RE: [PATCH] Fail XS_DIRECTORY for paths with no children

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: win-pv-devel <win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of 
> Marek Marczykowski-Górecki
> Sent: 10 January 2021 12:35
> To: Owen Smith <owen.smith@xxxxxxxxxx>
> Cc: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH] Fail XS_DIRECTORY for paths with no children
> 
> On Wed, Jan 06, 2021 at 04:17:50PM +0000, Owen Smith wrote:
> > When a xenstore path has no children, a response is generated which
> > contians only the double null terminator. Detect a 0-length response
> > payload and return STATUS_OBJECT_PATH_NOT_FOUND to indicate that this
> > path does not have any children
> 
> Is it really the right thing to do? I think it may confuse empty
> directory with non-existing directory. But I may be missing some context
> here.

For Directory I think ENOENT (aka STATUS_OBJECT_PATH_NOT_FOUND) is the most 
useful thing to hand back in both the empty and non-existent cases. If it 
becomes necessary to distinguish between the two then a Read can be issued 
which would succeed in the former case but fail in the latter.

  Paul

> 
> --
> Best Regards,
> Marek Marczykowski-Górecki
> Invisible Things Lab
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?