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