runtime/oat_file_assistant.h - platform/art - Gitiles

 /*
  * Copyright (C) 2014 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_OAT_FILE_ASSISTANT_H_
 #define ART_RUNTIME_OAT_FILE_ASSISTANT_H_

 #include <cstdint>
 #include <memory>
 #include <string>

 #include "arch/instruction_set.h"
 #include "base/scoped_flock.h"
 #include "base/unix_file/fd_file.h"
 #include "oat_file.h"
 #include "os.h"
 #include "profiler.h"

 namespace art {

 // Class for assisting with oat file management.
 //
 // This class collects common utilities for determining the status of an oat
 // file on the device, updating the oat file, and loading the oat file.
 //
 // The oat file assistant is intended to be used with dex locations not on the
 // boot class path. See the IsInBootClassPath method for a way to check if the
 // dex location is in the boot class path.
 //
 // TODO: All the profiling related code is old and untested. It should either
 // be restored and tested, or removed.
 class OatFileAssistant {
  public:
   enum DexOptNeeded {
     // kNoDexOptNeeded - The code for this dex location is up to date and can
     // be used as is.
     // Matches Java: dalvik.system.DexFile.NO_DEXOPT_NEEDED = 0
     kNoDexOptNeeded = 0,

     // kDex2OatNeeded - In order to make the code for this dex location up to
     // date, dex2oat must be run on the dex file.
     // Matches Java: dalvik.system.DexFile.DEX2OAT_NEEDED = 1
     kDex2OatNeeded = 1,

     // kPatchOatNeeded - In order to make the code for this dex location up to
     // date, patchoat must be run on the odex file.
     // Matches Java: dalvik.system.DexFile.PATCHOAT_NEEDED = 2
     kPatchOatNeeded = 2,

     // kSelfPatchOatNeeded - In order to make the code for this dex location
     // up to date, patchoat must be run on the oat file.
     // Matches Java: dalvik.system.DexFile.SELF_PATCHOAT_NEEDED = 3
     kSelfPatchOatNeeded = 3,
   };

   enum OatStatus {
     // kOatOutOfDate - An oat file is said to be out of date if the file does
     // not exist, or is out of date with respect to the dex file or boot
     // image.
     kOatOutOfDate,

     // kOatNeedsRelocation - An oat file is said to need relocation if the
     // code is up to date, but not yet properly relocated for address space
     // layout randomization (ASLR). In this case, the oat file is neither
     // "out of date" nor "up to date".
     kOatNeedsRelocation,

     // kOatUpToDate - An oat file is said to be up to date if it is not out of
     // date and has been properly relocated for the purposes of ASLR.
     kOatUpToDate,
   };

   // Constructs an OatFileAssistant object to assist the oat file
   // corresponding to the given dex location with the target instruction set.
   //
   // The dex_location must not be null and should remain available and
   // unchanged for the duration of the lifetime of the OatFileAssistant object.
   // Typically the dex_location is the absolute path to the original,
   // un-optimized dex file.
   //
   // Note: Currently the dex_location must have an extension.
   // TODO: Relax this restriction?
   //
   // The isa should be either the 32 bit or 64 bit variant for the current
   // device. For example, on an arm device, use arm or arm64. An oat file can
   // be loaded executable only if the ISA matches the current runtime.
   OatFileAssistant(const char* dex_location, const InstructionSet isa,
                    bool load_executable);

   // Constructs an OatFileAssistant, providing an explicit target oat_location
   // to use instead of the standard oat location.
   OatFileAssistant(const char* dex_location, const char* oat_location,
                    const InstructionSet isa, bool load_executable);

   // Constructs an OatFileAssistant, providing an additional package_name used
   // solely for the purpose of locating profile files.
   //
   // TODO: Why is the name of the profile file based on the package name and
   // not the dex location? If there is no technical reason the dex_location
   // can't be used, we should prefer that instead.
   OatFileAssistant(const char* dex_location, const InstructionSet isa,
                    bool load_executable, const char* package_name);

   // Constructs an OatFileAssistant with user specified oat location and a
   // package name.
   OatFileAssistant(const char* dex_location, const char* oat_location,
                    const InstructionSet isa, bool load_executable,
                    const char* package_name);

   ~OatFileAssistant();

