Initial commit - WPinternals 2.6

DiscUtils/ConcatStream.cs

@@ -0,0 +1,289 @@
+//
+// Copyright (c) 2008-2011, Kenneth Bell
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+//
+
+namespace DiscUtils
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Globalization;
+    using System.IO;
+
+    /// <summary>
+    /// The concatenation of multiple streams (read-only, for now).
+    /// </summary>
+    internal class ConcatStream : SparseStream
+    {
+        private SparseStream[] _streams;
+        private Ownership _ownsStreams;
+        private bool _canWrite;
+
+        private long _position;
+
+        public ConcatStream(Ownership ownsStreams, params SparseStream[] streams)
+        {
+            _ownsStreams = ownsStreams;
+            _streams = streams;
+
+            // Only allow writes if all streams can be written
+            _canWrite = true;
+            foreach (var stream in streams)
+            {
+                if (!stream.CanWrite)
+                {
+                    _canWrite = false;
+                }
+            }
+        }
+
+        public override bool CanRead
+        {
+            get
+            {
+                CheckDisposed();
+                return true;
+            }
+        }
+
+        public override bool CanSeek
+        {
+            get
+            {
+                CheckDisposed();
+                return true;
+            }
+        }
+
+        public override bool CanWrite
+        {
+            get
+            {
+                CheckDisposed();
+                return _canWrite;
+            }
+        }
+
+        public override long Length
+        {
+            get
+            {
+                CheckDisposed();
+                long length = 0;
+                for (int i = 0; i < _streams.Length; ++i)
+                {
+                    length += _streams[i].Length;
+                }
+
+                return length;
+            }
+        }
+
+        public override long Position
+        {
+            get
+            {
+                CheckDisposed();
+                return _position;
+            }
+
+            set
+            {
+                CheckDisposed();
+                _position = value;
+            }
+        }
+
+        public override IEnumerable<StreamExtent> Extents
+        {
+            get
+            {
+                CheckDisposed();
+                List<StreamExtent> extents = new List<StreamExtent>();
+
+                long pos = 0;
+                for (int i = 0; i < _streams.Length; ++i)
+                {
+                    foreach (StreamExtent extent in _streams[i].Extents)
+                    {
+                        extents.Add(new StreamExtent(extent.Start + pos, extent.Length));
+                    }
+
+                    pos += _streams[i].Length;
+                }
+
+                return extents;
+            }
+        }
+
+        public override void Flush()
+        {
+            CheckDisposed();
+            for (int i = 0; i < _streams.Length; ++i)
+            {
+                _streams[i].Flush();
+            }
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            CheckDisposed();
+
+            int totalRead = 0;
+            int numRead = 0;
+
+            do
+            {
+                long activeStreamStartPos;
+                int activeStream = GetActiveStream(out activeStreamStartPos);
+
+                _streams[activeStream].Position = _position - activeStreamStartPos;
+
+                numRead = _streams[activeStream].Read(buffer, offset + totalRead, count - totalRead);
+
+                totalRead += numRead;
+                _position += numRead;
+            }
+            while (numRead != 0);
+
+            return totalRead;
+        }
+
+        public override long Seek(long offset, System.IO.SeekOrigin origin)
+        {
+            CheckDisposed();
+
+            long effectiveOffset = offset;
+            if (origin == SeekOrigin.Current)
+            {
+                effectiveOffset += _position;
+            }
+            else if (origin == SeekOrigin.End)
+            {
+                effectiveOffset += Length;
+            }
+
+            if (effectiveOffset < 0)
+            {
+                throw new IOException("Attempt to move before beginning of disk");
+            }
+            else
+            {
+                Position = effectiveOffset;
+                return Position;
+            }
+        }
+
+        public override void SetLength(long value)
+        {
+            CheckDisposed();
+
+            long lastStreamOffset;
+            int lastStream = GetStream(Length, out lastStreamOffset);
+            if (value < lastStreamOffset)
+            {
+                throw new IOException(string.Format(CultureInfo.InvariantCulture, "Unable to reduce stream length to less than {0}", lastStreamOffset));
+            }
+
+            _streams[lastStream].SetLength(value - lastStreamOffset);
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            CheckDisposed();
+
+            int totalWritten = 0;
+            while (totalWritten != count)
+            {
+                // Offset of the stream = streamOffset
+                long streamOffset;
+                int streamIdx = GetActiveStream(out streamOffset);
+
+                // Offset within the stream = streamPos
+                long streamPos = _position - streamOffset;
+                _streams[streamIdx].Position = streamPos;
+
+                // Write (limited to the stream's length), except for final stream - that may be
+                // extendable
+                int numToWrite;
+                if (streamIdx == _streams.Length - 1)
+                {
+                    numToWrite = count - totalWritten;
+                }
+                else
+                {
+                    numToWrite = (int)Math.Min(count - totalWritten, _streams[streamIdx].Length - streamPos);
+                }
+
+                _streams[streamIdx].Write(buffer, offset + totalWritten, numToWrite);
+
+                totalWritten += numToWrite;
+                _position += numToWrite;
+            }
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            try
+            {
+                if (disposing && _ownsStreams == Ownership.Dispose && _streams != null)
+                {
+                    foreach (var stream in _streams)
+                    {
+                        stream.Dispose();
+                    }
+
+                    _streams = null;
+                }
+            }
+            finally
+            {
+                base.Dispose(disposing);
+            }
+        }
+
+        private int GetActiveStream(out long startPos)
+        {
+            return GetStream(_position, out startPos);
+        }
+
+        private int GetStream(long targetPos, out long streamStartPos)
+        {
+            // Find the stream that _position is within
+            streamStartPos = 0;
+            int focusStream = 0;
+            while (focusStream < _streams.Length - 1 && streamStartPos + _streams[focusStream].Length <= targetPos)
+            {
+                streamStartPos += _streams[focusStream].Length;
+                focusStream++;
+            }
+
+            return focusStream;
+        }
+
+        private void CheckDisposed()
+        {
+            if (_streams == null)
+            {
+                throw new ObjectDisposedException("ConcatStream");
+            }
+        }
+    }
+}