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using System;
using System.IO;
public sealed class HttpPostedFile : IDisposable
{
private string _name;
private string _contentType;
private Stream _stream;
private bool _disposed = false;
internal HttpPostedFile(string name, string content_type, Stream base_stream, long offset, long length)
{
_name = name;
_contentType = content_type;
_stream = new ReadSubStream(base_stream, offset, length);
}
public string ContentType => _contentType;
public int ContentLength => (int)_stream.Length;
public string FileName => _name;
public Stream InputStream => _stream;
/// <summary>
/// Releases the unmanaged resources and disposes of the managed resources used.
/// </summary>
public void Dispose()
{
if (_disposed)
{
return;
}
_stream.Dispose();
_stream = null;
_name = null;
_contentType = null;
_disposed = true;
}
private class ReadSubStream : Stream
{
private Stream _stream;
private long _offset;
private long _end;
private long _position;
public ReadSubStream(Stream s, long offset, long length)
{
_stream = s;
_offset = offset;
_end = offset + length;
_position = offset;
}
public override bool CanRead => true;
public override bool CanSeek => true;
public override bool CanWrite => false;
public override long Length => _end - _offset;
public override long Position
{
get => _position - _offset;
set
{
if (value > Length)
{
throw new ArgumentOutOfRangeException(nameof(value));
}
_position = Seek(value, SeekOrigin.Begin);
}
}
public override void Flush()
{
}
public override int Read(byte[] buffer, int dest_offset, int count)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (dest_offset < 0)
{
throw new ArgumentOutOfRangeException(nameof(dest_offset), "< 0");
}
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count), "< 0");
}
int len = buffer.Length;
if (dest_offset > len)
{
throw new ArgumentException("destination offset is beyond array size", nameof(dest_offset));
}
// reordered to avoid possible integer overflow
if (dest_offset > len - count)
{
throw new ArgumentException("Reading would overrun buffer", nameof(count));
}
if (count > _end - _position)
{
count = (int)(_end - _position);
}
if (count <= 0)
{
return 0;
}
_stream.Position = _position;
int result = _stream.Read(buffer, dest_offset, count);
if (result > 0)
{
_position += result;
}
else
{
_position = _end;
}
return result;
}
public override int ReadByte()
{
if (_position >= _end)
{
return -1;
}
_stream.Position = _position;
int result = _stream.ReadByte();
if (result < 0)
{
_position = _end;
}
else
{
_position++;
}
return result;
}
public override long Seek(long d, SeekOrigin origin)
{
long real;
switch (origin)
{
case SeekOrigin.Begin:
real = _offset + d;
break;
case SeekOrigin.End:
real = _end + d;
break;
case SeekOrigin.Current:
real = _position + d;
break;
default:
throw new ArgumentException("Unknown SeekOrigin value", nameof(origin));
}
long virt = real - _offset;
if (virt < 0 || virt > Length)
{
throw new ArgumentException("Invalid position", nameof(d));
}
_position = _stream.Seek(real, SeekOrigin.Begin);
return _position;
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException();
}
}
}
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