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

   1 #include "pthread_impl.h"
   2
   3 long __syscall_cp_asm(volatile void *, long, long, long, long, long, long, long);
   4
   5 long (__syscall_cp)(long nr, long u, long v, long w, long x, long y, long z)
   6 {
   7         pthread_t self;
   8         uintptr_t old_sp, old_ip;
   9         long r;
  10
  11         if (!libc.lock || (self = __pthread_self())->canceldisable)
  12                 return __syscall(nr, u, v, w, x, y, z);
  13
  14         old_sp = self->cp_sp;
  15         old_ip = self->cp_ip;
  16         self->cp_sp = 0;
  17         self->cp_ip = 0;
  18         r = __syscall_cp_asm(&self->cp_sp, nr, u, v, w, x, y, z);
  19         self->cp_sp = old_sp;
  20         self->cp_ip = old_ip;
  21         if (r == -EINTR && self->cancel) pthread_exit(PTHREAD_CANCELED);
  22         return r;
  23 }
  24
  25 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
  26 {
  27         pthread_t self = __pthread_self();
  28         ucontext_t *uc = ctx;
  29         uintptr_t sp = ((uintptr_t *)&uc->uc_mcontext)[CANCEL_REG_SP];
  30         uintptr_t ip = ((uintptr_t *)&uc->uc_mcontext)[CANCEL_REG_IP];
  31
  32         if (!self->cancel || self->canceldisable) return;
  33
  34         if (self->cancelasync) pthread_exit(PTHREAD_CANCELED);
  35
  36         if (sp != self->cp_sp) {
  37                 if (!sp) return;
  38                 sigaddset(&uc->uc_sigmask, SIGCANCEL);
  39                 __syscall(SYS_tgkill, self->pid, self->tid, SIGCANCEL);
  40                 return;
  41         }
  42
  43         if (ip <= self->cp_ip) pthread_exit(PTHREAD_CANCELED);
  44 }
  45
  46 static void testcancel()
  47 {
  48         pthread_t self = __pthread_self();
  49         if (self->cancel && !self->canceldisable)
  50                 pthread_exit(PTHREAD_CANCELED);
  51 }
  52
  53 static void init_cancellation()
  54 {
  55         struct sigaction sa = {
  56                 .sa_flags = SA_SIGINFO | SA_RESTART,
  57                 .sa_sigaction = cancel_handler
  58         };
  59         sigfillset(&sa.sa_mask);
  60         __libc_sigaction(SIGCANCEL, &sa, 0);
  61         libc.testcancel = testcancel;
  62 }
  63
  64 int pthread_cancel(pthread_t t)
  65 {
  66         static pthread_once_t once;
  67         pthread_once(&once, init_cancellation);
  68         a_store(&t->cancel, 1);
  69         return pthread_kill(t, SIGCANCEL);
  70 }