private PakEntryMetadata ReadEntryMetadata(BinaryReader reader)
{
var metadata = new PakEntryMetadata
{
Offset = reader.ReadInt64(),
Size = reader.ReadInt64(),
UncompressedSize = reader.ReadInt64(),
CompressionMethod = (PakCompressionMethod)reader.ReadInt32(),
Hash = reader.ReadBytes(20)
};
if (Version >= PakVersion.CompressionEncryption)
{
if (metadata.CompressionMethod != PakCompressionMethod.None)
{
// TODO: Compression blocks
throw new NotImplementedException();
}
metadata.Flags = (PakEntryFlags)reader.ReadByte();
metadata.CompressionBlockSize = reader.ReadInt32();
}
return(metadata);
}
/// <summary>
/// Gets a <see cref="Stream"/> that contains the decrypted data for an entry.
/// </summary>
/// <param name="metadata">The metadata for the entry.</param>
/// <param name="encryptionKey">The encryption key used to decrypt the data.</param>
/// <returns></returns>
public Task <Stream> GetEntryStreamAsync(PakEntryMetadata metadata, string encryptionKey)
{
return(Task.Run(() =>
{
var stream = GetEntryStream(metadata);
DecryptEntryStream(stream, metadata.Offset, encryptionKey);
return stream;
}));
}
private void SwapEntry(PakEntryMetadata metadata, Stream newFileStream)
{
newFileStream.Seek(0, SeekOrigin.Begin);
using (var writer = new BinaryWriter(_stream, Encoding.UTF8, true))
using (var reader = new BinaryReader(_stream, Encoding.UTF8, true))
{
metadata.Flags = PakEntryFlags.None;
// overwrite metadata
_stream.Seek(metadata.Offset, SeekOrigin.Begin);
WriteEntryMetadata(writer, metadata);
// overwrite file block
newFileStream.CopyTo(_stream);
}
}
private Stream GetEntryStream(PakEntryMetadata metadata)
{
var entryStream = new MemoryStream();
using (var reader = new BinaryReader(_stream, Encoding.UTF8, true))
using (var writer = new BinaryWriter(entryStream, Encoding.UTF8, true))
{
_stream.Seek(metadata.Offset, SeekOrigin.Begin);
ReadEntryMetadata(reader);
byte[] buffer = reader.ReadBytes((int)metadata.Size);
writer.Write(buffer, 0, buffer.Length);
}
entryStream.Seek(0, SeekOrigin.Begin);
return(entryStream);
}
private void WriteEntryMetadata(BinaryWriter writer, PakEntryMetadata metadata)
{
writer.Write(metadata.Offset);
writer.Write(metadata.Size);
writer.Write(metadata.UncompressedSize);
writer.Write((int)metadata.CompressionMethod);
writer.Write(metadata.Hash);
if (Version >= PakVersion.CompressionEncryption)
{
if (metadata.CompressionMethod != PakCompressionMethod.None)
{
// TODO: Compression blocks
throw new NotImplementedException();
}
writer.Write((byte)metadata.Flags);
writer.Write(metadata.CompressionBlockSize);
}
}
private void ReadEntries()
{
_entryTable = new PakEntryTable();
using (var reader = new BinaryReader(_stream, Encoding.UTF8, true))
{
_stream.Seek(_indexOffset, SeekOrigin.Begin);
MountPoint = reader.ReadFString();
int fileCount = reader.ReadInt32();
for (int i = 0; i < fileCount; i++)
{
string fileName = reader.ReadFString();
long metadataOffset = _stream.Position;
PakEntryMetadata metadata = ReadEntryMetadata(reader);
metadata.MetadataOffset = metadataOffset;
metadata.FileName = fileName;
_entryTable.Add(metadata);
}
}
}
private void ReadEntries(string encryptionKey)
{
if (!IsIndexEncrypted)
{
ReadEntries();
return;
}
_entryTable = new PakEntryTable();
byte[] indexBlock = DecryptIndexBlock(encryptionKey);
using (var reader = new BinaryReader(new MemoryStream(indexBlock)))
{
try
{
MountPoint = reader.ReadFString();
int fileCount = reader.ReadInt32();
for (int i = 0; i < fileCount; i++)
{
string fileName = reader.ReadFString();
long metadataOffset = reader.BaseStream.Position;
PakEntryMetadata metadata = ReadEntryMetadata(reader);
metadata.MetadataOffset = metadataOffset + _indexOffset;
metadata.FileName = fileName;
_entryTable.Add(metadata);
}
}
catch (ArgumentOutOfRangeException) // reader.ReadFString will throw this if MountPoint cannot be read
{
_entryTable = null;
throw new IncorrectEncryptionKeyException();
}
}
}
/// <summary>
/// Swaps the file data for the given entry with the new data.
/// </summary>
/// <param name="metadata"></param>
/// <param name="newFileStream"></param>
/// <returns></returns>
public Task SwapEntryAsync(PakEntryMetadata metadata, Stream newFileStream)
{
return(Task.Run(() => SwapEntry(metadata, newFileStream)));
}
/// <summary>
/// Gets a <see cref="Stream"/> that contains the data for an entry.
/// </summary>
/// <param name="metadata">The metadata for the entry.</param>
/// <returns></returns>
public Task <Stream> GetEntryStreamAsync(PakEntryMetadata metadata)
{
return(Task.Run(() => GetEntryStream(metadata)));
}