courgette/ensemble.cc

   1 // Copyright (c) 2010 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 #include "courgette/ensemble.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/string_number_conversions.h"
   9
  10 #include "courgette/image_info.h"
  11 #include "courgette/region.h"
  12 #include "courgette/streams.h"
  13 #include "courgette/simple_delta.h"
  14
  15 namespace courgette {
  16
  17 Element::Element(Kind kind, Ensemble* ensemble, const Region& region)
  18     : kind_(kind), ensemble_(ensemble), region_(region) {
  19 }
  20
  21 std::string Element::Name() const {
  22   return ensemble_->name() + "("
  23       + base::IntToString(kind()) + ","
  24       + base::Uint64ToString(offset_in_ensemble()) + ","
  25       + base::Uint64ToString(region().length()) + ")";
  26 }
  27
  28 // A subclass of Element that has a PEInfo.
  29 class ElementWinPE : public Element {
  30  public:
  31   ElementWinPE(Kind kind, Ensemble* ensemble, const Region& region,
  32                PEInfo* info)
  33       : Element(kind, ensemble, region),
  34         pe_info_(info) {
  35   }
  36
  37   virtual PEInfo* GetPEInfo() const { return pe_info_; }
  38
  39  protected:
  40   ~ElementWinPE() { delete pe_info_; }
  41
  42  private:
  43   PEInfo* pe_info_;  // Owned by |this|.
  44 };
  45
  46 // Scans the Ensemble's region, sniffing out Elements.  We assume that the
  47 // elements do not overlap.
  48 Status Ensemble::FindEmbeddedElements() {
  49   size_t length = region_.length();
  50   const uint8* start = region_.start();
  51
  52   size_t position = 0;
  53   while (position < length) {
  54     // Quick test; Windows executables begin with 'MZ'.
  55     if (start[position] == 'M' &&
  56         position + 1 < length && start[position + 1] == 'Z') {
  57       courgette::PEInfo *info = new courgette::PEInfo();
  58       info->Init(start + position, length - position);
  59       if (info->ParseHeader()) {
  60         Region region(start + position, info->length());
  61
  62         if (info->has_text_section()) {
  63           if (info->is_32bit()) {
  64             Element* element = new ElementWinPE(Element::WIN32_X86_WITH_CODE,
  65                                                 this, region, info);
  66             owned_elements_.push_back(element);
  67             elements_.push_back(element);
  68             position += region.length();
  69             continue;
  70           }
  71           // TODO(sra): Extend to 64-bit executables.
  72         }
  73
  74         // If we had a clever transformation for resource-only executables we
  75         // should identify the suitable elements here:
  76         if (!info->has_text_section() && false) {
  77           Element* element = new ElementWinPE(Element::WIN32_NOCODE,
  78                                               this, region, info);
  79           owned_elements_.push_back(element);
  80           elements_.push_back(element);
  81           position += region.length();
  82           continue;
  83         }
  84       }
  85       delete info;
  86     }
  87
  88     // This is where to add new formats, e.g. Linux executables, Dalvik
  89     // executables etc.
  90
  91     // No Element found at current position.
  92     ++position;
  93   }
  94   return C_OK;
  95 }
  96
  97 Ensemble::~Ensemble() {
  98   for (size_t i = 0;  i < owned_elements_.size();  ++i)
  99     delete owned_elements_[i];
 100 }
 101
 102 }  // namespace