Re: Extended attributes

[Christopher Faylor <cgf-use-the-mailinglist-please@cygwin.com>]

On Thu, Jan 16, 2014 at 10:16:00AM +0100, Corinna Vinschen wrote:
>On Jan 16 10:08, Pavel Fedin wrote:
>>  Hello!
>> 
>> > >  What do you think about adding other possible namespaces (system,
>> > > security, and... don't remember the 3rd one) ? So that when
>> > > manipulating UNIX archives etc these attributes could be kept along
>> > > with files ? At least we have one use case now.
>> > 
>> > That doesn't make sense.  Extended attributes as implemented by Windows
>> > are user attributes, not system attributes.  The non-user attributes on
>> > Linux have a very special meaning to the kernel and/or are restricted
>> > to privileged users only.  Their functionality is already provided by
>> > other OS functions (as for system.posix_acl_access) or not at all (as
>> > for security.selinux).
>> 
>>  I know they have special meaning. At the other hand, if we allow
>>  them, we will allow to store them on a filesystem. Wouldn't it be
>>  nice ? This is useful at least for SquashFS image preparation.
>>  I guess for similar reasons we have support e. g. for device nodes
>>  (/dev) with their major/minor numbers. They are also ignored by
>>  Cygwin, and just stored on the filesystem (or do i miss something ?).
>
>Yes, the history.  The device nodes were a start to implement actual
>loadable device handler code (application level, not actual device
>drivers), but for some reason it was never fully implemented.

If you're talking about the ability to create a device file anywhere
that was something that I did.  It wasn't to implement loadable device
handlers but just so that we could eventually have a real /dev populated
with device files.  However, we have since gone the route of creating a
pseudo-filesystem /dev so that's no longer necessary.

I also did this to allow the creation of fifos anywhere so that's still
a valid use case.  And, actually, creating a device node anywhere is
certainly something that you need to be able to do if you want to claim
Linux-like functionality.

Device nodes are not (or are not supposed to be) "ignored by Cygwin".

cgf

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