel();
  30         return r;
  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         uintptr_t sp = ((uintptr_t *)&uc->uc_mcontext)[CANCEL_REG_SP];
  38         uintptr_t ip = ((uintptr_t *)&uc->uc_mcontext)[CANCEL_REG_IP];
  39
  40         if (!self->cancel || self->canceldisable) return;
  41
  42         sigaddset(&uc->uc_sigmask, SIGCANCEL);
  43
  44         if (self->cancelasync || sp == self->cp_sp && ip <= self->cp_ip) {
  45                 self->canceldisable = 1;
  46                 pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
  47                 __cancel();
  48         }
  49
  50         if (self->cp_sp)
  51                 __syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
  52 }
  53
  54 static void testcancel()
  55 {
  56         pthread_t self = __pthread_self();
  57         if (self->cancel && !self->canceldisable)
  58                 __cancel();
  59 }
  60
  61 static void init_cancellation()
  62 {
  63         struct sigaction sa = {
  64                 .sa_flags = SA_SIGINFO | SA_RESTART,
  65                 .sa_sigaction = cancel_handler
  66         };
  67         sigfillset(&sa.sa_mask);
  68         __libc_sigaction(SIGCANCEL, &sa, 0);
  69         libc.testcancel = testcancel;
  70 }
  71
  72 int pthread_cancel(pthread_t t)
  73 {
  74         static int init;
  75         if (!init) {
  76                 init_cancellation();
  77                 init = 1;
  78         }
  79         a_store(&t->cancel, 1);
  80         return pthread_kill(t, SIGCANCEL);
  81 }