Chapter 1

� Function() gives me the request code;
� Int0(), Int1(), Int2(), and Int3() return the message parameters as integers;
� Ptr0(), Ptr1(), Ptr2(), and Ptr3() return the message parameters as TAny*
pointers;
� Complete() completes the message, returning the TInt completion code.
My philosophy here is to get beyond the shaky, type-unsafe stage as soon as possible. So I
contain all knowledge of RMessage parameter numbers and types within ServiceL(), and
call second-level handler functions, specified with type-safe parameters, to do the real work.
Most second-level functions don't then need to use any RMessage-related functions at all.
Those that do can get the current RMessage by using the server's Message() function.
Error handling
If the client request is malformed, we panic the client thread – just as we would panic our
own thread if a conventional function call were made in error. The default case is handled
by
Server()->PanicClient(EBadRequest);
This calls my CGsdpServer::PanicClient() function:
void CGsdpServer::PanicClient(TInt aPanic) const
}
{
// Let's have a look before we panic the client
__DEBUGGER()
// OK, go for it
const_cast (Message().Client()).
Panic(_L("GSDP-Server"),aPanic);
The heart of this function is the RThread::Panic() call to panic the client thread, that is,
the client for the message currently being processed.
Until I put the __DEBUGGER() line in, it was impossible to analyze the cause of the panic
under the emulator. The thread being panicked was in the middle of a send–receive function,
somewhere in the kernel executive, and the corresponding debug information was not
supplied in the SDK. However, the real cause of the panic is hidden inside the state of the
server, so invoking the debugger from the server thread gives a much better clue about why
the client thread was about to be panicked. The __DEBUGGER() macro only affects
emulator debug builds, so I don't need to put any conditional compilation constructs around
it.
If the function servicing the client request leaves, then the CGsdpServer::RunError()
function is called:
TInt CGsdpServer::RunError(TInt aErr)
{
// if it's a bad descriptor, panic the client
if (aErr==KErrBadDescriptor) // client had a bad descriptor
{