runtime/native/dalvik_system_DexFile.cc - platform/art - Gitiles

 /*
  * Copyright (C) 2008 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.
  */

 #include "dalvik_system_DexFile.h"

 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/stringprintf.h"
 #include "class_linker.h"
 #include "common_throws.h"
 #include "dex_file-inl.h"
 #include "jni_internal.h"
 #include "mirror/class_loader.h"
 #include "mirror/object-inl.h"
 #include "mirror/string.h"
 #include "oat_file_assistant.h"
 #include "oat_file_manager.h"
 #include "os.h"
 #include "profiler.h"
 #include "runtime.h"
 #include "scoped_thread_state_change.h"
 #include "ScopedLocalRef.h"
 #include "ScopedUtfChars.h"
 #include "utils.h"
 #include "well_known_classes.h"
 #include "zip_archive.h"

 namespace art {

 static bool ConvertJavaArrayToDexFiles(
     JNIEnv* env,
     jobject arrayObject,
     /*out*/ std::vector<const DexFile*>& dex_files,
     /*out*/ const OatFile*& oat_file) {
   jarray array = reinterpret_cast<jarray>(arrayObject);

   jsize array_size = env->GetArrayLength(array);
   if (env->ExceptionCheck() == JNI_TRUE) {
     return false;
   }

   // TODO: Optimize. On 32bit we can use an int array.
   jboolean is_long_data_copied;
   jlong* long_data = env->GetLongArrayElements(reinterpret_cast<jlongArray>(array),
                                                &is_long_data_copied);
   if (env->ExceptionCheck() == JNI_TRUE) {
     return false;
   }

   oat_file = reinterpret_cast<const OatFile*>(static_cast<uintptr_t>(long_data[kOatFileIndex]));
   dex_files.reserve(array_size - 1);
   for (jsize i = kDexFileIndexStart; i < array_size; ++i) {
     dex_files.push_back(reinterpret_cast<const DexFile*>(static_cast<uintptr_t>(long_data[i])));
   }

   env->ReleaseLongArrayElements(reinterpret_cast<jlongArray>(array), long_data, JNI_ABORT);
   return env->ExceptionCheck() != JNI_TRUE;
 }

 static jlongArray ConvertDexFilesToJavaArray(JNIEnv* env,
                                              const OatFile* oat_file,
                                              std::vector<std::unique_ptr<const DexFile>>& vec) {
   // Add one for the oat file.
   jlongArray long_array = env->NewLongArray(static_cast<jsize>(kDexFileIndexStart + vec.size()));
   if (env->ExceptionCheck() == JNI_TRUE) {
     return nullptr;
   }

   jboolean is_long_data_copied;
   jlong* long_data = env->GetLongArrayElements(long_array, &is_long_data_copied);
   if (env->ExceptionCheck() == JNI_TRUE) {
     return nullptr;
   }

   long_data[kOatFileIndex] = reinterpret_cast<uintptr_t>(oat_file);
   for (size_t i = 0; i < vec.size(); ++i) {
     long_data[kDexFileIndexStart + i] = reinterpret_cast<uintptr_t>(vec[i].get());
   }

   env->ReleaseLongArrayElements(long_array, long_data, 0);
   if (env->ExceptionCheck() == JNI_TRUE) {
     return nullptr;
   }

   // Now release all the unique_ptrs.
   for (auto& dex_file : vec) {
     dex_file.release();
   }

   return long_array;
 }

 // A smart pointer that provides read-only access to a Java string's UTF chars.
 // Unlike libcore's NullableScopedUtfChars, this will *not* throw NullPointerException if
 // passed a null jstring. The correct idiom is:
 //
 //   NullableScopedUtfChars name(env, javaName);
 //   if (env->ExceptionCheck()) {
 //       return null;
 //   }
 //   // ... use name.c_str()
 //
 // TODO: rewrite to get rid of this, or change ScopedUtfChars to offer this option.
 class NullableScopedUtfChars {
  public:
   NullableScopedUtfChars(JNIEnv* env, jstring s) : mEnv(env), mString(s) {
     mUtfChars = (s != nullptr) ? env->GetStringUTFChars(s, nullptr) : nullptr;
   }

