runtime/vdex_file.h - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef ART_RUNTIME_VDEX_FILE_H_
 #define ART_RUNTIME_VDEX_FILE_H_

 #include <stdint.h>
 #include <string>

 #include "base/array_ref.h"
 #include "base/macros.h"
 #include "base/mem_map.h"
 #include "base/os.h"
 #include "dex/compact_offset_table.h"
 #include "dex/dex_file.h"
 #include "quicken_info.h"

 namespace art {

 class ClassLoaderContext;

 namespace verifier {
 class VerifierDeps;
 }  // namespace verifier

 // VDEX files contain extracted DEX files. The VdexFile class maps the file to
 // memory and provides tools for accessing its individual sections.
 //
 // File format:
 //   VdexFile::VerifierDepsHeader    fixed-length header
 //      Dex file checksums
 //
 //   Optionally:
 //      VdexFile::DexSectionHeader   fixed-length header
 //
 //      quicken_table_off[0]  offset into QuickeningInfo section for offset table for DEX[0].
 //      DEX[0]                array of the input DEX files, the bytecode may have been quickened.
 //      quicken_table_off[1]
 //      DEX[1]
 //      ...
 //      DEX[D]
 //
 //   VerifierDeps
 //      uint8[D][]                 verification dependencies
 //
 //   Optionally:
 //      QuickeningInfo
 //        uint8[D][]                  quickening data
 //        uint32[D][]                 quickening data offset tables

 class VdexFile {
  public:
   using VdexChecksum = uint32_t;
   using QuickeningTableOffsetType = uint32_t;

   struct VerifierDepsHeader {
    public:
     VerifierDepsHeader(uint32_t number_of_dex_files_,
                        uint32_t verifier_deps_size,
                        bool has_dex_section,
                        uint32_t bootclasspath_checksums_size = 0,
                        uint32_t class_loader_context_size = 0);

     const char* GetMagic() const { return reinterpret_cast<const char*>(magic_); }
     const char* GetVerifierDepsVersion() const {
       return reinterpret_cast<const char*>(verifier_deps_version_);
     }
     const char* GetDexSectionVersion() const {
       return reinterpret_cast<const char*>(dex_section_version_);
     }
     bool IsMagicValid() const;
     bool IsVerifierDepsVersionValid() const;
     bool IsDexSectionVersionValid() const;
     bool IsValid() const {
       return IsMagicValid() && IsVerifierDepsVersionValid() && IsDexSectionVersionValid();
     }
     bool HasDexSection() const;

     uint32_t GetVerifierDepsSize() const { return verifier_deps_size_; }
     uint32_t GetNumberOfDexFiles() const { return number_of_dex_files_; }
     uint32_t GetBootClassPathChecksumStringSize() const { return bootclasspath_checksums_size_; }
     uint32_t GetClassLoaderContextStringSize() const { return class_loader_context_size_; }

     size_t GetSizeOfChecksumsSection() const {
       return sizeof(VdexChecksum) * GetNumberOfDexFiles();
     }

     const VdexChecksum* GetDexChecksumsArray() const {
       return reinterpret_cast<const VdexChecksum*>(
           reinterpret_cast<const uint8_t*>(this) + sizeof(VerifierDepsHeader));
     }

     VdexChecksum GetDexChecksumAtOffset(size_t idx) const {
       DCHECK_LT(idx, GetNumberOfDexFiles());
       return GetDexChecksumsArray()[idx];
     }

     static constexpr uint8_t kVdexInvalidMagic[] = { 'w', 'd', 'e', 'x' };

    private:
     static constexpr uint8_t kVdexMagic[] = { 'v', 'd', 'e', 'x' };

     // The format version of the verifier deps header and the verifier deps.
     // Last update: Add boot checksum, class loader context.
     static constexpr uint8_t kVerifierDepsVersion[] = { '0', '2', '1', '\0' };

     // The format version of the dex section header and the dex section, containing
     // both the dex code and the quickening data.
     // Last update: Add owned section for CompactDex.
     static constexpr uint8_t kDexSectionVersion[] = { '0', '0', '2', '\0' };

