mirror of https://github.com/icsharpcode/ILSpy.git
11 changed files with 317 additions and 50 deletions
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@@ -0,0 +1,129 @@
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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
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// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
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using System; |
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using System.IO; |
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using System.Text; |
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using System.Xml; |
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using ICSharpCode.AvalonEdit.Utils; |
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namespace ICSharpCode.ILSpy |
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{ |
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/// <summary>
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/// Static methods for determining the type of a file.
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/// </summary>
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public static class GuessFileType |
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{ |
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public static FileType DetectFileType(Stream stream) |
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{ |
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StreamReader reader; |
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if (stream.Length >= 2) { |
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int firstByte = stream.ReadByte(); |
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int secondByte = stream.ReadByte(); |
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switch ((firstByte << 8) | secondByte) { |
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case 0xfffe: // UTF-16 LE BOM / UTF-32 LE BOM
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case 0xfeff: // UTF-16 BE BOM
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stream.Position -= 2; |
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reader = new StreamReader(stream, detectEncodingFromByteOrderMarks: true); |
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break; |
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case 0xefbb: // start of UTF-8 BOM
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if (stream.ReadByte() == 0xbf) { |
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reader = new StreamReader(stream, Encoding.UTF8); |
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break; |
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} else { |
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return FileType.Binary; |
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} |
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default: |
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if (IsUTF8(stream, (byte)firstByte, (byte)secondByte)) { |
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stream.Position = 0; |
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reader = new StreamReader(stream, Encoding.UTF8); |
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break; |
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} else { |
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return FileType.Binary; |
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} |
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} |
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} else { |
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return FileType.Binary; |
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} |
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// Now we got a StreamReader with the correct encoding
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// Check for XML now
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try { |
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XmlTextReader xmlReader = new XmlTextReader(stream); |
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xmlReader.XmlResolver = null; |
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xmlReader.MoveToContent(); |
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return FileType.Xml; |
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} catch (XmlException) { |
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return FileType.Text; |
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} |
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} |
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static bool IsUTF8(Stream fs, byte firstByte, byte secondByte) |
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{ |
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int max = (int)Math.Min(fs.Length, 500000); // look at max. 500 KB
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const int ASCII = 0; |
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const int Error = 1; |
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const int UTF8 = 2; |
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const int UTF8Sequence = 3; |
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int state = ASCII; |
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int sequenceLength = 0; |
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byte b; |
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for (int i = 0; i < max; i++) { |
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if (i == 0) { |
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b = firstByte; |
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} else if (i == 1) { |
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b = secondByte; |
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} else { |
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b = (byte)fs.ReadByte(); |
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} |
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if (b < 0x80) { |
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// normal ASCII character
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if (state == UTF8Sequence) { |
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state = Error; |
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break; |
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} |
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} else if (b < 0xc0) { |
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// 10xxxxxx : continues UTF8 byte sequence
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if (state == UTF8Sequence) { |
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--sequenceLength; |
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if (sequenceLength < 0) { |
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state = Error; |
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break; |
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} else if (sequenceLength == 0) { |
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state = UTF8; |
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} |
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} else { |
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state = Error; |
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break; |
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} |
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} else if (b >= 0xc2 && b < 0xf5) { |
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// beginning of byte sequence
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if (state == UTF8 || state == ASCII) { |
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state = UTF8Sequence; |
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if (b < 0xe0) { |
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sequenceLength = 1; // one more byte following
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} else if (b < 0xf0) { |
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sequenceLength = 2; // two more bytes following
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} else { |
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sequenceLength = 3; // three more bytes following
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} |
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} else { |
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state = Error; |
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break; |
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} |
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} else { |
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// 0xc0, 0xc1, 0xf5 to 0xff are invalid in UTF-8 (see RFC 3629)
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state = Error; |
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break; |
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} |
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} |
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return state != Error; |
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} |
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} |
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public enum FileType |
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{ |
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Binary, |
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Text, |
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Xml |
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} |
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} |
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