libs/androidfw/ApkAssets.cpp - android_frameworks_base - 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.
  */

 #include "androidfw/ApkAssets.h"

 #include <algorithm>

 #include "android-base/errors.h"
 #include "android-base/file.h"
 #include "android-base/logging.h"
 #include "android-base/stringprintf.h"
 #include "android-base/unique_fd.h"
 #include "android-base/utf8.h"
 #include "utils/Compat.h"
 #include "ziparchive/zip_archive.h"

 #include "androidfw/Asset.h"
 #include "androidfw/Idmap.h"
 #include "androidfw/misc.h"
 #include "androidfw/Util.h"

 namespace android {

 using base::SystemErrorCodeToString;
 using base::unique_fd;

 static const std::string kResourcesArsc("resources.arsc");

 ApkAssets::ApkAssets(std::unique_ptr<const AssetsProvider> assets_provider,
                      std::string path,
                      time_t last_mod_time,
                      package_property_t property_flags)
     : assets_provider_(std::move(assets_provider)),
       path_(std::move(path)),
       last_mod_time_(last_mod_time),
       property_flags_(property_flags) {
 }

 // Provides asset files from a zip file.
 class ZipAssetsProvider : public AssetsProvider {
  public:
   ~ZipAssetsProvider() override = default;

   static std::unique_ptr<const AssetsProvider> Create(const std::string& path) {
     ::ZipArchiveHandle unmanaged_handle;
     const int32_t result = ::OpenArchive(path.c_str(), &unmanaged_handle);
     if (result != 0) {
       LOG(ERROR) << "Failed to open APK '" << path << "' " << ::ErrorCodeString(result);
       ::CloseArchive(unmanaged_handle);
       return {};
     }

     return std::unique_ptr<AssetsProvider>(new ZipAssetsProvider(path, path, unmanaged_handle));
   }

   static std::unique_ptr<const AssetsProvider> Create(
       unique_fd fd, const std::string& friendly_name, const off64_t offset = 0,
       const off64_t length = ApkAssets::kUnknownLength) {

     ::ZipArchiveHandle unmanaged_handle;
     const int32_t result = (length == ApkAssets::kUnknownLength)
         ? ::OpenArchiveFd(fd.release(), friendly_name.c_str(), &unmanaged_handle)
         : ::OpenArchiveFdRange(fd.release(), friendly_name.c_str(), &unmanaged_handle, length,
                                offset);

     if (result != 0) {
       LOG(ERROR) << "Failed to open APK '" << friendly_name << "' through FD with offset " << offset
                  << " and length " << length << ": " << ::ErrorCodeString(result);
       ::CloseArchive(unmanaged_handle);
       return {};
     }

     return std::unique_ptr<AssetsProvider>(new ZipAssetsProvider({}, friendly_name,
                                                                  unmanaged_handle));
   }

   // Iterate over all files and directories within the zip. The order of iteration is not
   // guaranteed to be the same as the order of elements in the central directory but is stable for a
   // given zip file.
   bool ForEachFile(const std::string& root_path,
                    const std::function<void(const StringPiece&, FileType)>& f) const override {
     // If this is a resource loader from an .arsc, there will be no zip handle
     if (zip_handle_ == nullptr) {
       return false;
     }

     std::string root_path_full = root_path;
     if (root_path_full.back() != '/') {
       root_path_full += '/';
     }

     void* cookie;
     if (::StartIteration(zip_handle_.get(), &cookie, root_path_full, "") != 0) {
       return false;
     }

     std::string name;
     ::ZipEntry entry{};

     // We need to hold back directories because many paths will contain them and we want to only
     // surface one.
     std::set<std::string> dirs{};

     int32_t result;
     while ((result = ::Next(cookie, &entry, &name)) == 0) {
       StringPiece full_file_path(name);
       StringPiece leaf_file_path = full_file_path.substr(root_path_full.size());

       if (!leaf_file_path.empty()) {
         auto iter = std::find(leaf_file_path.begin(), leaf_file_path.end(), '/');
         if (iter != leaf_file_path.end()) {
           std::string dir =
               leaf_file_path.substr(0, std::distance(leaf_file_path.begin(), iter)).to_string();
           dirs.insert(std::move(dir));
         } else {
           f(leaf_file_path, kFileTypeRegular);
         }
       }
     }
     ::EndIteration(cookie);

     // Now present the unique directories.
     for (const std::string& dir : dirs) {
       f(dir, kFileTypeDirectory);
     }

