105 lines
3.2 KiB
C#
105 lines
3.2 KiB
C#
using System.Reflection;
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using System.Reflection.Emit;
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namespace System.Diagnostics.Internal
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{
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internal class ILReader
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{
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private static OpCode[] singleByteOpCode;
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private static OpCode[] doubleByteOpCode;
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private readonly byte[] _cil;
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private int ptr;
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public ILReader(byte[] cil) => _cil = cil;
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public OpCode OpCode { get; private set; }
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public int MetadataToken { get; private set; }
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public MemberInfo Operand { get; private set; }
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public bool Read(MethodBase methodInfo)
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{
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if (ptr < _cil.Length)
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{
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OpCode = ReadOpCode();
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Operand = ReadOperand(OpCode, methodInfo);
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return true;
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}
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return false;
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}
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OpCode ReadOpCode()
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{
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var instruction = ReadByte();
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if (instruction < 254)
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return singleByteOpCode[instruction];
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else
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return doubleByteOpCode[ReadByte()];
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}
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MemberInfo ReadOperand(OpCode code, MethodBase methodInfo)
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{
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MetadataToken = 0;
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switch (code.OperandType)
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{
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case OperandType.InlineMethod:
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MetadataToken = ReadInt();
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Type[] methodArgs = null;
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if (methodInfo.GetType() != typeof(ConstructorInfo) && !methodInfo.GetType().IsSubclassOf(typeof(ConstructorInfo)))
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{
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methodArgs = methodInfo.GetGenericArguments();
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}
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Type[] typeArgs = null;
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if (methodInfo.DeclaringType != null)
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{
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typeArgs = methodInfo.DeclaringType.GetGenericArguments();
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}
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try
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{
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return methodInfo.Module.ResolveMember(MetadataToken, typeArgs, methodArgs);
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}
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catch
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{
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// Can return System.ArgumentException : Token xxx is not a valid MemberInfo token in the scope of module xxx.dll
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return null;
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}
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}
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return null;
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}
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byte ReadByte() => _cil[ptr++];
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int ReadInt()
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{
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var b1 = ReadByte();
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var b2 = ReadByte();
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var b3 = ReadByte();
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var b4 = ReadByte();
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return b1 | b2 << 8 | b3 << 16 | b4 << 24;
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}
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static ILReader()
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{
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singleByteOpCode = new OpCode[225];
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doubleByteOpCode = new OpCode[31];
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var fields = GetOpCodeFields();
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for (var i = 0; i < fields.Length; i++)
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{
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var code = (OpCode)fields[i].GetValue(null);
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if (code.OpCodeType == OpCodeType.Nternal)
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continue;
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if (code.Size == 1)
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singleByteOpCode[code.Value] = code;
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else
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doubleByteOpCode[code.Value & 0xff] = code;
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}
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}
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static FieldInfo[] GetOpCodeFields() => typeof(OpCodes).GetFields(BindingFlags.Public | BindingFlags.Static);
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}
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}
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