Method StfsGetLevelNHashEntry

stfschk/StfsFileSystem.cs:530–607

(int BlockNumber, int Level, ref byte[] ExpectedHash, bool UseSecondaryBlock)

        }

        STF_HASH_ENTRY StfsGetLevelNHashEntry(int BlockNumber, int Level, ref byte[] ExpectedHash, bool UseSecondaryBlock)
        {
            int record = BlockNumber;
            if (Level > 0)
                record /= kDataBlocksPerHashLevel[Level - 1];

            record %= kDataBlocksPerHashLevel[0];

            if(BlockNumber == 0x0007f404 && Level == 0)
            {
                record = record;
            }

            var backingBlock = StfsComputeLevelNBackingHashBlockNumber(BlockNumber, Level);
            long hashOffset = StfsBackingBlockToOffset(backingBlock);

            if (UseSecondaryBlock && !StfsVolumeDescriptor.ReadOnlyFormat)
                hashOffset += kSectorSize;

            bool isInvalidTable = InvalidTables.Contains(hashOffset);
            if (!CachedTables.ContainsKey(hashOffset))
            {
                // Cache the table in memory, since it's likely to be needed again
                byte[] block = new byte[kSectorSize];
                if (Stream.Length > hashOffset)
                {
                    lock (StreamLock)
                    {
                        Stream.Seek(hashOffset, SeekOrigin.Begin);
                        Stream.Read(block, 0, (int)kSectorSize);
                    }
                }

                var hashBlock = Utility.BytesToStruct<STF_HASH_BLOCK>(block);
                hashBlock.EndianSwap();
                CachedTables.Add(hashOffset, hashBlock);

                if (!isInvalidTable)
                {
                    if (hashOffset >= Stream.Length)
                    {
                        // hash offset outside file...
                        isInvalidTable = true;
                        InvalidTables.Add(hashOffset);
                    }
                    else if (!SkipHashChecks)
                    {
                        // It's not cached and not in the invalid table array yet... lets check it
                        byte[] hash;
                        lock (Sha1)
                            hash = Sha1.ComputeHash(block);

                        if (!hash.BytesMatch(ExpectedHash))
                        {
                            isInvalidTable = true;
                            InvalidTables.Add(hashOffset);
                            //Console.WriteLine($"Invalid hash table at 0x{hashOffset:X}!");
                        }