Bug 1228799 - Part 1 - Move GetTableFromFontData to gfxFontUtils as a static function, and expose FindTableDirEntry helper method. r=emk

gfx/thebes/gfxFT2FontList.cpp

@@ -544,7 +544,8 @@ FT2FontEntry::GetFontTable(uint32_t aTableTag)
         FTUserFontData *userFontData = static_cast<FTUserFontData*>(
             cairo_font_face_get_user_data(mFontFace, &sFTUserFontDataKey));
         if (userFontData && userFontData->FontData()) {
-            return GetTableFromFontData(userFontData->FontData(), aTableTag);
+            return gfxFontUtils::GetTableFromFontData(userFontData->FontData(),
+                                                      aTableTag);
         }
     }
 

gfx/thebes/gfxFcPlatformFontList.cpp

@@ -422,7 +422,7 @@ gfxFontconfigFontEntry::GetFontTable(uint32_t aTableTag)
 {
     // for data fonts, read directly from the font data
     if (mFontData) {
-        return GetTableFromFontData(mFontData, aTableTag);
+        return gfxFontUtils::GetTableFromFontData(mFontData, aTableTag);
     }
 
     return gfxFontEntry::GetFontTable(aTableTag);

gfx/thebes/gfxFontEntry.cpp

@@ -674,33 +674,6 @@ gfxFontEntry::ShareFontTableAndGetBlob(uint32_t aTag,
     return entry->ShareTableAndGetBlob(Move(*aBuffer), mFontTableCache.get());
 }
 
-static int
-DirEntryCmp(const void* aKey, const void* aItem)
-{
-    int32_t tag = *static_cast<const int32_t*>(aKey);
-    const TableDirEntry* entry = static_cast<const TableDirEntry*>(aItem);
-    return tag - int32_t(entry->tag);
-}
-
-hb_blob_t*
-gfxFontEntry::GetTableFromFontData(const void* aFontData, uint32_t aTableTag)
-{
-    const SFNTHeader* header =
-        reinterpret_cast<const SFNTHeader*>(aFontData);
-    const TableDirEntry* dir =
-        reinterpret_cast<const TableDirEntry*>(header + 1);
-    dir = static_cast<const TableDirEntry*>
-        (bsearch(&aTableTag, dir, uint16_t(header->numTables),
-                 sizeof(TableDirEntry), DirEntryCmp));
-    if (dir) {
-        return hb_blob_create(reinterpret_cast<const char*>(aFontData) +
-                                  dir->offset, dir->length,
-                              HB_MEMORY_MODE_READONLY, nullptr, nullptr);
-
-    }
-    return nullptr;
-}
-
 already_AddRefed<gfxCharacterMap>
 gfxFontEntry::GetCMAPFromFontInfo(FontInfoData *aFontInfoData,
                                   uint32_t& aUVSOffset,

gfx/thebes/gfxFontEntry.h

@@ -484,14 +484,6 @@ protected:
         return NS_ERROR_FAILURE;
     }
 
-    // Return a blob that wraps a table found within a buffer of font data.
-    // The blob does NOT own its data; caller guarantees that the buffer
-    // will remain valid at least as long as the blob.
-    // Returns null if the specified table is not found.
-    // This method assumes aFontData is valid 'sfnt' data; before using this,
-    // caller is responsible to do any sanitization/validation necessary.
-    hb_blob_t* GetTableFromFontData(const void* aFontData, uint32_t aTableTag);
-
     // lookup the cmap in cached font data
     virtual already_AddRefed<gfxCharacterMap>
     GetCMAPFromFontInfo(FontInfoData *aFontInfoData,

gfx/thebes/gfxFontUtils.cpp

@@ -962,6 +962,41 @@ gfxFontUtils::DetermineFontDataType(const uint8_t *aFontData, uint32_t aFontData
     return GFX_USERFONT_UNKNOWN;
 }
 
+static int
+DirEntryCmp(const void* aKey, const void* aItem)
+{
+    int32_t tag = *static_cast<const int32_t*>(aKey);
+    const TableDirEntry* entry = static_cast<const TableDirEntry*>(aItem);
+    return tag - int32_t(entry->tag);
+}
+
+/* static */
+TableDirEntry*
+gfxFontUtils::FindTableDirEntry(const void* aFontData, uint32_t aTableTag)
+{
+    const SFNTHeader* header =
+        reinterpret_cast<const SFNTHeader*>(aFontData);
+    const TableDirEntry* dir =
+        reinterpret_cast<const TableDirEntry*>(header + 1);
+    return static_cast<TableDirEntry*>
+        (bsearch(&aTableTag, dir, uint16_t(header->numTables),
+                 sizeof(TableDirEntry), DirEntryCmp));
+}
+
+/* static */
+hb_blob_t*
+gfxFontUtils::GetTableFromFontData(const void* aFontData, uint32_t aTableTag)
+{
+    const TableDirEntry* dir = FindTableDirEntry(aFontData, aTableTag);
+    if (dir) {
+        return hb_blob_create(reinterpret_cast<const char*>(aFontData) +
+                                  dir->offset, dir->length,
+                              HB_MEMORY_MODE_READONLY, nullptr, nullptr);
+
+    }
+    return nullptr;
+}
+
 nsresult
 gfxFontUtils::RenameFont(const nsAString& aName, const uint8_t *aFontData, 
                          uint32_t aFontDataLength, FallibleTArray<uint8_t> *aNewFont)
@@ -1046,20 +1081,13 @@ gfxFontUtils::RenameFont(const nsAString& aName, const uint8_t *aFontData,
 
