Re: [fuse-devel] Permission denied: /dev/null

[James R. <jr...@ro...>]

On Thu, Jun 10, 2010 at 12:27 AM, Bernd Schubert <ber...@fa...
> wrote:

> On Wednesday 09 June 2010, James Rhodes wrote:
> > I'm writing a special kind of unionfs-style filesystem, where a readonly
> > copy of the root filesystem is shown, but a writable overlay runs on top,
> >  so that all file writes get redirected into the writable folder
> component,
> >  and the reads are determined based on whether or not there is a file in
> >  the writable folder (it's used for sandboxing applications).
>
> Why do you want to re-invent the wheel? There already exists unionfs-fuse
> (and
> the unmaintained funionfs).
>

Because I need to redirect writes, not just merge two filesystems together
(one, the root
filesystem, needs to be read-only.  Anything written to it needs to be
dumped into another
folder).  It's a little different from what unionfs does as far as I know.

>
> > However, I've run into a bit of trouble.  The filesystem works fine on
> > standard files, but I can't seem to get it working correctly for things
> >  like /dev/null.  I just get Permission denied (and I've confirmed that
> it
> >  isn't my filesystem which is causing the error).  From the FUSE logs
> >  (using fusepy with LoggingMixIn) the system doesn't even attempt to open
> >  /dev/null for writing - there's just a bunch of getattrs.
> >
> > Any ideas why I get Permission denied for /dev/null?
>
> You need to give the option "-o dev".


Thanks, that seems to have solved the issue.

Regards, James.