Subject: bug#20294: 25.0.50; Make Emacs work with GnuTLS 3.4.0 on MS-Windows

From: Chris Zheng <[email-masked]>
Date: Sat, 11 Apr 2015 20:35:34 +0800

From: Eli Zaretskii <[email-masked]>
Subject: Re: bug#20294: 25.0.50; Make Emacs work with GnuTLS 3.4.0 on MS-Windows
Date: Fri, 10 Apr 2015 20:48:10 +0300

Hi Eli,
> No, because libgnutls-30.dll exports a binary-incompatible ABI (that's
> why its name changes in the first place).  Just adding that DLL will
> cause Emacs compiled against an older GnuTLS to try loading the new
> DLL, or vice versa, which will most probably crash at run time.
Sorry I don't know it.
> Instead, we need to introduce a libgnutls-version variable, whose
> value depends on the version of GnuTLS as conveyed by version-related
> macros in the GnuTLS headers, and insert into dynamic-library-alist
> the DLL whose name matches the version with which Emacs was compiled,
> like we do with several image libraries.
According to your suggestion, I've reverted the patch.  Can this one
be the starting point?

Thanks,
Chris

>From 07162bcef08d398a2f69e81c83c28a4b722e2d0c Mon Sep 17 00:00:00 2001
From: Chris Zheng <[email-masked]>
Date: Fri, 10 Apr 2015 18:06:04 +0200
Subject: [PATCH] Add GnuTLS 3.4.0 support for MS-Windows

* src/gnutls.c
(libgnutls-version): New variable.
(syms_of_gnutls): Generate `libgnutls-version' from GnuTLS header.
* lisp/term/w32-win.el
(dynamic-library-alist): Set library name according to `libgnutls-version'.
---
 lisp/term/w32-win.el |  6 +++++-
 src/gnutls.c         | 10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/lisp/term/w32-win.el b/lisp/term/w32-win.el
index b5e6ff3..b0667e6 100644
--- a/lisp/term/w32-win.el
+++ b/lisp/term/w32-win.el
@@ -214,6 +214,8 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
 (defvar libgif-version)
 (defvar libjpeg-version)
 
+(defvar libgnutls-version)              ; gnutls.c
+
 ;;; Set default known names for external libraries
 (setq dynamic-library-alist
       (list
@@ -266,7 +268,9 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
        '(gdk-pixbuf "libgdk_pixbuf-2.0-0.dll")
        '(glib "libglib-2.0-0.dll")
        '(gobject "libgobject-2.0-0.dll")
-       '(gnutls "libgnutls-28.dll" "libgnutls-26.dll")
+       (if (>= libgnutls-version 30400)
+	   '(gnutls "libgnutls-30.dll")
+	 '(gnutls "libgnutls-28.dll" "libgnutls-26.dll"))
        '(libxml2 "libxml2-2.dll" "libxml2.dll")
        '(zlib "zlib1.dll" "libz-1.dll")))
 
diff --git a/src/gnutls.c b/src/gnutls.c
index 35f0eb4..ddd36a9 100644
--- a/src/gnutls.c
+++ b/src/gnutls.c
@@ -1645,6 +1645,16 @@ DEFUN ("gnutls-available-p", Fgnutls_available_p, Sgnutls_available_p, 0, 0, 0,
 void
 syms_of_gnutls (void)
 {
+  DEFSYM (Qlibgnutls_version, "libgnutls-version");
+  Fset (Qlibgnutls_version,
+#ifdef HAVE_GNUTLS
+	make_number (GNUTLS_VERSION_MAJOR * 10000
+		     + GNUTLS_VERSION_MINOR * 100
+		     + GNUTLS_VERSION_PATCH)
+#else
+	make_number (-1)
+#endif
+        );
 #ifdef HAVE_GNUTLS
   gnutls_global_initialized = 0;
 
-- 
2.3.5