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Date: Wed, 20 Mar 2013 19:37:18 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 10/11] block: Allow omitting the file name
 when using driver-specific options
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To: Eric Blake <eblake@redhat.com>
Cc: pbonzini@redhat.com, qemu-devel@nongnu.org

Am 20.03.2013 um 03:27 hat Eric Blake geschrieben:
> > +++ b/block/nbd.c
> > @@ -174,7 +174,6 @@ static void nbd_parse_filename(const char *filename, QDict *options,
> >  
> >      /* extract the host_spec - fail if it's not nbd:... */
> >      if (!strstart(file, "nbd:", &host_spec)) {
> > -        error_setg(errp, "File name string for NBD must start with 'nbd:'");
> >          goto out;
> >      }
> 
> Is this really right?  The code allows me to pass both file= and
> file.driver= at once; so what if I pass -drive file.driver=nbd,file=xyz.
>  Prior to this patch, I'd get a nice message about file=xyz not starting
> with nbd:, but now there is a silent failure.
> 
> I think it might be better if you keep the error_setg(), and instead
> rewrite the if on the previous line:
> 
> if (file && !strstart(file, "nbd:", &host_spec)) {

In fact, the additional check isn't even necessary because the function
is only called for file != NULL in the first place. I've put the error
back.

> Also, since it looks like the code allows me to pass both file.driver=
> and file= at once, if I pass both pieces of information, is there any
> sanity checking that the two are identical, and/or should we error out
> and declare that if driver options are used then nbd requires a NULL
> filename?

I've added another patch that checks that only one of host/port/filename
is specified.

Kevin