bug#52477: 27.1; .crx and .crx3 are zip files

[Michael Albinus]

Eli Zaretskii <eliz@gnu.org> writes:

Hi Eli,

>> > The first couple of bytes of that files is "Cr24", while a normal zip
>> > file starts with "PK".
>>
>> Yes, and that's why libarchive(3) doesn't handle it. Sadly, I cannot add
>> it to tramp-archive.el, therefore.
>>
>> But there's no reason to prevent it from adding to arc-mode.el and/or
>> dired-aux.el.
>
> If the file doesn't follow the PKZip spec in the initial signature,
> who knows what else in that spec doesn't it follow?  The ZIP spec has
> a lot of special rules and formatting requirements, so if a file
> doesn't follow them, how can we support it without knowing its exact
> format specification?

".crx" files are Chrome Extensions, as shown by Stefan. They are
specified, see for example 
<https://developer.chrome.com/docs/extensions/reference/>.

Personally, I have no strong opinion whether we shall support them.

Best regards, Michael.