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//
// CodeReader.cs
//
// Author:
// Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2011 Jb Evain
//
// 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 Mono.Cecil.PE;
using Mono.Collections.Generic;
using RVA = System.UInt32;
namespace Mono.Cecil.Cil {
sealed class CodeReader : ByteBuffer {
readonly internal MetadataReader reader;
int start;
Section code_section;
MethodDefinition method;
MethodBody body;
int Offset {
get { return base.position - start; }
}
public CodeReader (Section section, MetadataReader reader)
: base (section.Data)
{
this.code_section = section;
this.reader = reader;
}
public MethodBody ReadMethodBody (MethodDefinition method)
{
this.method = method;
this.body = new MethodBody (method);
reader.context = method;
ReadMethodBody ();
return this.body;
}
public void MoveTo (int rva)
{
if (!IsInSection (rva)) {
code_section = reader.image.GetSectionAtVirtualAddress ((uint) rva);
Reset (code_section.Data);
}
base.position = rva - (int) code_section.VirtualAddress;
}
bool IsInSection (int rva)
{
return code_section.VirtualAddress <= rva && rva < code_section.VirtualAddress + code_section.SizeOfRawData;
}
void ReadMethodBody ()
{
MoveTo (method.RVA);
var flags = ReadByte ();
switch (flags & 0x3) {
case 0x2: // tiny
body.code_size = flags >> 2;
body.MaxStackSize = 8;
ReadCode ();
break;
case 0x3: // fat
base.position--;
ReadFatMethod ();
break;
default:
throw new InvalidOperationException ();
}
var symbol_reader = reader.module.SymbolReader;
if (symbol_reader != null) {
var instructions = body.Instructions;
symbol_reader.Read (body, offset => GetInstruction (instructions, offset));
}
}
void ReadFatMethod ()
{
var flags = ReadUInt16 ();
body.max_stack_size = ReadUInt16 ();
body.code_size = (int) ReadUInt32 ();
body.local_var_token = new MetadataToken (ReadUInt32 ());
body.init_locals = (flags & 0x10) != 0;
if (body.local_var_token.RID != 0)
body.variables = ReadVariables (body.local_var_token);
ReadCode ();
if ((flags & 0x8) != 0)
ReadSection ();
}
public VariableDefinitionCollection ReadVariables (MetadataToken local_var_token)
{
var position = reader.position;
var variables = reader.ReadVariables (local_var_token);
reader.position = position;
return variables;
}
void ReadCode ()
{
start = position;
var code_size = body.code_size;
if (code_size < 0 || buffer.Length <= (uint) (code_size + position))
code_size = 0;
var end = start + code_size;
var instructions = body.instructions = new InstructionCollection (code_size / 3);
while (position < end) {
var offset = base.position - start;
var opcode = ReadOpCode ();
var current = new Instruction (offset, opcode);
if (opcode.OperandType != OperandType.InlineNone)
current.operand = ReadOperand (current);
instructions.Add (current);
}
ResolveBranches (instructions);
}
OpCode ReadOpCode ()
{
var il_opcode = ReadByte ();
return il_opcode != 0xfe
? OpCodes.OneByteOpCode [il_opcode]
: OpCodes.TwoBytesOpCode [ReadByte ()];
}
object ReadOperand (Instruction instruction)
{
switch (instruction.opcode.OperandType) {
case OperandType.InlineSwitch:
var length = ReadInt32 ();
var base_offset = Offset + (4 * length);
var branches = new int [length];
for (int i = 0; i < length; i++)
branches [i] = base_offset + ReadInt32 ();
return branches;
case OperandType.ShortInlineBrTarget:
return ReadSByte () + Offset;
case OperandType.InlineBrTarget:
return ReadInt32 () + Offset;
case OperandType.ShortInlineI:
if (instruction.opcode == OpCodes.Ldc_I4_S)
return ReadSByte ();
return ReadByte ();
case OperandType.InlineI:
return ReadInt32 ();
case OperandType.ShortInlineR:
return ReadSingle ();
case OperandType.InlineR:
return ReadDouble ();
case OperandType.InlineI8:
return ReadInt64 ();
case OperandType.ShortInlineVar:
return GetVariable (ReadByte ());
case OperandType.InlineVar:
return GetVariable (ReadUInt16 ());
case OperandType.ShortInlineArg:
return GetParameter (ReadByte ());
case OperandType.InlineArg:
return GetParameter (ReadUInt16 ());
case OperandType.InlineSig:
return GetCallSite (ReadToken ());
case OperandType.InlineString:
return GetString (ReadToken ());
case OperandType.InlineTok:
case OperandType.InlineType:
case OperandType.InlineMethod:
case OperandType.InlineField:
return reader.LookupToken (ReadToken ());
default:
throw new NotSupportedException ();
