fix SCM_STACK_OVERFLOW_P bug

[bpt/guile.git] / libguile / stackchk.h

diff --git a/libguile/stackchk.h b/libguile/stackchk.h
index 6aa0fec..68dec76 100644 (file)
--- a/libguile/stackchk.h
+++ b/libguile/stackchk.h
@@ -3,7 +3,7 @@
 #ifndef SCM_STACKCHK_H
 #define SCM_STACKCHK_H
 
-/* Copyright (C) 1995,1996,1998,2000, 2003, 2006, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 1995,1996,1998,2000, 2003, 2006, 2008, 2009, 2010 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -34,15 +34,13 @@
  */
 #define SCM_STACK_CHECKING_P SCM_STACK_LIMIT
 
-#ifdef STACK_CHECKING
+#if defined BUILDING_LIBGUILE && defined STACK_CHECKING
 # if SCM_STACK_GROWS_UP
 #  define SCM_STACK_OVERFLOW_P(s)\
-   (SCM_STACK_PTR (s) \
-    > (SCM_I_CURRENT_THREAD->base + SCM_STACK_LIMIT))
+   ((SCM_STACK_PTR (s) - SCM_I_CURRENT_THREAD->base) > SCM_STACK_LIMIT)
 # else
 #  define SCM_STACK_OVERFLOW_P(s)\
-   (SCM_STACK_PTR (s) \
-    < (SCM_I_CURRENT_THREAD->base - SCM_STACK_LIMIT))
+   ((SCM_I_CURRENT_THREAD->base - SCM_STACK_PTR (s)) > SCM_STACK_LIMIT)
 # endif
 # define SCM_CHECK_STACK\
     {\
@@ -52,7 +50,7 @@
     }
 #else
 # define SCM_CHECK_STACK /**/
-#endif /* STACK_CHECKING */
+#endif
 
 SCM_API int scm_stack_checking_enabled_p;