input_server: Notify apps of new key map

Define a new message, B_KEY_MAP_LOADED, that is broadcast to applications by
the Input Server each time a key map is loaded. This allows apps that cache
key-map data to know when their copy has become stale.

Change InputServer::HandleGetSetKeyMap() so it returns an error in the event
loading even the system (fallback) key map fails.

Change-Id: Icc6c884f695ca59c687d83c680bb2fb467dd90cc
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1741
Reviewed-by: waddlesplash <[email protected]>

headers/os/app/AppDefs.h

@@ -38,6 +38,7 @@ enum {
 	B_KEY_UP					= '_KYU',
 	B_UNMAPPED_KEY_DOWN			= '_UKD',
 	B_UNMAPPED_KEY_UP			= '_UKU',
+	B_KEY_MAP_LOADED			= '_KML',
 	B_LAYOUT_WINDOW				= '_LAY',
 	B_MODIFIERS_CHANGED			= '_MCH',
 	B_MINIMIZE					= '_WMN',

src/servers/input/InputServer.cpp

@@ -932,21 +932,33 @@ InputServer::HandleGetSetKeyMap(BMessage* message, BMessage* reply)
 {
 	CALLED();
 
+	status_t status;
 	if (message->what == IS_GET_KEY_MAP) {
-		status_t status = reply->AddData("keymap", B_ANY_TYPE, &fKeys, sizeof(fKeys));
+		status = reply->AddData("keymap", B_ANY_TYPE, &fKeys, sizeof(fKeys));
 		if (status == B_OK)
 			status = reply->AddData("key_buffer", B_ANY_TYPE, fChars, fCharsSize);
 
 		return status;
 	}
 
-	if (_LoadKeymap() != B_OK)
-		_LoadSystemKeymap();
+	status = _LoadKeymap();
+	if (status != B_OK) {
+		status = _LoadSystemKeymap();
+		if (status != B_OK)
+			return status;
+	}
 
 	BMessage msg(IS_CONTROL_DEVICES);
 	msg.AddInt32("type", B_KEYBOARD_DEVICE);
 	msg.AddInt32("code", B_KEY_MAP_CHANGED);
-	return fAddOnManager->PostMessage(&msg);
+	status = fAddOnManager->PostMessage(&msg);
+
+	if (status == B_OK) {
+		BMessage appMsg(B_KEY_MAP_LOADED);
+		be_roster->Broadcast(&appMsg);
+	}
+
+	return status;
 }