Introduce the possibility to access global variables through

functions on platform were that's the best way to handle exporting
global variables in shared libraries.  To enable this functionality,
one must configure with "EXPORT_VAR_AS_FN" or defined the C macro
"OPENSSL_EXPORT_VAR_AS_FUNCTION" in crypto/opensslconf.h (the latter
is normally done by Configure or something similar).

To implement a global variable, use the macro OPENSSL_IMPLEMENT_GLOBAL
in the source file (foo.c) like this:

	OPENSSL_IMPLEMENT_GLOBAL(int,foo)=1;
	OPENSSL_IMPLEMENT_GLOBAL(double,bar);

To declare a global variable, use the macros OPENSSL_DECLARE_GLOBAL
and OPENSSL_GLOBAL_REF in the header file (foo.h) like this:

	OPENSSL_DECLARE_GLOBAL(int,foo);
	#define foo OPENSSL_GLOBAL_REF(foo)
	OPENSSL_DECLARE_GLOBAL(double,bar);
	#define bar OPENSSL_GLOBAL_REF(bar)

The #defines are very important, and therefore so is including the
header file everywere where the defined globals are used.

The macro OPENSSL_EXPORT_VAR_AS_FUNCTION also affects the definition
of ASN.1 items, but that structure is a bt different.

The largest change is in util/mkdef.pl which has been enhanced with
better and easier to understand logic to choose which symbols should
go into the Windows .def files as well as a number of fixes and code
cleanup (among others, algorithm keywords are now sorted
lexicographically to avoid constant rewrites).

1 files changed, 22 insertions, 0 deletions

diff --git a/e_os2.h b/e_os2.h
index be20eac623..f279fa1d93 100644
--- a/e_os2.h
+++ b/e_os2.h
@@ -200,6 +200,28 @@ extern "C" {
 #endif
 #define OPENSSL_EXTERN OPENSSL_IMPORT
 
+/* Macros to allow global variables to be reached through function calls when
+   required (if a shared library version requvres it, for example.
+   The way it's done allows definitions like this:
+
+	// in foobar.c
+	OPENSSL_IMPLEMENT_GLOBAL(int,foobar) = 0;
+	// in foobar.h
+	OPENSSL_DECLARE_GLOBAL(int,foobar);
+	#define foobar OPENSSL_GLOBAL_REF(foobar)
+*/
+#ifdef OPENSSL_EXPORT_VAR_AS_FUNCTION
+# define OPENSSL_IMPLEMENT_GLOBAL(type,name) extern static type _hide_##name; \
+        type *_shadow_##name(void) { static type local_var; return &local_var; } \
+        static type _hide_##name
+# define OPENSSL_DECLARE_GLOBAL(type,name) type *_shadow_##name(void)
+# define OPENSSL_GLOBAL_REF(name) (*(_shadow_##name()))
+#else
+# define OPENSSL_IMPLEMENT_GLOBAL(type,name) OPENSSL_GLOBAL type _shadow_##name
+# define OPENSSL_DECLARE_GLOBAL(type,name) OPENSSL_EXPORT type _shadow_##name
+# define OPENSSL_GLOBAL_REF(name) _shadow_##name
+#endif
+
 #ifdef  __cplusplus
 }
 #endif