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* Copyright (C) 2015 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "oat_file_manager.h"
#include <memory>
#include <queue>
#include <vector>
#include "base/logging.h"
#include "base/stl_util.h"
#include "class_linker.h"
#include "dex_file-inl.h"
#include "gc/space/image_space.h"
#include "handle_scope-inl.h"
#include "mirror/class_loader.h"
#include "oat_file_assistant.h"
#include "scoped_thread_state_change.h"
#include "thread-inl.h"
#include "thread_list.h"
namespace art {
// For b/21333911.
// Only enabled for debug builds to prevent bit rot. There are too many performance regressions for
// normal builds.
static constexpr bool kDuplicateClassesCheck = kIsDebugBuild;
// If true, then we attempt to load the application image if it exists.
static constexpr bool kEnableAppImage = true;
const OatFile* OatFileManager::RegisterOatFile(std::unique_ptr<const OatFile> oat_file) {
WriterMutexLock mu(Thread::Current(), *Locks::oat_file_manager_lock_);
DCHECK(oat_file != nullptr);
if (kIsDebugBuild) {
CHECK(oat_files_.find(oat_file) == oat_files_.end());
for (const std::unique_ptr<const OatFile>& existing : oat_files_) {
CHECK_NE(oat_file.get(), existing.get()) << oat_file->GetLocation();
// Check that we don't have an oat file with the same address. Copies of the same oat file
// should be loaded at different addresses.
CHECK_NE(oat_file->Begin(), existing->Begin()) << "Oat file already mapped at that location";
have_non_pic_oat_file_ = have_non_pic_oat_file_ || !oat_file->IsPic();
const OatFile* ret = oat_file.get();
return ret;
void OatFileManager::UnRegisterAndDeleteOatFile(const OatFile* oat_file) {
WriterMutexLock mu(Thread::Current(), *Locks::oat_file_manager_lock_);
DCHECK(oat_file != nullptr);
std::unique_ptr<const OatFile> compare(oat_file);
auto it = oat_files_.find(compare);
CHECK(it != oat_files_.end());
const OatFile* OatFileManager::FindOpenedOatFileFromOatLocation(const std::string& oat_location)
const {
ReaderMutexLock mu(Thread::Current(), *Locks::oat_file_manager_lock_);
return FindOpenedOatFileFromOatLocationLocked(oat_location);
const OatFile* OatFileManager::FindOpenedOatFileFromOatLocationLocked(
const std::string& oat_location) const {
for (const std::unique_ptr<const OatFile>& oat_file : oat_files_) {
if (oat_file->GetLocation() == oat_location) {
return oat_file.get();
return nullptr;
std::vector<const OatFile*> OatFileManager::GetBootOatFiles() const {
std::vector<const OatFile*> oat_files;
std::vector<gc::space::ImageSpace*> image_spaces =
for (gc::space::ImageSpace* image_space : image_spaces) {
return oat_files;
const OatFile* OatFileManager::GetPrimaryOatFile() const {
ReaderMutexLock mu(Thread::Current(), *Locks::oat_file_manager_lock_);
std::vector<const OatFile*> boot_oat_files = GetBootOatFiles();
if (!boot_oat_files.empty()) {
for (const std::unique_ptr<const OatFile>& oat_file : oat_files_) {
if (std::find(boot_oat_files.begin(), boot_oat_files.end(), oat_file.get()) ==
boot_oat_files.end()) {
return oat_file.get();
return nullptr;
OatFileManager::~OatFileManager() {
// Explicitly clear oat_files_ since the OatFile destructor calls back into OatFileManager for
// UnRegisterOatFileLocation.
std::vector<const OatFile*> OatFileManager::RegisterImageOatFiles(
std::vector<gc::space::ImageSpace*> spaces) {
std::vector<const OatFile*> oat_files;
for (gc::space::ImageSpace* space : spaces) {
return oat_files;
class DexFileAndClassPair : ValueObject {
DexFileAndClassPair(const DexFile* dex_file, size_t current_class_index, bool from_loaded_oat)
: cached_descriptor_(GetClassDescriptor(dex_file, current_class_index)),
from_loaded_oat_(from_loaded_oat) {}
DexFileAndClassPair(const DexFileAndClassPair& rhs) = default;
DexFileAndClassPair& operator=(const DexFileAndClassPair& rhs) = default;
const char* GetCachedDescriptor() const {
return cached_descriptor_;
bool operator<(const DexFileAndClassPair& rhs) const {
const int cmp = strcmp(cached_descriptor_, rhs.cached_descriptor_);
if (cmp != 0) {
// Note that the order must be reversed. We want to iterate over the classes in dex files.
