LogicalFile provider usability

Stephen C. Tweedie sct at redhat.com
Fri Sep 6 12:46:13 UTC 2013


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.

--Stephen




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