fs: preserve readFile() errors when using a numeric fd and buffer option

[jibin7jose]

Version

v24.18.0

Platform

Windows 11 x64

Subsystem

fs

What steps will reproduce the bug?

'use strict';

const fs = require('node:fs');

fs.writeFileSync('repro.txt', 'Hello world');

fs.open('repro.txt', 'r', (err, fd) => {
if (err) throw err;

fs.readFile(fd, { buffer: Buffer.alloc(5) }, (err, data) => {
console.log('err:', err && err.code);
console.log('data:', data && data.toString());
fs.closeSync(fd);
});
});

How often does it reproduce? Is there a required condition?

Always, when fs.readFile() is called with:
a numeric file descriptor, and
options.buffer, and
the supplied buffer is too small for the file

What is the expected behavior? Why is that the expected behavior?

The call should fail with ERR_INVALID_ARG_VALUE because the provided buffer is too small to contain the full file contents.

What do you see instead?

The error is dropped for user-supplied file descriptors, and the callback can complete successfully instead of reporting ERR_INVALID_ARG_VALUE.

Additional information

Root cause appears to be in lib/internal/fs/read/context.js (lines 180-194): ReadFileContext.close(err) ignores err when isUserFd is true, so the final callback runs as if no failure occurred.