diff -durpN postgresql.3/src/interfaces/libpq/libpq-fe.h postgresql.4/src/interfaces/libpq/libpq-fe.h
--- postgresql.3/src/interfaces/libpq/libpq-fe.h	2013-01-02 09:19:03.929522614 +0100
+++ postgresql.4/src/interfaces/libpq/libpq-fe.h	2013-01-02 16:10:51.978974575 +0100
@@ -256,6 +256,16 @@ extern PGconn *PQsetdbLogin(const char *
 /* close the current connection and free the PGconn data structure */
 extern void PQfinish(PGconn *conn);
 
+/* macro to close the current connection and set the conn pointer to NULL */
+#define PQfinishSafe(conn)		\
+	{				\
+		if (conn)		\
+		{			\
+			PQfinish(conn);	\
+			conn = NULL;	\
+		}			\
+	}
+
 /* get info about connection options known to PQconnectdb */
 extern PQconninfoOption *PQconndefaults(void);
 
@@ -472,6 +482,16 @@ extern int	PQsendDescribePortal(PGconn *
 /* Delete a PGresult */
 extern void PQclear(PGresult *res);
 
+/* Macro to delete a PGresult and set the res pointer to NULL */
+#define PQclearSafe(res)		\
+	{				\
+		if (res)		\
+		{			\
+			PQclear(res);	\
+			res = NULL;	\
+		}			\
+	}
+
 /* For freeing other alloc'd results, such as PGnotify structs */
 extern void PQfreemem(void *ptr);