Source file src/runtime/export_unix_test.go

     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 unix
     6  
     7  package runtime
     8  
     9  import "unsafe"
    10  
    11  var NonblockingPipe = nonblockingPipe
    12  
    13  func sigismember(mask *sigset, i int) bool {
    14  	clear := *mask
    15  	sigdelset(&clear, i)
    16  	return clear != *mask
    17  }
    18  
    19  func Sigisblocked(i int) bool {
    20  	var sigmask sigset
    21  	sigprocmask(_SIG_SETMASK, nil, &sigmask)
    22  	return sigismember(&sigmask, i)
    23  }
    24  
    25  type M = m
    26  
    27  var waitForSigusr1 struct {
    28  	rdpipe int32
    29  	wrpipe int32
    30  	mID    int64
    31  }
    32  
    33  // WaitForSigusr1 blocks until a SIGUSR1 is received. It calls ready
    34  // when it is set up to receive SIGUSR1. The ready function should
    35  // cause a SIGUSR1 to be sent. The r and w arguments are a pipe that
    36  // the signal handler can use to report when the signal is received.
    37  //
    38  // Once SIGUSR1 is received, it returns the ID of the current M and
    39  // the ID of the M the SIGUSR1 was received on. If the caller writes
    40  // a non-zero byte to w, WaitForSigusr1 returns immediately with -1, -1.
    41  func WaitForSigusr1(r, w int32, ready func(mp *M)) (int64, int64) {
    42  	lockOSThread()
    43  	// Make sure we can receive SIGUSR1.
    44  	unblocksig(_SIGUSR1)
    45  
    46  	waitForSigusr1.rdpipe = r
    47  	waitForSigusr1.wrpipe = w
    48  
    49  	mp := getg().m
    50  	testSigusr1 = waitForSigusr1Callback
    51  	ready(mp)
    52  
    53  	// Wait for the signal. We use a pipe rather than a note
    54  	// because write is always async-signal-safe.
    55  	entersyscallblock()
    56  	var b byte
    57  	read(waitForSigusr1.rdpipe, noescape(unsafe.Pointer(&b)), 1)
    58  	exitsyscall()
    59  
    60  	gotM := waitForSigusr1.mID
    61  	testSigusr1 = nil
    62  
    63  	unlockOSThread()
    64  
    65  	if b != 0 {
    66  		// timeout signal from caller
    67  		return -1, -1
    68  	}
    69  	return mp.id, gotM
    70  }
    71  
    72  // waitForSigusr1Callback is called from the signal handler during
    73  // WaitForSigusr1. It must not have write barriers because there may
    74  // not be a P.
    75  //
    76  //go:nowritebarrierrec
    77  func waitForSigusr1Callback(gp *g) bool {
    78  	if gp == nil || gp.m == nil {
    79  		waitForSigusr1.mID = -1
    80  	} else {
    81  		waitForSigusr1.mID = gp.m.id
    82  	}
    83  	b := byte(0)
    84  	write(uintptr(waitForSigusr1.wrpipe), noescape(unsafe.Pointer(&b)), 1)
    85  	return true
    86  }
    87  
    88  // SendSigusr1 sends SIGUSR1 to mp.
    89  func SendSigusr1(mp *M) {
    90  	signalM(mp, _SIGUSR1)
    91  }
    92  
    93  const (
    94  	O_WRONLY = _O_WRONLY
    95  	O_CREAT  = _O_CREAT
    96  	O_TRUNC  = _O_TRUNC
    97  )
    98  

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