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Restore constrained. prefix

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de4dot 2012-04-06 16:08:35 +02:00
parent 1935e58dbf
commit 33e2177059
1 changed files with 36 additions and 0 deletions
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36
de4dot.code/deobfuscators/CliSecure/vm/CsvmToCilMethodConverter.cs
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@ -51,6 +51,7 @@ namespace de4dot.code.deobfuscators.CliSecure.vm {
if (operandRestorer.restore(cilMethod))
Log.w("Failed to restore one or more instruction operands in CSVM method {0:X8}", cilMethod.MetadataToken.ToInt32());
restoreConstrainedPrefix(cilMethod);
}
void fixLocals(IList<Instruction> instrs, IList<VariableDefinition> locals) {
@ -405,5 +406,40 @@ namespace de4dot.code.deobfuscators.CliSecure.vm {
throw new ApplicationException(string.Format("Could not find member ref: {0:X8}", token));
return memberRef;
}
static void restoreConstrainedPrefix(MethodDefinition method) {
if (method == null || method.Body == null)
return;
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count; i++) {
var instr = instrs[i];
if (instr.OpCode.Code != Code.Callvirt)
continue;
var calledMethod = instr.Operand as MethodReference;
if (calledMethod == null || !calledMethod.HasThis)
continue;
var thisType = MethodStack.getLoadedType(method, instrs, i, calledMethod.Parameters.Count) as ByReferenceType;
if (thisType == null)
continue;
if (hasPrefix(instrs, i, Code.Constrained))
continue;
instrs.Insert(i, Instruction.Create(OpCodes.Constrained, thisType.ElementType));
i++;
}
}
static bool hasPrefix(IList<Instruction> instrs, int index, Code prefix) {
index--;
for (; index >= 0; index--) {
var instr = instrs[index];
if (instr.OpCode.OpCodeType != OpCodeType.Prefix)
break;
if (instr.OpCode.Code == prefix)
return true;
}
return false;
}
}
}