   ~NullableScopedUtfChars() {
     if (mUtfChars) {
       mEnv->ReleaseStringUTFChars(mString, mUtfChars);
     }
   }

   const char* c_str() const {
     return mUtfChars;
   }

   size_t size() const {
     return strlen(mUtfChars);
   }

   // Element access.
   const char& operator[](size_t n) const {
     return mUtfChars[n];
   }

  private:
   JNIEnv* mEnv;
   jstring mString;
   const char* mUtfChars;

   // Disallow copy and assignment.
   NullableScopedUtfChars(const NullableScopedUtfChars&);
   void operator=(const NullableScopedUtfChars&);
 };

 static jobject DexFile_openDexFileNative(
     JNIEnv* env, jclass, jstring javaSourceName, jstring javaOutputName, jint) {
   ScopedUtfChars sourceName(env, javaSourceName);
   if (sourceName.c_str() == nullptr) {
     return 0;
   }
   NullableScopedUtfChars outputName(env, javaOutputName);
   if (env->ExceptionCheck()) {
     return 0;
   }

   Runtime* const runtime = Runtime::Current();
   ClassLinker* linker = runtime->GetClassLinker();
   std::vector<std::unique_ptr<const DexFile>> dex_files;
   std::vector<std::string> error_msgs;
   const OatFile* oat_file = nullptr;

   dex_files = runtime->GetOatFileManager().OpenDexFilesFromOat(sourceName.c_str(),
                                                                outputName.c_str(),
                                                                /*out*/ &oat_file,
                                                                /*out*/ &error_msgs);

   if (!dex_files.empty()) {
     jlongArray array = ConvertDexFilesToJavaArray(env, oat_file, dex_files);
     if (array == nullptr) {
       ScopedObjectAccess soa(env);
       for (auto& dex_file : dex_files) {
         if (linker->FindDexCache(soa.Self(), *dex_file, true) != nullptr) {
           dex_file.release();
         }
       }
     }
     return array;
   } else {
     ScopedObjectAccess soa(env);
     CHECK(!error_msgs.empty());
     // The most important message is at the end. So set up nesting by going forward, which will
     // wrap the existing exception as a cause for the following one.
     auto it = error_msgs.begin();
     auto itEnd = error_msgs.end();
     for ( ; it != itEnd; ++it) {
       ThrowWrappedIOException("%s", it->c_str());
     }

     return nullptr;
   }
 }

 static jboolean DexFile_closeDexFile(JNIEnv* env, jclass, jobject cookie) {
   std::vector<const DexFile*> dex_files;
   const OatFile* oat_file;
   if (!ConvertJavaArrayToDexFiles(env, cookie, dex_files, oat_file)) {
     Thread::Current()->AssertPendingException();
     return JNI_FALSE;
   }
   Runtime* const runtime = Runtime::Current();
   bool all_deleted = true;
   {
     ScopedObjectAccess soa(env);
     mirror::Object* dex_files_object = soa.Decode<mirror::Object*>(cookie);
     mirror::LongArray* long_dex_files = dex_files_object->AsLongArray();
     // Delete dex files associated with this dalvik.system.DexFile since there should not be running
     // code using it. dex_files is a vector due to multidex.
     ClassLinker* const class_linker = runtime->GetClassLinker();
     int32_t i = kDexFileIndexStart;  // Oat file is at index 0.
     for (const DexFile* dex_file : dex_files) {
       if (dex_file != nullptr) {
         // Only delete the dex file if the dex cache is not found to prevent runtime crashes if there
         // are calls to DexFile.close while the ART DexFile is still in use.
         if (class_linker->FindDexCache(soa.Self(), *dex_file, true) == nullptr) {
           // Clear the element in the array so that we can call close again.
           long_dex_files->Set(i, 0);
           delete dex_file;
         } else {
           all_deleted = false;
         }
       }
       ++i;
     }
   }

