courgette/patcher_x86_32.h

   1 // Copyright (c) 2012 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 // This is the transformation for Windows X86 executables.
   6 // The same patcher can be used for Windows X64 executables.
   7
   8 #ifndef COURGETTE_WIN32_X86_PATCHER_H_
   9 #define COURGETTE_WIN32_X86_PATCHER_H_
  10
  11 #include "courgette/ensemble.h"
  12
  13 namespace courgette {
  14
  15 // Courgette32X86Patcher is a TransformationPatcher for Windows 32-bit
  16 // and 64-bit executables.  We can use the same patcher for both.
  17 //
  18 class PatcherX86_32 : public TransformationPatcher {
  19  public:
  20   explicit PatcherX86_32(const Region& region)
  21       : ensemble_region_(region),
  22         base_offset_(0),
  23         base_length_(0) {
  24   }
  25
  26   Status Init(SourceStream* parameter_stream) {
  27     if (!parameter_stream->ReadVarint32(&base_offset_))
  28       return C_BAD_TRANSFORM;
  29     if (!parameter_stream->ReadVarint32(&base_length_))
  30       return C_BAD_TRANSFORM;
  31
  32     if (base_offset_ > ensemble_region_.length())
  33       return C_BAD_TRANSFORM;
  34     if (base_length_ > ensemble_region_.length() - base_offset_)
  35       return C_BAD_TRANSFORM;
  36
  37     return C_OK;
  38   }
  39
  40   Status PredictTransformParameters(SinkStreamSet* predicted_parameters) {
  41     // No code needed to write an 'empty' predicted parameter set.
  42     return C_OK;
  43   }
  44
  45   Status Transform(SourceStreamSet* corrected_parameters,
  46                    SinkStreamSet* transformed_element) {
  47     Status status;
  48     if (!corrected_parameters->Empty())
  49       return C_GENERAL_ERROR;   // Don't expect any corrected parameters.
  50
  51     AssemblyProgram* program = NULL;
  52     status = ParseDetectedExecutable(ensemble_region_.start() + base_offset_,
  53                                      base_length_,
  54                                      &program);
  55     if (status != C_OK)
  56       return status;
  57
  58     // Trim labels below a certain threshold
  59     Status trim_status = TrimLabels(program);
  60     if (trim_status != C_OK) {
  61       DeleteAssemblyProgram(program);
  62       return trim_status;
  63     }
  64
  65     EncodedProgram* encoded = NULL;
  66     status = Encode(program, &encoded);
  67     DeleteAssemblyProgram(program);
  68     if (status != C_OK)
  69       return status;
  70
  71     status = WriteEncodedProgram(encoded, transformed_element);
  72     DeleteEncodedProgram(encoded);
  73
  74     return status;
  75   }
  76
  77   Status Reform(SourceStreamSet* transformed_element,
  78                 SinkStream* reformed_element) {
  79     Status status;
  80     EncodedProgram* encoded_program = NULL;
  81     status = ReadEncodedProgram(transformed_element, &encoded_program);
  82     if (status != C_OK)
  83       return status;
  84
  85     status = Assemble(encoded_program, reformed_element);
  86     DeleteEncodedProgram(encoded_program);
  87     if (status != C_OK)
  88       return status;
  89
  90     return C_OK;
  91   }
  92
  93  private:
  94   Region ensemble_region_;
  95
  96   uint32 base_offset_;
  97   uint32 base_length_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(PatcherX86_32);
 100 };
 101
 102 }  // namespace
 103 #endif  // COURGETTE_WIN32_X86_PATCHER_H_