zlib: ZipFile.close() hangs after partially consuming file-backed contentIterator()

[trivikr]

Version

main

Platform

macOS 26.6.1

Subsystem

zlib

What steps will reproduce the bug?

import { mkdtempSync, writeFileSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { ZipEntry, createZipArchiveSync, ZipFile } from 'node:zlib';

const dir = mkdtempSync(join(tmpdir(), 'zip-close-hang-'));
const file = join(dir, 'archive.zip');

const chunks = [];
const entry = ZipEntry.createSync(
  'big.txt',
  Buffer.alloc(1024 * 1024, 0x61),
  { method: 'store' },
);

for (const chunk of createZipArchiveSync([entry])) {
  chunks.push(chunk);
}
writeFileSync(file, Buffer.concat(chunks));

const zip = ZipFile.openSync(file);
const readEntry = zip.getSync('big.txt');

const iterator = readEntry.contentIterator();
const first = await iterator.next();
console.log('read first chunk:', first.value.length);

const result = await Promise.race([
  zip.close().then(() => 'close resolved'),
  new Promise((resolve) => setTimeout(() => resolve('close timed out'), 1000)),
]);

console.log(result);

await iterator.return();
await zip.close();

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

Always

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

zip.close() should either close promptly or otherwise not wait forever for a paused iterator that is not actively performing an fd read.

What do you see instead?

read first chunk: 1048576
close timed out

After one chunk is consumed, zip.close() does not settle while the iterator is paused, so the repro prints close timed out.

Additional information

No response