safely duplicate close

binding/c/xdb_searcher.c

@@ -50,6 +50,7 @@ XDB_PUBLIC(int) xdb_new_with_buffer(xdb_searcher_t *xdb, const char *c_buffer) {
 XDB_PUBLIC(void) xdb_close(xdb_searcher_t *xdb) {
     if (xdb->handle != NULL) {
         fclose(xdb->handle);
+        xdb->handle = NULL;
     }
 }
 
@@ -339,4 +340,4 @@ XDB_PUBLIC(long) xdb_now() {
     struct timeval c_time;
     gettimeofday(&c_time, NULL);
     return c_time.tv_sec * (int)1e6 + c_time.tv_usec;
-}
\ No newline at end of file
+}