   // Returns true if the dex location refers to an element of the boot class
   // path.
   bool IsInBootClassPath();

   // Obtains a lock on the target oat file.
   // Only one OatFileAssistant object can hold the lock for a target oat file
   // at a time. The Lock is released automatically when the OatFileAssistant
   // object goes out of scope. The Lock() method must not be called if the
   // lock has already been acquired.
   //
   // Returns true on success.
   // Returns false on error, in which case error_msg will contain more
   // information on the error.
   //
   // The 'error_msg' argument must not be null.
   //
   // This is intended to be used to avoid race conditions when multiple
   // processes generate oat files, such as when a foreground Activity and
   // a background Service both use DexClassLoaders pointing to the same dex
   // file.
   bool Lock(std::string* error_msg);

   // Return what action needs to be taken to produce up-to-date code for this
   // dex location.
   DexOptNeeded GetDexOptNeeded();

   // Attempts to generate or relocate the oat file as needed to make it up to
   // date.
   // Returns true on success.
   //
   // If there is a failure, the value of error_msg will be set to a string
   // describing why there was failure. error_msg must not be null.
   bool MakeUpToDate(std::string* error_msg);

   // Returns an oat file that can be used for loading dex files.
   // Returns null if no suitable oat file was found.
   //
   // After this call, no other methods of the OatFileAssistant should be
   // called, because access to the loaded oat file has been taken away from
   // the OatFileAssistant object.
   std::unique_ptr<OatFile> GetBestOatFile();

   // Loads the dex files in the given oat file for the given dex location.
   // The oat file should be up to date for the given dex location.
   // This loads multiple dex files in the case of multidex.
   // Returns an empty vector if no dex files for that location could be loaded
   // from the oat file.
   //
   // The caller is responsible for freeing the dex_files returned, if any. The
   // dex_files will only remain valid as long as the oat_file is valid.
   static std::vector<std::unique_ptr<const DexFile>> LoadDexFiles(
       const OatFile& oat_file, const char* dex_location);

   // Returns true if there are dex files in the original dex location that can
   // be compiled with dex2oat for this dex location.
   // Returns false if there is no original dex file, or if the original dex
   // file is an apk/zip without a classes.dex entry.
   bool HasOriginalDexFiles();

   // If the dex file has been installed with a compiled oat file alongside
   // it, the compiled oat file will have the extension .odex, and is referred
   // to as the odex file. It is called odex for legacy reasons; the file is
   // really an oat file. The odex file will often, but not always, have a
   // patch delta of 0 and need to be relocated before use for the purposes of
   // ASLR. The odex file is treated as if it were read-only.
   // These methods return the location and status of the odex file for the dex
   // location.
   // Notes:
   //  * OdexFileName may return null if the odex file name could not be
   //    determined.
   const std::string* OdexFileName();
   bool OdexFileExists();
   OatStatus OdexFileStatus();
   bool OdexFileIsOutOfDate();
   bool OdexFileNeedsRelocation();
   bool OdexFileIsUpToDate();

   // When the dex files is compiled on the target device, the oat file is the
   // result. The oat file will have been relocated to some
   // (possibly-out-of-date) offset for ASLR.
   // These methods return the location and status of the target oat file for
   // the dex location.
   //
   // Notes:
   //  * OatFileName may return null if the oat file name could not be
   //    determined.
   const std::string* OatFileName();
   bool OatFileExists();
   OatStatus OatFileStatus();
   bool OatFileIsOutOfDate();
   bool OatFileNeedsRelocation();
   bool OatFileIsUpToDate();

   // These methods return the status for a given opened oat file with respect
   // to the dex location.
   OatStatus GivenOatFileStatus(const OatFile& file);
   bool GivenOatFileIsOutOfDate(const OatFile& file);
   bool GivenOatFileNeedsRelocation(const OatFile& file);
   bool GivenOatFileIsUpToDate(const OatFile& file);

   // Returns true if there is an accessible profile associated with the dex
   // location.
   // This returns false if profiling is disabled.
   bool ProfileExists();

   // The old profile is a file containing a previous snapshot of profiling
   // information associated with the dex file code. This is used to track how
   // the profiling information has changed over time.
   //
   // Returns true if there is an accessible old profile associated with the
   // dex location.
   // This returns false if profiling is disabled.
   bool OldProfileExists();

