Re: [toolbox] Extended Attributes

[Maxwell, A. R <ada...@pn...>]

On Jun 24, 2005, at 03:55, J=E9r=F4me Laurens wrote:

> I don't know how many developers are there but at least  we can =20
> start a discussion.
>
> Tiger now supports xattrs BSD feature, and it is -really- a major =20
> step forward.
> To play with xattrs, you can download
> <http://www.macs.hw.ac.uk/~rpointon/osx/xattr.html>
> I don't know how far those xattrs are linked to their file when =20
> moving around the internet but things are promising.
>
> Using xattrs, you can store any kind of meta data that are not =20
> strictly necessary but makes life so easy.
> You can also store vital data such as character encoding.
> I can see here another mean to store the TeX source(s) of a pdf =20
> file with the output, without forgetting the pdfsync file...

That would be cool!  I don't see a size limit on the xattrs, either.

> AFAIK, the actual context is:
> - Adam made a draft cocoa bridge

Which is just a category on NSFileManager that wraps the xattr calls; =20=

it needs a bit more work to be really useful.

> - there is a pythonmac bridge too
> - some links from google about EAs (Extended attributes) and ACLs =20
> (Access Control List) related to  the linux kernel
> - we already discussed a bit on the mactex list concerning =20
> specifications, but we should edit some general usage specifications.
> - I did not find anything about a concrete use of xattrs to store =20
> the character encoding,

The closest thing I've found is from the man page for getattrlist(2):

"ATTR_CMN_SCRIPT
(read/write) A text_encoding_t containing a text encoding hint for =20
the file system object's name. It is included to facilitate the =20
lossless round trip conversion of names between Unicode and =20
traditional Mac OS script encodings. The values are defined in =20
<CarbonCore/TextCommon.h>. File systems that do not have an =20
appropriate text encoding value should return =20
kTextEncodingMacUnicode. See DTS Q&A 1173 File Manager Text Encoding =20
Hints"."

This appears to be the encoding of the file name itself, though; I'm =20
not familiar with the Carbon resource fork APIs, but maybe Jon Guyer =20
has some insight on this.

We could probably just agree on encoding keys to be used by members =20
of this project, such as net-sourceforge-mactextoolbox-=20
characterencoding, and store either the IANA name (doesn't exist for =20
NSNonlossyASCIIStringEncoding, though) or the encoding constant itself.

--=20
Adam=