Re: [PATCH 3/4] localspl: Add support for monitors providing the MONITOR2 interface.

[Huw Davies]

On Wed, Sep 04, 2019 at 09:58:31AM +0100, Huw Davies wrote:
> On Wed, Sep 04, 2019 at 04:34:14PM +0800, Dmitry Timoshkov wrote:
> > Hi Huw,
> >
> > Huw Davies  wrote:
> > > > @@ -66,9 +66,9 @@ typedef struct {
> > > >      LPWSTR          dllname;
> > > >      PMONITORUI      monitorUI;
> > > >      LPMONITOR       monitor;
> > > > - LPMONITOR2      monitor2;
> > > > HMODULE         hdll;
> > > > DWORD           refcount;
> > > > - DWORD           dwMonitorSize;
> > > >
> > > > } monitor_t;
> > >
> > > Hi Dmitry,
> > >
> > > Is there a reason why we can't simply replace the MONITOR struct with
> > > a MONITOR2 struct?   It would require a bit more work at initialisation
> > > but then calling the functions would be rather simpler.
> >
> > I considered that, and even have done an initial implementation that way.
> > However, the structures have different prototypes for some callbacks, and
> > in order to take care of this we'd need to create wrappers. I'd rather
> > decided to use an appropriate table instead.
>
> It's only a couple of functions (OpenPortEx and XcvOpenPort) and all you'd
> need would be something like:
>
> if (monitor.cbSize == sizeof(MONITOR))
>   monitor.pfnXcvOpenPort( old_args );
> else
>   monitor.pfnXcvOpenPort( new_args );

Of course it's a bit more complicated than this.  What you could do is
change monitor_t to something like:

...
PMONITORUI      monitorUI;
MONITOR2        monitor;
BOOL  (WINAPI *old_open_port_ex)(LPWSTR, LPWSTR, PHANDLE, struct _MONITOR *);
BOOL  (WINAPI *old_xcv_open_port)(LPCWSTR, ACCESS_MASK, PHANDLE);
HMODULE         hdll;
...

On initialization set up the monitor fn ptrs as appropriate, then the call
to XcvOpenPort looks like:

if (pm->monitor.old_xcv_open_port)
    pm->monitor.old_xcv_open_port( old_args );
else
    pm->monitor.pfnXcvOpenPort( new_args );

The call to OpenPortEx will be a little trickier, but we don't use that
at the moment anyway.

Huw.