   // Returns true if there has been a significant change between the old
   // profile and the current profile.
   // This returns false if profiling is disabled.
   bool IsProfileChangeSignificant();

   // Copy the current profile to the old profile location.
   void CopyProfileFile();

   // Generates the oat file by relocation from the named input file.
   // This does not check the current status before attempting to relocate the
   // oat file.
   // Returns true on success.
   // This will fail if dex2oat is not enabled in the current runtime.
   //
   // If there is a failure, the value of error_msg will be set to a string
   // describing why there was failure. error_msg must not be null.
   bool RelocateOatFile(const std::string* input_file, std::string* error_msg);

   // Generate the oat file from the dex file.
   // This does not check the current status before attempting to generate the
   // oat file.
   // Returns true on success.
   // This will fail if dex2oat is not enabled in the current runtime.
   //
   // If there is a failure, the value of error_msg will be set to a string
   // describing why there was failure. error_msg must not be null.
   bool GenerateOatFile(std::string* error_msg);

   // Executes dex2oat using the current runtime configuration overridden with
   // the given arguments. This does not check to see if dex2oat is enabled in
   // the runtime configuration.
   // Returns true on success.
   //
   // If there is a failure, the value of error_msg will be set to a string
   // describing why there was failure. error_msg must not be null.
   //
   // TODO: The OatFileAssistant probably isn't the right place to have this
   // function.
   static bool Dex2Oat(const std::vector<std::string>& args, std::string* error_msg);

   // Constructs the odex file name for the given dex location.
   // Returns true on success, in which case odex_filename is set to the odex
   // file name.
   // Returns false on error, in which case error_msg describes the error.
   // Neither odex_filename nor error_msg may be null.
   static bool DexFilenameToOdexFilename(const std::string& location,
       InstructionSet isa, std::string* odex_filename, std::string* error_msg);

  private:
   struct ImageInfo {
     uint32_t oat_checksum = 0;
     uintptr_t oat_data_begin = 0;
     int32_t patch_delta = 0;
     std::string location;
   };

   // Returns the path to the dalvik cache directory.
   // Does not check existence of the cache or try to create it.
   // Includes the trailing slash.
   // Returns an empty string if we can't get the dalvik cache directory path.
   std::string DalvikCacheDirectory();

   // Constructs the filename for the profile file.
   // Returns an empty string if we do not have the necessary information to
   // construct the filename.
   std::string ProfileFileName();

   // Constructs the filename for the old profile file.
   // Returns an empty string if we do not have the necessary information to
   // construct the filename.
   std::string OldProfileFileName();

   // Returns the current image location.
   // Returns an empty string if the image location could not be retrieved.
   //
   // TODO: This method should belong with an image file manager, not
   // the oat file assistant.
   static std::string ImageLocation();

   // Gets the dex checksum required for an up-to-date oat file.
   // Returns dex_checksum if a required checksum was located. Returns
   // null if the required checksum was not found.
   // The caller shouldn't clean up or free the returned pointer.
   // This sets the has_original_dex_files_ field to true if a checksum was
   // found for the dex_location_ dex file.
   const uint32_t* GetRequiredDexChecksum();

   // Returns the loaded odex file.
   // Loads the file if needed. Returns null if the file failed to load.
   // The caller shouldn't clean up or free the returned pointer.
   const OatFile* GetOdexFile();

   // Returns true if the odex file is opened executable.
   bool OdexFileIsExecutable();

   // Clear any cached information about the odex file that depends on the
   // contents of the file.
   void ClearOdexFileCache();

   // Returns the loaded oat file.
   // Loads the file if needed. Returns null if the file failed to load.
   // The caller shouldn't clean up or free the returned pointer.
   const OatFile* GetOatFile();

   // Returns true if the oat file is opened executable.
   bool OatFileIsExecutable();

   // Clear any cached information about the oat file that depends on the
   // contents of the file.
   void ClearOatFileCache();

   // Returns the loaded image info.
   // Loads the image info if needed. Returns null if the image info failed
   // to load.
   // The caller shouldn't clean up or free the returned pointer.
   const ImageInfo* GetImageInfo();

