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

[Roger Pau Monne <roger.pau@citrix.com>]

Ian Campbell escribió:
> 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.

Yes, it's not the first time that I've made that mistake. Since it never 
returns anything I guess that's why I never saw any errors.


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