ZLP: enable the patch only if --enable-zlp is used

The Zero Length Packet patch has issues with some non-bogus readers. So
the patch is _disabled_ by default.

If your Gemalto reader suffer from the ZLP problem then recompile the CCID
reader with:
$ ./configure --enable-zlp

configure.ac

@@ -265,6 +265,15 @@ if test x$use_embedded = xyes; then
   AC_DEFINE(NO_LOG, 1, [Disable logging support])
 fi
 
+# --enable-zlp
+AC_ARG_ENABLE(zlp,
+  AS_HELP_STRING([--enable-zlp],[enable the Zero Length Packet patch for some Gemalto readers]),
+  [ use_zlp="${enableval}" ])
+
+if test x$use_zlp = xyes; then
+  AC_DEFINE(ENABLE_ZLP, 1, [Enable Zero Length Packet patch])
+fi
+
 # Setup dist stuff
 AC_SUBST(ac_aux_dir)
 AC_SUBST(bundle)

src/ccid.c

@@ -67,6 +67,7 @@ int ccid_open_hack_pre(unsigned int reader_index)
 			ccid_descriptor->readTimeout = 60*1000; /* 60 seconds */
 			break;
 
+#ifdef ENABLE_ZLP
 		case GEMPCTWIN:
 		case GEMPCKEY:
 		case DELLSCRK:
@@ -79,6 +80,7 @@ int ccid_open_hack_pre(unsigned int reader_index)
 				DEBUG_INFO1("ZLP fixup");
 			}
 			break;
+#endif
 
 		case OZ776:
 		case OZ776_7772:

src/ccid.h

@@ -138,10 +138,12 @@ typedef struct
 	 */
 	struct GEMALTO_FIRMWARE_FEATURES *gemalto_firmware_features;
 
+#ifdef ENABLE_ZLP
 	/*
 	 * Zero Length Packet fixup (boolean)
 	 */
 	char zlp;
+#endif
 } _ccid_descriptor;
 
 /* Features from dwFeatures */

src/ccid_serial.c

@@ -614,7 +614,9 @@ static status_t set_ccid_descriptor(unsigned int reader_index,
 	serialDevice[reader_index].ccid.dwSlotStatus = IFD_ICC_PRESENT;
 	serialDevice[reader_index].ccid.bVoltageSupport = 0x07;	/* 1.8V, 3V and 5V */
 	serialDevice[reader_index].ccid.gemalto_firmware_features = NULL;
+#ifdef ENABLE_ZLP
 	serialDevice[reader_index].ccid.zlp = FALSE;
+#endif
 	serialDevice[reader_index].echo = TRUE;
 
 	/* change some values depending on the reader */

src/ccid_usb.c

@@ -722,7 +722,9 @@ status_t OpenUSBByName(unsigned int reader_index, /*@null@*/ char *device)
 				usbDevice[reader_index].ccid.bVoltageSupport = device_descriptor[5];
 				usbDevice[reader_index].ccid.sIFD_serial_number = NULL;
 				usbDevice[reader_index].ccid.gemalto_firmware_features = NULL;
+#ifdef ENABLE_ZLP
 				usbDevice[reader_index].ccid.zlp = FALSE;
+#endif
 				if (desc.iSerialNumber)
 				{
 					unsigned char serial[128];
@@ -822,6 +824,7 @@ status_t WriteUSB(unsigned int reader_index, unsigned int length,
 	(void)snprintf(debug_header, sizeof(debug_header), "-> %06X ",
 		(int)reader_index);
 
+#ifdef ENABLE_ZLP
 	if (usbDevice[reader_index].ccid.zlp)
 	{ /* Zero Length Packet */
 		int dummy_length;
@@ -831,6 +834,7 @@ status_t WriteUSB(unsigned int reader_index, unsigned int length,
 		(void)libusb_bulk_transfer(usbDevice[reader_index].dev_handle,
 			usbDevice[reader_index].bulk_in, NULL, 0, &dummy_length, 10);
 	}
+#endif
 
 	DEBUG_XXD(debug_header, buffer, length);