// They are sorted lexicographically. Thus, the priority-queue must be a min-queue.
return cmp > 0;
return dex_file_ < rhs.dex_file_;
bool DexFileHasMoreClasses() const {
return current_class_index_ + 1 < dex_file_->NumClassDefs();
void Next() {
cached_descriptor_ = GetClassDescriptor(dex_file_.get(), current_class_index_);
size_t GetCurrentClassIndex() const {
return current_class_index_;
bool FromLoadedOat() const {
return from_loaded_oat_;
const DexFile* GetDexFile() const {
return dex_file_.get();
static const char* GetClassDescriptor(const DexFile* dex_file, size_t index) {
const DexFile::ClassDef& class_def = dex_file->GetClassDef(static_cast<uint16_t>(index));
return dex_file->StringByTypeIdx(class_def.class_idx_);
const char* cached_descriptor_;
std::shared_ptr<const DexFile> dex_file_;
size_t current_class_index_;
bool from_loaded_oat_; // We only need to compare mismatches between what we load now
// and what was loaded before. Any old duplicates must have been
// OK, and any new "internal" duplicates are as well (they must
// be from multidex, which resolves correctly).
static void AddDexFilesFromOat(const OatFile* oat_file,
bool already_loaded,
/*out*/std::priority_queue<DexFileAndClassPair>* heap) {
for (const OatDexFile* oat_dex_file : oat_file->GetOatDexFiles()) {
std::string error;
std::unique_ptr<const DexFile> dex_file = oat_dex_file->OpenDexFile(&error);
if (dex_file == nullptr) {
LOG(WARNING) << "Could not create dex file from oat file: " << error;
} else if (dex_file->NumClassDefs() > 0U) {
heap->emplace(dex_file.release(), /*current_class_index*/0U, already_loaded);
static void AddNext(/*inout*/DexFileAndClassPair* original,
/*inout*/std::priority_queue<DexFileAndClassPair>* heap) {
if (original->DexFileHasMoreClasses()) {
// Check for class-def collisions in dex files.
// This works by maintaining a heap with one class from each dex file, sorted by the class
// descriptor. Then a dex-file/class pair is continually removed from the heap and compared
// against the following top element. If the descriptor is the same, it is now checked whether
// the two elements agree on whether their dex file was from an already-loaded oat-file or the
// new oat file. Any disagreement indicates a collision.
bool OatFileManager::HasCollisions(const OatFile* oat_file,
std::string* error_msg /*out*/) const {
DCHECK(oat_file != nullptr);
DCHECK(error_msg != nullptr);
if (!kDuplicateClassesCheck) {
return false;
// Dex files are registered late - once a class is actually being loaded. We have to compare
// against the open oat files. Take the oat_file_manager_lock_ that protects oat_files_ accesses.
ReaderMutexLock mu(Thread::Current(), *Locks::oat_file_manager_lock_);
std::priority_queue<DexFileAndClassPair> queue;
// Add dex files from already loaded oat files, but skip boot.
std::vector<const OatFile*> boot_oat_files = GetBootOatFiles();
// The same OatFile can be loaded multiple times at different addresses. In this case, we don't
// need to check both against each other since they would have resolved the same way at compile
// time.
std::unordered_set<std::string> unique_locations;
for (const std::unique_ptr<const OatFile>& loaded_oat_file : oat_files_) {
DCHECK_NE(loaded_oat_file.get(), oat_file);
const std::string& location = loaded_oat_file->GetLocation();
if (std::find(boot_oat_files.begin(), boot_oat_files.end(), loaded_oat_file.get()) ==
boot_oat_files.end() && location != oat_file->GetLocation() &&
unique_locations.find(location) == unique_locations.end()) {
AddDexFilesFromOat(loaded_oat_file.get(), /*already_loaded*/true, &queue);
if (queue.empty()) {
// No other oat files, return early.
return false;
// Add dex files from the oat file to check.
AddDexFilesFromOat(oat_file, /*already_loaded*/false, &queue);
// Now drain the queue.
while (!queue.empty()) {
// Modifying the top element is only safe if we pop right after.
DexFileAndClassPair compare_pop(;
// Compare against the following elements.
while (!queue.empty()) {
DexFileAndClassPair top(;
if (strcmp(compare_pop.GetCachedDescriptor(), top.GetCachedDescriptor()) == 0) {
// Same descriptor. Check whether it's crossing old-oat-files to new-oat-files.
if (compare_pop.FromLoadedOat() != top.FromLoadedOat()) {
*error_msg =
StringPrintf("Found duplicated class when checking oat files: '%s' in %s and %s",
return true;
AddNext(&top, &queue);
} else {
// Something else. Done here.
AddNext(&compare_pop, &queue);
return false;
std::vector<std::unique_ptr<const DexFile>> OatFileManager::OpenDexFilesFromOat(
const char* dex_location,
const char* oat_location,
jobject class_loader,
jobjectArray dex_elements,
const OatFile** out_oat_file,
std::vector<std::string>* error_msgs) {
CHECK(dex_location != nullptr);
CHECK(error_msgs != nullptr);
// Verify we aren't holding the mutator lock, which could starve GC if we
// have to generate or relocate an oat file.