     // table directory entries begin immediately following SFNT header
     TableDirEntry *dirEntry =
-        reinterpret_cast<TableDirEntry*>(newFontData + sizeof(SFNTHeader));
+        FindTableDirEntry(newFontData, TRUETYPE_TAG('n','a','m','e'));
+    // function only called if font validates, so this should always be true
+    MOZ_ASSERT(dirEntry, "attempt to rename font with no name table");
 
     uint32_t numTables = sfntHeader->numTables;
     
-    for (i = 0; i < numTables; i++, dirEntry++) {
-        if (dirEntry->tag == TRUETYPE_TAG('n','a','m','e')) {
-            break;
-        }
-    }
-    
-    // function only called if font validates, so this should always be true
-    NS_ASSERTION(i < numTables, "attempt to rename font with no name table");
-
-    // note: dirEntry now points to name record
+    // note: dirEntry now points to 'name' table record
     
     // recalculate name table checksum
     uint32_t checkSum = 0;
@@ -1116,25 +1144,11 @@ gfxFontUtils::GetFullNameFromSFNT(const uint8_t* aFontData, uint32_t aLength,
 {
     aFullName.AssignLiteral("(MISSING NAME)"); // should always get replaced
 
-    NS_ENSURE_TRUE(aLength >= sizeof(SFNTHeader), NS_ERROR_UNEXPECTED);
-    const SFNTHeader *sfntHeader =
-        reinterpret_cast<const SFNTHeader*>(aFontData);
     const TableDirEntry *dirEntry =
-        reinterpret_cast<const TableDirEntry*>(aFontData + sizeof(SFNTHeader));
-    uint32_t numTables = sfntHeader->numTables;
-    NS_ENSURE_TRUE(aLength >=
-                   sizeof(SFNTHeader) + numTables * sizeof(TableDirEntry),
-                   NS_ERROR_UNEXPECTED);
-    bool foundName = false;
-    for (uint32_t i = 0; i < numTables; i++, dirEntry++) {
-        if (dirEntry->tag == TRUETYPE_TAG('n','a','m','e')) {
-            foundName = true;
-            break;
-        }
-    }
+        FindTableDirEntry(aFontData, TRUETYPE_TAG('n','a','m','e'));
     
     // should never fail, as we're only called after font validation succeeded
-    NS_ENSURE_TRUE(foundName, NS_ERROR_NOT_AVAILABLE);
+    NS_ENSURE_TRUE(dirEntry, NS_ERROR_NOT_AVAILABLE);
 
     uint32_t len = dirEntry->length;
     NS_ENSURE_TRUE(aLength > len && aLength - len >= dirEntry->offset,

gfx/thebes/gfxFontUtils.h

@@ -858,6 +858,20 @@ public:
     GetFamilyNameFromTable(hb_blob_t *aNameTable,
                            nsAString& aFamilyName);
 
+    // Find the table directory entry for a given table tag, in a (validated)
+    // buffer of 'sfnt' data. Returns null if the tag is not present.
+    static mozilla::TableDirEntry*
+    FindTableDirEntry(const void* aFontData, uint32_t aTableTag);
+
+    // Return a blob that wraps a table found within a buffer of font data.
+    // The blob does NOT own its data; caller guarantees that the buffer
+    // will remain valid at least as long as the blob.
+    // Returns null if the specified table is not found.
+    // This method assumes aFontData is valid 'sfnt' data; before using this,
+    // caller is responsible to do any sanitization/validation necessary.
+    static hb_blob_t*
+    GetTableFromFontData(const void* aFontData, uint32_t aTableTag);
+
     // create a new name table and build a new font with that name table
     // appended on the end, returns true on success
     static nsresult

gfx/thebes/gfxFontconfigFonts.cpp

@@ -652,7 +652,7 @@ gfxDownloadedFcFontEntry::GetFontTable(uint32_t aTableTag)
     // so we can just return a blob that "wraps" the appropriate chunk of it.
     // The blob should not attempt to free its data, as the entire sfnt data
     // will be freed when the font entry is deleted.
-    return GetTableFromFontData(mFontData, aTableTag);
+    return gfxFontUtils::GetTableFromFontData(mFontData, aTableTag);
 }
 
 /*