export_unix_test.go

Documentation: runtime

		 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  }
		95
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