From 5bd460ecf027bb36ffd21d325739bb51df94521f Mon Sep 17 00:00:00 2001
From: Ralf Habacker <ralf.habacker@freenet.de>
Date: Tue, 10 May 2016 16:53:57 +0200
Subject: [PATCH 2/2] On Windows make access to member 'refcount' of struct
 DBusBabysitter thread save.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=95191
---
 dbus/dbus-internals.h |  1 +
 dbus/dbus-spawn-win.c | 42 +++++++++++++++++++++++++++++++++++-------
 dbus/dbus-sysdeps.h   |  3 +++
 3 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/dbus/dbus-internals.h b/dbus/dbus-internals.h
index 82950a0..7ec77e5 100644
--- a/dbus/dbus-internals.h
+++ b/dbus/dbus-internals.h
@@ -124,6 +124,7 @@ static void _dbus_verbose(const char * x,...) {;}
 #  define _dbus_is_verbose() FALSE 
 #endif /* !DBUS_ENABLE_VERBOSE_MODE */
 
+DBUS_PRIVATE_EXPORT
 void _dbus_trace_ref (const char *obj_name,
                       void       *obj,
                       int         old_refcount,
diff --git a/dbus/dbus-spawn-win.c b/dbus/dbus-spawn-win.c
index 964888f..516cc9d 100644
--- a/dbus/dbus-spawn-win.c
+++ b/dbus/dbus-spawn-win.c
@@ -60,7 +60,7 @@
  */
 struct DBusBabysitter
   {
-    int refcount;
+    DBusAtomic refcount;
 
     HANDLE start_sync_event;
 #ifdef DBUS_ENABLE_EMBEDDED_TESTS
@@ -89,16 +89,40 @@ struct DBusBabysitter
     int child_status;
   };
 
+static void
+_dbus_babysitter_trace_ref (DBusBabysitter *sitter,
+                            int old_refcount,
+                            int new_refcount,
+                            const char *why);
+
+void
+_dbus_babysitter_trace_ref (DBusBabysitter *sitter,
+    int old_refcount,
+    int new_refcount,
+    const char *why)
+{
+#ifdef DBUS_ENABLE_VERBOSE_MODE
+  static int enabled = -1;
+
+  _dbus_trace_ref ("DBusBabysitter", sitter, old_refcount, new_refcount, why,
+      "DBUS_BABYSITTER_TRACE", &enabled);
+#endif
+}
+
 static DBusBabysitter*
 _dbus_babysitter_new (void)
 {
   DBusBabysitter *sitter;
+  static int enabled = -1;
+  dbus_int32_t old_refcount;
 
   sitter = dbus_new0 (DBusBabysitter, 1);
   if (sitter == NULL)
     return NULL;
 
-  sitter->refcount = 1;
+  old_refcount = _dbus_atomic_inc (&sitter->refcount);
+
+  _dbus_babysitter_trace_ref (sitter, old_refcount, old_refcount+1, __FUNCTION__);
 
   sitter->start_sync_event = CreateEvent (NULL, FALSE, FALSE, NULL);
   if (sitter->start_sync_event == NULL)
@@ -146,11 +170,13 @@ _dbus_babysitter_new (void)
 DBusBabysitter *
 _dbus_babysitter_ref (DBusBabysitter *sitter)
 {
+  dbus_int32_t old_refcount;
   PING();
   _dbus_assert (sitter != NULL);
-  _dbus_assert (sitter->refcount > 0);
+  _dbus_assert (_dbus_atomic_get (&sitter->refcount) > 0);
 
-  sitter->refcount += 1;
+  old_refcount = _dbus_atomic_inc (&sitter->refcount);
+  _dbus_babysitter_trace_ref (sitter, old_refcount, old_refcount+1, __FUNCTION__);
 
   return sitter;
 }
@@ -185,14 +211,16 @@ void
 _dbus_babysitter_unref (DBusBabysitter *sitter)
 {
   int i;
+  dbus_int32_t old_refcount;
 
   PING();
   _dbus_assert (sitter != NULL);
-  _dbus_assert (sitter->refcount > 0);
+  _dbus_assert (_dbus_atomic_get (&sitter->refcount) > 0);
 
-  sitter->refcount -= 1;
+  old_refcount = _dbus_atomic_dec (&sitter->refcount);
+  _dbus_babysitter_trace_ref (sitter, old_refcount, old_refcount-1, __FUNCTION__);
 
-  if (sitter->refcount == 0)
+  if (old_refcount == 1)
     {
       close_socket_to_babysitter (sitter);
 
diff --git a/dbus/dbus-sysdeps.h b/dbus/dbus-sysdeps.h
index 29356e1..00967dd 100644
--- a/dbus/dbus-sysdeps.h
+++ b/dbus/dbus-sysdeps.h
@@ -296,8 +296,11 @@ struct DBusAtomic
 #   undef DBUS_HAVE_ATOMIC_INT
 #endif
 
+DBUS_PRIVATE_EXPORT
 dbus_int32_t _dbus_atomic_inc (DBusAtomic *atomic);
+DBUS_PRIVATE_EXPORT
 dbus_int32_t _dbus_atomic_dec (DBusAtomic *atomic);
+DBUS_PRIVATE_EXPORT
 dbus_int32_t _dbus_atomic_get (DBusAtomic *atomic);
 
 #ifdef DBUS_WIN
-- 
1.8.4.5