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A reflection based disassembler
//
// MethodBaseRocks.cs
//
// Author:
// Jb Evain (jbevain@novell.com)
//
// WARNING: code now lives in http://github.com/jbevain/mono.reflection
//
// (C) 2009 Novell, Inc. (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
namespace Mono.Reflection
{
public sealed class Instruction
{
int offset;
OpCode opcode;
object operand;
Instruction previous;
Instruction next;
public int Offset
{
get { return offset; }
}
public OpCode OpCode
{
get { return opcode; }
}
public object Operand
{
get { return operand; }
internal set { operand = value; }
}
public Instruction Previous
{
get { return previous; }
internal set { previous = value; }
}
public Instruction Next
{
get { return next; }
internal set { next = value; }
}
internal Instruction(int offset, OpCode opcode)
{
this.offset = offset;
this.opcode = opcode;
}
public int GetSize()
{
int size = opcode.Size;
switch (opcode.OperandType)
{
case OperandType.InlineSwitch:
size += (1 + ((int[])operand).Length) * 4;
break;
case OperandType.InlineI8:
case OperandType.InlineR:
size += 8;
break;
case OperandType.InlineBrTarget:
case OperandType.InlineField:
case OperandType.InlineI:
case OperandType.InlineMethod:
case OperandType.InlineString:
case OperandType.InlineTok:
case OperandType.InlineType:
case OperandType.ShortInlineR:
size += 4;
break;
case OperandType.InlineVar:
size += 2;
break;
case OperandType.ShortInlineBrTarget:
case OperandType.ShortInlineI:
case OperandType.ShortInlineVar:
size += 1;
break;
}
return size;
}
public override string ToString()
{
return opcode.Name;
}
}
class MethodBodyReader
{
static OpCode[] one_byte_opcodes;
static OpCode[] two_bytes_opcodes;
static MethodBodyReader()
{
one_byte_opcodes = new OpCode[0xe1];
two_bytes_opcodes = new OpCode[0x1f];
var fields = GetOpCodeFields();
for (int i = 0; i < fields.Length; i++)
{
var opcode = (OpCode)fields[i].GetValue(null);
if (opcode.OpCodeType == OpCodeType.Nternal)
continue;
if (opcode.Size == 1)
one_byte_opcodes[opcode.Value] = opcode;
else
two_bytes_opcodes[opcode.Value & 0xff] = opcode;
}
}
static FieldInfo[] GetOpCodeFields()
{
return typeof(OpCodes).GetFields(BindingFlags.Public | BindingFlags.Static);
}
class ByteBuffer
{
internal byte[] buffer;
internal int position;
public ByteBuffer(byte[] buffer)
{
this.buffer = buffer;
}
public byte ReadByte()
{
CheckCanRead(1);
return buffer[position++];
}
public byte[] ReadBytes(int length)
{
CheckCanRead(length);
var value = new byte[length];
Buffer.BlockCopy(buffer, position, value, 0, length);
position += length;
return value;
}
public short ReadInt16()
{
CheckCanRead(2);
short value = (short)(buffer[position]
| (buffer[position + 1] << 8));
position += 2;
return value;
}
public int ReadInt32()
{
CheckCanRead(4);
int value = buffer[position]
| (buffer[position + 1] << 8)
| (buffer[position + 2] << 16)
| (buffer[position + 3] << 24);
position += 4;
return value;
}
public long ReadInt64()
{
CheckCanRead(8);
uint low = (uint)(buffer[position]
| (buffer[position + 1] << 8)
| (buffer[position + 2] << 16)
| (buffer[position + 3] << 24));
uint high = (uint)(buffer[position + 4]
| (buffer[position + 5] << 8)
| (buffer[position + 6] << 16)
| (buffer[position + 7] << 24));
long value = (((long)high) << 32) | low;
position += 8;
return value;
}
public float ReadSingle()
{
if (!BitConverter.IsLittleEndian)
{
var bytes = ReadBytes(4);
Array.Reverse(bytes);
return BitConverter.ToSingle(bytes, 0);
}
CheckCanRead(4);
float value = BitConverter.ToSingle(buffer, position);
position += 4;
return value;
}
public double ReadDouble()
{
if (!BitConverter.IsLittleEndian)
{
var bytes = ReadBytes(8);
Array.Reverse(bytes);
return BitConverter.ToDouble(bytes, 0);
}
CheckCanRead(8);
double value = BitConverter.ToDouble(buffer, position);
position += 8;
return value;
}
void CheckCanRead(int count)
{
if (position + count > buffer.Length)
throw new ArgumentOutOfRangeException();
}
}
MethodBase method;
MethodBody body;
Module module;
Type[] type_arguments;
