using System; using System.IO; using System.Runtime.CompilerServices; using System.Threading; using System.Threading.Tasks; namespace Org.BouncyCastle.Utilities.IO { public class PushbackStream : FilterStream { private int m_buf = -1; public PushbackStream(Stream s) : base(s) { } public override void CopyTo(Stream destination, int bufferSize) { if (m_buf != -1) { destination.WriteByte((byte)m_buf); m_buf = -1; } Streams.CopyTo(s, destination, bufferSize); } [AsyncStateMachine(typeof(<CopyToAsync>d__3))] public override Task CopyToAsync(Stream destination, int bufferSize, CancellationToken cancellationToken) { <CopyToAsync>d__3 stateMachine = default(<CopyToAsync>d__3); stateMachine.<>t__builder = AsyncTaskMethodBuilder.Create(); stateMachine.<>4__this = this; stateMachine.destination = destination; stateMachine.bufferSize = bufferSize; stateMachine.cancellationToken = cancellationToken; stateMachine.<>1__state = -1; stateMachine.<>t__builder.Start(ref stateMachine); return stateMachine.<>t__builder.Task; } public override int Read(byte[] buffer, int offset, int count) { Streams.ValidateBufferArguments(buffer, offset, count); if (m_buf != -1) { if (count < 1) return 0; buffer[offset] = (byte)m_buf; m_buf = -1; return 1; } return s.Read(buffer, offset, count); } public override int Read(Span<byte> buffer) { if (m_buf != -1) { if (buffer.IsEmpty) return 0; buffer[0] = (byte)m_buf; m_buf = -1; return 1; } return s.Read(buffer); } public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default(CancellationToken)) { if (m_buf != -1) { if (buffer.IsEmpty) return new ValueTask<int>(0); buffer.Span[0] = (byte)m_buf; m_buf = -1; return new ValueTask<int>(1); } return Streams.ReadAsync(s, buffer, cancellationToken); } public override int ReadByte() { if (m_buf != -1) { int buf = m_buf; m_buf = -1; return buf; } return s.ReadByte(); } public virtual void Unread(int b) { if (m_buf != -1) throw new InvalidOperationException("Can only push back one byte"); m_buf = (b & 255); } } }