   // Returns the loaded profile.
   // Loads the profile if needed. Returns null if the profile failed
   // to load.
   // The caller shouldn't clean up or free the returned pointer.
   ProfileFile* GetProfile();

   // Returns the loaded old profile.
   // Loads the old profile if needed. Returns null if the old profile
   // failed to load.
   // The caller shouldn't clean up or free the returned pointer.
   ProfileFile* GetOldProfile();

   // To implement Lock(), we lock a dummy file where the oat file would go
   // (adding ".flock" to the target file name) and retain the lock for the
   // remaining lifetime of the OatFileAssistant object.
   ScopedFlock flock_;

   // In a properly constructed OatFileAssistant object, dex_location_ should
   // never be null.
   const char* dex_location_ = nullptr;

   // In a properly constructed OatFileAssistant object, isa_ should be either
   // the 32 or 64 bit variant for the current device.
   const InstructionSet isa_ = kNone;

   // The package name, used solely to find the profile file.
   // This may be null in a properly constructed object. In this case,
   // profile_load_attempted_ and old_profile_load_attempted_ will be true, and
   // profile_load_succeeded_ and old_profile_load_succeeded_ will be false.
   const char* package_name_ = nullptr;

   // Whether we will attempt to load oat files executable.
   bool load_executable_ = false;

   // Cached value of the required dex checksum.
   // This should be accessed only by the GetRequiredDexChecksum() method.
   uint32_t cached_required_dex_checksum_;
   bool required_dex_checksum_attempted_ = false;
   bool required_dex_checksum_found_;
   bool has_original_dex_files_;

   // Cached value of the odex file name.
   // This should be accessed only by the OdexFileName() method.
   bool cached_odex_file_name_attempted_ = false;
   bool cached_odex_file_name_found_;
   std::string cached_odex_file_name_;

   // Cached value of the loaded odex file.
   // Use the GetOdexFile method rather than accessing this directly, unless you
   // know the odex file isn't out of date.
   bool odex_file_load_attempted_ = false;
   std::unique_ptr<OatFile> cached_odex_file_;

   // Cached results for OdexFileIsOutOfDate
   bool odex_file_is_out_of_date_attempted_ = false;
   bool cached_odex_file_is_out_of_date_;

   // Cached results for OdexFileIsUpToDate
   bool odex_file_is_up_to_date_attempted_ = false;
   bool cached_odex_file_is_up_to_date_;

   // Cached value of the oat file name.
   // This should be accessed only by the OatFileName() method.
   bool cached_oat_file_name_attempted_ = false;
   bool cached_oat_file_name_found_;
   std::string cached_oat_file_name_;

   // Cached value of the loaded oat file.
   // Use the GetOatFile method rather than accessing this directly, unless you
   // know the oat file isn't out of date.
   bool oat_file_load_attempted_ = false;
   std::unique_ptr<OatFile> cached_oat_file_;

   // Cached results for OatFileIsOutOfDate
   bool oat_file_is_out_of_date_attempted_ = false;
   bool cached_oat_file_is_out_of_date_;

   // Cached results for OatFileIsUpToDate
   bool oat_file_is_up_to_date_attempted_ = false;
   bool cached_oat_file_is_up_to_date_;

   // Cached value of the image info.
   // Use the GetImageInfo method rather than accessing these directly.
   // TODO: The image info should probably be moved out of the oat file
   // assistant to an image file manager.
   bool image_info_load_attempted_ = false;
   bool image_info_load_succeeded_ = false;
   ImageInfo cached_image_info_;

   // Cached value of the profile file.
   // Use the GetProfile method rather than accessing these directly.
   bool profile_load_attempted_ = false;
   bool profile_load_succeeded_ = false;
   ProfileFile cached_profile_;

   // Cached value of the profile file.
   // Use the GetOldProfile method rather than accessing these directly.
   bool old_profile_load_attempted_ = false;
   bool old_profile_load_succeeded_ = false;
   ProfileFile cached_old_profile_;

   // For debugging only.
   // If this flag is set, the oat or odex file has been released to the user
   // of the OatFileAssistant object and the OatFileAssistant object is in a
   // bad state and should no longer be used.
   bool oat_file_released_ = false;

   DISALLOW_COPY_AND_ASSIGN(OatFileAssistant);
 };

