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Source file src/os/wait_waitid.go

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

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