Honor `Accept` header when downloading directories

[maxnoe]

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Is your feature request related to a problem? Please describe.

The file format one gets when downloading a directory seems to depend on the HTTP User-Agent and does not honor the Accept header.

macos user agents seem to get tar files, while everyone else gets zip files.

This makes it hard to write instructions to e.g. download files and unpack them via the command line (e.g. curl / wget) that are valid cross platform.

Describe the solution you'd like

It would be great if Nextcloud would honor the Accept header when downloading a directory, so that e.g. it is guaranteed that:

$ curl -LO -H 'Accept: application/x-tar' <share-link>
# or
$ curl -LO -H 'Accept: application/zip' <share-link>

always produces a tar file and a zip file respectively, independent of platform / user agent.

Describe alternatives you've considered

A possible alternative would be a query parameter for the filetype.

[solracsf]

Yes.

server/lib/private/Streamer.php

Lines 43 to 44 in 5c2610a

	// array of regexp. Matching user agents will get tar instead of zip
	private array $preferTarFor = [ '/macintosh|mac os x/i' ];

[joshtrichards]

You could always specify the User-Agent too. ;-)

Joking aside, unfortunately even User-Agent wouldn't be sufficient as archive size is also a factor:

server/lib/private/Streamer.php

Lines 84 to 90 in 1de151a

	if ($size > 0 && $size < 4 * 1000 * 1000 * 1000 && $numberOfFiles < 65536) {
	$this->streamerInstance = new ZipStreamer(['zip64' => false]);
	} elseif ($request->isUserAgent($this->preferTarFor)) {
	$this->streamerInstance = new TarStreamer();
	} else {
	$this->streamerInstance = new ZipStreamer(['zip64' => PHP_INT_SIZE !== 4]);
	}

Outside of possible quirks in the zip stream library we use (and maybe 32-bit support?), I wonder if there's still a need for different cross-platform archive handling?

[solracsf]

I believe this was implemented because TAR is native on MacOS, and has (had?) some problems with Zip64 files.

[skjnldsv]

Fixed by #48098