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