Add CHECK_POINTER_HAS_TYPE macro, and use it to make *_data macros safer.

[pspp-builds.git] / src / libpspp / range-map.h

diff --git a/src/libpspp/range-map.h b/src/libpspp/range-map.h
index 3dd77c9ffac30f2fb85429df8a35091ce108c7ef..024fe93790e507a052e14e4990152b9b17c7ea91 100644 (file)
--- a/src/libpspp/range-map.h
+++ b/src/libpspp/range-map.h
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -33,12 +33,14 @@
 #include <stdbool.h>
 
 #include <libpspp/bt.h>
+#include <libpspp/cast.h>
 
 /* Returns the data structure corresponding to the given NODE,
    assuming that NODE is embedded as the given MEMBER name in
    data type STRUCT. */
 #define range_map_data(NODE, STRUCT, MEMBER)                            \
-        ((STRUCT *) ((char *) (NODE) - offsetof (STRUCT, MEMBER)))
+        (CHECK_POINTER_HAS_TYPE (NODE, struct range_map_node *),        \
+         UP_CAST (NODE, STRUCT, MEMBER))
 
 /* A range map node, to be embedded in the data value. */
 struct range_map_node