 }  // namespace art

 #endif  // ART_RUNTIME_OAT_FILE_ASSISTANT_H_
	/*
	* Copyright (C) 2014 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_OAT_FILE_ASSISTANT_H_
	#define ART_RUNTIME_OAT_FILE_ASSISTANT_H_

	#include <cstdint>
	#include <memory>
	#include <string>

	#include "arch/instruction_set.h"
	#include "base/scoped_flock.h"
	#include "base/unix_file/fd_file.h"
	#include "oat_file.h"
	#include "os.h"
	#include "profiler.h"

	namespace art {

	// Class for assisting with oat file management.
	//
	// This class collects common utilities for determining the status of an oat
	// file on the device, updating the oat file, and loading the oat file.
	//
	// The oat file assistant is intended to be used with dex locations not on the
	// boot class path. See the IsInBootClassPath method for a way to check if the
	// dex location is in the boot class path.
	//
	// TODO: All the profiling related code is old and untested. It should either
	// be restored and tested, or removed.
	class OatFileAssistant {
	public:
	enum DexOptNeeded {
	// kNoDexOptNeeded - The code for this dex location is up to date and can
	// be used as is.
	// Matches Java: dalvik.system.DexFile.NO_DEXOPT_NEEDED = 0
	kNoDexOptNeeded = 0,

	// kDex2OatNeeded - In order to make the code for this dex location up to
	// date, dex2oat must be run on the dex file.
	// Matches Java: dalvik.system.DexFile.DEX2OAT_NEEDED = 1
	kDex2OatNeeded = 1,

	// kPatchOatNeeded - In order to make the code for this dex location up to
	// date, patchoat must be run on the odex file.
	// Matches Java: dalvik.system.DexFile.PATCHOAT_NEEDED = 2
	kPatchOatNeeded = 2,

	// kSelfPatchOatNeeded - In order to make the code for this dex location
	// up to date, patchoat must be run on the oat file.
	// Matches Java: dalvik.system.DexFile.SELF_PATCHOAT_NEEDED = 3
	kSelfPatchOatNeeded = 3,
	};

	enum OatStatus {
	// kOatOutOfDate - An oat file is said to be out of date if the file does
	// not exist, or is out of date with respect to the dex file or boot
	// image.
	kOatOutOfDate,

	// kOatNeedsRelocation - An oat file is said to need relocation if the
	// code is up to date, but not yet properly relocated for address space
	// layout randomization (ASLR). In this case, the oat file is neither
	// "out of date" nor "up to date".
	kOatNeedsRelocation,

	// kOatUpToDate - An oat file is said to be up to date if it is not out of
	// date and has been properly relocated for the purposes of ASLR.
	kOatUpToDate,
	};

	// Constructs an OatFileAssistant object to assist the oat file
	// corresponding to the given dex location with the target instruction set.
	//
	// The dex_location must not be null and should remain available and
	// unchanged for the duration of the lifetime of the OatFileAssistant object.
	// Typically the dex_location is the absolute path to the original,
	// un-optimized dex file.
	//
	// Note: Currently the dex_location must have an extension.
	// TODO: Relax this restriction?
	//
	// The isa should be either the 32 bit or 64 bit variant for the current
	// device. For example, on an arm device, use arm or arm64. An oat file can
	// be loaded executable only if the ISA matches the current runtime.
	OatFileAssistant(const char* dex_location, const InstructionSet isa,
	bool load_executable);

	// Constructs an OatFileAssistant, providing an explicit target oat_location
	// to use instead of the standard oat location.
	OatFileAssistant(const char* dex_location, const char* oat_location,
	const InstructionSet isa, bool load_executable);

	// Constructs an OatFileAssistant, providing an additional package_name used
	// solely for the purpose of locating profile files.
	//
	// TODO: Why is the name of the profile file based on the package name and
	// not the dex location? If there is no technical reason the dex_location
	// can't be used, we should prefer that instead.
	OatFileAssistant(const char* dex_location, const InstructionSet isa,
	bool load_executable, const char* package_name);

	// Constructs an OatFileAssistant with user specified oat location and a
	// package name.
	OatFileAssistant(const char* dex_location, const char* oat_location,
	const InstructionSet isa, bool load_executable,
	const char* package_name);

	~OatFileAssistant();