     // If the .vdex file has no dex section (hence no dex code nor quickening data),
     // we encode this magic version.
     static constexpr uint8_t kDexSectionVersionEmpty[] = { '0', '0', '0', '\0' };

     uint8_t magic_[4];
     uint8_t verifier_deps_version_[4];
     uint8_t dex_section_version_[4];
     uint32_t number_of_dex_files_;
     uint32_t verifier_deps_size_;
     uint32_t bootclasspath_checksums_size_;
     uint32_t class_loader_context_size_;
   };

   struct DexSectionHeader {
    public:
     DexSectionHeader(uint32_t dex_size,
                      uint32_t dex_shared_data_size,
                      uint32_t quickening_info_size);

     uint32_t GetDexSize() const { return dex_size_; }
     uint32_t GetDexSharedDataSize() const { return dex_shared_data_size_; }
     uint32_t GetQuickeningInfoSize() const { return quickening_info_size_; }

     size_t GetDexSectionSize() const {
       return sizeof(DexSectionHeader) +
            GetDexSize() +
            GetDexSharedDataSize();
     }

    private:
     uint32_t dex_size_;
     uint32_t dex_shared_data_size_;
     uint32_t quickening_info_size_;

     friend class VdexFile;  // For updating quickening_info_size_.
   };

   size_t GetComputedFileSize() const {
     size_t size = sizeof(VerifierDepsHeader);
     const VerifierDepsHeader& header = GetVerifierDepsHeader();
     size += header.GetVerifierDepsSize();
     size += header.GetSizeOfChecksumsSection();
     if (header.HasDexSection()) {
       size += GetDexSectionHeader().GetDexSectionSize();
       size += GetDexSectionHeader().GetQuickeningInfoSize();
     }
     size += header.GetBootClassPathChecksumStringSize();
     size += header.GetClassLoaderContextStringSize();
     return size;
   }

   // Note: The file is called "primary" to match the naming with profiles.
   static const constexpr char* kVdexNameInDmFile = "primary.vdex";

   explicit VdexFile(MemMap&& mmap) : mmap_(std::move(mmap)) {}

   // Returns nullptr if the vdex file cannot be opened or is not valid.
   // The mmap_* parameters can be left empty (nullptr/0/false) to allocate at random address.
   static std::unique_ptr<VdexFile> OpenAtAddress(uint8_t* mmap_addr,
                                                  size_t mmap_size,
                                                  bool mmap_reuse,
                                                  const std::string& vdex_filename,
                                                  bool writable,
                                                  bool low_4gb,
                                                  bool unquicken,
                                                  std::string* error_msg);

   // Returns nullptr if the vdex file cannot be opened or is not valid.
   // The mmap_* parameters can be left empty (nullptr/0/false) to allocate at random address.
   static std::unique_ptr<VdexFile> OpenAtAddress(uint8_t* mmap_addr,
                                                  size_t mmap_size,
                                                  bool mmap_reuse,
                                                  int file_fd,
                                                  size_t vdex_length,
                                                  const std::string& vdex_filename,
                                                  bool writable,
                                                  bool low_4gb,
                                                  bool unquicken,
                                                  std::string* error_msg);

   // Returns nullptr if the vdex file cannot be opened or is not valid.
   static std::unique_ptr<VdexFile> Open(const std::string& vdex_filename,
                                         bool writable,
                                         bool low_4gb,
                                         bool unquicken,
                                         std::string* error_msg) {
     return OpenAtAddress(nullptr,
                          0,
                          false,
                          vdex_filename,
                          writable,
                          low_4gb,
                          unquicken,
                          error_msg);
   }

   // Returns nullptr if the vdex file cannot be opened or is not valid.
   static std::unique_ptr<VdexFile> Open(int file_fd,
                                         size_t vdex_length,
                                         const std::string& vdex_filename,
                                         bool writable,
                                         bool low_4gb,
                                         bool unquicken,
                                         std::string* error_msg) {
     return OpenAtAddress(nullptr,
                          0,
                          false,
                          file_fd,
                          vdex_length,
                          vdex_filename,
                          writable,
                          low_4gb,
                          unquicken,
                          error_msg);
   }

   const uint8_t* Begin() const { return mmap_.Begin(); }
   const uint8_t* End() const { return mmap_.End(); }
   size_t Size() const { return mmap_.Size(); }

   const VerifierDepsHeader& GetVerifierDepsHeader() const {
     return *reinterpret_cast<const VerifierDepsHeader*>(Begin());
   }

