324 lines
8.1 KiB
C#
324 lines
8.1 KiB
C#
//
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// System.IO.BufferedStream
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//
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// Author:
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// Matt Kimball (matt@kimball.net)
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// Ville Palo <vi64pa@kolumbus.fi>
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//
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// Copyright (C) 2004 Novell (http://www.novell.com)
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//
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//
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// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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using System.Globalization;
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using System.Runtime.InteropServices;
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namespace System.IO {
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[ComVisible (true)]
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public sealed class BufferedStream : Stream {
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Stream m_stream;
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byte[] m_buffer;
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int m_buffer_pos;
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int m_buffer_read_ahead;
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bool m_buffer_reading;
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private bool disposed = false;
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public BufferedStream (Stream stream) : this (stream, 4096)
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{
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}
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public BufferedStream (Stream stream, int bufferSize)
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{
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if (stream == null)
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throw new ArgumentNullException ("stream");
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// LAMESPEC: documented as < 0
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if (bufferSize <= 0)
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throw new ArgumentOutOfRangeException ("bufferSize", "<= 0");
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if (!stream.CanRead && !stream.CanWrite) {
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throw new ObjectDisposedException (
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Locale.GetText ("Cannot access a closed Stream."));
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}
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m_stream = stream;
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m_buffer = new byte [bufferSize];
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}
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public override bool CanRead {
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get {
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return m_stream.CanRead;
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}
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}
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public override bool CanWrite {
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get {
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return m_stream.CanWrite;
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}
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}
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public override bool CanSeek {
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get {
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return m_stream.CanSeek;
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}
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}
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public override long Length {
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get {
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Flush ();
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return m_stream.Length;
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}
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}
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public override long Position {
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get {
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CheckObjectDisposedException ();
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return m_stream.Position - m_buffer_read_ahead + m_buffer_pos;
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}
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set {
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if (value < Position && (Position - value <= m_buffer_pos) && m_buffer_reading) {
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m_buffer_pos -= (int) (Position - value);
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}
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else if (value > Position && (value - Position < m_buffer_read_ahead - m_buffer_pos) && m_buffer_reading) {
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m_buffer_pos += (int) (value - Position);
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}
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else {
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Flush();
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m_stream.Position = value;
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}
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}
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}
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protected override void Dispose (bool disposing)
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{
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if (disposed)
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return;
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if (m_buffer != null)
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Flush();
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m_stream.Close();
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m_buffer = null;
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disposed = true;
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}
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public override void Flush ()
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{
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CheckObjectDisposedException ();
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if (m_buffer_reading) {
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if (CanSeek)
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m_stream.Position = Position;
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} else if (m_buffer_pos > 0) {
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m_stream.Write(m_buffer, 0, m_buffer_pos);
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}
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m_buffer_read_ahead = 0;
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m_buffer_pos = 0;
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}
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public override long Seek (long offset, SeekOrigin origin)
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{
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CheckObjectDisposedException ();
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if (!CanSeek) {
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throw new NotSupportedException (
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Locale.GetText ("Non seekable stream."));
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}
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Flush ();
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return m_stream.Seek (offset, origin);
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}
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public override void SetLength (long value)
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{
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CheckObjectDisposedException ();
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if (value < 0)
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throw new ArgumentOutOfRangeException ("value must be positive");
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if (!m_stream.CanWrite && !m_stream.CanSeek)
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throw new NotSupportedException ("the stream cannot seek nor write.");
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if ((m_stream == null) || (!m_stream.CanRead && !m_stream.CanWrite))
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throw new IOException ("the stream is not open");
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m_stream.SetLength(value);
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if (Position > value)
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Position = value;
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}
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public override int ReadByte ()
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{
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CheckObjectDisposedException ();
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if (!m_stream.CanRead) {
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throw new NotSupportedException (
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Locale.GetText ("Cannot read from stream"));
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}
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if (!m_buffer_reading) {
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Flush ();
