1#define _GNU_SOURCE
  2#include <string.h>
  3#include "pthread_impl.h"
  4#include "syscall.h"
  5
  6#ifdef __wasilibc_unmodified_upstream
  7hidden long __cancel(), __syscall_cp_asm(), __syscall_cp_c();
  8
  9long __cancel()
 10{
 11	pthread_t self = __pthread_self();
 12	if (self->canceldisable == PTHREAD_CANCEL_ENABLE || self->cancelasync)
 13		pthread_exit(PTHREAD_CANCELED);
 14	self->canceldisable = PTHREAD_CANCEL_DISABLE;
 15	return -ECANCELED;
 16}
 17
 18long __syscall_cp_asm(volatile void *, syscall_arg_t,
 19                      syscall_arg_t, syscall_arg_t, syscall_arg_t,
 20                      syscall_arg_t, syscall_arg_t, syscall_arg_t);
 21
 22long __syscall_cp_c(syscall_arg_t nr,
 23                    syscall_arg_t u, syscall_arg_t v, syscall_arg_t w,
 24                    syscall_arg_t x, syscall_arg_t y, syscall_arg_t z)
 25{
 26	pthread_t self;
 27	long r;
 28	int st;
 29
 30	if ((st=(self=__pthread_self())->canceldisable)
 31	    && (st==PTHREAD_CANCEL_DISABLE || nr==SYS_close))
 32		return __syscall(nr, u, v, w, x, y, z);
 33
 34	r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z);
 35	if (r==-EINTR && nr!=SYS_close && self->cancel &&
 36	    self->canceldisable != PTHREAD_CANCEL_DISABLE)
 37		r = __cancel();
 38	return r;
 39}
 40
 41static void _sigaddset(sigset_t *set, int sig)
 42{
 43	unsigned s = sig-1;
 44	set->__bits[s/8/sizeof *set->__bits] |= 1UL<<(s&8*sizeof *set->__bits-1);
 45}
 46
 47extern hidden const char __cp_begin[1], __cp_end[1], __cp_cancel[1];
 48
 49static void cancel_handler(int sig, siginfo_t *si, void *ctx)
 50{
 51	pthread_t self = __pthread_self();
 52	ucontext_t *uc = ctx;
 53	uintptr_t pc = uc->uc_mcontext.MC_PC;
 54
 55	a_barrier();
 56	if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return;
 57
 58	_sigaddset(&uc->uc_sigmask, SIGCANCEL);
 59
 60	if (self->cancelasync) {
 61		pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0);
 62		__cancel();
 63	}
 64
 65	if (pc >= (uintptr_t)__cp_begin && pc < (uintptr_t)__cp_end) {
 66		uc->uc_mcontext.MC_PC = (uintptr_t)__cp_cancel;
 67#ifdef CANCEL_GOT
 68		uc->uc_mcontext.MC_GOT = CANCEL_GOT;
 69#endif
 70		return;
 71	}
 72
 73	__syscall(SYS_tkill, self->tid, SIGCANCEL);
 74}
 75
 76void __testcancel()
 77{
 78	pthread_t self = __pthread_self();
 79	if (self->cancel && !self->canceldisable)
 80		__cancel();
 81}
 82
 83static void init_cancellation()
 84{
 85	struct sigaction sa = {
 86		.sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK,
 87		.sa_sigaction = cancel_handler
 88	};
 89	memset(&sa.sa_mask, -1, _NSIG/8);
 90	__libc_sigaction(SIGCANCEL, &sa, 0);
 91}
 92
 93int pthread_cancel(pthread_t t)
 94{
 95	static int init;
 96	if (!init) {
 97		init_cancellation();
 98		init = 1;
 99	}
100	a_store(&t->cancel, 1);
101	if (t == pthread_self()) {
102		if (t->canceldisable == PTHREAD_CANCEL_ENABLE && t->cancelasync)
103			pthread_exit(PTHREAD_CANCELED);
104		return 0;
105	}
106	return pthread_kill(t, SIGCANCEL);
107}
108#else
109int pthread_cancel(pthread_t t)
110{
111	return ENOTSUP;
112}
113#endif