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using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace Apewer.Web
{
internal sealed class MiniReader : Stream
{
bool _disposed = false;
MiniConnection _connection;
Stream _stream;
long _remaining;
internal byte[] RemainsBytes = null;
int _offset = 0;
long _total = 0L;
internal MiniReader(MiniConnection connection, long remaining = -1)
{
_connection = connection;
_stream = connection.Stream;
_remaining = remaining;
}
public bool Disposed { get => _disposed; }
public override bool CanRead { get => true; }
public override bool CanWrite { get => false; }
public override bool CanSeek { get => false; }
public override long Length { get => throw new NotSupportedException(); }
public override long Position { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }
public override void Close() => _disposed = true;
public override void Flush() { }
public override long Seek(long offset, SeekOrigin origin) => throw new NotSupportedException();
public override void SetLength(long value) => throw new NotSupportedException();
#region read
int ReadRemins(byte[] buffer, int offset, int count)
{
// 返回 0,读取 Remains 已经完成,由外层继续读取。
if (RemainsBytes == null) return 0;
var length = RemainsBytes.Length;
if (length < 1) return 0;
// Remains 中剩余的长度,并根据 count 参数限制读取数量。
var result = length - offset;
if (result < 1) return 0;
if (result > count) result = count;
// Content-Length 指定的剩余长度。
if (_remaining > 0 && result > _remaining) result = (int)_remaining;
// RemainsBytes 长度溢出限制。
if (result + _offset > length) result = length - _offset;
// 从 Remains 中读取,返回具体的字节数。
Buffer.BlockCopy(RemainsBytes, _offset, buffer, offset, result);
_offset += result;
_remaining -= result;
_total += result;
// 已完成 Remains 的读取。
if (_offset >= length) RemainsBytes = null;
return result;
}
public override int Read(byte[] buffer, int offset, int count)
{
if (_connection.Server.SynchronousIO)
{
if (_disposed) throw new ObjectDisposedException(typeof(Stream).FullName);
// 检查参数。
if (buffer == null) throw new ArgumentNullException("参数 buffer 无效。");
if (offset < 0) throw new ArgumentOutOfRangeException("offset", "参数 offset 小于 0。");
if (count < 0) throw new ArgumentOutOfRangeException("count", "参数 count 小于 0。");
int bufferLength = buffer.Length;
if (offset > bufferLength) throw new ArgumentOutOfRangeException("offset", "指定的 offset 的值超出了 buffer 数组的容量。");
if (offset + count > bufferLength) throw new ArgumentException("指定的 offset 和 count 超出了 buffer 数组的容量。");
if (count == 0) return 0;
// 检查剩余读取量。
if (_remaining == 0) return 0;
// 从 Remains 中读取。
var nread = ReadRemins(buffer, offset, count);
if (nread > 0) return nread;
// 根据 Content-Length 限定长度。
if (_remaining > 0 && _remaining < count) count = (int)_remaining;
var read = _stream.Read(buffer, offset, count);
if (read > 0 && _remaining > 0) _remaining -= read;
return read;
}
else
{
var async = BeginRead(buffer, offset, count, null, null);
var result = EndRead(async);
return result;
}
}
public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback cback, object state)
{
#if DEBUG
if (_disposed) throw new ObjectDisposedException(typeof(Stream).FullName);
// 检查参数。
if (buffer == null) throw new ArgumentNullException("参数 buffer 无效。");
if (offset < 0) throw new ArgumentOutOfRangeException("offset", "参数 offset 小于 0。");
if (count < 0) throw new ArgumentOutOfRangeException("count", "参数 count 小于 0。");
int bufferLength = buffer.Length;
if (offset > bufferLength) throw new ArgumentOutOfRangeException("offset", "指定的 offset 的值超出了 buffer 数组的容量。");
if (offset + count > bufferLength) throw new ArgumentException("指定的 offset 和 count 超出了 buffer 数组的容量。");
// Content-Length
if (_remaining == 0)
{
var ares = new MiniStreamAsyncResult();
ares.Buffer = buffer;
ares.Offset = offset;
ares.Count = count;
ares.Callback = cback;
ares.State = state;
ares.SynchRead = 0;
ares.Complete();
return ares;
}
if (_remaining > 0 && _remaining < count) count = (int)_remaining;
return _stream.BeginRead(buffer, offset, count, cback, state);
#else
throw new NotSupportedException();
#endif
}
public override int EndRead(IAsyncResult ar)
{
#if DEBUG
if (_disposed) throw new ObjectDisposedException(typeof(Stream).FullName);
if (ar == null) throw new ArgumentNullException(nameof(ar));
if (ar is MiniStreamAsyncResult)
{
var r = (MiniStreamAsyncResult)ar;
if (!ar.IsCompleted) ar.AsyncWaitHandle.WaitOne();
return r.SynchRead;
}
int nread = _stream.EndRead(ar);
if (_remaining > 0 && nread > 0) _remaining -= nread;
return nread;
#else
throw new NotSupportedException();
#endif
}
#endregion
#region write
public override void Write(byte[] buffer, int offset, int count) => throw new NotSupportedException();
public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state) => throw new NotSupportedException();
public override void EndWrite(IAsyncResult ar) => throw new NotSupportedException();
#endregion
}
}