Re: [Xen-devel] [PATCH v4 3/4] libxl: call hotplug scripts from libxl for vbd

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2012-05-14 at 13:38 +0100, Roger Pau Monne wrote:
> >> +# Hack to prevent the execution of hotplug scripts from udev if the domain
> >> +# has been launched from libxl
> >> +if [ -n "${UDEV_CALL}" ]&&  \
> >> +   `xenstore-read "libxl/disable_udev">/dev/null 2>&1`; then
> >
> > This reads something from xenstore and executes it as a shell command!
> > (Also it will go wrong if the value read is empty eg becaue the key
> > doesn't exist.)
> 
> Are you sure about this? This command never returns anything, because it 
> is redirected to /dev/null, so we only evaluate if it is able to read 
> libxl/disable_udev. If libxl/disable_udev exists this test is passed.

You don't need the backticks for that though. With the backticks it will
execute whatever happens to be in the key -- I guess it's something
quite benign right now or you'd have seen errors.

Ian.



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