	// Returns true if the dex location refers to an element of the boot class
	// path.
	bool IsInBootClassPath();

	// Obtains a lock on the target oat file.
	// Only one OatFileAssistant object can hold the lock for a target oat file
	// at a time. The Lock is released automatically when the OatFileAssistant
	// object goes out of scope. The Lock() method must not be called if the
	// lock has already been acquired.
	//
	// Returns true on success.
	// Returns false on error, in which case error_msg will contain more
	// information on the error.
	//
	// The 'error_msg' argument must not be null.
	//
	// This is intended to be used to avoid race conditions when multiple
	// processes generate oat files, such as when a foreground Activity and
	// a background Service both use DexClassLoaders pointing to the same dex
	// file.
	bool Lock(std::string* error_msg);

	// Return what action needs to be taken to produce up-to-date code for this
	// dex location.
	DexOptNeeded GetDexOptNeeded();

	// Attempts to generate or relocate the oat file as needed to make it up to
	// date.
	// Returns true on success.
	//
	// If there is a failure, the value of error_msg will be set to a string
	// describing why there was failure. error_msg must not be null.
	bool MakeUpToDate(std::string* error_msg);

	// Returns an oat file that can be used for loading dex files.
	// Returns null if no suitable oat file was found.
	//
	// After this call, no other methods of the OatFileAssistant should be
	// called, because access to the loaded oat file has been taken away from
	// the OatFileAssistant object.
	std::unique_ptr<OatFile> GetBestOatFile();

	// Loads the dex files in the given oat file for the given dex location.
	// The oat file should be up to date for the given dex location.
	// This loads multiple dex files in the case of multidex.
	// Returns an empty vector if no dex files for that location could be loaded
	// from the oat file.
	//
	// The caller is responsible for freeing the dex_files returned, if any. The
	// dex_files will only remain valid as long as the oat_file is valid.
	static std::vector<std::unique_ptr<const DexFile>> LoadDexFiles(
	const OatFile& oat_file, const char* dex_location);

	// Returns true if there are dex files in the original dex location that can
	// be compiled with dex2oat for this dex location.
	// Returns false if there is no original dex file, or if the original dex
	// file is an apk/zip without a classes.dex entry.
	bool HasOriginalDexFiles();

	// If the dex file has been installed with a compiled oat file alongside
	// it, the compiled oat file will have the extension .odex, and is referred
	// to as the odex file. It is called odex for legacy reasons; the file is
	// really an oat file. The odex file will often, but not always, have a
	// patch delta of 0 and need to be relocated before use for the purposes of
	// ASLR. The odex file is treated as if it were read-only.
	// These methods return the location and status of the odex file for the dex
	// location.
	// Notes:
	// * OdexFileName may return null if the odex file name could not be
	// determined.
	const std::string* OdexFileName();
	bool OdexFileExists();
	OatStatus OdexFileStatus();
	bool OdexFileIsOutOfDate();
	bool OdexFileNeedsRelocation();
	bool OdexFileIsUpToDate();

	// When the dex files is compiled on the target device, the oat file is the
	// result. The oat file will have been relocated to some
	// (possibly-out-of-date) offset for ASLR.
	// These methods return the location and status of the target oat file for
	// the dex location.
	//
	// Notes:
	// * OatFileName may return null if the oat file name could not be
	// determined.
	const std::string* OatFileName();
	bool OatFileExists();
	OatStatus OatFileStatus();
	bool OatFileIsOutOfDate();
	bool OatFileNeedsRelocation();
	bool OatFileIsUpToDate();

	// These methods return the status for a given opened oat file with respect
	// to the dex location.
	OatStatus GivenOatFileStatus(const OatFile& file);
	bool GivenOatFileIsOutOfDate(const OatFile& file);
	bool GivenOatFileNeedsRelocation(const OatFile& file);
	bool GivenOatFileIsUpToDate(const OatFile& file);

	// Returns true if there is an accessible profile associated with the dex
	// location.
	// This returns false if profiling is disabled.
	bool ProfileExists();

	// The old profile is a file containing a previous snapshot of profiling
	// information associated with the dex file code. This is used to track how
	// the profiling information has changed over time.
	//
	// Returns true if there is an accessible old profile associated with the
	// dex location.
	// This returns false if profiling is disabled.
	bool OldProfileExists();

