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