}
}
public string GetString (MetadataToken token)
{
return reader.image.UserStringHeap.Read (token.RID);
}
public ParameterDefinition GetParameter (int index)
{
return body.GetParameter (index);
}
public VariableDefinition GetVariable (int index)
{
return body.GetVariable (index);
}
public CallSite GetCallSite (MetadataToken token)
{
return reader.ReadCallSite (token);
}
void ResolveBranches (Collection<Instruction> instructions)
{
var items = instructions.items;
var size = instructions.size;
for (int i = 0; i < size; i++) {
var instruction = items [i];
switch (instruction.opcode.OperandType) {
case OperandType.ShortInlineBrTarget:
case OperandType.InlineBrTarget:
instruction.operand = GetInstruction ((int) instruction.operand);
break;
case OperandType.InlineSwitch:
var offsets = (int []) instruction.operand;
var branches = new Instruction [offsets.Length];
for (int j = 0; j < offsets.Length; j++)
branches [j] = GetInstruction (offsets [j]);
instruction.operand = branches;
break;
}
}
}
Instruction GetInstruction (int offset)
{
return GetInstruction (body.Instructions, offset);
}
static Instruction GetInstruction (Collection<Instruction> instructions, int offset)
{
var size = instructions.size;
var items = instructions.items;
if (offset < 0 || offset > items [size - 1].offset)
return null;
int min = 0;
int max = size - 1;
while (min <= max) {
int mid = min + ((max - min) / 2);
var instruction = items [mid];
var instruction_offset = instruction.offset;
if (offset == instruction_offset)
return instruction;
if (offset < instruction_offset)
max = mid - 1;
else
min = mid + 1;
}
return null;
}
void ReadSection ()
{
Align (4);
const byte fat_format = 0x40;
const byte more_sects = 0x80;
var flags = ReadByte ();
if ((flags & fat_format) == 0)
ReadSmallSection ();
else
ReadFatSection ();
if ((flags & more_sects) != 0)
ReadSection ();
}
void ReadSmallSection ()
{
var count = ReadByte () / 12;
Advance (2);
ReadExceptionHandlers (
count,
() => (int) ReadUInt16 (),
() => (int) ReadByte ());
}
void ReadFatSection ()
{
position--;
var count = (ReadInt32 () >> 8) / 24;
ReadExceptionHandlers (
count,
ReadInt32,
ReadInt32);
}
// inline ?
void ReadExceptionHandlers (int count, Func<int> read_entry, Func<int> read_length)
{
for (int i = 0; i < count; i++) {
var handler = new ExceptionHandler (
(ExceptionHandlerType) (read_entry () & 0x7));
handler.TryStart = GetInstruction (read_entry ());
handler.TryEnd = GetInstruction (handler.TryStart.Offset + read_length ());
handler.HandlerStart = GetInstruction (read_entry ());
handler.HandlerEnd = GetInstruction (handler.HandlerStart.Offset + read_length ());
ReadExceptionHandlerSpecific (handler);
this.body.ExceptionHandlers.Add (handler);
}
}
void ReadExceptionHandlerSpecific (ExceptionHandler handler)
{
switch (handler.HandlerType) {
case ExceptionHandlerType.Catch:
handler.CatchType = (TypeReference) reader.LookupToken (ReadToken ());
break;
case ExceptionHandlerType.Filter:
handler.FilterStart = GetInstruction (ReadInt32 ());
break;
default:
Advance (4);
break;
}
}
void Align (int align)
{
align--;
Advance (((position + align) & ~align) - position);
}
public MetadataToken ReadToken ()
{
return new MetadataToken (ReadUInt32 ());
}
#if !READ_ONLY
public ByteBuffer PatchRawMethodBody (MethodDefinition method, CodeWriter writer, out MethodSymbols symbols)
{
var buffer = new ByteBuffer ();
symbols = new MethodSymbols (method.Name);
this.method = method;
reader.context = method;
MoveTo (method.RVA);
var flags = ReadByte ();
MetadataToken local_var_token;
switch (flags & 0x3) {
case 0x2: // tiny
buffer.WriteByte (flags);
local_var_token = MetadataToken.Zero;
symbols.code_size = flags >> 2;
PatchRawCode (buffer, symbols.code_size, writer);
break;
case 0x3: // fat
base.position--;
PatchRawFatMethod (buffer, symbols, writer, out local_var_token);
break;
default:
throw new NotSupportedException ();
}
var symbol_reader = reader.module.SymbolReader;
if (symbol_reader != null && writer.metadata.write_symbols) {
symbols.method_token = GetOriginalToken (writer.metadata, method);
symbols.local_var_token = local_var_token;
symbol_reader.Read (symbols);
}
return buffer;
}
void PatchRawFatMethod (ByteBuffer buffer, MethodSymbols symbols, CodeWriter writer, out MetadataToken local_var_token)
{
var flags = ReadUInt16 ();
buffer.WriteUInt16 (flags);
