Bug 1256678 - Account for truncated font names in ScaledFontWin::GetFontFileData() - r=jfkthame

gfx/2d/SFNTData.cpp

@@ -204,11 +204,20 @@ SFNTData::GetU16FullNames(Vector<mozilla::u16string>& aU16FullNames)
 
 bool
 SFNTData::GetIndexForU16Name(const mozilla::u16string& aU16FullName,
-                             uint32_t* aIndex)
+                             uint32_t* aIndex, size_t aTruncatedLen)
 {
   for (size_t i = 0; i < mFonts.length(); ++i) {
     mozilla::u16string name;
-    if (mFonts[i]->GetU16FullName(name) && name == aU16FullName) {
+    if (!mFonts[i]->GetU16FullName(name)) {
+      continue;
+    }
+
+    if (aTruncatedLen) {
+      MOZ_ASSERT(aU16FullName.length() <= aTruncatedLen);
+      name = name.substr(0, aTruncatedLen);
+    }
+
+    if (name == aU16FullName) {
       *aIndex = i;
       return true;
     }

gfx/2d/SFNTData.h

@@ -70,9 +70,11 @@ public:
    *
    * @param aU16FullName full name to find.
    * @param aIndex out param for the index if found.
+   * @param aTruncatedLen length to truncate the compared font name to.
    * @return true if the full name is successfully read.
    */
-  bool GetIndexForU16Name(const mozilla::u16string& aU16FullName, uint32_t* aIndex);
+  bool GetIndexForU16Name(const mozilla::u16string& aU16FullName, uint32_t* aIndex,
+                          size_t aTruncatedLen = 0);
 
 private:
 

gfx/2d/ScaledFontWin.cpp

@@ -65,7 +65,7 @@ ScaledFontWin::GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton)
     // We cast here because for VS2015 char16_t != wchar_t, even though they are
     // both 16 bit.
     if (!sfntData->GetIndexForU16Name(
-          reinterpret_cast<char16_t*>(mLogFont.lfFaceName), &index)) {
+          reinterpret_cast<char16_t*>(mLogFont.lfFaceName), &index, LF_FACESIZE - 1)) {
       gfxWarning() << "Failed to get index for face name.";
       return false;
     }