text: // Copyright (c) 2011 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_DISASSEMBLER_H_
  #define COURGETTE_DISASSEMBLER_H_
  
  #include "base/basictypes.h"
  
  #include "courgette/courgette.h"
  
  // COURGETTE_HISTOGRAM_TARGETS prints out a histogram of how frequently
  // different target addresses are referenced.  Purely for debugging.
  #define COURGETTE_HISTOGRAM_TARGETS 0
  
  namespace courgette {
  
  class AssemblyProgram;
  
  // A Relative Virtual Address is the address in the image file after it is
  // loaded into memory relative to the image load address.
  typedef uint32 RVA;
  
  class Disassembler {
   public:
    virtual ~Disassembler();
  
    virtual ExecutableType kind() { return EXE_UNKNOWN; }
  
    // ok() may always be called but returns 'true' only after ParseHeader
    // succeeds.
    bool ok() const { return failure_reason_ == NULL; }
  
    // Returns 'true' if the buffer appears to be a valid executable of the
    // expected type. It is not required that this be called before Disassemble.
    virtual bool ParseHeader() = 0;
  
    // Disassembles the item passed to the factory method into the output
    // parameter 'program'.
    virtual bool Disassemble(AssemblyProgram* program) = 0;
  
    // Returns the length of the source executable. May reduce after ParseHeader.
    size_t length() const { return length_; }
    const uint8* start() const { return start_; }
    const uint8* end() const { return end_; }
  
    // Returns a pointer into the memory copy of the file format.
    // FileOffsetToPointer(0) returns a pointer to the start of the file format.
    const uint8* OffsetToPointer(size_t offset) const;
  
   protected:
    Disassembler(const void* start, size_t length);
  
    bool Good();
    bool Bad(const char *reason);
  
    // These helper functions avoid the need for casts in the main code.
    uint16 ReadU16(const uint8* address, size_t offset) {
      return *reinterpret_cast<const uint16*>(address + offset);
    }
  
    uint32 ReadU32(const uint8* address, size_t offset) {
      return *reinterpret_cast<const uint32*>(address + offset);
    }
  
    uint64 ReadU64(const uint8* address, size_t offset) {
      return *reinterpret_cast<const uint64*>(address + offset);
    }
  
    static uint32 Read32LittleEndian(const void* address) {
      return *reinterpret_cast<const uint32*>(address);
    }
  
    static uint16 Read16LittleEndian(const void* address) {
      return *reinterpret_cast<const uint16*>(address);
    }
  
    // Reduce the length of the image in memory. Does not actually free
    // (or realloc) any memory. Usually only called via ParseHeader()
    void ReduceLength(size_t reduced_length);
  
   private:
    const char* failure_reason_;
  
    //
    // Basic information that is always valid after Construction, though
    // ParseHeader may shorten the length if the executable is shorter than
    // the total data.
    //
    size_t length_;         // In current memory.
    const uint8* start_;    // In current memory, base for 'file offsets'.
    const uint8* end_;      // In current memory.
  
    DISALLOW_COPY_AND_ASSIGN(Disassembler);
  };
  
  }  // namespace courgette
  #endif  // COURGETTE_DISASSEMBLER_H_
  