Remote{Message|DrawingEngine}: Add some more debug output.

src/servers/app/drawing/interface/remote/RemoteDrawingEngine.cpp

@@ -1011,19 +1011,40 @@ RemoteDrawingEngine::_DrawingEngineResult(void* cookie, RemoteMessage& message)
 
 	switch (message.Code()) {
 		case RP_DRAW_STRING_RESULT:
-			if (message.Read(engine->fDrawStringResult) != B_OK)
+		{
+			status_t result = message.Read(engine->fDrawStringResult);
+			if (result != B_OK) {
+				TRACE_ERROR("failed to read draw string result: %s\n",
+					strerror(result));
 				return false;
+			}
+
 			break;
+		}
 
 		case RP_STRING_WIDTH_RESULT:
-			if (message.Read(engine->fStringWidthResult) != B_OK)
+		{
+			status_t result = message.Read(engine->fStringWidthResult);
+			if (result != B_OK) {
+				TRACE_ERROR("failed to read string width result: %s\n",
+					strerror(result));
 				return false;
+			}
+
 			break;
+		}
 
 		case RP_READ_BITMAP_RESULT:
-			if (message.ReadBitmap(&engine->fReadBitmapResult) != B_OK)
+		{
+			status_t result = message.ReadBitmap(&engine->fReadBitmapResult);
+			if (result != B_OK) {
+				TRACE_ERROR("failed to read bitmap of read bitmap result: %s\n",
+					strerror(result));
 				return false;
+			}
+
 			break;
+		}
 
 		default:
 			return false;

src/servers/app/drawing/interface/remote/RemoteMessage.cpp

@@ -28,27 +28,49 @@
 #include <new>
 
 
+#ifdef CLIENT_COMPILE
+#define TRACE_ALWAYS(x...)		printf("RemoteMessage: " x)
+#else
+#define TRACE_ALWAYS(x...)		debug_printf("RemoteMessage: " x)
+#endif
+
+#define TRACE(x...)				/*TRACE_ALWAYS(x)*/
+#define TRACE_ERROR(x...)		TRACE_ALWAYS(x)
+
+
 status_t
 RemoteMessage::NextMessage(uint16& code)
 {
 	if (fDataLeft > 0) {
 		// discard remainder of message
 		int32 readSize = fSource->Read(NULL, fDataLeft);
-		if (readSize < 0)
+		if (readSize < 0) {
+			TRACE_ERROR("failed to read from source: %s\n", strerror(readSize));
 			return readSize;
+		}
 	}
 
 	static const uint32 kHeaderSize = sizeof(uint16) + sizeof(uint32);
 
 	fDataLeft = kHeaderSize;
-	Read(code);
+	status_t result = Read(code);
-	uint32 dataLeft;
+	if (result != B_OK) {
-	status_t result = Read(dataLeft);
+		TRACE_ERROR("failed to read message code: %s\n", strerror(result));
-	if (result != B_OK)
 		return result;
+	}
 
-	if (dataLeft < kHeaderSize)
+	uint32 dataLeft;
+	result = Read(dataLeft);
+	if (result != B_OK) {
+		TRACE_ERROR("failed to read message length: %s\n", strerror(result));
+		return result;
+	}
+
+	if (dataLeft < kHeaderSize) {
+		TRACE_ERROR("message claims %" B_PRIu32 " bytes, needed at least %"
+			B_PRIu32 " for the header\n", dataLeft, kHeaderSize);
 		return B_ERROR;
+	}
 
 	fDataLeft = dataLeft - kHeaderSize;
 	fCode = code;