	// Returns true if there has been a significant change between the old
	// profile and the current profile.
	// This returns false if profiling is disabled.
	bool IsProfileChangeSignificant();

	// Copy the current profile to the old profile location.
	void CopyProfileFile();

	// Generates the oat file by relocation from the named input file.
	// This does not check the current status before attempting to relocate the
	// oat file.
	// Returns true on success.
	// This will fail if dex2oat is not enabled in the current runtime.
	//
	// If there is a failure, the value of error_msg will be set to a string
	// describing why there was failure. error_msg must not be null.
	bool RelocateOatFile(const std::string* input_file, std::string* error_msg);

	// Generate the oat file from the dex file.
	// This does not check the current status before attempting to generate the
	// oat file.
	// Returns true on success.
	// This will fail if dex2oat is not enabled in the current runtime.
	//
	// If there is a failure, the value of error_msg will be set to a string
	// describing why there was failure. error_msg must not be null.
	bool GenerateOatFile(std::string* error_msg);

	// Executes dex2oat using the current runtime configuration overridden with
	// the given arguments. This does not check to see if dex2oat is enabled in
	// the runtime configuration.
	// Returns true on success.
	//
	// If there is a failure, the value of error_msg will be set to a string
	// describing why there was failure. error_msg must not be null.
	//
	// TODO: The OatFileAssistant probably isn't the right place to have this
	// function.
	static bool Dex2Oat(const std::vector<std::string>& args, std::string* error_msg);

	// Constructs the odex file name for the given dex location.
	// Returns true on success, in which case odex_filename is set to the odex
	// file name.
	// Returns false on error, in which case error_msg describes the error.
	// Neither odex_filename nor error_msg may be null.
	static bool DexFilenameToOdexFilename(const std::string& location,
	InstructionSet isa, std::string* odex_filename, std::string* error_msg);

	private:
	struct ImageInfo {
	uint32_t oat_checksum = 0;
	uintptr_t oat_data_begin = 0;
	int32_t patch_delta = 0;
	std::string location;
	};

	// Returns the path to the dalvik cache directory.
	// Does not check existence of the cache or try to create it.
	// Includes the trailing slash.
	// Returns an empty string if we can't get the dalvik cache directory path.
	std::string DalvikCacheDirectory();

	// Constructs the filename for the profile file.
	// Returns an empty string if we do not have the necessary information to
	// construct the filename.
	std::string ProfileFileName();

	// Constructs the filename for the old profile file.
	// Returns an empty string if we do not have the necessary information to
	// construct the filename.
	std::string OldProfileFileName();

	// Returns the current image location.
	// Returns an empty string if the image location could not be retrieved.
	//
	// TODO: This method should belong with an image file manager, not
	// the oat file assistant.
	static std::string ImageLocation();

	// Gets the dex checksum required for an up-to-date oat file.
	// Returns dex_checksum if a required checksum was located. Returns
	// null if the required checksum was not found.
	// The caller shouldn't clean up or free the returned pointer.
	// This sets the has_original_dex_files_ field to true if a checksum was
	// found for the dex_location_ dex file.
	const uint32_t* GetRequiredDexChecksum();

	// Returns the loaded odex file.
	// Loads the file if needed. Returns null if the file failed to load.
	// The caller shouldn't clean up or free the returned pointer.
	const OatFile* GetOdexFile();

	// Returns true if the odex file is opened executable.
	bool OdexFileIsExecutable();

	// Clear any cached information about the odex file that depends on the
	// contents of the file.
	void ClearOdexFileCache();

	// Returns the loaded oat file.
	// Loads the file if needed. Returns null if the file failed to load.
	// The caller shouldn't clean up or free the returned pointer.
	const OatFile* GetOatFile();

	// Returns true if the oat file is opened executable.
	bool OatFileIsExecutable();

	// Clear any cached information about the oat file that depends on the
	// contents of the file.
	void ClearOatFileCache();

	// Returns the loaded image info.
	// Loads the image info if needed. Returns null if the image info failed
	// to load.
	// The caller shouldn't clean up or free the returned pointer.
	const ImageInfo* GetImageInfo();

	// Returns the loaded profile.
	// Loads the profile if needed. Returns null if the profile failed
	// to load.
	// The caller shouldn't clean up or free the returned pointer.
	ProfileFile* GetProfile();

