//
// System.IO.BufferedStream
//
// Author:
// Matt Kimball (matt@kimball.net)
// Ville Palo <vi64pa@kolumbus.fi>
//
// Copyright (C) 2004 Novell (http://www.novell.com)
//
//
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
//
// 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.
//
using System.Globalization;
using System.Runtime.InteropServices;
namespace System.IO{
[ComVisible (true)]
public sealed class BufferedStream : Stream {
Stream m_stream;
byte[] m_buffer;
int m_buffer_pos;
int m_buffer_read_ahead;
bool m_buffer_reading;
private bool disposed = false;
public BufferedStream (Stream stream) : this (stream, 4096)
{
}
public BufferedStream (Stream stream, int bufferSize)
{
if (stream == null)
throw new ArgumentNullException ("stream");
// LAMESPEC: documented as < 0
if (bufferSize <= 0)
throw new ArgumentOutOfRangeException ("bufferSize", "<= 0");
if (!stream.CanRead && !stream.CanWrite) {
throw new ObjectDisposedException (
Locale.GetText ("Cannot access a closed Stream."));
}
m_stream = stream;
m_buffer = new byte [bufferSize];
}
public override bool CanRead {
get {
return m_stream.CanRead;
}
}
public override bool CanWrite {
get {
return m_stream.CanWrite;
}
}
public override bool CanSeek {
get {
return m_stream.CanSeek;
}
}
public override long Length {
get {
Flush ();
return m_stream.Length;
}
}
public override long Position {
get {
CheckObjectDisposedException ();
return m_stream.Position - m_buffer_read_ahead + m_buffer_pos;
}
set {
if (value < Position && (Position - value <= m_buffer_pos) && m_buffer_reading) {
m_buffer_pos -= (int) (Position - value);
}
else if (value > Position && (value - Position < m_buffer_read_ahead - m_buffer_pos) && m_buffer_reading) {
m_buffer_pos += (int) (value - Position);
}
else {
Flush();
m_stream.Position = value;
}
}
}
protected override void Dispose (bool disposing)
{
if (disposed)
return;
if (m_buffer != null)
Flush();
m_stream.Close();
m_buffer = null;
disposed = true;
}
public override void Flush ()
{
CheckObjectDisposedException ();
if (m_buffer_reading) {
if (CanSeek)
m_stream.Position = Position;
} else if (m_buffer_pos > 0) {
m_stream.Write(m_buffer, 0, m_buffer_pos);
}
m_buffer_read_ahead = 0;
m_buffer_pos = 0;
}
public override long Seek (long offset, SeekOrigin origin)
{
CheckObjectDisposedException ();
if (!CanSeek) {
throw new NotSupportedException (
Locale.GetText ("Non seekable stream."));
}
Flush ();
return m_stream.Seek (offset, origin);
}
public override void SetLength (long value)
{
CheckObjectDisposedException ();
if (value < 0)
throw new ArgumentOutOfRangeException ("value must be positive");
if (!m_stream.CanWrite && !m_stream.CanSeek)
throw new NotSupportedException ("the stream cannot seek nor write.");
if ((m_stream == null) || (!m_stream.CanRead && !m_stream.CanWrite))
throw new IOException ("the stream is not open");
m_stream.SetLength(value);
if (Position > value)
Position = value;
}
public override int ReadByte ()
{
CheckObjectDisposedException ();
if (!m_stream.CanRead) {
throw new NotSupportedException (
Locale.GetText ("Cannot read from stream"));
}
if (!m_buffer_reading) {
Flush ();
m_buffer_reading = true;
}
if (1 <= m_buffer_read_ahead - m_buffer_pos) {
return m_buffer [m_buffer_pos++];
}
else
{
if (m_buffer_pos >= m_buffer_read_ahead) {
m_buffer_pos = 0;
m_buffer_read_ahead = 0;
}
m_buffer_read_ahead = m_stream.Read (m_buffer, 0, m_buffer.Length);
if (1 <= m_buffer_read_ahead) {
return m_buffer [m_buffer_pos++];
} else {
return -1;
}
}
}
public override void WriteByte (byte value)
{
CheckObjectDisposedException ();
if (!m_stream.CanWrite) {
throw new NotSupportedException (
Locale.GetText ("Cannot write to stream"));
}
if (m_buffer_reading) {
Flush ();
m_buffer_reading = false;
}
else
// reordered to avoid possible integer overflow
if (m_buffer_pos >= m_buffer.Length - 1) {
Flush ();
}
m_buffer [m_buffer_pos++] = value;
}
public override int Read ([In,Out] byte[] array, int offset, int count)
{
if (array == null)
throw new ArgumentNullException ("array");
CheckObjectDisposedException ();
if (!m_stream.CanRead) {
throw new NotSupportedException (
Locale.GetText ("Cannot read from stream"));
}
if (offset < 0)
throw new ArgumentOutOfRangeException ("offset", "< 0");
if (count < 0)
throw new ArgumentOutOfRangeException ("count", "< 0");
// re-ordered to avoid possible integer overflow
if (array.Length - offset < count)
throw new ArgumentException ("array.Length - offset < count");
if (!m_buffer_reading) {
Flush();
m_buffer_reading = true;
}
if (count <= m_buffer_read_ahead - m_buffer_pos) {
Buffer.BlockCopyInternal (m_buffer, m_buffer_pos, array, offset, count);
m_buffer_pos += count;
if (m_buffer_pos == m_buffer_read_ahead) {
m_buffer_pos = 0;
m_buffer_read_ahead = 0;
}
return count;
}
int ret = m_buffer_read_ahead - m_buffer_pos;
Buffer.BlockCopyInternal (m_buffer, m_buffer_pos, array, offset, ret);
m_buffer_pos = 0;
m_buffer_read_ahead = 0;
offset += ret;
count -= ret;
if (count >= m_buffer.Length) {
ret += m_stream.Read (array, offset, count);
} else {
m_buffer_read_ahead = m_stream.Read (m_buffer, 0, m_buffer.Length);
if (count < m_buffer_read_ahead) {
Buffer.BlockCopyInternal (m_buffer, 0, array, offset, count);
m_buffer_pos = count;
ret += count;
} else {
Buffer.BlockCopyInternal (m_buffer, 0, array, offset, m_buffer_read_ahead);
ret += m_buffer_read_ahead;
m_buffer_read_ahead = 0;
}
}
return ret;
}
public override void Write (byte[] array, int offset, int count)
{
if (array == null)
throw new ArgumentNullException ("array");
CheckObjectDisposedException ();
if (!m_stream.CanWrite) {
throw new NotSupportedException (
Locale.GetText ("Cannot write to stream"));
}
if (offset < 0)
throw new ArgumentOutOfRangeException ("offset", "< 0");
if (count < 0)
throw new ArgumentOutOfRangeException ("count", "< 0");
// avoid possible integer overflow
if (array.Length - offset < count)
throw new ArgumentException ("array.Length - offset < count");
if (m_buffer_reading) {
Flush();
m_buffer_reading = false;
}
// reordered to avoid possible integer overflow
if (m_buffer_pos >= m_buffer.Length - count) {
Flush ();
m_stream.Write (array, offset, count);
}
else {
Buffer.BlockCopyInternal (array, offset, m_buffer, m_buffer_pos, count);
m_buffer_pos += count;
}
}
private void CheckObjectDisposedException ()
{
if (disposed) {
throw new ObjectDisposedException ("BufferedStream",
Locale.GetText ("Stream is closed"));
}
}
}
}
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