Thread* const self = Thread::Current();
Runtime* const runtime = Runtime::Current();
OatFileAssistant oat_file_assistant(dex_location,
// Lock the target oat location to avoid races generating and loading the
// oat file.
std::string error_msg;
if (!oat_file_assistant.Lock(/*out*/&error_msg)) {
// Don't worry too much if this fails. If it does fail, it's unlikely we
// can generate an oat file anyway.
VLOG(class_linker) << "OatFileAssistant::Lock: " << error_msg;
const OatFile* source_oat_file = nullptr;
// Update the oat file on disk if we can. This may fail, but that's okay.
// Best effort is all that matters here.
if (!oat_file_assistant.MakeUpToDate(/*out*/&error_msg)) {
LOG(INFO) << error_msg;
// Get the oat file on disk.
std::unique_ptr<const OatFile> oat_file(oat_file_assistant.GetBestOatFile().release());
if (oat_file != nullptr) {
// Take the file only if it has no collisions, or we must take it because of preopting.
bool accept_oat_file = !HasCollisions(oat_file.get(), /*out*/ &error_msg);
if (!accept_oat_file) {
// Failed the collision check. Print warning.
if (Runtime::Current()->IsDexFileFallbackEnabled()) {
LOG(WARNING) << "Found duplicate classes, falling back to interpreter mode for "
<< dex_location;
} else {
LOG(WARNING) << "Found duplicate classes, dex-file-fallback disabled, will be failing to "
" load classes for " << dex_location;
LOG(WARNING) << error_msg;
// However, if the app was part of /system and preopted, there is no original dex file
// available. In that case grudgingly accept the oat file.
if (!DexFile::MaybeDex(dex_location)) {
accept_oat_file = true;
LOG(WARNING) << "Dex location " << dex_location << " does not seem to include dex file. "
<< "Allow oat file use. This is potentially dangerous.";
if (accept_oat_file) {
VLOG(class_linker) << "Registering " << oat_file->GetLocation();
source_oat_file = RegisterOatFile(std::move(oat_file));
*out_oat_file = source_oat_file;
std::vector<std::unique_ptr<const DexFile>> dex_files;
// Load the dex files from the oat file.
if (source_oat_file != nullptr) {
bool added_image_space = false;
if (source_oat_file->IsExecutable()) {
std::unique_ptr<gc::space::ImageSpace> image_space(
kEnableAppImage ? oat_file_assistant.OpenImageSpace(source_oat_file) : nullptr);
if (image_space != nullptr) {
ScopedObjectAccess soa(self);
StackHandleScope<1> hs(self);
Handle<mirror::ClassLoader> h_loader(
// Can not load app image without class loader.
if (h_loader.Get() != nullptr) {
std::string temp_error_msg;
// Add image space has a race condition since other threads could be reading from the
// spaces array.
ScopedThreadSuspension sts(self, kSuspended);
ScopedSuspendAll ssa("Add image space");
added_image_space = true;
if (!runtime->GetClassLinker()->AddImageSpace(image_space.get(),
/*out*/&temp_error_msg)) {
LOG(INFO) << "Failed to add image file " << temp_error_msg;
ScopedThreadSuspension sts(self, kSuspended);
ScopedSuspendAll ssa("Remove image space");
added_image_space = false;
// Non-fatal, don't update error_msg.
if (!added_image_space) {
dex_files = oat_file_assistant.LoadDexFiles(*source_oat_file, dex_location);
if (dex_files.empty()) {
error_msgs->push_back("Failed to open dex files from " + source_oat_file->GetLocation());
// Fall back to running out of the original dex file if we couldn't load any
// dex_files from the oat file.
if (dex_files.empty()) {
if (oat_file_assistant.HasOriginalDexFiles()) {
if (Runtime::Current()->IsDexFileFallbackEnabled()) {
if (!DexFile::Open(dex_location, dex_location, /*out*/ &error_msg, &dex_files)) {
LOG(WARNING) << error_msg;
error_msgs->push_back("Failed to open dex files from " + std::string(dex_location));
} else {
error_msgs->push_back("Fallback mode disabled, skipping dex files.");
} else {
error_msgs->push_back("No original dex files found for dex location "
+ std::string(dex_location));
return dex_files;
bool OatFileManager::RegisterOatFileLocation(const std::string& oat_location) {
WriterMutexLock mu(Thread::Current(), *Locks::oat_file_count_lock_);
auto it = oat_file_count_.find(oat_location);
if (it != oat_file_count_.end()) {
return false;
oat_file_count_.insert(std::pair<std::string, size_t>(oat_location, 1u));
return true;
void OatFileManager::UnRegisterOatFileLocation(const std::string& oat_location) {
WriterMutexLock mu(Thread::Current(), *Locks::oat_file_count_lock_);
auto it = oat_file_count_.find(oat_location);
if (it != oat_file_count_.end()) {
if (it->second == 0) {
} // namespace art