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