Modified platform bitmap to support GDI being unavailable

skia/ext/bitmap_platform_device_win.cc

Index: skia/ext/bitmap_platform_device_win.cc
diff --git a/skia/ext/bitmap_platform_device_win.cc b/skia/ext/bitmap_platform_device_win.cc
index 63108209abc313b305256319246a06fa7d03424c..ccffc9bdf4468babcc6afb1925fead5b7993b742 100644
--- a/skia/ext/bitmap_platform_device_win.cc
+++ b/skia/ext/bitmap_platform_device_win.cc
@@ -16,6 +16,27 @@
 
 namespace {
 
+typedef decltype(GetProcessMitigationPolicy)* GetProcessMitigationPolicyType;
+
+bool IsWin32kLockdownEnabled() {
+  GetProcessMitigationPolicyType GetProcessMitigationPolicyFunc =

[scottmg, 2015/09/04 02:46:19]

GetProcessMitigationPolicyFunc should be get_process_mitigation_policy[_func]

[forshaw, 2015/09/04 09:58:05]

Done.

+    reinterpret_cast<GetProcessMitigationPolicyType>(::GetProcAddress(

[scottmg, 2015/09/04 02:46:19]

remove unnecessary :: qualifiers (or add them everywhere, but it looks like most
don't have them in this file (e.g. MapViewOfFile, GetCurrentProcess)

[forshaw, 2015/09/04 09:58:05]

Done.

+                                            ::GetModuleHandle(L"kernel32.dll"),
+                                            "GetProcessMitigationPolicy"));
+
+  if (!GetProcessMitigationPolicyFunc)
+    return false;
+
+  PROCESS_MITIGATION_SYSTEM_CALL_DISABLE_POLICY policy = {0};
+  if (GetProcessMitigationPolicyFunc(GetCurrentProcess(),
+                                     ProcessSystemCallDisablePolicy,
+                                     &policy,
+                                     sizeof(policy)))
+    return policy.DisallowWin32kSystemCalls != 0;
+
+  return false;

[Will Harris, 2015/09/04 02:25:50]

can you cache the result of this function with a static, maybe?

[forshaw, 2015/09/04 09:58:05]

Will cache with static, don't think it needs to be thread safe.

+}
+
 HBITMAP CreateHBitmap(int width, int height, bool is_opaque,
                              HANDLE shared_section, void** data) {
   // CreateDIBSection appears to get unhappy if we create an empty bitmap, so
@@ -57,6 +78,7 @@ namespace skia {
 
 void DrawToNativeContext(SkCanvas* canvas, HDC hdc, int x, int y,
                          const RECT* src_rect) {
+  DCHECK(!IsWin32kLockdownEnabled());
   PlatformDevice* platform_device = GetPlatformDevice(GetTopDevice(*canvas));
   if (platform_device)
     platform_device->DrawToHDC(hdc, x, y, src_rect);
@@ -65,6 +87,7 @@ void DrawToNativeContext(SkCanvas* canvas, HDC hdc, int x, int y,
 void PlatformDevice::DrawToHDC(HDC, int x, int y, const RECT* src_rect) {}
 
 HDC BitmapPlatformDevice::GetBitmapDC() {
+  DCHECK(!IsWin32kLockdownEnabled());
   if (!hdc_) {
     hdc_ = CreateCompatibleDC(NULL);
     InitializeDC(hdc_);
@@ -76,11 +99,13 @@ HDC BitmapPlatformDevice::GetBitmapDC() {
 }
 
 void BitmapPlatformDevice::ReleaseBitmapDC() {
-  SkASSERT(hdc_);
-  SelectObject(hdc_, old_hbitmap_);
-  DeleteDC(hdc_);
-  hdc_ = NULL;
-  old_hbitmap_ = NULL;
+  if (!IsWin32kLockdownEnabled()) {
+    SkASSERT(hdc_);
+    SelectObject(hdc_, old_hbitmap_);
+    DeleteDC(hdc_);
+    hdc_ = NULL;
+    old_hbitmap_ = NULL;
+  }
 }
 
 bool BitmapPlatformDevice::IsBitmapDCCreated()
@@ -108,7 +133,12 @@ void BitmapPlatformDevice::LoadConfig() {
 }
 
