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path: root/crypto/src/asn1/BEROctetStringGenerator.cs
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using System;
using System.IO;

using Org.BouncyCastle.Utilities.IO;

namespace Org.BouncyCastle.Asn1
{
	public class BerOctetStringGenerator
		: BerGenerator
	{
		public BerOctetStringGenerator(Stream outStream)
			: base(outStream)
		{
			WriteBerHeader(Asn1Tags.Constructed | Asn1Tags.OctetString);
		}

		public BerOctetStringGenerator(
			Stream	outStream,
			int		tagNo,
			bool	isExplicit)
			: base(outStream, tagNo, isExplicit)
		{
			WriteBerHeader(Asn1Tags.Constructed | Asn1Tags.OctetString);
		}

		public Stream GetOctetOutputStream()
		{
			return GetOctetOutputStream(new byte[1000]); // limit for CER encoding.
		}

		public Stream GetOctetOutputStream(
			int bufSize)
		{
			return bufSize < 1
				?	GetOctetOutputStream()
				:	GetOctetOutputStream(new byte[bufSize]);
		}

		public Stream GetOctetOutputStream(
			byte[] buf)
		{
			return new BufferedBerOctetStream(this, buf);
		}

        private class BufferedBerOctetStream
            : BaseOutputStream
        {
            private byte[] _buf;
            private int _off;
            private readonly BerOctetStringGenerator _gen;
            private readonly DerOutputStream _derOut;

            internal BufferedBerOctetStream(
                BerOctetStringGenerator gen,
                byte[] buf)
            {
                _gen = gen;
                _buf = buf;
                _off = 0;
                _derOut = new DerOutputStream(_gen.Out);
            }

            public override void WriteByte(
                byte b)
            {
                _buf[_off++] = b;

                if (_off == _buf.Length)
                {
                    DerOctetString.Encode(_derOut, _buf, 0, _off);
                    _off = 0;
                }
            }

            public override void Write(
                byte[] buf,
                int offset,
                int len)
            {
                while (len > 0)
                {
                    int numToCopy = System.Math.Min(len, _buf.Length - _off);

                    if (numToCopy == _buf.Length)
                    {
                        DerOctetString.Encode(_derOut, buf, offset, numToCopy);
                    }
                    else
                    {
                        Array.Copy(buf, offset, _buf, _off, numToCopy);

                        _off += numToCopy;
                        if (_off < _buf.Length)
                            break;

                        DerOctetString.Encode(_derOut, _buf, 0, _off);
                        _off = 0;
                    }

                    offset += numToCopy;
                    len -= numToCopy;
                }
            }

            protected override void Dispose(bool disposing)
            {
                if (disposing)
                {
                    if (_off != 0)
                    {
                        DerOctetString.Encode(_derOut, _buf, 0, _off);
                    }

                    _gen.WriteBerEnd();
                }

                base.Dispose(disposing);
            }
        }
	}
}