From 0cafe2dfb913996075f3a3d6c9bde77449cec65b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stephan=20A=C3=9Fmus?= <superstippi@gmx.de>
Date: Tue, 26 Aug 2008 18:30:47 +0000
Subject: [PATCH] * Fixed a race condition in BWindow::Show(). If it was the
 first time Show()   was called, the calling thread could be preempted, or
 simply be blocked on   calling Lock() after running the window thread. The
 window thread in turn   could be processing messages. In that case,
 fShowLevel would still have the   wrong value. For example, MediaPlayer would
 call IsHidden() on one of it's   views, which would then return true for this
 case. The result was that the   video view was not hidden and a black
 rectangle was showing on top of the   controls. This may also have caused
 other similar problems of course. * fRunCalled was accessed without holding
 the lock.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@27209 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/kits/interface/Window.cpp | 36 ++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/kits/interface/Window.cpp b/src/kits/interface/Window.cpp
index d4d4138aba..fb537158e6 100644
--- a/src/kits/interface/Window.cpp
+++ b/src/kits/interface/Window.cpp
@@ -2317,8 +2317,24 @@ BWindow::ResizeTo(float width, float height)
 void
 BWindow::Show()
 {
-	if (!fRunCalled) {
-		// this is the fist time Show() is called, which implicitly runs the looper
+	bool runCalled = true;
+	if (Lock()) {
+		fShowLevel++;
+
+		if (fShowLevel == 1) {
+			fLink->StartMessage(AS_SHOW_WINDOW);
+			fLink->Flush();
+		}
+
+		runCalled = fRunCalled;
+
+		Unlock();
+	}
+
+	if (!runCalled) {
+		// This is the fist time Show() is called, which implicitly runs the
+		// looper. NOTE: The window is still locked if it has not been
+		// run yet, so accessing members is safe.
 		if (fLink->SenderPort() < B_OK) {
 			// We don't have valid app_server connection; there is no point
 			// in starting our looper
@@ -2327,18 +2343,6 @@ BWindow::Show()
 		} else
 			Run();
 	}
-
-	if (Lock()) {
-		fShowLevel++;
-
-		if (fShowLevel == 1) {
-			STRACE(("BWindow(%s): sending AS_SHOW_WINDOW message...\n", Name()));
-			fLink->StartMessage(AS_SHOW_WINDOW);
-			fLink->Flush();
-		}
-
-		Unlock();
-	}
 }
 
 
@@ -2348,7 +2352,9 @@ BWindow::Hide()
 	if (!Lock())
 		return;
 
-	if (--fShowLevel == 0) {
+	fShowLevel--;
+
+	if (fShowLevel == 0) {
 		fLink->StartMessage(AS_HIDE_WINDOW);
 		fLink->Flush();
 	}