   // oat_file can be null if we are running without dex2oat.
   if (all_deleted && oat_file != nullptr) {
     // If all of the dex files are no longer in use we can unmap the corresponding oat file.
     VLOG(class_linker) << "Unregistering " << oat_file;
     runtime->GetOatFileManager().UnRegisterAndDeleteOatFile(oat_file);
   }
   return all_deleted ? JNI_TRUE : JNI_FALSE;
 }

 static jclass DexFile_defineClassNative(JNIEnv* env,
                                         jclass,
                                         jstring javaName,
                                         jobject javaLoader,
                                         jobject cookie) {
   std::vector<const DexFile*> dex_files;
   const OatFile* oat_file;
   if (!ConvertJavaArrayToDexFiles(env, cookie, /*out*/ dex_files, /*out*/ oat_file)) {
     VLOG(class_linker) << "Failed to find dex_file";
     DCHECK(env->ExceptionCheck());
     return nullptr;
   }

   ScopedUtfChars class_name(env, javaName);
   if (class_name.c_str() == nullptr) {
     VLOG(class_linker) << "Failed to find class_name";
     return nullptr;
   }
   const std::string descriptor(DotToDescriptor(class_name.c_str()));
   const size_t hash(ComputeModifiedUtf8Hash(descriptor.c_str()));
   for (auto& dex_file : dex_files) {
     const DexFile::ClassDef* dex_class_def = dex_file->FindClassDef(descriptor.c_str(), hash);
     if (dex_class_def != nullptr) {
       ScopedObjectAccess soa(env);
       ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
       StackHandleScope<1> hs(soa.Self());
       Handle<mirror::ClassLoader> class_loader(
           hs.NewHandle(soa.Decode<mirror::ClassLoader*>(javaLoader)));
       class_linker->RegisterDexFile(
           *dex_file,
           class_linker->GetOrCreateAllocatorForClassLoader(class_loader.Get()));
       mirror::Class* result = class_linker->DefineClass(soa.Self(),
                                                         descriptor.c_str(),
                                                         hash,
                                                         class_loader,
                                                         *dex_file,
                                                         *dex_class_def);
       if (result != nullptr) {
         VLOG(class_linker) << "DexFile_defineClassNative returning " << result
                            << " for " << class_name.c_str();
         return soa.AddLocalReference<jclass>(result);
       }
     }
   }
   VLOG(class_linker) << "Failed to find dex_class_def " << class_name.c_str();
   return nullptr;
 }

 // Needed as a compare functor for sets of const char
 struct CharPointerComparator {
   bool operator()(const char *str1, const char *str2) const {
     return strcmp(str1, str2) < 0;
   }
 };

 // Note: this can be an expensive call, as we sort out duplicates in MultiDex files.
 static jobjectArray DexFile_getClassNameList(JNIEnv* env, jclass, jobject cookie) {
   const OatFile* oat_file = nullptr;
   std::vector<const DexFile*> dex_files;
   if (!ConvertJavaArrayToDexFiles(env, cookie, /*out */ dex_files, /* out */ oat_file)) {
     DCHECK(env->ExceptionCheck());
     return nullptr;
   }

   // Push all class descriptors into a set. Use set instead of unordered_set as we want to
   // retrieve all in the end.
   std::set<const char*, CharPointerComparator> descriptors;
   for (auto& dex_file : dex_files) {
     for (size_t i = 0; i < dex_file->NumClassDefs(); ++i) {
       const DexFile::ClassDef& class_def = dex_file->GetClassDef(i);
       const char* descriptor = dex_file->GetClassDescriptor(class_def);
       descriptors.insert(descriptor);
     }
   }

   // Now create output array and copy the set into it.
   jobjectArray result = env->NewObjectArray(descriptors.size(),
                                             WellKnownClasses::java_lang_String,
                                             nullptr);
   if (result != nullptr) {
     auto it = descriptors.begin();
     auto it_end = descriptors.end();
     jsize i = 0;
     for (; it != it_end; it++, ++i) {
       std::string descriptor(DescriptorToDot(*it));
       ScopedLocalRef<jstring> jdescriptor(env, env->NewStringUTF(descriptor.c_str()));
       if (jdescriptor.get() == nullptr) {
         return nullptr;
       }
       env->SetObjectArrayElement(result, i, jdescriptor.get());
     }
   }
   return result;
 }

