courgette/patcher_x86_32.h

   1 // Copyright 2012 The Chromium Authors
   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_PATCHER_X86_32_H_
   6 #define COURGETTE_PATCHER_X86_32_H_
   7
   8 #include <stdint.h>
   9
  10 #include "base/logging.h"
  11 #include "courgette/courgette_flow.h"
  12 #include "courgette/ensemble.h"
  13 #include "courgette/region.h"
  14 #include "courgette/streams.h"
  15
  16 namespace courgette {
  17
  18 // PatcherX86_32 is the universal patcher for all executables. The executable
  19 // type is determined by the program detector.
  20 class PatcherX86_32 : public TransformationPatcher {
  21  public:
  22   explicit PatcherX86_32(const Region& region)
  23       : ensemble_region_(region),
  24         base_offset_(0),
  25         base_length_(0) {
  26   }
  27
  28   PatcherX86_32(const PatcherX86_32&) = delete;
  29   PatcherX86_32& operator=(const PatcherX86_32&) = delete;
  30
  31   Status Init(SourceStream* parameter_stream) {
  32     if (!parameter_stream->ReadVarint32(&base_offset_))
  33       return C_BAD_TRANSFORM;
  34     if (!parameter_stream->ReadVarint32(&base_length_))
  35       return C_BAD_TRANSFORM;
  36
  37     if (base_offset_ > ensemble_region_.length())
  38       return C_BAD_TRANSFORM;
  39     if (base_length_ > ensemble_region_.length() - base_offset_)
  40       return C_BAD_TRANSFORM;
  41
  42     return C_OK;
  43   }
  44
  45   Status PredictTransformParameters(SinkStreamSet* predicted_parameters) {
  46     // No code needed to write an 'empty' predicted parameter set.
  47     return C_OK;
  48   }
  49
  50   Status Transform(SourceStreamSet* corrected_parameters,
  51                    SinkStreamSet* transformed_element) {
  52     if (!corrected_parameters->Empty())
  53       return C_GENERAL_ERROR;  // Don't expect any corrected parameters.
  54
  55     CourgetteFlow flow;
  56     RegionBuffer only_buffer(
  57         Region(ensemble_region_.start() + base_offset_, base_length_));
  58     flow.ReadDisassemblerFromBuffer(flow.ONLY, only_buffer);
  59     flow.CreateAssemblyProgramFromDisassembler(flow.ONLY, false);
  60     flow.CreateEncodedProgramFromDisassemblerAndAssemblyProgram(flow.ONLY);
  61     flow.DestroyAssemblyProgram(flow.ONLY);
  62     flow.DestroyDisassembler(flow.ONLY);
  63     flow.WriteSinkStreamSetFromEncodedProgram(flow.ONLY, transformed_element);
  64     if (flow.failed())
  65       LOG(ERROR) << flow.message();
  66     return flow.status();
  67   }
  68
  69   Status Reform(SourceStreamSet* transformed_element,
  70                 SinkStream* reformed_element) {
  71     CourgetteFlow flow;
  72     flow.ReadEncodedProgramFromSourceStreamSet(flow.ONLY, transformed_element);
  73     flow.WriteExecutableFromEncodedProgram(flow.ONLY, reformed_element);
  74     if (flow.failed())
  75       LOG(ERROR) << flow.message();
  76     return flow.status();
  77   }
  78
  79  private:
  80   Region ensemble_region_;
  81
  82   uint32_t base_offset_;
  83   uint32_t base_length_;
  84 };
  85
  86 }  // namespace courgette
  87
  88 #endif  // COURGETTE_PATCHER_X86_32_H_