Re: silent semantic changes with reiser4

Spam
2004-08-26T11:15:47Z

> Spam <spam@tnonline.net> wrote:
>>
>>
>>
>> > Spam <spam@tnonline.net> wrote:
>> >>
>> >>
>> >>
>> >> > Spam <spam@tnonline.net> wrote:
>> >> >>
>> >> >> Yes, for example documents, image files etc. The multiple data
>> >> >> streams can contain thumbnails, info about who is editing the file
>> >> >> (useful for networked files) etc. Could be used for version handling
>> >> >> and much more.
>> >>
>> >> > All of which can be handled in userspace library code.
>> >>
>> >> > What compelling reason is there for doing this in the kernel?
>> >>
>> >>
>> >> Because having user space tools and code will make it not work with
>> >> everything. Keeping stuff in the kernel should make the new features
>> >> transparent to the applications.
>> >>
>> >> Applications that support the new features will benefit, all others
>> >> will continue to work without destroying data.
>>
>> > Sorry, but that all sounds a bit fluffy. Please provide some examples.
>>
>> We already had the examples with cp and mv. Both should continue to
>> work and the files will still be copied. The same with Konqueror and
>> Nautilus. Files and their meta-files/streams/attributes will be
>> retained as long as applications are using the OS API.
>>
>> However, if things are to implemented in user-space, then old
>> applications will not work correctly and there is risk that all the
>> extra information will be lost or corrupted.
>>
>> You said it would be socially hard. I think it would be very much
>> close to impossible to get it right. Imagine that Gnome and Nautilus
>> would implement support for these. I doubt that cp, mv, KDE, mc,
>> app-xyz would implement this anytime soon and in the meantime the
>> data is at risk.
>>

> No. All of the applications which you initially identified can be
> implemented by putting the various bits of data into a single file and
> getting applications to agree on the format of that file.

> For example, some image file formats already support embedded metadata, do
> they not?

Yes, JPEG, TIFF and PNG files for example. But, if you modify any of
these with an application that doesn't support the extensions then
you will loose them.

Also, you are thinking _very_ narrowly now. There are thousands of
file formats. Implementing the support for meta-data/ streams/
attributes in the kernel will make it possible to use this
generically for all files.

I use this in Windows quite much. I put information description
fields for lots of different files. These descriptions are then
searchable etc. I could use the command prompt to copy the files and
the descriptions would still be there.

Secondly, do you expect file managers like Nautilus and Konqueror to
support every piece of file format on the planet so they could read
information directly from the documents?

~S