Move Courgette...

courgette/assembly_program.h

+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COURGETTE_ASSEMBLY_PROGRAM_H_
+#define COURGETTE_ASSEMBLY_PROGRAM_H_
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/basictypes.h"
+
+#include "courgette/image_info.h"
+
+namespace courgette {
+
+class EncodedProgram;
+class Instruction;
+
+// A Label is a symbolic reference to an address.  Unlike a conventional
+// assembly language, we always know the address.  The address will later be
+// stored in a table and the Label will be replaced with the index into the
+// table.
+//
+// TODO(sra): Make fields private and add setters and getters.
+class Label {
+ public:
+  static const int kNoIndex = -1;
+  Label() : rva_(0), index_(kNoIndex) {}
+  explicit Label(RVA rva) : rva_(rva), index_(kNoIndex) {}
+
+  RVA rva_;    // Address refered to by the label.
+  int index_;  // Index of address in address table, kNoIndex until assigned.
+};
+
+typedef std::map<RVA, Label*> RVAToLabel;
+
+// An AssemblyProgram is the result of disassembling an executable file.
+//
+// * The disassembler creates labels in the AssemblyProgram and emits
+//   'Instructions'.
+// * The disassembler then calls DefaultAssignIndexes to assign
+//   addresses to positions in the address tables.
+// * [Optional step]
+// * At this point the AssemblyProgram can be converted into an
+//   EncodedProgram and serialized to an output stream.
+// * Later, the EncodedProgram can be deserialized and assembled into
+//   the original file.
+//
+// The optional step is to modify the AssemblyProgram.  One form of modification
+// is to assign indexes in such a way as to make the EncodedProgram for this
+// AssemblyProgram look more like the EncodedProgram for some other
+// AssemblyProgram.  The modification process should call UnassignIndexes, do
+// its own assignment, and then call AssignRemainingIndexes to ensure all
+// indexes are assigned.
+//
+class AssemblyProgram {
+ public:
+  AssemblyProgram();
+  ~AssemblyProgram();
+
+  void set_image_base(uint64 image_base) { image_base_ = image_base; }
+
+  // Instructions will be assembled in the order they are emitted.
+
+  // Generates an entire base relocation table.
+  void EmitMakeRelocsInstruction();
+
+  // Following instruction will be assembled at address 'rva'.
+  void EmitOriginInstruction(RVA rva);
+
+  // Generates a single byte of data or machine instruction.
+  void EmitByteInstruction(uint8 byte);
+
+  // Generates 4-byte relative reference to address of 'label'.
+  void EmitRel32(Label* label);
+
+  // Generates 4-byte absolute reference to address of 'label'.
+  void EmitAbs32(Label* label);
+
+  Label* FindOrMakeAbs32Label(RVA rva);
+  Label* FindOrMakeRel32Label(RVA rva);
+
+  void DefaultAssignIndexes();
+  void UnassignIndexes();
+  void AssignRemainingIndexes();
+
+  EncodedProgram* Encode() const;
+
+  // Accessor for instruction list.
+  const std::vector<Instruction*>& instructions() const {
+    return instructions_;
+  }
+
+  // Returns the label if the instruction contains and absolute address,
+  // otherwise returns NULL.
+  Label* InstructionAbs32Label(const Instruction* instruction) const;
+
+  // Returns the label if the instruction contains and rel32 offset,
+  // otherwise returns NULL.
+  Label* InstructionRel32Label(const Instruction* instruction) const;
+
+
+ private:
+  void Emit(Instruction* instruction) { instructions_.push_back(instruction); }
+
+  Label* FindLabel(RVA rva, RVAToLabel* labels);
+
+  // Helper methods for the public versions.
+  static void UnassignIndexes(RVAToLabel* labels);
+  static void DefaultAssignIndexes(RVAToLabel* labels);
+  static void AssignRemainingIndexes(RVAToLabel* labels);
+
+  // Sharing instructions that emit a single byte saves a lot of space.
+  Instruction* GetByteInstruction(uint8 byte);
+  Instruction** byte_instruction_cache_;
+
+  uint64 image_base_;  // Desired or mandated base address of image.
+
+  std::vector<Instruction*> instructions_;  // All the instructions in program.
+
+  // These are lookup maps to find the label associated with a given address.
+  // We have separate label spaces for addresses referenced by rel32 labels and
+  // abs32 labels.  This is somewhat arbitrary.
+  RVAToLabel rel32_labels_;
+  RVAToLabel abs32_labels_;
+
+  DISALLOW_COPY_AND_ASSIGN(AssemblyProgram);
+};
+
+}  // namespace courgette
+#endif  // COURGETTE_ASSEMBLY_PROGRAM_H_