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//go:build dragonfly || freebsd || netbsd
6// +build dragonfly freebsd netbsd
7
8package os
9
10import (
11	"runtime"
12	"syscall"
13)
14
15const _P_PID = 0
16
17// blockUntilWaitable attempts to block until a call to p.Wait will
18// succeed immediately, and reports whether it has done so.
19// It does not actually call p.Wait.
20func (p *Process) blockUntilWaitable() (bool, error) {
21	var errno syscall.Errno
22	for {
23		// The arguments on 32-bit FreeBSD look like the following:
24		// - freebsd32_wait6_args{ idtype, id1, id2, status, options, wrusage, info } or
25		// - freebsd32_wait6_args{ idtype, pad, id1, id2, status, options, wrusage, info } when PAD64_REQUIRED=1 on ARM, MIPS or PowerPC
26		if runtime.GOOS == "freebsd" && runtime.GOARCH == "386" {
27			_, _, errno = syscall.Syscall9(syscall.SYS_WAIT6, _P_PID, uintptr(p.Pid), 0, 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0, 0, 0)
28		} else if runtime.GOOS == "freebsd" && runtime.GOARCH == "arm" {
29			_, _, errno = syscall.Syscall9(syscall.SYS_WAIT6, _P_PID, 0, uintptr(p.Pid), 0, 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0, 0)
30		} else {
31			_, _, errno = syscall.Syscall6(syscall.SYS_WAIT6, _P_PID, uintptr(p.Pid), 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0)
32		}
33		if errno != syscall.EINTR {
34			break
35		}
36	}
37	runtime.KeepAlive(p)
38	if errno == syscall.ENOSYS {
39		return false, nil
40	} else if errno != 0 {
41		return false, NewSyscallError("wait6", errno)
42	}
43	return true, nil
44}
45