   uint32_t GetDexSectionHeaderOffset() const {
     return sizeof(VerifierDepsHeader) + GetVerifierDepsHeader().GetSizeOfChecksumsSection();
   }

   const DexSectionHeader& GetDexSectionHeader() const {
     DCHECK(GetVerifierDepsHeader().HasDexSection());
     return *reinterpret_cast<const DexSectionHeader*>(Begin() + GetDexSectionHeaderOffset());
   }

   const uint8_t* GetVerifierDepsStart() const {
     const uint8_t* result = Begin() + GetDexSectionHeaderOffset();
     if (GetVerifierDepsHeader().HasDexSection()) {
       // When there is a dex section, the verifier deps are after it, but before the quickening.
       return result + GetDexSectionHeader().GetDexSectionSize();
     } else {
       // When there is no dex section, the verifier deps are just after the header.
       return result;
     }
   }

   ArrayRef<const uint8_t> GetVerifierDepsData() const {
     return ArrayRef<const uint8_t>(
         GetVerifierDepsStart(),
         GetVerifierDepsHeader().GetVerifierDepsSize());
   }

   ArrayRef<const uint8_t> GetQuickeningInfo() const {
     return ArrayRef<const uint8_t>(
         GetVerifierDepsData().end(),
         GetVerifierDepsHeader().HasDexSection()
             ? GetDexSectionHeader().GetQuickeningInfoSize() : 0);
   }

   ArrayRef<const uint8_t> GetBootClassPathChecksumData() const {
     return ArrayRef<const uint8_t>(
         GetQuickeningInfo().end(),
         GetVerifierDepsHeader().GetBootClassPathChecksumStringSize());
   }

   ArrayRef<const uint8_t> GetClassLoaderContextData() const {
     return ArrayRef<const uint8_t>(
         GetBootClassPathChecksumData().end(),
         GetVerifierDepsHeader().GetClassLoaderContextStringSize());
   }

   bool IsValid() const {
     return mmap_.Size() >= sizeof(VerifierDepsHeader) && GetVerifierDepsHeader().IsValid();
   }

   // This method is for iterating over the dex files in the vdex. If `cursor` is null,
   // the first dex file is returned. If `cursor` is not null, it must point to a dex
   // file and this method returns the next dex file if there is one, or null if there
   // is none.
   const uint8_t* GetNextDexFileData(const uint8_t* cursor) const;

   // Get the location checksum of the dex file number `dex_file_index`.
   uint32_t GetLocationChecksum(uint32_t dex_file_index) const {
     DCHECK_LT(dex_file_index, GetVerifierDepsHeader().GetNumberOfDexFiles());
     return reinterpret_cast<const uint32_t*>(Begin() + sizeof(VerifierDepsHeader))[dex_file_index];
   }

   // Open all the dex files contained in this vdex file.
   bool OpenAllDexFiles(std::vector<std::unique_ptr<const DexFile>>* dex_files,
                        std::string* error_msg) const;

   // In-place unquicken the given `dex_files` based on `quickening_info`.
   // `decompile_return_instruction` controls if RETURN_VOID_BARRIER instructions are
   // decompiled to RETURN_VOID instructions using the slower ClassAccessor instead of the faster
   // QuickeningInfoIterator.
   // Always unquickens using the vdex dex files as the source for quicken tables.
   void Unquicken(const std::vector<const DexFile*>& target_dex_files,
                  bool decompile_return_instruction) const;

   void UnquickenInPlace(bool decompile_return_instruction) const;

   // Fully unquicken `target_dex_file` based on `quickening_info`.
   void UnquickenDexFile(const DexFile& target_dex_file,
                         const DexFile& source_dex_file,
                         bool decompile_return_instruction) const;

   // Return the quickening info of a given method index (or null if it's empty).
   ArrayRef<const uint8_t> GetQuickenedInfoOf(const DexFile& dex_file,
                                              uint32_t dex_method_idx) const;

   bool HasDexSection() const {
     return GetVerifierDepsHeader().HasDexSection();
   }