 static jint GetDexOptNeeded(JNIEnv* env,
                             const char* filename,
                             const char* pkgname,
                             const char* instruction_set,
                             const jboolean defer) {
   if ((filename == nullptr) || !OS::FileExists(filename)) {
     LOG(ERROR) << "DexFile_getDexOptNeeded file '" << filename << "' does not exist";
     ScopedLocalRef<jclass> fnfe(env, env->FindClass("java/io/FileNotFoundException"));
     const char* message = (filename == nullptr) ? "<empty file name>" : filename;
     env->ThrowNew(fnfe.get(), message);
     return OatFileAssistant::kNoDexOptNeeded;
   }

   const InstructionSet target_instruction_set = GetInstructionSetFromString(instruction_set);
   if (target_instruction_set == kNone) {
     ScopedLocalRef<jclass> iae(env, env->FindClass("java/lang/IllegalArgumentException"));
     std::string message(StringPrintf("Instruction set %s is invalid.", instruction_set));
     env->ThrowNew(iae.get(), message.c_str());
     return 0;
   }

   // TODO: Verify the dex location is well formed, and throw an IOException if
   // not?

   OatFileAssistant oat_file_assistant(filename, target_instruction_set, false, pkgname);

   // Always treat elements of the bootclasspath as up-to-date.
   if (oat_file_assistant.IsInBootClassPath()) {
     return OatFileAssistant::kNoDexOptNeeded;
   }

   // TODO: Checking the profile should probably be done in the GetStatus()
   // function. We have it here because GetStatus() should not be copying
   // profile files. But who should be copying profile files?
   if (oat_file_assistant.OdexFileIsOutOfDate()) {
     // Needs recompile if profile has changed significantly.
     if (Runtime::Current()->GetProfilerOptions().IsEnabled()) {
       if (oat_file_assistant.IsProfileChangeSignificant()) {
         if (!defer) {
           oat_file_assistant.CopyProfileFile();
         }
         return OatFileAssistant::kDex2OatNeeded;
       } else if (oat_file_assistant.ProfileExists()
           && !oat_file_assistant.OldProfileExists()) {
         if (!defer) {
           oat_file_assistant.CopyProfileFile();
         }
       }
     }
   }

   return oat_file_assistant.GetDexOptNeeded();
 }

 static jint DexFile_getDexOptNeeded(JNIEnv* env,
                                     jclass,
                                     jstring javaFilename,
                                     jstring javaPkgname,
                                     jstring javaInstructionSet,
                                     jboolean defer) {
   ScopedUtfChars filename(env, javaFilename);
   if (env->ExceptionCheck()) {
     return 0;
   }

   NullableScopedUtfChars pkgname(env, javaPkgname);

   ScopedUtfChars instruction_set(env, javaInstructionSet);
   if (env->ExceptionCheck()) {
     return 0;
   }

   return GetDexOptNeeded(env,
                          filename.c_str(),
                          pkgname.c_str(),
                          instruction_set.c_str(),
                          defer);
 }

 // public API, null pkgname
 static jboolean DexFile_isDexOptNeeded(JNIEnv* env, jclass, jstring javaFilename) {
   const char* instruction_set = GetInstructionSetString(kRuntimeISA);
   ScopedUtfChars filename(env, javaFilename);
   jint status = GetDexOptNeeded(env, filename.c_str(), nullptr /* pkgname */,
                                 instruction_set, false /* defer */);
   return (status != OatFileAssistant::kNoDexOptNeeded) ? JNI_TRUE : JNI_FALSE;
 }

 static JNINativeMethod gMethods[] = {
   NATIVE_METHOD(DexFile, closeDexFile, "(Ljava/lang/Object;)Z"),
   NATIVE_METHOD(DexFile, defineClassNative,
                 "(Ljava/lang/String;Ljava/lang/ClassLoader;Ljava/lang/Object;)Ljava/lang/Class;"),
   NATIVE_METHOD(DexFile, getClassNameList, "(Ljava/lang/Object;)[Ljava/lang/String;"),
   NATIVE_METHOD(DexFile, isDexOptNeeded, "(Ljava/lang/String;)Z"),
   NATIVE_METHOD(DexFile, getDexOptNeeded,
                 "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Z)I"),
   NATIVE_METHOD(DexFile, openDexFileNative,
                 "(Ljava/lang/String;Ljava/lang/String;I)Ljava/lang/Object;"),
 };

 void register_dalvik_system_DexFile(JNIEnv* env) {
   REGISTER_NATIVE_METHODS("dalvik/system/DexFile");
 }

