/// <summary>
/// Open file by hash
/// </summary>
/// <param name="hash"></param>
/// <returns>file stream</returns>
/// <exception cref="FileNotFoundException"></exception>
public DecimaCoreFile OpenFile(long hash)
{
if (!RecordTableByHash.TryGetValue(hash, out var recordIndex))
{
throw new FileNotFoundException($"Cannot find hash {hash:X16}");
}
var record = RecordTable[(int)recordIndex];
var(chunk, index) = BlockTable.Select((x, y) => new KeyValuePair <DecimaCacheBlockTableEntry, int>(x, y)).First(x =>
{
var(key, _) = x;
return(key.ChunkOffset + key.ChunkSize > record.Offset);
});
var buffer = new MemoryStream(record.Size);
while (buffer.Position < record.Size)
{
var block = OpenBlock(chunk);
var start = 0;
if (chunk.ChunkOffset < record.Offset)
{
start = (int)(record.Offset - chunk.ChunkOffset);
}
var end = block.Length - start;
if (end + buffer.Position > record.Size)
{
end = (int)(record.Size - buffer.Position);
}
buffer.Write(block.Slice(start, end));
index += 1;
if (index >= BlockTable.Count)
{
break;
}
chunk = BlockTable[index];
}
// Debug.Assert(buffer.Length == record.Size, "buffer.Length == record.Size");
buffer.Position = 0;
return(new DecimaCoreFile(buffer));
}
