LogicalFile provider usability

Jan Synacek jsynacek at redhat.com
Fri Sep 6 12:52:41 UTC 2013


On 09/06/2013 02:46 PM, Stephen C. Tweedie wrote:
> Hi,
> 
> On Fri, 2013-09-06 at 14:29 +0200, Jan Synacek wrote:
>> On 09/06/2013 01:29 PM, Stephen C. Tweedie wrote:
>>> On Fri, 2013-09-06 at 10:32 +0200, Jan Synacek wrote:
> 
>> Well, my original concern was if there is a way to specify more files by one
>> path. It just takes me a while to get the question right:)
> 
> Ahh, OK.
> 
>> So, my understanding is that there is no such way. At any given time,
>> /home/jsynacek/file is always only one file.
> 
> Nearly always, yes.  The exceptions are special cases that you can
> probably ignore for now.
> 
> There are two places where this breaks down.  One is "magic" files which
> are context-dependent; /proc/self/ is the obvious one, which will point
> to a completely different /proc/ subtree depending on which process is
> calling it.
> 
> Second is filesystem namespaces, where a group of related processes can
> be set up to have a distinct set of mount points separate from the
> default; and the related chroot functionality which allows different
> processes to consider / to be different places within the mounted
> hierarchy.  
> 
> Both of these allow a given path to resolve to completely different
> files depending on which process is calling; but in both cases, any one
> process still has a unique mapping.  So as far as the provider itself is
> concerned, a path resolves uniquely; as far as the whole system is
> concerned, that's only part of the picture.
> 
> I'd recommend against worrying about this for now, and just use the
> default namespace that the provider lives in.  If we want to expose
> additional namespace semantics, that's an optional future feature.
> 

Ok, thanks for the explanation!

-- 
Jan Synacek
Software Engineer, Red Hat


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