1// Copyright 2017 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 aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris
6
7package runtime
8
9import "unsafe"
10
11var NonblockingPipe = nonblockingPipe
12var Pipe = pipe
13var SetNonblock = setNonblock
14var Closeonexec = closeonexec
15
16func sigismember(mask *sigset, i int) bool {
17	clear := *mask
18	sigdelset(&clear, i)
19	return clear != *mask
20}
21
22func Sigisblocked(i int) bool {
23	var sigmask sigset
24	sigprocmask(_SIG_SETMASK, nil, &sigmask)
25	return sigismember(&sigmask, i)
26}
27
28type M = m
29
30var waitForSigusr1 struct {
31	rdpipe int32
32	wrpipe int32
33	mID    int64
34}
35
36// WaitForSigusr1 blocks until a SIGUSR1 is received. It calls ready
37// when it is set up to receive SIGUSR1. The ready function should
38// cause a SIGUSR1 to be sent. The r and w arguments are a pipe that
39// the signal handler can use to report when the signal is received.
40//
41// Once SIGUSR1 is received, it returns the ID of the current M and
42// the ID of the M the SIGUSR1 was received on. If the caller writes
43// a non-zero byte to w, WaitForSigusr1 returns immediately with -1, -1.
44func WaitForSigusr1(r, w int32, ready func(mp *M)) (int64, int64) {
45	lockOSThread()
46	// Make sure we can receive SIGUSR1.
47	unblocksig(_SIGUSR1)
48
49	waitForSigusr1.rdpipe = r
50	waitForSigusr1.wrpipe = w
51
52	mp := getg().m
53	testSigusr1 = waitForSigusr1Callback
54	ready(mp)
55
56	// Wait for the signal. We use a pipe rather than a note
57	// because write is always async-signal-safe.
58	entersyscallblock()
59	var b byte
60	read(waitForSigusr1.rdpipe, noescape(unsafe.Pointer(&b)), 1)
61	exitsyscall()
62
63	gotM := waitForSigusr1.mID
64	testSigusr1 = nil
65
66	unlockOSThread()
67
68	if b != 0 {
69		// timeout signal from caller
70		return -1, -1
71	}
72	return mp.id, gotM
73}
74
75// waitForSigusr1Callback is called from the signal handler during
76// WaitForSigusr1. It must not have write barriers because there may
77// not be a P.
78//
79//go:nowritebarrierrec
80func waitForSigusr1Callback(gp *g) bool {
81	if gp == nil || gp.m == nil {
82		waitForSigusr1.mID = -1
83	} else {
84		waitForSigusr1.mID = gp.m.id
85	}
86	b := byte(0)
87	write(uintptr(waitForSigusr1.wrpipe), noescape(unsafe.Pointer(&b)), 1)
88	return true
89}
90
91// SendSigusr1 sends SIGUSR1 to mp.
92func SendSigusr1(mp *M) {
93	panic("SendSigusr1")
94}
95