Type[] method_arguments;
ByteBuffer il;
ParameterInfo[] parameters;
IList<LocalVariableInfo> locals;
List<Instruction> instructions = new List<Instruction>();
MethodBodyReader(MethodBase method)
{
this.method = method;
this.body = method.GetMethodBody();
if (this.body == null)
return;
var bytes = body.GetILAsByteArray();
if (bytes == null)
throw new ArgumentException();
if (!(method is ConstructorInfo))
method_arguments = method.GetGenericArguments();
if (method.DeclaringType != null)
type_arguments = method.DeclaringType.GetGenericArguments();
this.parameters = method.GetParameters();
this.locals = body.LocalVariables;
this.module = method.Module;
this.il = new ByteBuffer(bytes);
}
void ReadInstructions()
{
Instruction previous = null;
if (il?.buffer == null)
{
return;
}
while (il.position < il.buffer.Length)
{
var instruction = new Instruction(il.position, ReadOpCode());
ReadOperand(instruction);
if (previous != null)
{
instruction.Previous = previous;
previous.Next = instruction;
}
instructions.Add(instruction);
previous = instruction;
}
}
void ReadOperand(Instruction instruction)
{
switch (instruction.OpCode.OperandType)
{
case OperandType.InlineNone:
break;
case OperandType.InlineSwitch:
int length = il.ReadInt32();
int[] branches = new int[length];
int[] offsets = new int[length];
for (int i = 0; i < length; i++)
offsets[i] = il.ReadInt32();
for (int i = 0; i < length; i++)
branches[i] = il.position + offsets[i];
instruction.Operand = branches;
break;
case OperandType.ShortInlineBrTarget:
instruction.Operand = (sbyte)(il.ReadByte() + il.position);
break;
case OperandType.InlineBrTarget:
instruction.Operand = il.ReadInt32() + il.position;
break;
case OperandType.ShortInlineI:
if (instruction.OpCode == OpCodes.Ldc_I4_S)
instruction.Operand = (sbyte)il.ReadByte();
else
instruction.Operand = il.ReadByte();
break;
case OperandType.InlineI:
instruction.Operand = il.ReadInt32();
break;
case OperandType.ShortInlineR:
instruction.Operand = il.ReadSingle();
break;
case OperandType.InlineR:
instruction.Operand = il.ReadDouble();
break;
case OperandType.InlineI8:
instruction.Operand = il.ReadInt64();
break;
case OperandType.InlineSig:
instruction.Operand = module.ResolveSignature(il.ReadInt32());
break;
case OperandType.InlineString:
instruction.Operand = module.ResolveString(il.ReadInt32());
break;
case OperandType.InlineTok:
instruction.Operand = module.ResolveMember(il.ReadInt32(), type_arguments, method_arguments);
break;
case OperandType.InlineType:
instruction.Operand = module.ResolveType(il.ReadInt32(), type_arguments, method_arguments);
break;
case OperandType.InlineMethod:
instruction.Operand = module.ResolveMethod(il.ReadInt32(), type_arguments, method_arguments);
break;
case OperandType.InlineField:
instruction.Operand = module.ResolveField(il.ReadInt32(), type_arguments, method_arguments);
break;
case OperandType.ShortInlineVar:
instruction.Operand = GetVariable(instruction, il.ReadByte());
break;
case OperandType.InlineVar:
instruction.Operand = GetVariable(instruction, il.ReadInt16());
break;
default:
throw new NotSupportedException();
}
}
object GetVariable(Instruction instruction, int index)
{
if (TargetsLocalVariable(instruction.OpCode))
return GetLocalVariable(index);
else
return GetParameter(index);
}
static bool TargetsLocalVariable(OpCode opcode)
{
return opcode.Name.Contains("loc");
}
LocalVariableInfo GetLocalVariable(int index)
{
return locals[index];
}
ParameterInfo GetParameter(int index)
{
if (!method.IsStatic)
index--;
return parameters[index];
}
OpCode ReadOpCode()
{
byte op = il.ReadByte();
return op != 0xfe
? one_byte_opcodes[op]
: two_bytes_opcodes[il.ReadByte()];
}
public static List<Instruction> GetInstructions(MethodBase method)
{
var reader = new MethodBodyReader(method);
reader.ReadInstructions();
return reader.instructions;
}
}
public static class MethodBaseRocks
{
public static IList<Instruction> GetInstructions(this MethodBase self)
{
return MethodBodyReader.GetInstructions(self).AsReadOnly();
}
}
}
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