Add a macro to calculate, from the size of an AirpcapKeysCollection

structure, the number of keys in the key list, and use it.

svn path=/trunk/; revision=47718

2 files changed, 7 insertions, 4 deletions

diff --git a/airpcap.h b/airpcap.h
index dd245451dc..d9df93a290 100644
--- a/airpcap.h
+++ b/airpcap.h
@@ -190,7 +190,10 @@ typedef struct _AirpcapKeysCollection
     AirpcapKey Keys[0];             /* < Array of nKeys keys. */
 } AirpcapKeysCollection, *PAirpcapKeysCollection;
 
-#define AirpcapKeysCollectionSize(nKeys) (sizeof(AirpcapKeysCollection) + ((nKeys) * sizeof(AirpcapKey)))
+#define AirpcapKeysCollectionSize(nKeys) \
+	(sizeof(AirpcapKeysCollection) + ((nKeys) * sizeof(AirpcapKey)))
+#define AirpcapKeysCollectionSizeToKeyCount(size) \
+	(guint)(((size) - AirpcapKeysCollectionSize(0))/sizeof(AirpcapKey))
 
 /*!
   \brief Packet header.
diff --git a/airpcap_loader.c b/airpcap_loader.c
index fca1d3179d..bd24eb6403 100644
--- a/airpcap_loader.c
+++ b/airpcap_loader.c
@@ -568,7 +568,7 @@ save_wlan_driver_wep_keys(void)
 
     /* Number of keys in key list */
     if (fake_info_if->keysCollectionSize != 0)
-        keys_in_list = (guint)((fake_info_if->keysCollectionSize -  sizeof(AirpcapKeysCollection))/sizeof(AirpcapKey));
+        keys_in_list = AirpcapKeysCollectionSizeToKeyCount(fake_info_if->keysCollectionSize);
     else
         keys_in_list = 0;
 
@@ -1775,7 +1775,7 @@ get_airpcap_device_keys(airpcap_if_info_t* info_if)
 
     /* Number of keys in key list */
     if (info_if->keysCollectionSize != 0)
-        keys_in_list = (guint)((info_if->keysCollectionSize -  sizeof(AirpcapKeysCollection))/sizeof(AirpcapKey));
+        keys_in_list = AirpcapKeysCollectionSizeToKeyCount(info_if->keysCollectionSize);
     else
         keys_in_list = 0;
 
@@ -1847,7 +1847,7 @@ get_airpcap_driver_keys(void)
 
     /* Number of keys in key list */
     if (fake_info_if->keysCollectionSize != 0)
-        keys_in_list = (guint)((fake_info_if->keysCollectionSize -  sizeof(AirpcapKeysCollection))/sizeof(AirpcapKey));
+        keys_in_list = AirpcapKeysCollectionSizeToKeyCount(fake_info_if->keysCollectionSize);
     else
         keys_in_list = 0;