239 lines
7.4 KiB
C#
239 lines
7.4 KiB
C#
/*
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Copyright (C) 2011-2015 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.DeepSea {
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class ArrayBlockState {
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ModuleDefMD module;
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FieldDefAndDeclaringTypeDict<FieldInfo> fieldToInfo = new FieldDefAndDeclaringTypeDict<FieldInfo>();
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public class FieldInfo {
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public readonly ElementType elementType;
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public readonly FieldDef field;
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public readonly FieldDef arrayInitField;
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public readonly Array array;
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public FieldInfo(FieldDef field, FieldDef arrayInitField) {
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this.field = field;
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this.elementType = ((SZArraySig)field.FieldType).Next.GetElementType();
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this.arrayInitField = arrayInitField;
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this.array = CreateArray(elementType, arrayInitField.InitialValue);
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}
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static Array CreateArray(ElementType etype, byte[] data) {
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switch (etype) {
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case ElementType.Boolean:
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case ElementType.I1:
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case ElementType.U1:
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return (byte[])data.Clone();
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case ElementType.Char:
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case ElementType.I2:
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case ElementType.U2:
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var ary2 = new ushort[data.Length / 2];
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Buffer.BlockCopy(data, 0, ary2, 0, ary2.Length * 2);
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return ary2;
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case ElementType.I4:
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case ElementType.U4:
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var ary4 = new uint[data.Length / 4];
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Buffer.BlockCopy(data, 0, ary4, 0, ary4.Length * 4);
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return ary4;
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default:
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throw new ApplicationException("Invalid etype");
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}
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}
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public uint ReadArrayElement(int index) {
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switch (elementType) {
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case ElementType.Boolean:
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case ElementType.I1:
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case ElementType.U1:
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return ((byte[])array)[index];
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case ElementType.Char:
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case ElementType.I2:
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case ElementType.U2:
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return ((ushort[])array)[index];
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case ElementType.I4:
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case ElementType.U4:
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return ((uint[])array)[index];
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default:
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throw new ApplicationException("Invalid etype");
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}
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}
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}
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public bool Detected {
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get { return fieldToInfo.Count != 0; }
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}
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public ArrayBlockState(ModuleDefMD module) {
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this.module = module;
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}
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public void Initialize(ISimpleDeobfuscator simpleDeobfuscator) {
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InitializeArrays(simpleDeobfuscator, DotNetUtils.GetModuleTypeCctor(module));
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}
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void InitializeArrays(ISimpleDeobfuscator simpleDeobfuscator, MethodDef method) {
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if (method == null || method.Body == null)
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return;
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while (InitializeArrays2(simpleDeobfuscator, method)) {
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}
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}
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bool InitializeArrays2(ISimpleDeobfuscator simpleDeobfuscator, MethodDef method) {
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bool foundField = false;
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simpleDeobfuscator.Deobfuscate(method, SimpleDeobfuscatorFlags.Force);
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var instructions = method.Body.Instructions;
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for (int i = 0; i < instructions.Count; i++) {
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var ldci4 = instructions[i];
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if (!ldci4.IsLdcI4())
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continue;
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i++;
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var instrs = DotNetUtils.GetInstructions(instructions, i, OpCodes.Newarr, OpCodes.Dup, OpCodes.Ldtoken, OpCodes.Call, OpCodes.Stsfld);
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if (instrs == null)
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continue;
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var arrayInitField = instrs[2].Operand as FieldDef;
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if (arrayInitField == null || arrayInitField.InitialValue == null || arrayInitField.InitialValue.Length == 0)
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continue;
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var calledMethod = instrs[3].Operand as IMethod;
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if (calledMethod == null || calledMethod.FullName != "System.Void System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(System.Array,System.RuntimeFieldHandle)")
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continue;
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var targetField = instrs[4].Operand as FieldDef;
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if (targetField == null || targetField.FieldType.GetElementType() != ElementType.SZArray)
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continue;
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var etype = ((SZArraySig)targetField.FieldType).Next.GetElementType();
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if (etype < ElementType.Boolean || etype > ElementType.U4)
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continue;
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if (fieldToInfo.Find(targetField) == null) {
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fieldToInfo.Add(targetField, new FieldInfo(targetField, arrayInitField));
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foundField = true;
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}
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}
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return foundField;
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}
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public FieldInfo GetFieldInfo(IField fieldRef) {
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if (fieldRef == null)
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return null;
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return fieldToInfo.Find(fieldRef);
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}
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public IEnumerable<FieldDef> CleanUp() {
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var removedFields = new List<FieldDef>();
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var moduleCctor = DotNetUtils.GetModuleTypeCctor(module);
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if (moduleCctor == null)
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return removedFields;
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var moduleCctorBlocks = new Blocks(moduleCctor);
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var keep = FindFieldsToKeep();
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foreach (var fieldInfo in fieldToInfo.GetValues()) {
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if (keep.ContainsKey(fieldInfo))
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continue;
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if (RemoveInitCode(moduleCctorBlocks, fieldInfo)) {
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removedFields.Add(fieldInfo.field);
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removedFields.Add(fieldInfo.arrayInitField);
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}
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fieldInfo.arrayInitField.InitialValue = new byte[1];
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fieldInfo.arrayInitField.FieldSig.Type = module.CorLibTypes.Byte;
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fieldInfo.arrayInitField.RVA = 0;
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}
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IList<Instruction> allInstructions;
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IList<ExceptionHandler> allExceptionHandlers;
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moduleCctorBlocks.GetCode(out allInstructions, out allExceptionHandlers);
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DotNetUtils.RestoreBody(moduleCctorBlocks.Method, allInstructions, allExceptionHandlers);
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return removedFields;
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}
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bool RemoveInitCode(Blocks blocks, FieldInfo info) {
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bool removedSomething = false;
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foreach (var block in blocks.MethodBlocks.GetAllBlocks()) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count - 5; i++) {
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var ldci4 = instrs[i];
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if (!ldci4.IsLdcI4())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Newarr)
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continue;
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if (instrs[i + 2].OpCode.Code != Code.Dup)
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continue;
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var ldtoken = instrs[i + 3];
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if (ldtoken.OpCode.Code != Code.Ldtoken)
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continue;
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if (ldtoken.Operand != info.arrayInitField)
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continue;
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var call = instrs[i + 4];
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if (call.OpCode.Code != Code.Call)
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continue;
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var calledMethod = call.Operand as IMethod;
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if (calledMethod == null || calledMethod.FullName != "System.Void System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(System.Array,System.RuntimeFieldHandle)")
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continue;
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var stsfld = instrs[i + 5];
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if (stsfld.OpCode.Code != Code.Stsfld)
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continue;
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if (stsfld.Operand != info.field)
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continue;
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block.Remove(i, 6);
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i--;
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removedSomething = true;
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}
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}
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return removedSomething;
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}
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Dictionary<FieldInfo, bool> FindFieldsToKeep() {
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var keep = new Dictionary<FieldInfo, bool>();
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foreach (var type in module.GetTypes()) {
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foreach (var method in type.Methods) {
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if (type == DotNetUtils.GetModuleType(module) && method.Name == ".cctor")
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continue;
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if (method.Body == null)
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continue;
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foreach (var instr in method.Body.Instructions) {
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var field = instr.Operand as IField;
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if (field == null)
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continue;
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var fieldInfo = fieldToInfo.Find(field);
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if (fieldInfo == null)
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continue;
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keep[fieldInfo] = true;
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}
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}
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}
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return keep;
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}
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}
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}
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