public static async Task <bool> IsL33TZipAsync(Stream stream, CancellationToken ct = default)
{
var oldPosition = stream.Position;
try
{
using var reader = new AsyncBinaryReader(stream, new UTF8Encoding(), true);
var fileHeader = new string(await reader.ReadCharsAsync(4, ct));
switch (fileHeader.ToLower())
{
case L33THeader:
case L66THeader:
break;
default:
throw new InvalidOperationException($"Header '{fileHeader}' is not recognized as a valid type");
}
return(true);
}
#pragma warning disable CA1031 // Do not catch general exception types
catch (Exception)
{
return(false);
}
#pragma warning restore CA1031 // Do not catch general exception types
finally
{
stream.Position = oldPosition;
}
}
public static async Task DecompressL33TZipAsync(
Stream inputStream,
Stream outputStream,
IProgress <double> progress = null,
CancellationToken ct = default)
{
//Get extracted content length
long fileLength;
using (var reader = new AsyncBinaryReader(inputStream, new UTF8Encoding(), true))
{
var fileHeader = new string(await reader.ReadCharsAsync(4, ct));
switch (fileHeader.ToLower())
{
case L33THeader:
fileLength = await reader.ReadInt32Async(ct);
break;
case L66THeader:
fileLength = await reader.ReadInt64Async(ct);
break;
default:
throw new InvalidOperationException($"Header '{fileHeader}' is not recognized as a valid type");
}
//Skip deflate specification (2 Byte)
reader.BaseStream.Position += 2;
}
//Extract content
var buffer = new byte[BufferSize];
int bytesRead;
var totalBytesRead = 0L;
var lastProgress = 0d;
using var compressedStream = new DeflateStream(inputStream, CompressionMode.Decompress);
while ((bytesRead = await compressedStream.ReadAsync(buffer, 0, buffer.Length, ct)) > 0)
{
ct.ThrowIfCancellationRequested();
if (bytesRead > fileLength)
{
totalBytesRead += fileLength;
await outputStream.WriteAsync(buffer, 0, (int)fileLength, ct);
}
else if (totalBytesRead + bytesRead <= fileLength)
{
totalBytesRead += bytesRead;
await outputStream.WriteAsync(buffer, 0, bytesRead, ct);
}
else if (totalBytesRead + bytesRead > fileLength)
{
var leftToRead = fileLength - totalBytesRead;
totalBytesRead += leftToRead;
await outputStream.WriteAsync(buffer, 0, (int)leftToRead, ct);
}
var newProgress = (double)totalBytesRead / fileLength * 100;
if (newProgress - lastProgress > 1)
{
progress?.Report(newProgress);
lastProgress = newProgress;
}
if (totalBytesRead >= fileLength)
{
break;
}
}
}
