public byte[] ExtractFile(int file_index)
{
if (file_index >= GetFileCount())
{
return(null);
}
IndexFile.Seek(file_index * 6, SeekOrigin.Begin);
int file_size = (IndexFile.ReadByte() << 16) + (IndexFile.ReadByte() << 8) + IndexFile.ReadByte();
int chunk_offset = (IndexFile.ReadByte() << 16) + (IndexFile.ReadByte() << 8) + IndexFile.ReadByte();
if (chunk_offset < 0 || chunk_offset > DataFile.Length / 520L)
{
return(null);
}
byte[] out_buffer = new byte[file_size];
int write_offset = 0;
for (int chunk_index = 0; write_offset < file_size; chunk_index++)
{
if (chunk_offset == 0)
{
return(null);
}
int chunk_size = Math.Min(512, file_size - write_offset);
DataFile.Seek(chunk_offset * 520L, SeekOrigin.Begin);
if (DataFile.Position + chunk_size + 8 > DataFile.Length)
{
return(null);
}
int checksum_file_index = (DataFile.ReadByte() << 8) + DataFile.ReadByte();
int checksum_chunk_index = (DataFile.ReadByte() << 8) + DataFile.ReadByte();
int next_chunk_offset = (DataFile.ReadByte() << 16) + (DataFile.ReadByte() << 8) + DataFile.ReadByte();
int checksum_archive_index = DataFile.ReadByte();
if (checksum_file_index != file_index || checksum_chunk_index != chunk_index || checksum_archive_index - 1 != ArchiveIndex)
{
return(null);
}
if (next_chunk_offset < 0 || next_chunk_offset * 520L > DataFile.Length)
{
return(null);
}
DataFile.Read(out_buffer, write_offset, chunk_size);
write_offset += chunk_size;
chunk_offset = next_chunk_offset;
}
if (ArchiveIndex > 0)
{
int i = 0;
try
{
GZipStream gzipinputstream = new GZipStream(new MemoryStream(out_buffer), CompressionMode.Decompress);
do
{
if (i == gzip_buffer.Length)
{
return(null);
}
int k = gzipinputstream.Read(gzip_buffer, i, gzip_buffer.Length - i);
if (k == 0)
{
break;
}
i += k;
} while (true);
out_buffer = new byte[i];
Array.Copy(gzip_buffer, out_buffer, out_buffer.Length);
}
catch (Exception)
{
return(null);
}
}
return(out_buffer);
}
public int GetFileSize(int file_index)
{
IndexFile.Seek(file_index * 6, SeekOrigin.Begin);
return((IndexFile.ReadByte() << 16) + (IndexFile.ReadByte() << 8) + IndexFile.ReadByte());
}
public int GetChunkOffset(int file_index)
{
IndexFile.Seek(file_index * 6 + 3, SeekOrigin.Begin);
return((IndexFile.ReadByte() << 16) + (IndexFile.ReadByte() << 8) + IndexFile.ReadByte());
}
public bool WriteFile(bool exists, int file_index, int file_size, byte[] data)
{
try
{
int chunk_offset = 0;
if (exists)
{
IndexFile.Seek(file_index * 6 + 3, SeekOrigin.Begin);
chunk_offset = (IndexFile.ReadByte() << 16) + (IndexFile.ReadByte() << 8) + IndexFile.ReadByte();
if (chunk_offset <= 0 || (long)chunk_offset > DataFile.Length / 520L)
{
return(false);
}
}
else
{
chunk_offset = (int)((DataFile.Length + 519L) / 520L);
if (chunk_offset == 0)
{
chunk_offset = 1;
}
}
IndexFile.Seek(file_index * 6, SeekOrigin.Begin);
IndexFile.WriteByte((byte)(file_size >> 16));
IndexFile.WriteByte((byte)(file_size >> 8));
IndexFile.WriteByte((byte)file_size);
IndexFile.WriteByte((byte)(chunk_offset >> 16));
IndexFile.WriteByte((byte)(chunk_offset >> 8));
IndexFile.WriteByte((byte)chunk_offset);
int write_offset = 0;
for (int chunk_index = 0; write_offset < file_size; chunk_index++)
{
int next_chunk_offset = 0;
if (exists)
{
DataFile.Seek(chunk_offset * 520L, SeekOrigin.Begin);
if (DataFile.Position + 8 >= DataFile.Length)
{
int checksum_file_index = (DataFile.ReadByte() << 8) + DataFile.ReadByte();
int checksum_chunk_index = (DataFile.ReadByte() << 8) + DataFile.ReadByte();
next_chunk_offset = (DataFile.ReadByte() << 16) + (DataFile.ReadByte() << 8) + DataFile.ReadByte();
int checksum_archive_index = DataFile.ReadByte();
if (checksum_file_index != file_index || checksum_chunk_index != chunk_index || checksum_archive_index - 1 != ArchiveIndex)
{
return(false);
}
if (next_chunk_offset < 0 || (long)next_chunk_offset > DataFile.Length / 520L)
{
return(false);
}
}
else
{
DataFile.Position = DataFile.Length - 1;
}
}
if (next_chunk_offset == 0)
{
exists = false;
next_chunk_offset = (int)((DataFile.Length + 519L) / 520L);
if (next_chunk_offset == 0)
{
next_chunk_offset++;
}
if (next_chunk_offset == chunk_offset)
{
next_chunk_offset++;
}
}
if (file_size - write_offset <= 512)
{
next_chunk_offset = 0;
}
DataFile.Seek(chunk_offset * 520L, SeekOrigin.Begin);
DataFile.WriteByte((byte)(file_index >> 8));
DataFile.WriteByte((byte)file_index);
DataFile.WriteByte((byte)(chunk_index >> 8));
DataFile.WriteByte((byte)chunk_index);
DataFile.WriteByte((byte)(next_chunk_offset >> 16));
DataFile.WriteByte((byte)(next_chunk_offset >> 8));
DataFile.WriteByte((byte)next_chunk_offset);
DataFile.WriteByte((byte)(ArchiveIndex + 1));
int chunk_size = file_size - write_offset;
if (chunk_size > 512)
{
chunk_size = 512;
}
DataFile.Write(data, write_offset, chunk_size);
write_offset += chunk_size;
chunk_offset = next_chunk_offset;
}
return(true);
}
catch (Exception)
{
return(false);
}
}
