1
0
mirror of https://github.com/golang/go synced 2024-11-06 08:26:12 -07:00
go/src/os/wait_wait6.go
Ian Lance Taylor e69912e6f4 os: use runtime.Keepalive for *Process values
The os package sets a finalizer on *Process. I looked through all the
uses of *Process in the package, looking for each case where a *Process
was passed as an argument and the final reference to the argument was
not a function or method call. I added a call to runtime.KeepAlive after
each such final reference (there were only three).

The code is safe today without the KeepAlive calls because the compiler
keeps arguments alive for the duration of the function. However, that is
not a language requirement, so adding the KeepAlive calls ensures that
this code remains safe even if the compiler changes in the future.

I also removed an existing unnecessry call to runtime.KeepAlive. The
syscall.Syscall function is handled specially by the compiler to keep
its arguments alive.

Change-Id: Ibd2ff20b31ed3de4f6a59dd1633c1b44001d91d9
Reviewed-on: https://go-review.googlesource.com/27637
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-08-24 16:57:09 +00:00

42 lines
1.5 KiB
Go

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build freebsd
package os
import (
"runtime"
"syscall"
)
const _P_PID = 0
// blockUntilWaitable attempts to block until a call to p.Wait will
// succeed immediately, and returns whether it has done so.
// It does not actually call p.Wait.
func (p *Process) blockUntilWaitable() (bool, error) {
var errno syscall.Errno
// The arguments on 32-bit FreeBSD look like the following:
// - freebsd32_wait6_args{ idtype, id1, id2, status, options, wrusage, info } or
// - freebsd32_wait6_args{ idtype, pad, id1, id2, status, options, wrusage, info } when PAD64_REQUIRED=1 on ARM, MIPS or PowerPC
if runtime.GOARCH == "386" {
_, _, errno = syscall.Syscall9(syscall.SYS_WAIT6, _P_PID, uintptr(p.Pid), 0, 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0, 0, 0)
} else if runtime.GOARCH == "arm" {
_, _, errno = syscall.Syscall9(syscall.SYS_WAIT6, _P_PID, 0, uintptr(p.Pid), 0, 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0, 0)
} else {
_, _, errno = syscall.Syscall6(syscall.SYS_WAIT6, _P_PID, uintptr(p.Pid), 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0)
}
runtime.KeepAlive(p)
if errno != 0 {
// The wait6 system call is supported only on FreeBSD
// 9.3 and above, so it may return an ENOSYS error.
if errno == syscall.ENOSYS {
return false, nil
}
return false, NewSyscallError("wait6", errno)
}
return true, nil
}