	// Returns the loaded old profile.
	// Loads the old profile if needed. Returns null if the old profile
	// failed to load.
	// The caller shouldn't clean up or free the returned pointer.
	ProfileFile* GetOldProfile();

	// To implement Lock(), we lock a dummy file where the oat file would go
	// (adding ".flock" to the target file name) and retain the lock for the
	// remaining lifetime of the OatFileAssistant object.
	ScopedFlock flock_;

	// In a properly constructed OatFileAssistant object, dex_location_ should
	// never be null.
	const char* dex_location_ = nullptr;

	// In a properly constructed OatFileAssistant object, isa_ should be either
	// the 32 or 64 bit variant for the current device.
	const InstructionSet isa_ = kNone;

	// The package name, used solely to find the profile file.
	// This may be null in a properly constructed object. In this case,
	// profile_load_attempted_ and old_profile_load_attempted_ will be true, and
	// profile_load_succeeded_ and old_profile_load_succeeded_ will be false.
	const char* package_name_ = nullptr;

	// Whether we will attempt to load oat files executable.
	bool load_executable_ = false;

	// Cached value of the required dex checksum.
	// This should be accessed only by the GetRequiredDexChecksum() method.
	uint32_t cached_required_dex_checksum_;
	bool required_dex_checksum_attempted_ = false;
	bool required_dex_checksum_found_;
	bool has_original_dex_files_;

	// Cached value of the odex file name.
	// This should be accessed only by the OdexFileName() method.
	bool cached_odex_file_name_attempted_ = false;
	bool cached_odex_file_name_found_;
	std::string cached_odex_file_name_;

	// Cached value of the loaded odex file.
	// Use the GetOdexFile method rather than accessing this directly, unless you
	// know the odex file isn't out of date.
	bool odex_file_load_attempted_ = false;
	std::unique_ptr<OatFile> cached_odex_file_;

	// Cached results for OdexFileIsOutOfDate
	bool odex_file_is_out_of_date_attempted_ = false;
	bool cached_odex_file_is_out_of_date_;

	// Cached results for OdexFileIsUpToDate
	bool odex_file_is_up_to_date_attempted_ = false;
	bool cached_odex_file_is_up_to_date_;

	// Cached value of the oat file name.
	// This should be accessed only by the OatFileName() method.
	bool cached_oat_file_name_attempted_ = false;
	bool cached_oat_file_name_found_;
	std::string cached_oat_file_name_;

	// Cached value of the loaded oat file.
	// Use the GetOatFile method rather than accessing this directly, unless you
	// know the oat file isn't out of date.
	bool oat_file_load_attempted_ = false;
	std::unique_ptr<OatFile> cached_oat_file_;

	// Cached results for OatFileIsOutOfDate
	bool oat_file_is_out_of_date_attempted_ = false;
	bool cached_oat_file_is_out_of_date_;

	// Cached results for OatFileIsUpToDate
	bool oat_file_is_up_to_date_attempted_ = false;
	bool cached_oat_file_is_up_to_date_;

	// Cached value of the image info.
	// Use the GetImageInfo method rather than accessing these directly.
	// TODO: The image info should probably be moved out of the oat file
	// assistant to an image file manager.
	bool image_info_load_attempted_ = false;
	bool image_info_load_succeeded_ = false;
	ImageInfo cached_image_info_;

	// Cached value of the profile file.
	// Use the GetProfile method rather than accessing these directly.
	bool profile_load_attempted_ = false;
	bool profile_load_succeeded_ = false;
	ProfileFile cached_profile_;

	// Cached value of the profile file.
	// Use the GetOldProfile method rather than accessing these directly.
	bool old_profile_load_attempted_ = false;
	bool old_profile_load_succeeded_ = false;
	ProfileFile cached_old_profile_;

	// For debugging only.
	// If this flag is set, the oat or odex file has been released to the user
	// of the OatFileAssistant object and the OatFileAssistant object is in a
	// bad state and should no longer be used.
	bool oat_file_released_ = false;

	DISALLOW_COPY_AND_ASSIGN(OatFileAssistant);
	};

	} // namespace art

	#endif // ART_RUNTIME_OAT_FILE_ASSISTANT_H_