github.com/gidoBOSSftw5731/go/src@v0.0.0-20210226122457-d24b0edbf019/runtime/export_unix_test.go (about) 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 //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris 6 // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris 7 8 package runtime 9 10 import "unsafe" 11 12 var NonblockingPipe = nonblockingPipe 13 var SetNonblock = setNonblock 14 var Closeonexec = closeonexec 15 16 func sigismember(mask *sigset, i int) bool { 17 clear := *mask 18 sigdelset(&clear, i) 19 return clear != *mask 20 } 21 22 func Sigisblocked(i int) bool { 23 var sigmask sigset 24 sigprocmask(_SIG_SETMASK, nil, &sigmask) 25 return sigismember(&sigmask, i) 26 } 27 28 type M = m 29 30 var 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. 44 func 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 80 func 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. 92 func SendSigusr1(mp *M) { 93 signalM(mp, _SIGUSR1) 94 }