   // Writes a vdex into `path` and returns true on success.
   // The vdex will not contain a dex section but will store checksums of `dex_files`,
   // encoded `verifier_deps`, as well as the current boot class path cheksum and
   // encoded `class_loader_context`.
   static bool WriteToDisk(const std::string& path,
                           const std::vector<const DexFile*>& dex_files,
                           const verifier::VerifierDeps& verifier_deps,
                           const std::string& class_loader_context,
                           std::string* error_msg);

   // Returns true if the dex file checksums stored in the vdex header match
   // the checksums in `dex_headers`. Both the number of dex files and their
   // order must match too.
   bool MatchesDexFileChecksums(const std::vector<const DexFile::Header*>& dex_headers) const;

   // Returns true if the boot class path checksum stored in the vdex matches
   // the checksum of boot class path in the current runtime.
   bool MatchesBootClassPathChecksums() const;

   // Returns true if the class loader context stored in the vdex matches `context`.
   bool MatchesClassLoaderContext(const ClassLoaderContext& context) const;

   // Make the Vdex file & underlying dex-files RW or RO. Should only be used for in-place
   // dequickening.
   void AllowWriting(bool value) const;

  private:
   uint32_t GetQuickeningInfoTableOffset(const uint8_t* source_dex_begin) const;

   // Source dex must be the in the vdex file.
   void UnquickenDexFile(const DexFile& target_dex_file,
                         const uint8_t* source_dex_begin,
                         bool decompile_return_instruction) const;

   CompactOffsetTable::Accessor GetQuickenInfoOffsetTable(
         const DexFile& dex_file,
         const ArrayRef<const uint8_t>& quickening_info) const;

   CompactOffsetTable::Accessor GetQuickenInfoOffsetTable(
       const uint8_t* source_dex_begin,
       const ArrayRef<const uint8_t>& quickening_info) const;

   bool ContainsDexFile(const DexFile& dex_file) const;

   const uint8_t* DexBegin() const {
     DCHECK(HasDexSection());
     return Begin() + GetDexSectionHeaderOffset() + sizeof(DexSectionHeader);
   }

   const uint8_t* DexEnd() const {
     DCHECK(HasDexSection());
     return DexBegin() + GetDexSectionHeader().GetDexSize();
   }

   // mutable for AllowWriting()
   mutable MemMap mmap_;

   DISALLOW_COPY_AND_ASSIGN(VdexFile);
 };

 }  // namespace art

 #endif  // ART_RUNTIME_VDEX_FILE_H_
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef ART_RUNTIME_VDEX_FILE_H_
	#define ART_RUNTIME_VDEX_FILE_H_

	#include <stdint.h>
	#include <string>

	#include "base/array_ref.h"
	#include "base/macros.h"
	#include "base/mem_map.h"
	#include "base/os.h"
	#include "dex/compact_offset_table.h"
	#include "dex/dex_file.h"
	#include "quicken_info.h"

	namespace art {

	class ClassLoaderContext;

	namespace verifier {
	class VerifierDeps;
	} // namespace verifier

	// VDEX files contain extracted DEX files. The VdexFile class maps the file to
	// memory and provides tools for accessing its individual sections.
	//
	// File format:
	// VdexFile::VerifierDepsHeader fixed-length header
	// Dex file checksums
	//
	// Optionally:
	// VdexFile::DexSectionHeader fixed-length header
	//
	// quicken_table_off[0] offset into QuickeningInfo section for offset table for DEX[0].
	// DEX[0] array of the input DEX files, the bytecode may have been quickened.
	// quicken_table_off[1]
	// DEX[1]
	// ...
	// DEX[D]
	//
	// VerifierDeps
	// uint8[D][] verification dependencies
	//
	// Optionally:
	// QuickeningInfo
	// uint8[D][] quickening data
	// uint32[D][] quickening data offset tables

	class VdexFile {
	public:
	using VdexChecksum = uint32_t;
	using QuickeningTableOffsetType = uint32_t;

	struct VerifierDepsHeader {
	public:
	VerifierDepsHeader(uint32_t number_of_dex_files_,
	uint32_t verifier_deps_size,
	bool has_dex_section,
	uint32_t bootclasspath_checksums_size = 0,
	uint32_t class_loader_context_size = 0);