 }  // namespace art
	/*
	* Copyright (C) 2008 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.
	*/

	#include "dalvik_system_DexFile.h"

	#include "base/logging.h"
	#include "base/stl_util.h"
	#include "base/stringprintf.h"
	#include "class_linker.h"
	#include "common_throws.h"
	#include "dex_file-inl.h"
	#include "jni_internal.h"
	#include "mirror/class_loader.h"
	#include "mirror/object-inl.h"
	#include "mirror/string.h"
	#include "oat_file_assistant.h"
	#include "oat_file_manager.h"
	#include "os.h"
	#include "profiler.h"
	#include "runtime.h"
	#include "scoped_thread_state_change.h"
	#include "ScopedLocalRef.h"
	#include "ScopedUtfChars.h"
	#include "utils.h"
	#include "well_known_classes.h"
	#include "zip_archive.h"

	namespace art {

	static bool ConvertJavaArrayToDexFiles(
	JNIEnv* env,
	jobject arrayObject,
	/out/ std::vector<const DexFile*>& dex_files,
	/out/ const OatFile*& oat_file) {
	jarray array = reinterpret_cast<jarray>(arrayObject);

	jsize array_size = env->GetArrayLength(array);
	if (env->ExceptionCheck() == JNI_TRUE) {
	return false;
	}

	// TODO: Optimize. On 32bit we can use an int array.
	jboolean is_long_data_copied;
	jlong* long_data = env->GetLongArrayElements(reinterpret_cast<jlongArray>(array),
	&is_long_data_copied);
	if (env->ExceptionCheck() == JNI_TRUE) {
	return false;
	}

	oat_file = reinterpret_cast<const OatFile*>(static_cast<uintptr_t>(long_data[kOatFileIndex]));
	dex_files.reserve(array_size - 1);
	for (jsize i = kDexFileIndexStart; i < array_size; ++i) {
	dex_files.push_back(reinterpret_cast<const DexFile*>(static_cast<uintptr_t>(long_data[i])));
	}

	env->ReleaseLongArrayElements(reinterpret_cast<jlongArray>(array), long_data, JNI_ABORT);
	return env->ExceptionCheck() != JNI_TRUE;
	}

	static jlongArray ConvertDexFilesToJavaArray(JNIEnv* env,
	const OatFile* oat_file,
	std::vector<std::unique_ptr<const DexFile>>& vec) {
	// Add one for the oat file.
	jlongArray long_array = env->NewLongArray(static_cast<jsize>(kDexFileIndexStart + vec.size()));
	if (env->ExceptionCheck() == JNI_TRUE) {
	return nullptr;
	}

	jboolean is_long_data_copied;
	jlong* long_data = env->GetLongArrayElements(long_array, &is_long_data_copied);
	if (env->ExceptionCheck() == JNI_TRUE) {
	return nullptr;
	}

	long_data[kOatFileIndex] = reinterpret_cast<uintptr_t>(oat_file);
	for (size_t i = 0; i < vec.size(); ++i) {
	long_data[kDexFileIndexStart + i] = reinterpret_cast<uintptr_t>(vec[i].get());
	}

	env->ReleaseLongArrayElements(long_array, long_data, 0);
	if (env->ExceptionCheck() == JNI_TRUE) {
	return nullptr;
	}

	// Now release all the unique_ptrs.
	for (auto& dex_file : vec) {
	dex_file.release();
	}

	return long_array;
	}

	// A smart pointer that provides read-only access to a Java string's UTF chars.
	// Unlike libcore's NullableScopedUtfChars, this will not throw NullPointerException if
	// passed a null jstring. The correct idiom is:
	//
	// NullableScopedUtfChars name(env, javaName);
	// if (env->ExceptionCheck()) {
	// return null;
	// }
	// // ... use name.c_str()
	//
	// TODO: rewrite to get rid of this, or change ScopedUtfChars to offer this option.
	class NullableScopedUtfChars {
	public:
	NullableScopedUtfChars(JNIEnv* env, jstring s) : mEnv(env), mString(s) {
	mUtfChars = (s != nullptr) ? env->GetStringUTFChars(s, nullptr) : nullptr;
	}

