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
