DefiniteLengthInputStream.cs :  » PDF » iTextSharp » Org » BouncyCastle » Asn1 » C# / CSharp Open Source

using System;
using System.IO;

using Org.BouncyCastle.Utilities.IO;

namespace Org.BouncyCastle.Asn1{
    class DefiniteLengthInputStream
        : LimitedInputStream
    {
    private static readonly byte[] EmptyBytes = new byte[0];

    private readonly int _originalLength;
    private int _remaining;

        internal DefiniteLengthInputStream(
            Stream  inStream,
            int    length)
            : base(inStream)
        {
      if (length < 0)
        throw new ArgumentException("negative lengths not allowed", "length");

      this._originalLength = length;
      this._remaining = length;

      if (length == 0)
      {
        SetParentEofDetect(true);
      }
        }

    internal int Remaining
    {
      get { return _remaining; }
    }

    public override int ReadByte()
        {
      if (_remaining == 0)
        return -1;

      int b = _in.ReadByte();

      if (b < 0)
        throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);

      if (--_remaining == 0)
      {
        SetParentEofDetect(true);
      }

      return b;
        }

    public override int Read(
      byte[]  buf,
      int    off,
      int    len)
    {
      if (_remaining == 0)
        return 0;

      int toRead = System.Math.Min(len, _remaining);
      int numRead = _in.Read(buf, off, toRead);

      if (numRead < 1)
        throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);

      if ((_remaining -= numRead) == 0)
      {
        SetParentEofDetect(true);
      }

      return numRead;
    }

    internal byte[] ToArray()
    {
      if (_remaining == 0)
        return EmptyBytes;

      byte[] bytes = new byte[_remaining];
      if ((_remaining -= Streams.ReadFully(_in, bytes)) != 0)
        throw new EndOfStreamException("DEF length " + _originalLength + " object truncated by " + _remaining);
      SetParentEofDetect(true);
      return bytes;
    }
    }
}