waitForExit() ignored for running process that never terminates

[jarv]

On Linux, the timeout on waitForExit() is ignored in some cases.

Example

import osproc
import streams

let args = ["-c", "cat"]
let process = startProcess(command = "/bin/sh", args = args)
let ret = waitForExit(p = process, timeout = 1000)

let strm = process.outputStream()
echo strm.readAll()
echo ret

https://play.nim-lang.org/#ix=3zQo

On MacOS the timeout is respected, on Linux the timeout is ignored while cat is blocked on reading input.

Interestingly this only happens when cat is invoked in a subshell,

let process = startProcess(command = "cat", args = args)

handles the timeout correct, as well as

let args = ["-c", "sleep 100"]
let process = startProcess(command = "/bin/sh", args = args)

Version

# nim -v
Nim Compiler Version 1.4.8 [Linux: amd64]
Compiled at 2021-05-25
Copyright (c) 2006-2021 by Andreas Rumpf

git hash: 44e653a9314e1b8503f0fa4a8a34c3380b26fff3
active boot switches: -d:release -d:danger