There is no need for them to be writable and with the previous commit
this change will also not result in any compiler warnings. Simply change
all of the static definitions to be static const.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
The function only uses the passed command as a const buffer and makes a
copy immediately. As such, there is also no need for a destroy callback
as the caller can simply clean up afterwards.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
If the button shield command cannot be executed due to an underlying
error then resp is NULL. Avoid the crash by adding the appropriate
check.
Closes: #694
