stream.unshift() after end event

[HitkoDev]

In some cases calling readableStream.read can reach the end of the stream (e.g. on a short file, or when stream emits everything in a single chunk), or stream may end for other reasons, causing readableStream.unshift to throw an error.

[Borewit]

@HitkoDev Can you provide a file and description how to reproduce this issue?

[HitkoDev]

Sure:

const buff = Buffer.from(whatever);

class MyStream extends Readable {
  _read() {
    this.push(buff);
    this.push(null); 
  }
}

const s = new MyStream();
fileType.stream(s).then(res => console.log(res.fileType));

[bencmbrook]

Interesting.. Our test fixtures should definitely cover this case. Did anything change with the .stream tests?

[bencmbrook]

@HitkoDev are you reading from your stream before calling fileType.stream?

[HitkoDev]

@bencmbrook I'm not reading from source stream, I'm always reading from the stream returned by fileType. As I said, this usually happens when dealing with really small files, file uploads, or any other readable stream where everything is returned in a single chunk and there's nothing left after calling

file-type/core.js

Line 1287 in 99beda8

const chunk = readableStream.read(minimumBytes) || readableStream.read() || Buffer.alloc(0);

[bencmbrook]

Fixed it on my branch, thanks.

Hey @sindresorhus, any chance I can get repo permissions to PR without a fork?

[sindresorhus]

@bencmbrook Oh yeah. I must have forgotten to do that previously... Done. Prefer PRs over pushing directly to master though.

[Borewit]

Are you taking care of this one @bencmbrook?

[bencmbrook]

@Borewit yes I have a fix, but @sindresorhus I don't think I received the access rights?

git push --set-upstream  origin bencmbrook/short-stream

ERROR: Permission to sindresorhus/file-type.git denied to bencmbrook.
fatal: Could not read from remote repository.

---

In the interest of time, my change to core.js is

file-type/core.js

Line 1295 in 99beda8

readableStream.unshift(chunk);

to:

		if (readableStream.readableEnded || readableStream._readableState.ended) {
			readableStream.unshift();
		} else {
			readableStream.unshift(chunk);
		}

and a test for test.js

test('.stream() method - short stream', async t => {
	const buffer = Buffer.from([0, 1, 0, 1]);
	class MyStream extends stream.Readable {
		_read() {
			this.push(buffer);
			this.push(null);
		}
	}

	const shortStream = new MyStream();
	const newStream = await FileType.stream(shortStream);
	t.is(newStream.fileType, undefined);
});

[Borewit]

Hmm, via comments, is not really the way I guess. but it is good news you took care of the issue.

Maybe push it via your cloned file-type repo?

[sindresorhus]

@bencmbrook You have to accept the invitation.

[bencmbrook]

Hah, my bad. Received, thank you.