	~NullableScopedUtfChars() {
	if (mUtfChars) {
	mEnv->ReleaseStringUTFChars(mString, mUtfChars);
	}
	}

	const char* c_str() const {
	return mUtfChars;
	}

	size_t size() const {
	return strlen(mUtfChars);
	}

	// Element access.
	const char& operator[](size_t n) const {
	return mUtfChars[n];
	}

	private:
	JNIEnv* mEnv;
	jstring mString;
	const char* mUtfChars;

	// Disallow copy and assignment.
	NullableScopedUtfChars(const NullableScopedUtfChars&);
	void operator=(const NullableScopedUtfChars&);
	};

	static jobject DexFile_openDexFileNative(
	JNIEnv* env, jclass, jstring javaSourceName, jstring javaOutputName, jint) {
	ScopedUtfChars sourceName(env, javaSourceName);
	if (sourceName.c_str() == nullptr) {
	return 0;
	}
	NullableScopedUtfChars outputName(env, javaOutputName);
	if (env->ExceptionCheck()) {
	return 0;
	}

	Runtime* const runtime = Runtime::Current();
	ClassLinker* linker = runtime->GetClassLinker();
	std::vector<std::unique_ptr<const DexFile>> dex_files;
	std::vector<std::string> error_msgs;
	const OatFile* oat_file = nullptr;

	dex_files = runtime->GetOatFileManager().OpenDexFilesFromOat(sourceName.c_str(),
	outputName.c_str(),
	/out/ &oat_file,
	/out/ &error_msgs);

	if (!dex_files.empty()) {
	jlongArray array = ConvertDexFilesToJavaArray(env, oat_file, dex_files);
	if (array == nullptr) {
	ScopedObjectAccess soa(env);
	for (auto& dex_file : dex_files) {
	if (linker->FindDexCache(soa.Self(), *dex_file, true) != nullptr) {
	dex_file.release();
	}
	}
	}
	return array;
	} else {
	ScopedObjectAccess soa(env);
	CHECK(!error_msgs.empty());
	// The most important message is at the end. So set up nesting by going forward, which will
	// wrap the existing exception as a cause for the following one.
	auto it = error_msgs.begin();
	auto itEnd = error_msgs.end();
	for ( ; it != itEnd; ++it) {
	ThrowWrappedIOException("%s", it->c_str());
	}

	return nullptr;
	}
	}

	static jboolean DexFile_closeDexFile(JNIEnv* env, jclass, jobject cookie) {
	std::vector<const DexFile*> dex_files;
	const OatFile* oat_file;
	if (!ConvertJavaArrayToDexFiles(env, cookie, dex_files, oat_file)) {
	Thread::Current()->AssertPendingException();
	return JNI_FALSE;
	}
	Runtime* const runtime = Runtime::Current();
	bool all_deleted = true;
	{
	ScopedObjectAccess soa(env);
	mirror::Object* dex_files_object = soa.Decode<mirror::Object*>(cookie);
	mirror::LongArray* long_dex_files = dex_files_object->AsLongArray();
	// Delete dex files associated with this dalvik.system.DexFile since there should not be running
	// code using it. dex_files is a vector due to multidex.
	ClassLinker* const class_linker = runtime->GetClassLinker();
	int32_t i = kDexFileIndexStart; // Oat file is at index 0.
	for (const DexFile* dex_file : dex_files) {
	if (dex_file != nullptr) {
	// Only delete the dex file if the dex cache is not found to prevent runtime crashes if there
	// are calls to DexFile.close while the ART DexFile is still in use.
	if (class_linker->FindDexCache(soa.Self(), *dex_file, true) == nullptr) {
	// Clear the element in the array so that we can call close again.
	long_dex_files->Set(i, 0);
	delete dex_file;
	} else {
	all_deleted = false;
	}
	}
	++i;
	}
	}