 static void DeleteHBitmapCallback(void* addr, void* context) {
-  DeleteObject(static_cast<HBITMAP>(context));
+  // If context is not NULL then it's a valid HBITMAP to delete.
+  // Otherwise we just unmap the pixel memory.
+  if (context)
+    DeleteObject(static_cast<HBITMAP>(context));
+  else
+    UnmapViewOfFile(addr);
 }
 
 static bool InstallHBitmapPixels(SkBitmap* bitmap, int width, int height,
@@ -117,6 +147,7 @@ static bool InstallHBitmapPixels(SkBitmap* bitmap, int width, int height,
   const SkImageInfo info = SkImageInfo::MakeN32(width, height, at);
   const size_t rowBytes = info.minRowBytes();
   SkColorTable* color_table = NULL;
+

[Will Harris, 2015/09/04 02:25:50]

nit: line

   return bitmap->installPixels(info, data, rowBytes, color_table,
                                DeleteHBitmapCallback, hbitmap);
 }
@@ -133,10 +164,22 @@ BitmapPlatformDevice* BitmapPlatformDevice::Create(
     bool do_clear) {
 
   void* data;
-  HBITMAP hbitmap = CreateHBitmap(width, height, is_opaque, shared_section,
+
+  HBITMAP hbitmap = NULL;

[scottmg, 2015/09/04 02:46:19]

NULL -> nullptr, and elsewhere

[forshaw, 2015/09/04 09:58:05]

Was just being consistent with the rest of the file which used NULL. Don't want
to unnecessarily change all uses of NULL unless there's a policy to move all
modified code to using nullptr or live with mixed usage in a single file.

+
+  if (IsWin32kLockdownEnabled()) {
+    CHECK(shared_section != NULL);
+    data = MapViewOfFile(shared_section, FILE_MAP_WRITE,
+        0, 0, width * height * 4);
+    DCHECK(data != NULL);
+    if (!data)
+      return NULL;
+  } else {
+    hbitmap = CreateHBitmap(width, height, is_opaque, shared_section,
                                   &data);
-  if (!hbitmap)
-    return NULL;
+    if (!hbitmap)
+      return NULL;
+  }
 
   SkBitmap bitmap;
   if (!InstallHBitmapPixels(&bitmap, width, height, is_opaque, data, hbitmap))
@@ -180,12 +223,14 @@ BitmapPlatformDevice::BitmapPlatformDevice(
   // The data object is already ref'ed for us by create().
   SkDEBUGCODE(begin_paint_count_ = 0);
   SetPlatformDevice(this, this);
-  // Initialize the clip region to the entire bitmap.
-  BITMAP bitmap_data;
-  if (GetObject(hbitmap_, sizeof(BITMAP), &bitmap_data)) {
-    SkIRect rect;
-    rect.set(0, 0, bitmap_data.bmWidth, bitmap_data.bmHeight);
-    clip_region_ = SkRegion(rect);
+  if (hbitmap) {
+    // Initialize the clip region to the entire bitmap.
+    BITMAP bitmap_data;
+    if (GetObject(hbitmap_, sizeof(BITMAP), &bitmap_data)) {
+      SkIRect rect;
+      rect.set(0, 0, bitmap_data.bmWidth, bitmap_data.bmHeight);
+      clip_region_ = SkRegion(rect);
+    }
   }
 }
 
@@ -213,6 +258,8 @@ void BitmapPlatformDevice::setMatrixClip(const SkMatrix& transform,
 
 void BitmapPlatformDevice::DrawToHDC(HDC dc, int x, int y,
                                      const RECT* src_rect) {
+  DCHECK(!IsWin32kLockdownEnabled());
+
   bool created_dc = !IsBitmapDCCreated();
   HDC source_dc = BeginPlatformPaint();
 
@@ -305,6 +352,7 @@ PlatformBitmap::~PlatformBitmap() {
 }
 
 bool PlatformBitmap::Allocate(int width, int height, bool is_opaque) {
+  DCHECK(!IsWin32kLockdownEnabled());
   void* data;
   HBITMAP hbitmap = CreateHBitmap(width, height, is_opaque, 0, &data);
   if (!hbitmap)