1// Copyright 2016 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// +build linux,amd64
6
7#include <errno.h>
8#include <stddef.h>
9#include <stdint.h>
10#include <string.h>
11#include <signal.h>
12
13#include "libcgo.h"
14
15// go_sigaction_t is a C version of the sigactiont struct from
16// defs_linux_amd64.go.  This definition — and its conversion to and from struct
17// sigaction — are specific to linux/amd64.
18typedef struct {
19	uintptr_t handler;
20	uint64_t flags;
21	uintptr_t restorer;
22	uint64_t mask;
23} go_sigaction_t;
24
25// SA_RESTORER is part of the kernel interface.
26// This is GNU/Linux i386/amd64 specific.
27#ifndef SA_RESTORER
28#define SA_RESTORER 0x4000000
29#endif
30
31int32_t
32x_cgo_sigaction(intptr_t signum, const go_sigaction_t *goact, go_sigaction_t *oldgoact) {
33	int32_t ret;
34	struct sigaction act;
35	struct sigaction oldact;
36	int i;
37
38	_cgo_tsan_acquire();
39
40	memset(&act, 0, sizeof act);
41	memset(&oldact, 0, sizeof oldact);
42
43	if (goact) {
44		if (goact->flags & SA_SIGINFO) {
45			act.sa_sigaction = (void(*)(int, siginfo_t*, void*))(goact->handler);
46		} else {
47			act.sa_handler = (void(*)(int))(goact->handler);
48		}
49		sigemptyset(&act.sa_mask);
50		for (i = 0; i < 8 * sizeof(goact->mask); i++) {
51			if (goact->mask & ((uint64_t)(1)<<i)) {
52				sigaddset(&act.sa_mask, i+1);
53			}
54		}
55		act.sa_flags = goact->flags & ~SA_RESTORER;
56	}
57
58	ret = sigaction(signum, goact ? &act : NULL, oldgoact ? &oldact : NULL);
59	if (ret == -1) {
60		// runtime.rt_sigaction expects _cgo_sigaction to return errno on error.
61		_cgo_tsan_release();
62		return errno;
63	}
64
65	if (oldgoact) {
66		if (oldact.sa_flags & SA_SIGINFO) {
67			oldgoact->handler = (uintptr_t)(oldact.sa_sigaction);
68		} else {
69			oldgoact->handler = (uintptr_t)(oldact.sa_handler);
70		}
71		oldgoact->mask = 0;
72		for (i = 0; i < 8 * sizeof(oldgoact->mask); i++) {
73			if (sigismember(&oldact.sa_mask, i+1) == 1) {
74				oldgoact->mask |= (uint64_t)(1)<<i;
75			}
76		}
77		oldgoact->flags = oldact.sa_flags;
78	}
79
80	_cgo_tsan_release();
81	return ret;
82}
83