1 files changed, 17 insertions, 0 deletions

diff --git a/src/hashfunctionstring.cpp b/src/hashfunctionstring.cpp
index 6ce7bb3..bd14643 100644
--- a/src/hashfunctionstring.cpp
+++ b/src/hashfunctionstring.cpp
@@ -1,4 +1,7 @@
 #include "hashfunctionstring.h"
+#ifndef NULL
+#define NULL ((void *) 0)
+#endif
 
 HashFunctionString::HashFunctionString()
 {
@@ -10,6 +13,11 @@ HashFunctionString::~HashFunctionString()
 
 unsigned long int HashFunctionString::hash( const void *id )
 {
+        if (id == NULL)
+        {
+                return 0;
+        }
+        
         unsigned long int nPos = 0;
         for( const char *s = (const char *)id; *s; s++ )
         {
@@ -20,6 +28,15 @@ unsigned long int HashFunctionString::hash( const void *id )
 
 bool HashFunctionString::cmpIDs( const void *id1, const void *id2 )
 {
+        if (id1 == NULL || id2 == NULL)
+        {
+                return false;
+        }
+        if (id1 == id2)
+        {
+                return true;
+        }
+        
         const char *str1 = (const char *)id1;
         const char *str2 = (const char *)id2;