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