/*---------------------------------------------------------------------------------------------
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* Copyright (c) Microsoft Corporation. All rights reserved.
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* Licensed under the MIT License. See License.txt in the project root for license information.
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*--------------------------------------------------------------------------------------------*/
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using System;
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using System.IO;
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namespace Microsoft.Unity.VisualStudio.Editor
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{
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public sealed class Image : IDisposable
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{
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long position;
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Stream stream;
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Image(Stream stream)
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{
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this.stream = stream;
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this.position = stream.Position;
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this.stream.Position = 0;
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}
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bool Advance(int length)
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{
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if (stream.Position + length >= stream.Length)
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return false;
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stream.Seek(length, SeekOrigin.Current);
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return true;
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}
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bool MoveTo(uint position)
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{
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if (position >= stream.Length)
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return false;
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stream.Position = position;
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return true;
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}
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void IDisposable.Dispose()
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{
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stream.Position = position;
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}
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ushort ReadUInt16()
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{
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return (ushort)(stream.ReadByte()
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| (stream.ReadByte() << 8));
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}
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uint ReadUInt32()
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{
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return (uint)(stream.ReadByte()
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| (stream.ReadByte() << 8)
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| (stream.ReadByte() << 16)
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| (stream.ReadByte() << 24));
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}
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bool IsManagedAssembly()
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{
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if (stream.Length < 318)
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return false;
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if (ReadUInt16() != 0x5a4d)
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return false;
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if (!Advance(58))
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return false;
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if (!MoveTo(ReadUInt32()))
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return false;
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if (ReadUInt32() != 0x00004550)
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return false;
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if (!Advance(20))
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return false;
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if (!Advance(ReadUInt16() == 0x20b ? 222 : 206))
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return false;
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return ReadUInt32() != 0;
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}
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public static bool IsAssembly(string file)
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{
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if (file == null)
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throw new ArgumentNullException("file");
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using (var stream = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.Read))
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return IsAssembly(stream);
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}
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public static bool IsAssembly(Stream stream)
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{
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if (stream == null)
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throw new ArgumentNullException(nameof(stream));
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if (!stream.CanRead)
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throw new ArgumentException(nameof(stream));
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if (!stream.CanSeek)
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throw new ArgumentException(nameof(stream));
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using (var image = new Image(stream))
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return image.IsManagedAssembly();
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}
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}
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}
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