+#include "syscall.h"
+#include "libc.h"
+
+long __cancel()
+{
+ pthread_t self = __pthread_self();
+ if (self->canceldisable == PTHREAD_CANCEL_ENABLE || self->cancelasync)
+ pthread_exit(PTHREAD_CANCELED);
+ self->canceldisable = PTHREAD_CANCEL_DISABLE;
+ return -ECANCELED;
+}
+
+/* If __syscall_cp_asm has adjusted the stack pointer, it must provide a
+ * definition of __cp_cancel to undo those adjustments and call __cancel.
+ * Otherwise, __cancel provides a definition for __cp_cancel. */
+
+weak_alias(__cancel, __cp_cancel);
+
+long __syscall_cp_asm(volatile void *, syscall_arg_t,
+ syscall_arg_t, syscall_arg_t, syscall_arg_t,
+ syscall_arg_t, syscall_arg_t, syscall_arg_t);
+
+long __syscall_cp_c(syscall_arg_t nr,
+ syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
+ syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
+{
+ pthread_t self;
+ long r;
+ int st;
+
+ if (!libc.has_thread_pointer || (st=(self=__pthread_self())->canceldisable)
+ && (st==PTHREAD_CANCEL_DISABLE || nr==SYS_close))
+ return __syscall(nr, u, v, w, x, y, z);
+
+ r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
+ if (r==-EINTR && nr!=SYS_close && self->cancel &&
+ self->canceldisable != PTHREAD_CANCEL_DISABLE)
+ r = __cancel();
+ return r;
+}
+
+static void _sigaddset(sigset_t *set, int sig)
+{
+ unsigned s = sig-1;
+ set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
+}
+
+static void cancel_handler(int sig, siginfo_t *si, void *ctx)
+{
+ pthread_t self = __pthread_self();
+ ucontext_t *uc = ctx;
+ const char *ip = ((char **)&uc->uc_mcontext)[CANCEL_REG_IP];
+ extern const char __cp_begin[1], __cp_end[1];
+
+ a_barrier();
+ if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return;
+
+ _sigaddset(&uc->uc_sigmask, SIGCANCEL);
+
+ if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) {
+ ((char **)&uc->uc_mcontext)[CANCEL_REG_IP] = (char *)__cp_cancel;
+ return;
+ }
+
+ __syscall(SYS_tkill, self->tid, SIGCANCEL);
+}
+
+void __testcancel()
+{
+ if (!libc.has_thread_pointer) return;
+ pthread_t self = __pthread_self();
+ if (self->cancel && !self->canceldisable)
+ __cancel();
+}
+
+static void init_cancellation()
+{
+ struct sigaction sa = {
+ .sa_flags = SA_SIGINFO | SA_RESTART,
+ .sa_sigaction = cancel_handler
+ };
+ sigfillset(&sa.sa_mask);
+ __libc_sigaction(SIGCANCEL, &sa, 0);
+}