implemented proper refcounting using atomic operations

src/libstrongswan/types.c

@@ -25,6 +25,7 @@
 #include <time.h>
 #include <stdio.h>
 #include <stdarg.h>
+#include <pthread.h>
 
 #include "types.h"
 
@@ -198,6 +199,43 @@ void *clalloc(void * pointer, size_t size)
 	return (data);
 }
 
+/**
+ * We use a single mutex for all refcount variables. This
+ * is not optimal for performance, but the critical section
+ * is not that long...
+ * TODO: Consider to include a mutex in each refcount_t variable.
+ */
+static pthread_mutex_t ref_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/**
+ * Described in header.
+ * 
+ * TODO: May be implemented with atomic CPU instructions
+ * instead of a mutex.
+ */
+void ref_get(refcount_t *ref)
+{
+	pthread_mutex_lock(&ref_mutex);
+	(*ref)++;
+	pthread_mutex_unlock(&ref_mutex);
+}
+
+/**
+ * Described in header.
+ * 
+ * TODO: May be implemented with atomic CPU instructions
+ * instead of a mutex.
+ */
+bool ref_put(refcount_t *ref)
+{
+	bool more_refs;
+	
+	pthread_mutex_lock(&ref_mutex);
+	more_refs = --(*ref);
+	pthread_mutex_unlock(&ref_mutex);
+	return !more_refs;
+}
+
 /*
  * Names of the months used by timetoa()
  */

src/libstrongswan/types.h

@@ -200,6 +200,32 @@ void chunk_to_hex(char *buf, size_t buflen, chunk_t chunk);
  */
 void *clalloc(void *pointer, size_t size);
 
+/**
+ * Special type to count references
+ */
+typedef volatile u_int refcount_t;
+
+/**
+ * @brief Get a new reference.
+ *
+ * Increments the reference counter atomic.
+ *
+ * @param ref	pointer to ref counter
+ */
+void ref_get(refcount_t *ref);
+
+/**
+ * @brief Put back a unused reference.
+ *
+ * Decrements the reference counter atomic and 
+ * says if more references available.
+ *
+ * @param ref	pointer to ref counter
+ * @return		TRUE if no more references counted
+ */
+bool ref_put(refcount_t *ref);
+
+
 #define UNDEFINED_TIME	0
 #define TIMETOA_BUF 	30