From 4828211e97e00b8b4aca51892785feed9090084a Mon Sep 17 00:00:00 2001
From: Romain Tartiere <romain.tartiere@gmail.com>
Date: Wed, 18 May 2011 22:25:09 +0000
Subject: [PATCH] Fix crash when usb_bulk_read() fails.

---
 libnfc/drivers/pn53x_usb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libnfc/drivers/pn53x_usb.c b/libnfc/drivers/pn53x_usb.c
index 41c3019..2a102da 100644
--- a/libnfc/drivers/pn53x_usb.c
+++ b/libnfc/drivers/pn53x_usb.c
@@ -77,7 +77,8 @@ int
 pn53x_usb_bulk_read (struct pn53x_usb_data *data, byte_t abtRx[], const size_t szRx)
 {
   int res = usb_bulk_read (data->pudh, data->uiEndPointIn, (char *) abtRx, szRx, USB_TIMEOUT);
-  PRINT_HEX ("RX", abtRx, res);
+  if (res > 0)
+      PRINT_HEX ("RX", abtRx, res);
   return res;
 }
 int