text: // Copyright 2015 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CHROME_COMMON_SAFE_BROWSING_MACH_O_IMAGE_READER_MAC_H_
  #define CHROME_COMMON_SAFE_BROWSING_MACH_O_IMAGE_READER_MAC_H_
  
  #include <mach-o/loader.h>
  #include <stddef.h>
  #include <stdint.h>
  
  #include <memory>
  #include <vector>
  
  #include "base/macros.h"
  
  namespace safe_browsing {
  
  class ByteSlice;
  
  // MachOImageReader is used to extract information about a Mach-O binary image.
  // This class supports fat and thin images. Initialize() must be called before
  // any other methods; if it returns false, it is illegal to call any other
  // methods on this class.
  class MachOImageReader {
   public:
    // Represents a Mach-O load command, including all of its data.
    struct LoadCommand {
      LoadCommand();
      LoadCommand(const LoadCommand& other);
      ~LoadCommand();
  
      uint32_t cmd() const {
        return as_command<load_command>()->cmd;
      }
  
      uint32_t cmdsize() const {
        return as_command<load_command>()->cmdsize;
      }
  
      template <typename T>
      const T* as_command() const {
        if (data.size() < sizeof(T))
          return nullptr;
        return reinterpret_cast<const T*>(&data[0]);
      }
  
      std::vector<uint8_t> data;
    };
  
    // Returns true if |magic| is any Mach-O magic number. This can be used on the
    // first four bytes of a file (either in little- or big-endian) to quickly
    // determine whether or not the file is potentially a Mach-O file. An instance
    // of this class must be used for a true validity check.
    static bool IsMachOMagicValue(uint32_t magic);
  
    MachOImageReader();
    ~MachOImageReader();
  
    // Initializes the instance and verifies that the data is a valid Mach-O
    // image. This does not take ownership of the bytes, so the data must
    // remain valid for the lifetime of this object. Returns true if the
    // instance is initialized and valid, false if the file could not be parsed
    // as a Mach-O image.
    bool Initialize(const uint8_t* image, size_t image_size);
  
    // Returns whether this is a fat Mach-O image. If this returns true, it is
    // only valid to call GetFatImages() and none of the other methods.
    bool IsFat();
  
    // It is only valid to call this method if IsFat() returns true. This
    // returns an image reader for each architecture in the fat file.
    std::vector<MachOImageReader*> GetFatImages();
  
    // Returns whether the image is a 64-bit image.
    bool Is64Bit();
  
    // Retrieves the mach_header structure for the appropriate architecture.
    const mach_header* GetMachHeader();
    const mach_header_64* GetMachHeader64();
  
    // Returns the Mach-O filetype field from the header.
    uint32_t GetFileType();
  
    // Returns an array of all the load commands in the image.
    const std::vector<MachOImageReader::LoadCommand>& GetLoadCommands();
  
    // If the image has a LC_CODE_SIGNATURE command, this retreives the code
    // signature blob in the __LINKEDIT segment.
    bool GetCodeSignatureInfo(std::vector<uint8_t>* info);
  
   private:
    std::unique_ptr<ByteSlice> data_;
  
    bool is_fat_;
    std::vector<std::unique_ptr<MachOImageReader>> fat_images_;
  
    bool is_64_bit_;
    std::vector<LoadCommand> commands_;
  
    DISALLOW_COPY_AND_ASSIGN(MachOImageReader);
  };
  
  }  // namespace safe_browsing
  
  #endif  // CHROME_COMMON_SAFE_BROWSING_MACH_O_IMAGE_READER_MAC_H_
  