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m_buffer_reading = true;
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}
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if (1 <= m_buffer_read_ahead - m_buffer_pos) {
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return m_buffer [m_buffer_pos++];
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}
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else
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{
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if (m_buffer_pos >= m_buffer_read_ahead) {
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m_buffer_pos = 0;
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m_buffer_read_ahead = 0;
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}
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m_buffer_read_ahead = m_stream.Read (m_buffer, 0, m_buffer.Length);
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if (1 <= m_buffer_read_ahead) {
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return m_buffer [m_buffer_pos++];
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} else {
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return -1;
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}
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}
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}
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public override void WriteByte (byte value)
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{
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CheckObjectDisposedException ();
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if (!m_stream.CanWrite) {
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throw new NotSupportedException (
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Locale.GetText ("Cannot write to stream"));
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}
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if (m_buffer_reading) {
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Flush ();
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m_buffer_reading = false;
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}
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else
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// reordered to avoid possible integer overflow
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if (m_buffer_pos >= m_buffer.Length - 1) {
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Flush ();
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}
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m_buffer [m_buffer_pos++] = value;
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}
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public override int Read ([In,Out] byte[] array, int offset, int count)
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{
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if (array == null)
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throw new ArgumentNullException ("array");
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CheckObjectDisposedException ();
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if (!m_stream.CanRead) {
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throw new NotSupportedException (
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Locale.GetText ("Cannot read from stream"));
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}
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if (offset < 0)
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throw new ArgumentOutOfRangeException ("offset", "< 0");
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if (count < 0)
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throw new ArgumentOutOfRangeException ("count", "< 0");
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// re-ordered to avoid possible integer overflow
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if (array.Length - offset < count)
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throw new ArgumentException ("array.Length - offset < count");
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if (!m_buffer_reading) {
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Flush();
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m_buffer_reading = true;
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}
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if (count <= m_buffer_read_ahead - m_buffer_pos) {
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Buffer.BlockCopyInternal (m_buffer, m_buffer_pos, array, offset, count);
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m_buffer_pos += count;
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if (m_buffer_pos == m_buffer_read_ahead) {
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m_buffer_pos = 0;
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m_buffer_read_ahead = 0;
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}
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return count;
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}
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int ret = m_buffer_read_ahead - m_buffer_pos;
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Buffer.BlockCopyInternal (m_buffer, m_buffer_pos, array, offset, ret);
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m_buffer_pos = 0;
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m_buffer_read_ahead = 0;
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offset += ret;
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count -= ret;
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if (count >= m_buffer.Length) {
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ret += m_stream.Read (array, offset, count);
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} else {
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m_buffer_read_ahead = m_stream.Read (m_buffer, 0, m_buffer.Length);
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if (count < m_buffer_read_ahead) {
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Buffer.BlockCopyInternal (m_buffer, 0, array, offset, count);
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m_buffer_pos = count;
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ret += count;
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} else {
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Buffer.BlockCopyInternal (m_buffer, 0, array, offset, m_buffer_read_ahead);
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ret += m_buffer_read_ahead;
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m_buffer_read_ahead = 0;
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}
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}
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return ret;
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}
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public override void Write (byte[] array, int offset, int count)
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{
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if (array == null)
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throw new ArgumentNullException ("array");
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CheckObjectDisposedException ();
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if (!m_stream.CanWrite) {
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throw new NotSupportedException (
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Locale.GetText ("Cannot write to stream"));
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}
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if (offset < 0)
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throw new ArgumentOutOfRangeException ("offset", "< 0");
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if (count < 0)
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throw new ArgumentOutOfRangeException ("count", "< 0");
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// avoid possible integer overflow
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if (array.Length - offset < count)
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throw new ArgumentException ("array.Length - offset < count");
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if (m_buffer_reading) {
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Flush();
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m_buffer_reading = false;
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}
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// reordered to avoid possible integer overflow
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if (m_buffer_pos >= m_buffer.Length - count) {
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Flush ();
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m_stream.Write (array, offset, count);
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}
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else {
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Buffer.BlockCopyInternal (array, offset, m_buffer, m_buffer_pos, count);
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m_buffer_pos += count;
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}
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}
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private void CheckObjectDisposedException ()
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{
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if (disposed) {
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throw new ObjectDisposedException ("BufferedStream",
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Locale.GetText ("Stream is closed"));
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}
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}
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}
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}
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