UserAttributeSubpacketsReader.cs :  » PDF » iTextSharp » Org » BouncyCastle » Bcpg » C# / CSharp Open Source

using System;
using System.IO;
using Org.BouncyCastle.Bcpg.Attr;
using Org.BouncyCastle.Utilities.IO;

namespace Org.BouncyCastle.Bcpg{
  /**
  * reader for user attribute sub-packets
  */
  public class UserAttributeSubpacketsParser
  {
    private readonly Stream input;

    public UserAttributeSubpacketsParser(
      Stream input)
    {
      this.input = input;
    }

    public UserAttributeSubpacket ReadPacket()
    {
      int l = input.ReadByte();
      if (l < 0)
        return null;

      int bodyLen = 0;
      if (l < 192)
      {
        bodyLen = l;
      }
      else if (l <= 223)
      {
        bodyLen = ((l - 192) << 8) + (input.ReadByte()) + 192;
      }
      else if (l == 255)
      {
        bodyLen = (input.ReadByte() << 24) | (input.ReadByte() << 16)
          |  (input.ReadByte() << 8)  | input.ReadByte();
      }
      else
      {
        // TODO Error?
      }

      int tag = input.ReadByte();
      if (tag < 0)
        throw new EndOfStreamException("unexpected EOF reading user attribute sub packet");

      byte[] data = new byte[bodyLen - 1];
      if (Streams.ReadFully(input, data) < data.Length)
        throw new EndOfStreamException();

      UserAttributeSubpacketTag type = (UserAttributeSubpacketTag) tag;
      switch (type)
      {
        case UserAttributeSubpacketTag.ImageAttribute:
          return new ImageAttrib(data);
      }
      return new UserAttributeSubpacket(type, data);
    }
  }
}