This patch fixes an aliasing problem of the 'close' method signature
that prevented the Input::Root_component::close method to be called.
This way, the event-queue state was not reset at session-close time,
which prevented a subsequent session-creation request to succeed. With
the patch, input servers like ps2_drv, usb_drv that rely on the
Input::Root_component support the dynamic re-opening of sessions. This
happens in particular when using a dynamically configured input filter.
This patch reduces the number of exception types by facilitating
globally defined exceptions for common usage patterns shared by most
services. In particular, RPC functions that demand a session-resource
upgrade not longer reflect this condition via a session-specific
exception but via the 'Out_of_ram' or 'Out_of_caps' types.
Furthermore, the 'Parent::Service_denied', 'Parent::Unavailable',
'Root::Invalid_args', 'Root::Unavailable', 'Service::Invalid_args',
'Service::Unavailable', and 'Local_service::Factory::Denied' types have
been replaced by the single 'Service_denied' exception type defined in
'session/session.h'.
This consolidation eases the error handling (there are fewer exceptions
to handle), alleviates the need to convert exceptions along the
session-creation call chain, and avoids possible aliasing problems
(catching the wrong type with the same name but living in a different
scope).
This patch changes both the Input::Session interface and the skeleton
for the server-side implementation of this interface
('input/component.h').
The Input::Session interface offers a new 'sigh' function, which can be
called be the client to register a signal handler. The signal handler
gets notified on the arrival of new input. This alleviates the need to
poll for input events at the client side.
The server-side skeleton for implementing input services underwent a
redesign to make it more modular and robust. I.e., there are no
global functions needed at the server side and the event-queue
enable/disable mechanism is implemented at a central place (in the root
component) rather than inside each driver.
Fixes#46