	const char* GetMagic() const { return reinterpret_cast<const char*>(magic_); }
	const char* GetVerifierDepsVersion() const {
	return reinterpret_cast<const char*>(verifier_deps_version_);
	}
	const char* GetDexSectionVersion() const {
	return reinterpret_cast<const char*>(dex_section_version_);
	}
	bool IsMagicValid() const;
	bool IsVerifierDepsVersionValid() const;
	bool IsDexSectionVersionValid() const;
	bool IsValid() const {
	return IsMagicValid() && IsVerifierDepsVersionValid() && IsDexSectionVersionValid();
	}
	bool HasDexSection() const;

	uint32_t GetVerifierDepsSize() const { return verifier_deps_size_; }
	uint32_t GetNumberOfDexFiles() const { return number_of_dex_files_; }
	uint32_t GetBootClassPathChecksumStringSize() const { return bootclasspath_checksums_size_; }
	uint32_t GetClassLoaderContextStringSize() const { return class_loader_context_size_; }

	size_t GetSizeOfChecksumsSection() const {
	return sizeof(VdexChecksum) * GetNumberOfDexFiles();
	}

	const VdexChecksum* GetDexChecksumsArray() const {
	return reinterpret_cast<const VdexChecksum*>(
	reinterpret_cast<const uint8_t*>(this) + sizeof(VerifierDepsHeader));
	}

	VdexChecksum GetDexChecksumAtOffset(size_t idx) const {
	DCHECK_LT(idx, GetNumberOfDexFiles());
	return GetDexChecksumsArray()[idx];
	}

	static constexpr uint8_t kVdexInvalidMagic[] = { 'w', 'd', 'e', 'x' };

	private:
	static constexpr uint8_t kVdexMagic[] = { 'v', 'd', 'e', 'x' };

	// The format version of the verifier deps header and the verifier deps.
	// Last update: Add boot checksum, class loader context.
	static constexpr uint8_t kVerifierDepsVersion[] = { '0', '2', '1', '\0' };

	// The format version of the dex section header and the dex section, containing
	// both the dex code and the quickening data.
	// Last update: Add owned section for CompactDex.
	static constexpr uint8_t kDexSectionVersion[] = { '0', '0', '2', '\0' };

	// If the .vdex file has no dex section (hence no dex code nor quickening data),
	// we encode this magic version.
	static constexpr uint8_t kDexSectionVersionEmpty[] = { '0', '0', '0', '\0' };

	uint8_t magic_[4];
	uint8_t verifier_deps_version_[4];
	uint8_t dex_section_version_[4];
	uint32_t number_of_dex_files_;
	uint32_t verifier_deps_size_;
	uint32_t bootclasspath_checksums_size_;
	uint32_t class_loader_context_size_;
	};

	struct DexSectionHeader {
	public:
	DexSectionHeader(uint32_t dex_size,
	uint32_t dex_shared_data_size,
	uint32_t quickening_info_size);

	uint32_t GetDexSize() const { return dex_size_; }
	uint32_t GetDexSharedDataSize() const { return dex_shared_data_size_; }
	uint32_t GetQuickeningInfoSize() const { return quickening_info_size_; }

	size_t GetDexSectionSize() const {
	return sizeof(DexSectionHeader) +
	GetDexSize() +
	GetDexSharedDataSize();
	}

	private:
	uint32_t dex_size_;
	uint32_t dex_shared_data_size_;
	uint32_t quickening_info_size_;

	friend class VdexFile; // For updating quickening_info_size_.
	};

	size_t GetComputedFileSize() const {
	size_t size = sizeof(VerifierDepsHeader);
	const VerifierDepsHeader& header = GetVerifierDepsHeader();
	size += header.GetVerifierDepsSize();
	size += header.GetSizeOfChecksumsSection();
	if (header.HasDexSection()) {
	size += GetDexSectionHeader().GetDexSectionSize();
	size += GetDexSectionHeader().GetQuickeningInfoSize();
	}
	size += header.GetBootClassPathChecksumStringSize();
	size += header.GetClassLoaderContextStringSize();
	return size;
	}

	// Note: The file is called "primary" to match the naming with profiles.
	static const constexpr char* kVdexNameInDmFile = "primary.vdex";

	explicit VdexFile(MemMap&& mmap) : mmap_(std::move(mmap)) {}

	// Returns nullptr if the vdex file cannot be opened or is not valid.
	// The mmap_* parameters can be left empty (nullptr/0/false) to allocate at random address.
	static std::unique_ptr<VdexFile> OpenAtAddress(uint8_t* mmap_addr,
	size_t mmap_size,
	bool mmap_reuse,
	const std::string& vdex_filename,
	bool writable,
	bool low_4gb,
	bool unquicken,
	std::string* error_msg);