	// oat_file can be null if we are running without dex2oat.
	if (all_deleted && oat_file != nullptr) {
	// If all of the dex files are no longer in use we can unmap the corresponding oat file.
	VLOG(class_linker) << "Unregistering " << oat_file;
	runtime->GetOatFileManager().UnRegisterAndDeleteOatFile(oat_file);
	}
	return all_deleted ? JNI_TRUE : JNI_FALSE;
	}

	static jclass DexFile_defineClassNative(JNIEnv* env,
	jclass,
	jstring javaName,
	jobject javaLoader,
	jobject cookie) {
	std::vector<const DexFile*> dex_files;
	const OatFile* oat_file;
	if (!ConvertJavaArrayToDexFiles(env, cookie, /out/ dex_files, /out/ oat_file)) {
	VLOG(class_linker) << "Failed to find dex_file";
	DCHECK(env->ExceptionCheck());
	return nullptr;
	}

	ScopedUtfChars class_name(env, javaName);
	if (class_name.c_str() == nullptr) {
	VLOG(class_linker) << "Failed to find class_name";
	return nullptr;
	}
	const std::string descriptor(DotToDescriptor(class_name.c_str()));
	const size_t hash(ComputeModifiedUtf8Hash(descriptor.c_str()));
	for (auto& dex_file : dex_files) {
	const DexFile::ClassDef* dex_class_def = dex_file->FindClassDef(descriptor.c_str(), hash);
	if (dex_class_def != nullptr) {
	ScopedObjectAccess soa(env);
	ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
	StackHandleScope<1> hs(soa.Self());
	Handle<mirror::ClassLoader> class_loader(
	hs.NewHandle(soa.Decode<mirror::ClassLoader*>(javaLoader)));
	class_linker->RegisterDexFile(
	*dex_file,
	class_linker->GetOrCreateAllocatorForClassLoader(class_loader.Get()));
	mirror::Class* result = class_linker->DefineClass(soa.Self(),
	descriptor.c_str(),
	hash,
	class_loader,
	*dex_file,
	*dex_class_def);
	if (result != nullptr) {
	VLOG(class_linker) << "DexFile_defineClassNative returning " << result
	<< " for " << class_name.c_str();
	return soa.AddLocalReference<jclass>(result);
	}
	}
	}
	VLOG(class_linker) << "Failed to find dex_class_def " << class_name.c_str();
	return nullptr;
	}

	// Needed as a compare functor for sets of const char
	struct CharPointerComparator {
	bool operator()(const char str1, const char str2) const {
	return strcmp(str1, str2) < 0;
	}
	};

	// Note: this can be an expensive call, as we sort out duplicates in MultiDex files.
	static jobjectArray DexFile_getClassNameList(JNIEnv* env, jclass, jobject cookie) {
	const OatFile* oat_file = nullptr;
	std::vector<const DexFile*> dex_files;
	if (!ConvertJavaArrayToDexFiles(env, cookie, /out / dex_files, /* out */ oat_file)) {
	DCHECK(env->ExceptionCheck());
	return nullptr;
	}

	// Push all class descriptors into a set. Use set instead of unordered_set as we want to
	// retrieve all in the end.
	std::set<const char*, CharPointerComparator> descriptors;
	for (auto& dex_file : dex_files) {
	for (size_t i = 0; i < dex_file->NumClassDefs(); ++i) {
	const DexFile::ClassDef& class_def = dex_file->GetClassDef(i);
	const char* descriptor = dex_file->GetClassDescriptor(class_def);
	descriptors.insert(descriptor);
	}
	}

	// Now create output array and copy the set into it.
	jobjectArray result = env->NewObjectArray(descriptors.size(),
	WellKnownClasses::java_lang_String,
	nullptr);
	if (result != nullptr) {
	auto it = descriptors.begin();
	auto it_end = descriptors.end();
	jsize i = 0;
	for (; it != it_end; it++, ++i) {
	std::string descriptor(DescriptorToDot(*it));
	ScopedLocalRef<jstring> jdescriptor(env, env->NewStringUTF(descriptor.c_str()));
	if (jdescriptor.get() == nullptr) {
	return nullptr;
	}
	env->SetObjectArrayElement(result, i, jdescriptor.get());
	}
	}
	return result;
	}

