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Source file src/os/wait_waitid.go

Documentation: os

     1  // Copyright 2016 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  // We used to used this code for Darwin, but according to issue #19314
     6  // waitid returns if the process is stopped, even when using WEXITED.
     7  
     8  // +build linux
     9  
    10  package os
    11  
    12  import (
    13  	"runtime"
    14  	"syscall"
    15  	"unsafe"
    16  )
    17  
    18  const _P_PID = 1
    19  
    20  // blockUntilWaitable attempts to block until a call to p.Wait will
    21  // succeed immediately, and returns whether it has done so.
    22  // It does not actually call p.Wait.
    23  func (p *Process) blockUntilWaitable() (bool, error) {
    24  	// The waitid system call expects a pointer to a siginfo_t,
    25  	// which is 128 bytes on all GNU/Linux systems.
    26  	// On Darwin, it requires greater than or equal to 64 bytes
    27  	// for darwin/{386,arm} and 104 bytes for darwin/amd64.
    28  	// We don't care about the values it returns.
    29  	var siginfo [16]uint64
    30  	psig := &siginfo[0]
    31  	_, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0)
    32  	runtime.KeepAlive(p)
    33  	if e != 0 {
    34  		// waitid has been available since Linux 2.6.9, but
    35  		// reportedly is not available in Ubuntu on Windows.
    36  		// See issue 16610.
    37  		if e == syscall.ENOSYS {
    38  			return false, nil
    39  		}
    40  		return false, NewSyscallError("waitid", e)
    41  	}
    42  	return true, nil
    43  }
    44  

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