Compressing tar files using CompressionStream broke in Deno 1.43.0

[jespertheend]

Version: Deno 1.43.0

This is a reduced test case of a script I'm using to archive and compress several files. In Deno 1.42.4 this creates the archive just fine, but in Deno 1.43.0 this always results in a file of 41 bytes.

To reproduce, store this in a file and run with deno run -A compress.ts

import { copy, readableStreamFromReader, readerFromStreamReader } from "https://deno.land/std@0.204.0/streams/mod.ts";
import { Tar } from "https://deno.land/std@0.204.0/archive/tar.ts";
import * as stdPath from "https://deno.land/std@0.221.0/path/mod.ts";

const selfPath = stdPath.fromFileUrl(import.meta.url);
const tar = new Tar();
tar.append("self.ts", {
	filePath: selfPath,
});
const tarPath = stdPath.resolve(stdPath.dirname(selfPath), "compressed.tar.gz");
const writer = await Deno.open(tarPath, {
	create: true,
	truncate: true,
	write: true,
});
const compressionReader = readableStreamFromReader(tar.getReader()).pipeThrough(new CompressionStream("gzip"))
	.getReader();
await copy(readerFromStreamReader(compressionReader), writer);
writer.close();

I think this may have regressed in #21199

[dsherret]

I don't think this one is a bug. copy doesn't guarantee it copies all the bytes—it returns back a number of bytes that it copies: https://deno.land/std@0.204.0/streams/mod.ts?s=copy

I think the code is just not handling that.

[dsherret]

Nevermind, I looked into the implementation of copy and it loops to write the whole reader to the writer. This does seem like a bug.

[0f-0b]

tar.append returns a promise that isn't awaited, so the file might not have been added yet by the time tar.getReader is called.

[lucacasonato]

I can not reproduce this in Deno 1.46.2-canary (with or without the await). Is there any particular reason you are still on Deno 1.43?

[dsherret]

@0f-0b that's the issue.

I'm able to reproduce on canary, but once I await the append the issue no longer occurs.

Still waiting for the day that TypeScript adds diagnostics to disallow floating promises so that we can all be saved from this.

[jespertheend]

Is there any particular reason you are still on Deno 1.43?

Not really, that's just the first version where this started failing. I'd like to use the latest version but I can reproduce this in 1.46.2 as well.