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 reports 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