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