	// Returns nullptr if the vdex file cannot be opened or is not valid.
	// The mmap_* parameters can be left empty (nullptr/0/false) to allocate at random address.
	static std::unique_ptr<VdexFile> OpenAtAddress(uint8_t* mmap_addr,
	size_t mmap_size,
	bool mmap_reuse,
	int file_fd,
	size_t vdex_length,
	const std::string& vdex_filename,
	bool writable,
	bool low_4gb,
	bool unquicken,
	std::string* error_msg);

	// Returns nullptr if the vdex file cannot be opened or is not valid.
	static std::unique_ptr<VdexFile> Open(const std::string& vdex_filename,
	bool writable,
	bool low_4gb,
	bool unquicken,
	std::string* error_msg) {
	return OpenAtAddress(nullptr,
	0,
	false,
	vdex_filename,
	writable,
	low_4gb,
	unquicken,
	error_msg);
	}

	// Returns nullptr if the vdex file cannot be opened or is not valid.
	static std::unique_ptr<VdexFile> Open(int file_fd,
	size_t vdex_length,
	const std::string& vdex_filename,
	bool writable,
	bool low_4gb,
	bool unquicken,
	std::string* error_msg) {
	return OpenAtAddress(nullptr,
	0,
	false,
	file_fd,
	vdex_length,
	vdex_filename,
	writable,
	low_4gb,
	unquicken,
	error_msg);
	}

	const uint8_t* Begin() const { return mmap_.Begin(); }
	const uint8_t* End() const { return mmap_.End(); }
	size_t Size() const { return mmap_.Size(); }

	const VerifierDepsHeader& GetVerifierDepsHeader() const {
	return reinterpret_cast<const VerifierDepsHeader>(Begin());
	}

	uint32_t GetDexSectionHeaderOffset() const {
	return sizeof(VerifierDepsHeader) + GetVerifierDepsHeader().GetSizeOfChecksumsSection();
	}

	const DexSectionHeader& GetDexSectionHeader() const {
	DCHECK(GetVerifierDepsHeader().HasDexSection());
	return reinterpret_cast<const DexSectionHeader>(Begin() + GetDexSectionHeaderOffset());
	}

	const uint8_t* GetVerifierDepsStart() const {
	const uint8_t* result = Begin() + GetDexSectionHeaderOffset();
	if (GetVerifierDepsHeader().HasDexSection()) {
	// When there is a dex section, the verifier deps are after it, but before the quickening.
	return result + GetDexSectionHeader().GetDexSectionSize();
	} else {
	// When there is no dex section, the verifier deps are just after the header.
	return result;
	}
	}

	ArrayRef<const uint8_t> GetVerifierDepsData() const {
	return ArrayRef<const uint8_t>(
	GetVerifierDepsStart(),
	GetVerifierDepsHeader().GetVerifierDepsSize());
	}

	ArrayRef<const uint8_t> GetQuickeningInfo() const {
	return ArrayRef<const uint8_t>(
	GetVerifierDepsData().end(),
	GetVerifierDepsHeader().HasDexSection()
	? GetDexSectionHeader().GetQuickeningInfoSize() : 0);
	}

	ArrayRef<const uint8_t> GetBootClassPathChecksumData() const {
	return ArrayRef<const uint8_t>(
	GetQuickeningInfo().end(),
	GetVerifierDepsHeader().GetBootClassPathChecksumStringSize());
	}

	ArrayRef<const uint8_t> GetClassLoaderContextData() const {
	return ArrayRef<const uint8_t>(
	GetBootClassPathChecksumData().end(),
	GetVerifierDepsHeader().GetClassLoaderContextStringSize());
	}

	bool IsValid() const {
	return mmap_.Size() >= sizeof(VerifierDepsHeader) && GetVerifierDepsHeader().IsValid();
	}

