Add a list_shift() function to the common linked list code.

git-svn-id: file:///home/svn/framework3/trunk@10052 4d416f70-5f16-0410-b530-b9f4589650da

c/meterpreter/source/common/list.c

@@ -2,9 +2,9 @@
 
 /*
  * An implementation of a simple thread safe double linked list structure. Can be used as either
- * a stack (via pop/push) or an array (via get/add/insert/remove). If performing a group of
+ * a stack (via pop/push), a queue (via push/shift) or an array (via get/add/insert/remove). If
- * actions on a list based on results from list actions, acquire the list lock before the group
+ * performing a group of actions on a list based on results from list actions, acquire the list 
- * of actions and release lock when done.
+ * lock before the group of actions and release lock when done.
  */
 
 /*
@@ -308,5 +308,29 @@ LPVOID list_pop( LIST * list )
 
 	lock_release( list->lock );
 
+	return data;
+}
+
+/*
+ * Pop a data value off the start of the list.
+ */
+LPVOID list_shift( LIST * list )
+{
+	LPVOID data = NULL;
+
+	if( list == NULL )
+		return NULL;
+
+	lock_acquire( list->lock );
+
+	if( list->start != NULL )
+	{
+		data = list->start->data;
+
+		list_remove_node( list, list->start );
+	}
+
+	lock_release( list->lock );
+
 	return data;
 }

c/meterpreter/source/common/list.h

@@ -38,6 +38,8 @@ BOOL list_push( LIST * list, LPVOID data );
 
 LPVOID list_pop( LIST * list );
 
+LPVOID list_shift( LIST * list );
+
 /*****************************************************************************************/
 
 #endif