WSL2 does not set up file descriptors for sub processes on the host #14201
Description
Windows Version
10.0.22631.6199
WSL Version
2.6.3.0
Are you using WSL 1 or WSL 2?
- WSL 2
- WSL 1
Kernel Version
6.6.87.2-1
Distro Version
Ubuntu 24.04
Other Software
Node 24.13.0
Repro Steps
The repro uses Node.js but in the original problem the parent process is node and the child process is Google Chrome.
The parent script starts a subprocess with 5 file descriptors. stdin, stdout, stderr + 2 custom ones. It sends data to the child over the fd 3.
// wslParent.mjs
import { spawn } from "node:child_process";
console.log("spawn")
const child = spawn('node.exe', ["wslChild.mjs"], {
stdio: ["inherit", "inherit", "pipe", "pipe", "pipe"],
});
console.log("writing to child via fd 3")
child.stdio[3].write('test');
child.on('error', err => {
console.log('error', err);
});
child.stdio[4].on('data', data => {
console.log('fd4', data.toString('utf-8'));
})
child.stderr.on('data', data => {
console.log('stderr', data.toString('utf-8'));
})
setTimeout(() => {
console.log("parent done");
process.exit(0)
}, 1000)
The child process reads the data from fd 3.
// wslChild.mjs
import fs from 'node:fs';
const stream = fs.createReadStream(null, { fd: 3 });
stream.on('data', data => {
console.log('child fd3', data.toString('utf-8'));
})
setTimeout(() => {
console.log("child done");
stream.close();
process.exit(0)
}, 1000)
Run node wslParent.mjs inside the WSL's Ubuntu terminal.
Expected Behavior
This should print the child fd3 test. If you replace node.exe with node to use the node within Ubuntu it works. If node.exe on the host is used, it fails.
Actual Behavior
It errors: "Error: EBADF: bad file descriptor, close" indicating that the file descriptor was not opened.
Diagnostic Logs
No response