	// This method is for iterating over the dex files in the vdex. If `cursor` is null,
	// the first dex file is returned. If `cursor` is not null, it must point to a dex
	// file and this method returns the next dex file if there is one, or null if there
	// is none.
	const uint8_t* GetNextDexFileData(const uint8_t* cursor) const;

	// Get the location checksum of the dex file number `dex_file_index`.
	uint32_t GetLocationChecksum(uint32_t dex_file_index) const {
	DCHECK_LT(dex_file_index, GetVerifierDepsHeader().GetNumberOfDexFiles());
	return reinterpret_cast<const uint32_t*>(Begin() + sizeof(VerifierDepsHeader))[dex_file_index];
	}

	// Open all the dex files contained in this vdex file.
	bool OpenAllDexFiles(std::vector<std::unique_ptr<const DexFile>>* dex_files,
	std::string* error_msg) const;

	// In-place unquicken the given `dex_files` based on `quickening_info`.
	// `decompile_return_instruction` controls if RETURN_VOID_BARRIER instructions are
	// decompiled to RETURN_VOID instructions using the slower ClassAccessor instead of the faster
	// QuickeningInfoIterator.
	// Always unquickens using the vdex dex files as the source for quicken tables.
	void Unquicken(const std::vector<const DexFile*>& target_dex_files,
	bool decompile_return_instruction) const;

	void UnquickenInPlace(bool decompile_return_instruction) const;

	// Fully unquicken `target_dex_file` based on `quickening_info`.
	void UnquickenDexFile(const DexFile& target_dex_file,
	const DexFile& source_dex_file,
	bool decompile_return_instruction) const;

	// Return the quickening info of a given method index (or null if it's empty).
	ArrayRef<const uint8_t> GetQuickenedInfoOf(const DexFile& dex_file,
	uint32_t dex_method_idx) const;

	bool HasDexSection() const {
	return GetVerifierDepsHeader().HasDexSection();
	}

	// Writes a vdex into `path` and returns true on success.
	// The vdex will not contain a dex section but will store checksums of `dex_files`,
	// encoded `verifier_deps`, as well as the current boot class path cheksum and
	// encoded `class_loader_context`.
	static bool WriteToDisk(const std::string& path,
	const std::vector<const DexFile*>& dex_files,
	const verifier::VerifierDeps& verifier_deps,
	const std::string& class_loader_context,
	std::string* error_msg);

	// Returns true if the dex file checksums stored in the vdex header match
	// the checksums in `dex_headers`. Both the number of dex files and their
	// order must match too.
	bool MatchesDexFileChecksums(const std::vector<const DexFile::Header*>& dex_headers) const;

	// Returns true if the boot class path checksum stored in the vdex matches
	// the checksum of boot class path in the current runtime.
	bool MatchesBootClassPathChecksums() const;

	// Returns true if the class loader context stored in the vdex matches `context`.
	bool MatchesClassLoaderContext(const ClassLoaderContext& context) const;

	// Make the Vdex file & underlying dex-files RW or RO. Should only be used for in-place
	// dequickening.
	void AllowWriting(bool value) const;

	private:
	uint32_t GetQuickeningInfoTableOffset(const uint8_t* source_dex_begin) const;

	// Source dex must be the in the vdex file.
	void UnquickenDexFile(const DexFile& target_dex_file,
	const uint8_t* source_dex_begin,
	bool decompile_return_instruction) const;

	CompactOffsetTable::Accessor GetQuickenInfoOffsetTable(
	const DexFile& dex_file,
	const ArrayRef<const uint8_t>& quickening_info) const;

	CompactOffsetTable::Accessor GetQuickenInfoOffsetTable(
	const uint8_t* source_dex_begin,
	const ArrayRef<const uint8_t>& quickening_info) const;

	bool ContainsDexFile(const DexFile& dex_file) const;

	const uint8_t* DexBegin() const {
	DCHECK(HasDexSection());
	return Begin() + GetDexSectionHeaderOffset() + sizeof(DexSectionHeader);
	}

	const uint8_t* DexEnd() const {
	DCHECK(HasDexSection());
	return DexBegin() + GetDexSectionHeader().GetDexSize();
	}

	// mutable for AllowWriting()
	mutable MemMap mmap_;

	DISALLOW_COPY_AND_ASSIGN(VdexFile);
	};

	} // namespace art

	#endif // ART_RUNTIME_VDEX_FILE_H_