A useful VFS change ...

[Volker Lendecke]

On Fri, Mar 14, 2014 at 08:56:12AM -0400, Dustin Oprea wrote:
> ?
> >
> > Don't we still have examples/VFS/skel_opaque.c that does
> > exactly what Jeremy suggested?
> >
> > Volker
> 
> It doesn't work by default (I submitted a simple patch for this at the same
> time, but I'm fairly certain that it was ignored), and the build is broken.
> Richard was working on this latter part, but there have been no further
> updates.
> 
> I'm not sure if Jeremy's solution will work, but you guys are the SMEs..
> Not me. Can a module theoretically work with everything but open, close,
> read, and write returning ENOTSUPP (as a theoretical "hello world" exercise
> for a newcomer)? As I understand it, every function has to be implemented,
> don't they?

You can always install your own VFS before the opaque
terminator in the chain. If skel_opaque.c does not build and
there were fixes on the list, please apologize: I must have
missed that patch. If you point me again at it, I'll take a
look.

So the setup would be

vfs_objects = dustin opaque

"vfs_dustin" would implement the bare mininum necessary
(open/close/etc) and not call the _NEXT_ functions, thus not
pass them on to the opaque module. The opaque module being
the last in the list avoids passing anything to the
vfs_default behaviour that you want to avoid.

Or are you asking for a bare minimum module that for example
provides a static "hello.txt" file with contents "world"?

Volker

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