courgette/disassembler.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COURGETTE_DISASSEMBLER_H_
   6 #define COURGETTE_DISASSEMBLER_H_
   7
   8 #include "base/basictypes.h"
   9
  10 #include "courgette/courgette.h"
  11 #include "courgette/image_utils.h"
  12
  13 namespace courgette {
  14
  15 class AssemblyProgram;
  16
  17 class Disassembler {
  18  public:
  19   virtual ~Disassembler();
  20
  21   virtual ExecutableType kind() { return EXE_UNKNOWN; }
  22
  23   // ok() may always be called but returns 'true' only after ParseHeader
  24   // succeeds.
  25   bool ok() const { return failure_reason_ == NULL; }
  26
  27   // Returns 'true' if the buffer appears to be a valid executable of the
  28   // expected type. It is not required that this be called before Disassemble.
  29   virtual bool ParseHeader() = 0;
  30
  31   // Disassembles the item passed to the factory method into the output
  32   // parameter 'program'.
  33   virtual bool Disassemble(AssemblyProgram* program) = 0;
  34
  35   // Returns the length of the source executable. May reduce after ParseHeader.
  36   size_t length() const { return length_; }
  37   const uint8* start() const { return start_; }
  38   const uint8* end() const { return end_; }
  39
  40   // Returns a pointer into the memory copy of the file format.
  41   // FileOffsetToPointer(0) returns a pointer to the start of the file format.
  42   const uint8* OffsetToPointer(size_t offset) const;
  43
  44  protected:
  45   Disassembler(const void* start, size_t length);
  46
  47   bool Good();
  48   bool Bad(const char *reason);
  49
  50   // Returns true if the array lies within our memory region.
  51   bool IsArrayInBounds(size_t offset, size_t elements, size_t element_size) {
  52     return offset <= length() && elements <= (length() - offset) / element_size;
  53   }
  54
  55   // Reduce the length of the image in memory. Does not actually free
  56   // (or realloc) any memory. Usually only called via ParseHeader()
  57   void ReduceLength(size_t reduced_length);
  58
  59  private:
  60   const char* failure_reason_;
  61
  62   //
  63   // Basic information that is always valid after Construction, though
  64   // ParseHeader may shorten the length if the executable is shorter than
  65   // the total data.
  66   //
  67   size_t length_;         // In current memory.
  68   const uint8* start_;    // In current memory, base for 'file offsets'.
  69   const uint8* end_;      // In current memory.
  70
  71   DISALLOW_COPY_AND_ASSIGN(Disassembler);
  72 };
  73
  74 }  // namespace courgette
  75
  76 #endif  // COURGETTE_DISASSEMBLER_H_