buffer.WriteUInt16 (ReadUInt16 ());
symbols.code_size = ReadInt32 ();
buffer.WriteInt32 (symbols.code_size);
local_var_token = ReadToken ();
if (local_var_token.RID > 0) {
var variables = symbols.variables = ReadVariables (local_var_token);
buffer.WriteUInt32 (variables != null
? writer.GetStandAloneSignature (symbols.variables).ToUInt32 ()
: 0);
} else
buffer.WriteUInt32 (0);
PatchRawCode (buffer, symbols.code_size, writer);
if ((flags & 0x8) != 0)
PatchRawSection (buffer, writer.metadata);
}
static MetadataToken GetOriginalToken (MetadataBuilder metadata, MethodDefinition method)
{
MetadataToken original;
if (metadata.TryGetOriginalMethodToken (method.token, out original))
return original;
return MetadataToken.Zero;
}
void PatchRawCode (ByteBuffer buffer, int code_size, CodeWriter writer)
{
var metadata = writer.metadata;
buffer.WriteBytes (ReadBytes (code_size));
var end = buffer.position;
buffer.position -= code_size;
while (buffer.position < end) {
OpCode opcode;
var il_opcode = buffer.ReadByte ();
if (il_opcode != 0xfe) {
opcode = OpCodes.OneByteOpCode [il_opcode];
} else {
var il_opcode2 = buffer.ReadByte ();
opcode = OpCodes.TwoBytesOpCode [il_opcode2];
}
switch (opcode.OperandType) {
case OperandType.ShortInlineI:
case OperandType.ShortInlineBrTarget:
case OperandType.ShortInlineVar:
case OperandType.ShortInlineArg:
buffer.position += 1;
break;
case OperandType.InlineVar:
case OperandType.InlineArg:
buffer.position += 2;
break;
case OperandType.InlineBrTarget:
case OperandType.ShortInlineR:
case OperandType.InlineI:
buffer.position += 4;
break;
case OperandType.InlineI8:
case OperandType.InlineR:
buffer.position += 8;
break;
case OperandType.InlineSwitch:
var length = buffer.ReadInt32 ();
buffer.position += length * 4;
break;
case OperandType.InlineString:
var @string = GetString (new MetadataToken (buffer.ReadUInt32 ()));
buffer.position -= 4;
buffer.WriteUInt32 (
new MetadataToken (
TokenType.String,
metadata.user_string_heap.GetStringIndex (@string)).ToUInt32 ());
break;
case OperandType.InlineSig:
var call_site = GetCallSite (new MetadataToken (buffer.ReadUInt32 ()));
buffer.position -= 4;
buffer.WriteUInt32 (writer.GetStandAloneSignature (call_site).ToUInt32 ());
break;
case OperandType.InlineTok:
case OperandType.InlineType:
case OperandType.InlineMethod:
case OperandType.InlineField:
var provider = reader.LookupToken (new MetadataToken (buffer.ReadUInt32 ()));
buffer.position -= 4;
buffer.WriteUInt32 (metadata.LookupToken (provider).ToUInt32 ());
break;
}
}
}
void PatchRawSection (ByteBuffer buffer, MetadataBuilder metadata)
{
var position = base.position;
Align (4);
buffer.WriteBytes (base.position - position);
const byte fat_format = 0x40;
const byte more_sects = 0x80;
var flags = ReadByte ();
if ((flags & fat_format) == 0) {
buffer.WriteByte (flags);
PatchRawSmallSection (buffer, metadata);
} else
PatchRawFatSection (buffer, metadata);
if ((flags & more_sects) != 0)
PatchRawSection (buffer, metadata);
}
void PatchRawSmallSection (ByteBuffer buffer, MetadataBuilder metadata)
{
var length = ReadByte ();
buffer.WriteByte (length);
Advance (2);
buffer.WriteUInt16 (0);
var count = length / 12;
PatchRawExceptionHandlers (buffer, metadata, count, false);
}
void PatchRawFatSection (ByteBuffer buffer, MetadataBuilder metadata)
{
position--;
var length = ReadInt32 ();
buffer.WriteInt32 (length);
var count = (length >> 8) / 24;
PatchRawExceptionHandlers (buffer, metadata, count, true);
}
void PatchRawExceptionHandlers (ByteBuffer buffer, MetadataBuilder metadata, int count, bool fat_entry)
{
const int fat_entry_size = 16;
const int small_entry_size = 6;
for (int i = 0; i < count; i++) {
ExceptionHandlerType handler_type;
if (fat_entry) {
var type = ReadUInt32 ();
handler_type = (ExceptionHandlerType) (type & 0x7);
buffer.WriteUInt32 (type);
} else {
var type = ReadUInt16 ();
handler_type = (ExceptionHandlerType) (type & 0x7);
buffer.WriteUInt16 (type);
}
buffer.WriteBytes (ReadBytes (fat_entry ? fat_entry_size : small_entry_size));
switch (handler_type) {
case ExceptionHandlerType.Catch:
var exception = reader.LookupToken (ReadToken ());
buffer.WriteUInt32 (metadata.LookupToken (exception).ToUInt32 ());
break;
default:
buffer.WriteUInt32 (ReadUInt32 ());
break;
}
}
}
#endif
}
}
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