os: os Process.Kill() not working on windows

[gianniLesl]

What version of Go are you using (go version)?

$ go version

Tested with go version 1.17, 1.17.1, 1.17.3, 1.17.6, and 1.17.7

The feature is working on 1.16.14 and earlier.

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env

GOOS="windows" GOARCH="amd64"

What did you do?

I created a small script to use to kill particular processes on windows. When I compile and run the executable though I get the error DuplicateHandle: The handle is invalid.

Source code: https://go.dev/play/p/Ik3UMsABNQI

What did you expect to see?

Expected Process.Kill to kill the running process without error

What did you see instead?

DuplicateHandle: The handle is invalid.

[bcmills]

The os.Process struct has unexported fields, so you can't expect to create a valid one using a struct literal.

Instead, look up the desired PID using os.FindProcess.

[gianniLesl]

We expected this to work because it was working in 1.16.14, so 1.17 breaks backwards compatibility. This seems to be the change that broke us 105c5b5?diff=split . When I run with the function

func TerminateProcess(process os.Process, exitCode int) error {
	h, e := syscall.OpenProcess(syscall.PROCESS_TERMINATE, false, uint32(process.Pid))
	if e != nil {
		return os.NewSyscallError("OpenProcess", e)
	}
	defer syscall.CloseHandle(h)
	e = syscall.TerminateProcess(h, uint32(exitCode))
	if e != nil {
		return os.NewSyscallError("TerminateProcess", e)
	}

	runtime.KeepAlive(process)
	return nil
}

execution succeeds.

Source Code: https://go.dev/play/p/mELlwQqiBZa

(Note: When we run os.FindProcess on 1.16 and 1.17 it returns "OpenProcess: Access is denied." for our processes)

[ianlancetaylor]

Writing

	process := os.Process{
		Pid: pid,
	}

was never supposed to work. I'm sorry that it did.

[beoran]

In this case, it should have been documented that it cannot work. While there are unexported members, it isn't immediately clear from the docs that Kill will not work.

[ianlancetaylor]

To me it seems clear from the documentation which explicitly says that Process stores information about a process created by StartProcess. But if someone wants to send a brief and to the point update to the docs we can certainly take a look. Thanks.