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Source file src/os/wait_waitid.go

Documentation: os

  // Copyright 2016 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // We used to used this code for Darwin, but according to issue #19314
  // waitid returns if the process is stopped, even when using WEXITED.
  
  // +build linux
  
  package os
  
  import (
  	"runtime"
  	"syscall"
  	"unsafe"
  )
  
  const _P_PID = 1
  
  // blockUntilWaitable attempts to block until a call to p.Wait will
  // succeed immediately, and returns whether it has done so.
  // It does not actually call p.Wait.
  func (p *Process) blockUntilWaitable() (bool, error) {
  	// The waitid system call expects a pointer to a siginfo_t,
  	// which is 128 bytes on all GNU/Linux systems.
  	// On Darwin, it requires greater than or equal to 64 bytes
  	// for darwin/{386,arm} and 104 bytes for darwin/amd64.
  	// We don't care about the values it returns.
  	var siginfo [16]uint64
  	psig := &siginfo[0]
  	_, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0)
  	runtime.KeepAlive(p)
  	if e != 0 {
  		// waitid has been available since Linux 2.6.9, but
  		// reportedly is not available in Ubuntu on Windows.
  		// See issue 16610.
  		if e == syscall.ENOSYS {
  			return false, nil
  		}
  		return false, NewSyscallError("waitid", e)
  	}
  	return true, nil
  }
  

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