NPOI/Code/Npoi.Core/Util/BlockingInputStream.cs

/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for Additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */


namespace Npoi.Core.Util
{
    using System;
    using System.IO;




    /**
     * Implementation of a BlockingInputStream to provide data to 
     * RawDataBlock that expects data in 512 byte chunks.  Useful to read
     * data from slow (ie, non FileInputStream) sources, for example when 
     * Reading an OLE2 Document over a network. 
     *
     * Possible extentions: add a timeout. Curently a call to Read(byte[]) on this
     *    class is blocking, so use at your own peril if your underlying stream blocks. 
     *
     * @author Jens Gerhard
     * @author aviks - documentation cleanups. 
     */
    public class BlockingInputStream : Stream
    {
        protected Stream stream;

        public BlockingInputStream(Stream stream)
        {
            this.stream = stream;
        }

        public int Available()
        {
            return (int)(stream.Length - stream.Position);
            //return stream.Available();
        }

        public void close()
        {
            stream.Dispose();
        }

        public void Mark(int readLimit)
        {
            throw new NotImplementedException();

        }

        public bool MarkSupported()
        {
            return false;
        }

        public int Read()
        {
            return stream.ReadByte();
        }

        /**
         * We had to revert to byte per byte Reading to keep
         * with slow network connections on one hand, without
         * missing the end-of-file. 
         * This is the only method that does its own thing in this class
         *    everything else is delegated to aggregated stream. 
         * THIS IS A BLOCKING BLOCK READ!!!
         */
        public int Read(byte[] bf)
        {

            int i = 0;
            int b = 4611;
            while (i < bf.Length)
            {
                b = stream.ReadByte();
                if (b == -1)
                    break;
                bf[i++] = (byte)b;
            }
            if (i == 0 && b == -1)
                return -1;
            return i;
        }

        public override int Read(byte[] bf, int s, int l)
        {
            return stream.Read(bf, s, l);
        }

        public void Reset()
        {
            stream.Seek(0, SeekOrigin.Begin);
        }

        public long Skip(long n)
        {
            return stream.Seek(n, SeekOrigin.Begin);
        }

        public override bool CanRead
        {
            get { return true; }
        }

        public override bool CanSeek
        {
            get { return true; }
        }

        public override bool CanWrite
        {
            get { return false; }
        }

        public override void Flush()
        {
        }

        public override long Length
        {
            get { return stream.Length; }
        }

        public override long Position
        {
            get
            {
                return stream.Position;
            }
            set
            {
                stream.Position = value;
            }
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            return stream.Seek(offset, origin);
        }

        public override void SetLength(long value)
        {
            stream.SetLength(value);
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            throw new NotImplementedException();
        }
    }
}