Don't assume that all notifications are NotifySlotChange

CCID defines another type of message type on the interrupt pipe,
HardwareError, and others may also be conceivably sent. So check the
message type instead of assuming it's a NotifySlotChange.

While at it, I added debug logging of HardwareError, it might be useful
for someone.

src/ccid_usb.c

@@ -1620,7 +1620,18 @@ int InterruptRead(int reader_index, int timeout /* in ms */)
 	switch (ret)
 	{
 		case LIBUSB_TRANSFER_COMPLETED:
-			DEBUG_XXD("NotifySlotChange: ", buffer, actual_length);
+			if (actual_length > 0)
+			{
+				switch (buffer[0])
+				{
+					case CCID_MESSAGE_TYPE_RDR_to_PC_NotifySlotChange:
+						DEBUG_XXD("NotifySlotChange: ", buffer, actual_length);
+						break;
+					case CCID_MESSAGE_TYPE_RDR_to_PC_HardwareError:
+						DEBUG_XXD("HardwareError: ", buffer, actual_length);
+						break;
+				}
+			}
 			break;
 
 		case LIBUSB_TRANSFER_TIMED_OUT:
@@ -1763,29 +1774,41 @@ static void *Multi_PollingProc(void *p_ext)
 					DEBUG_COMM3("Multi_PollingProc (%d/%d): OK",
 						usbDevice[msExt->reader_index].bus_number,
 						usbDevice[msExt->reader_index].device_address);
-					DEBUG_XXD("NotifySlotChange: ", buffer, actual_length);
-
-					/* log the RDR_to_PC_NotifySlotChange data */
-					slot = 0;
-					for (b=0; b<actual_length-1; b++)
+					if (actual_length > 0)
 					{
-						int s;
-
-						/* 4 slots per byte */
-						for (s=0; s<4; s++)
+						switch (buffer[0])
 						{
-							/* 2 bits per slot */
-							int slot_status = ((buffer[1+b] >> (s*2)) & 3);
-							const char *present, *change;
-
-							present = (slot_status & 1) ? "present" : "absent";
-							change = (slot_status & 2) ? "status changed" : "no change";
-
-							DEBUG_COMM3("slot %d status: %d",
-								s + slot, slot_status);
-							DEBUG_COMM3("ICC %s, %s", present, change);
+							case CCID_MESSAGE_TYPE_RDR_to_PC_NotifySlotChange:
+								DEBUG_XXD("NotifySlotChange: ", buffer, actual_length);
+
+								/* log the RDR_to_PC_NotifySlotChange data */
+								slot = 0;
+								for (b=0; b<actual_length-1; b++)
+								{
+									int s;
+
+									/* 4 slots per byte */
+									for (s=0; s<4; s++)
+									{
+										/* 2 bits per slot */
+										int slot_status = ((buffer[1+b] >> (s*2)) & 3);
+										const char *present, *change;
+
+										present = (slot_status & 1) ? "present" : "absent";
+										change = (slot_status & 2) ? "status changed" : "no change";
+
+										DEBUG_COMM3("slot %d status: %d",
+											s + slot, slot_status);
+										DEBUG_COMM3("ICC %s, %s", present, change);
+									}
+									slot += 4;
+								}
+								break;
+
+							case CCID_MESSAGE_TYPE_RDR_to_PC_HardwareError:
+								DEBUG_XXD("HardwareError: ", buffer, actual_length);
+								break;
 						}
-						slot += 4;
 					}
 					break;
 
@@ -1954,7 +1977,8 @@ static int Multi_InterruptRead(int reader_index, int timeout /* in ms */)
 	/* Not stopped */
 	if (status == LIBUSB_TRANSFER_COMPLETED)
 	{
-		if (0 == (buffer[interrupt_byte] & interrupt_mask))
+		if (buffer[0] == CCID_MESSAGE_TYPE_RDR_to_PC_NotifySlotChange
+			&& 0 == (buffer[interrupt_byte] & interrupt_mask))
 		{
 			DEBUG_PERIODIC2("Multi_InterruptRead (%d) -- skipped",
 				reader_index);