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mirror of synced 2024-12-14 16:42:58 +01:00
Switch-Toolbox/Switch_Toolbox_Library/IO/SubStream.cs
2019-08-17 09:58:17 -04:00

81 lines
3.0 KiB
C#

using System;
using System.IO;
namespace Toolbox.Library.IO
{
//From
//https://github.com/IcySon55/Kuriimu/blob/master/src/Kontract/IO/SubStream.cs
/// <summary>
/// Represenents a stream taked from another given an offset and length
/// Used for archives with streams left open
/// </summary>
public class SubStream : Stream
{
Stream baseStream;
readonly long length;
readonly long baseOffset;
public SubStream(Stream baseStream, long offset, long length)
{
if (baseStream == null) throw new ArgumentNullException("baseStream");
if (!baseStream.CanRead) throw new ArgumentException("baseStream.CanRead is false");
if (!baseStream.CanSeek) throw new ArgumentException("baseStream.CanSeek is false");
if (offset < 0) throw new ArgumentOutOfRangeException("offset");
if (offset + length > baseStream.Length) throw new ArgumentOutOfRangeException("length");
this.baseStream = baseStream;
this.length = length;
baseOffset = offset;
}
public SubStream(Stream baseStream, long offset)
{
long length = baseStream.Length - offset;
if (baseStream == null) throw new ArgumentNullException("baseStream");
if (!baseStream.CanRead) throw new ArgumentException("baseStream.CanRead is false");
if (!baseStream.CanSeek) throw new ArgumentException("baseStream.CanSeek is false");
if (offset < 0) throw new ArgumentOutOfRangeException("offset");
if (offset + length > baseStream.Length) throw new ArgumentOutOfRangeException("length");
this.baseStream = baseStream;
this.length = length;
baseOffset = offset;
}
public override int Read(byte[] buffer, int offset, int count)
{
baseStream.Position = baseOffset + offset + Position;
int read = baseStream.Read(buffer, offset, (int)Math.Min(count, length - Position));
Position += read;
return read;
}
public override long Length => length;
public override bool CanRead => true;
public override bool CanWrite => false;
public override bool CanSeek => true;
public override long Position { get; set; }
public override void Flush() => baseStream.Flush();
public override long Seek(long offset, SeekOrigin origin)
{
switch (origin)
{
case SeekOrigin.Begin: return Position = offset;
case SeekOrigin.Current: return Position += offset;
case SeekOrigin.End: return Position = length + offset;
}
throw new ArgumentException("origin is invalid");
}
public override void SetLength(long value)
{
throw new NotSupportedException();
}
public override void Write(byte[] buffer, int offset, int count)
{
throw new NotSupportedException();
}
}
}