From 6bb19351d92b3ea1691f96c15fdd230f2f4ce9ac Mon Sep 17 00:00:00 2001
From: Corinna Vinschen <corinna@vinschen.de>
Date: Wed, 29 Oct 2014 09:56:18 +0000
Subject: 	* common.din (__cxa_atexit): Define as cygwin__cxa_atexit. 
 * dcrt0.cc (cygwin__cxa_atexit): New function.  Explain what we do.

---
 winsup/cygwin/ChangeLog      |  5 +++++
 winsup/cygwin/common.din     |  2 +-
 winsup/cygwin/dcrt0.cc       | 18 ++++++++++++++++++
 winsup/cygwin/release/1.7.33 |  4 ++++
 4 files changed, 28 insertions(+), 1 deletion(-)

(limited to 'winsup/cygwin')

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index e8c833377..ee1fff587 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2014-10-29  Corinna Vinschen  <corinna@vinschen.de>
+
+	* common.din (__cxa_atexit): Define as cygwin__cxa_atexit.
+	* dcrt0.cc (cygwin__cxa_atexit): New function.  Explain what we do.
+
 2014-10-28  Corinna Vinschen  <corinna@vinschen.de>
 
 	* globals.cc (dos_file_warning): Set to false by default.
diff --git a/winsup/cygwin/common.din b/winsup/cygwin/common.din
index 95d6a7d98..3fcde65cc 100644
--- a/winsup/cygwin/common.din
+++ b/winsup/cygwin/common.din
@@ -41,7 +41,7 @@ __assert_func NOSIGFE
 __assertfail NOSIGFE
 __b64_ntop NOSIGFE
 __b64_pton NOSIGFE
-__cxa_atexit SIGFE
+__cxa_atexit = cygwin__cxa_atexit SIGFE
 __cxa_finalize SIGFE
 __dn_comp SIGFE
 __dn_expand SIGFE
diff --git a/winsup/cygwin/dcrt0.cc b/winsup/cygwin/dcrt0.cc
index b2bbe8657..f021f0281 100644
--- a/winsup/cygwin/dcrt0.cc
+++ b/winsup/cygwin/dcrt0.cc
@@ -1232,6 +1232,24 @@ do_exit (int status)
   myself.exit (n);
 }
 
+/* When introducing support for -fuse-cxa-atexit with Cygwin 1.7.32 and
+   GCC 4.8.3-3, we defined __dso_value as &ImageBase.  This supposedly allowed
+   a reproducible value which could also be easily evaluated in cygwin_atexit.
+   However, when building C++ applications with -fuse-cxa-atexit, G++ creates
+   calls to __cxa_atexit using the *address* of __dso_handle as DSO handle.
+   
+   So what we do here is this:  A call to __cxa_atexit from the application
+   actually calls cygwin__cxa_atexit.  From the dso_handle value we fetch the
+   ImageBase address, which is then used as the actual DSO handle value in
+   calls to __cxa_atexit and __cxa_finalize. */
+extern "C" int
+cygwin__cxa_atexit (void (*fn)(void *), void *obj, void *dso_handle)
+{
+  if (dso_handle)
+    dso_handle = *(void **) dso_handle;
+  return __cxa_atexit (fn, obj, dso_handle);
+}
+
 extern "C" int
 cygwin_atexit (void (*fn) (void))
 {
diff --git a/winsup/cygwin/release/1.7.33 b/winsup/cygwin/release/1.7.33
index 652a61ed4..02c07faad 100644
--- a/winsup/cygwin/release/1.7.33
+++ b/winsup/cygwin/release/1.7.33
@@ -88,3 +88,7 @@ Bug Fixes
 
 - Fix a SEGV in some 64 bit applications explicitely dlclosing DLLs.
   Addresses: https://cygwin.com/ml/cygwin/2014-10/msg00402.html
+
+- Fix -fuse-cxa-atexit handling where dlclose fails to trigger calling
+  global dtors in dynamically loaded modules in C++ applications (and
+  thus another potential SEGV).
-- 
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