Imported QtWebKit TP3 (git b57bc6801f1876c3220d5a4bfea33d620d477443)

Change-Id: I3b1d8a2808782c9f34d50240000e20cb38d3680f
Reviewed-by: Konstantin Tokarev <annulen@yandex.ru>

1 files changed, 19 insertions, 1 deletions

diff --git a/Source/WTF/wtf/OSAllocatorWin.cpp b/Source/WTF/wtf/OSAllocatorWin.cpp
index 78300dc71..6a457f423 100644
--- a/Source/WTF/wtf/OSAllocatorWin.cpp
+++ b/Source/WTF/wtf/OSAllocatorWin.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2010, 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -65,6 +65,16 @@ void OSAllocator::commit(void* address, size_t bytes, bool writable, bool execut
 
 void OSAllocator::decommit(void* address, size_t bytes)
 {
+    // According to http://msdn.microsoft.com/en-us/library/aa366892(VS.85).aspx,
+    // bytes (i.e. dwSize) being 0 when dwFreeType is MEM_DECOMMIT means that we'll
+    // decommit the entire region allocated by VirtualAlloc() instead of decommitting
+    // nothing as we would expect. Hence, we should check if bytes is 0 and handle it
+    // appropriately before calling VirtualFree().
+    // See: https://bugs.webkit.org/show_bug.cgi?id=121972.
+    if (!bytes)
+        return;
+    // Silence warning about using MEM_DECOMMIT instead of MEM_RELEASE:
+#pragma warning(suppress: 6250)
     bool result = VirtualFree(address, bytes, MEM_DECOMMIT);
     if (!result)
         CRASH();
@@ -72,6 +82,10 @@ void OSAllocator::decommit(void* address, size_t bytes)
 
 void OSAllocator::releaseDecommitted(void* address, size_t bytes)
 {
+    // See comment in OSAllocator::decommit(). Similarly, when bytes is 0, we
+    // don't want to release anything. So, don't call VirtualFree() below.
+    if (!bytes)
+        return;
     // According to http://msdn.microsoft.com/en-us/library/aa366892(VS.85).aspx,
     // dwSize must be 0 if dwFreeType is MEM_RELEASE.
     bool result = VirtualFree(address, 0, MEM_RELEASE);
@@ -79,6 +93,10 @@ void OSAllocator::releaseDecommitted(void* address, size_t bytes)
         CRASH();
 }
 
+void OSAllocator::hintMemoryNotNeededSoon(void*, size_t)
+{
+}
+
 } // namespace WTF
 
 #endif // OS(WINDOWS)