	static jint GetDexOptNeeded(JNIEnv* env,
	const char* filename,
	const char* pkgname,
	const char* instruction_set,
	const jboolean defer) {
	if ((filename == nullptr) \|\| !OS::FileExists(filename)) {
	LOG(ERROR) << "DexFile_getDexOptNeeded file '" << filename << "' does not exist";
	ScopedLocalRef<jclass> fnfe(env, env->FindClass("java/io/FileNotFoundException"));
	const char* message = (filename == nullptr) ? "<empty file name>" : filename;
	env->ThrowNew(fnfe.get(), message);
	return OatFileAssistant::kNoDexOptNeeded;
	}

	const InstructionSet target_instruction_set = GetInstructionSetFromString(instruction_set);
	if (target_instruction_set == kNone) {
	ScopedLocalRef<jclass> iae(env, env->FindClass("java/lang/IllegalArgumentException"));
	std::string message(StringPrintf("Instruction set %s is invalid.", instruction_set));
	env->ThrowNew(iae.get(), message.c_str());
	return 0;
	}

	// TODO: Verify the dex location is well formed, and throw an IOException if
	// not?

	OatFileAssistant oat_file_assistant(filename, target_instruction_set, false, pkgname);

	// Always treat elements of the bootclasspath as up-to-date.
	if (oat_file_assistant.IsInBootClassPath()) {
	return OatFileAssistant::kNoDexOptNeeded;
	}

	// TODO: Checking the profile should probably be done in the GetStatus()
	// function. We have it here because GetStatus() should not be copying
	// profile files. But who should be copying profile files?
	if (oat_file_assistant.OdexFileIsOutOfDate()) {
	// Needs recompile if profile has changed significantly.
	if (Runtime::Current()->GetProfilerOptions().IsEnabled()) {
	if (oat_file_assistant.IsProfileChangeSignificant()) {
	if (!defer) {
	oat_file_assistant.CopyProfileFile();
	}
	return OatFileAssistant::kDex2OatNeeded;
	} else if (oat_file_assistant.ProfileExists()
	&& !oat_file_assistant.OldProfileExists()) {
	if (!defer) {
	oat_file_assistant.CopyProfileFile();
	}
	}
	}
	}

	return oat_file_assistant.GetDexOptNeeded();
	}

	static jint DexFile_getDexOptNeeded(JNIEnv* env,
	jclass,
	jstring javaFilename,
	jstring javaPkgname,
	jstring javaInstructionSet,
	jboolean defer) {
	ScopedUtfChars filename(env, javaFilename);
	if (env->ExceptionCheck()) {
	return 0;
	}

	NullableScopedUtfChars pkgname(env, javaPkgname);

	ScopedUtfChars instruction_set(env, javaInstructionSet);
	if (env->ExceptionCheck()) {
	return 0;
	}

	return GetDexOptNeeded(env,
	filename.c_str(),
	pkgname.c_str(),
	instruction_set.c_str(),
	defer);
	}

	// public API, null pkgname
	static jboolean DexFile_isDexOptNeeded(JNIEnv* env, jclass, jstring javaFilename) {
	const char* instruction_set = GetInstructionSetString(kRuntimeISA);
	ScopedUtfChars filename(env, javaFilename);
	jint status = GetDexOptNeeded(env, filename.c_str(), nullptr /* pkgname */,
	instruction_set, false /* defer */);
	return (status != OatFileAssistant::kNoDexOptNeeded) ? JNI_TRUE : JNI_FALSE;
	}

	static JNINativeMethod gMethods[] = {
	NATIVE_METHOD(DexFile, closeDexFile, "(Ljava/lang/Object;)Z"),
	NATIVE_METHOD(DexFile, defineClassNative,
	"(Ljava/lang/String;Ljava/lang/ClassLoader;Ljava/lang/Object;)Ljava/lang/Class;"),
	NATIVE_METHOD(DexFile, getClassNameList, "(Ljava/lang/Object;)[Ljava/lang/String;"),
	NATIVE_METHOD(DexFile, isDexOptNeeded, "(Ljava/lang/String;)Z"),
	NATIVE_METHOD(DexFile, getDexOptNeeded,
	"(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Z)I"),
	NATIVE_METHOD(DexFile, openDexFileNative,
	"(Ljava/lang/String;Ljava/lang/String;I)Ljava/lang/Object;"),
	};

	void register_dalvik_system_DexFile(JNIEnv* env) {
	REGISTER_NATIVE_METHODS("dalvik/system/DexFile");
	}

	} // namespace art