     // -1 is end of iteration, anything else is an error.
     return result == -1;
   }

  protected:
   std::unique_ptr<Asset> OpenInternal(
       const std::string& path, Asset::AccessMode mode, bool* file_exists) const override {
     if (file_exists) {
       *file_exists = false;
     }

     ::ZipEntry entry;
     int32_t result = ::FindEntry(zip_handle_.get(), path, &entry);
     if (result != 0) {
       return {};
     }

     if (file_exists) {
       *file_exists = true;
     }

     const int fd = ::GetFileDescriptor(zip_handle_.get());
     const off64_t fd_offset = ::GetFileDescriptorOffset(zip_handle_.get());
     incfs::IncFsFileMap asset_map;
     if (entry.method == kCompressDeflated) {
       if (!asset_map.Create(fd, entry.offset + fd_offset, entry.compressed_length, GetPath())) {
         LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << friendly_name_ << "'";
         return {};
       }

       std::unique_ptr<Asset> asset =
           Asset::createFromCompressedMap(std::move(asset_map), entry.uncompressed_length, mode);
       if (asset == nullptr) {
         LOG(ERROR) << "Failed to decompress '" << path << "' in APK '" << friendly_name_ << "'";
         return {};
       }
       return asset;
     }

     if (!asset_map.Create(fd, entry.offset + fd_offset, entry.uncompressed_length, GetPath())) {
       LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << friendly_name_ << "'";
       return {};
     }

     unique_fd ufd;
     if (!GetPath()) {
       // If the `path` is not set, create a new `fd` for the new Asset to own in order to create
       // new file descriptors using Asset::openFileDescriptor. If the path is set, it will be used
       // to create new file descriptors.
       ufd = unique_fd(dup(fd));
       if (!ufd.ok()) {
         LOG(ERROR) << "Unable to dup fd '" << path << "' in APK '" << friendly_name_ << "'";
         return {};
       }
     }

     auto asset = Asset::createFromUncompressedMap(std::move(asset_map), mode, std::move(ufd));
     if (asset == nullptr) {
       LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << friendly_name_ << "'";
       return {};
     }
     return asset;
   }

  private:
   DISALLOW_COPY_AND_ASSIGN(ZipAssetsProvider);

   explicit ZipAssetsProvider(std::string path,
                              std::string friendly_name,
                              ZipArchiveHandle unmanaged_handle)
                              : zip_handle_(unmanaged_handle, ::CloseArchive),
                                path_(std::move(path)),
                                friendly_name_(std::move(friendly_name)) { }

   const char* GetPath() const {
     return path_.empty() ? nullptr : path_.c_str();
   }

   using ZipArchivePtr = std::unique_ptr<ZipArchive, void (*)(ZipArchiveHandle)>;
   ZipArchivePtr zip_handle_;
   std::string path_;
   std::string friendly_name_;
 };

 class DirectoryAssetsProvider : AssetsProvider {
  public:
   ~DirectoryAssetsProvider() override = default;

   static std::unique_ptr<const AssetsProvider> Create(const std::string& path) {
     struct stat sb{};
     const int result = stat(path.c_str(), &sb);
     if (result == -1) {
       LOG(ERROR) << "Failed to find directory '" << path << "'.";
       return nullptr;
     }

     if (!S_ISDIR(sb.st_mode)) {
       LOG(ERROR) << "Path '" << path << "' is not a directory.";
       return nullptr;
     }

     return std::unique_ptr<AssetsProvider>(new DirectoryAssetsProvider(path));
   }

  protected:
   std::unique_ptr<Asset> OpenInternal(
       const std::string& path, Asset::AccessMode /* mode */, bool* file_exists) const override {
     const std::string resolved_path = ResolvePath(path);
     if (file_exists) {
       struct stat sb{};
       const int result = stat(resolved_path.c_str(), &sb);
       *file_exists = result != -1 && S_ISREG(sb.st_mode);
     }

     return ApkAssets::CreateAssetFromFile(resolved_path);
   }

  private:
   DISALLOW_COPY_AND_ASSIGN(DirectoryAssetsProvider);

   explicit DirectoryAssetsProvider(std::string path) : path_(std::move(path)) { }

   inline std::string ResolvePath(const std::string& path) const {
     return base::StringPrintf("%s%c%s", path_.c_str(), OS_PATH_SEPARATOR, path.c_str());
   }

   const std::string path_;
 };

 // AssetProvider implementation that does not provide any assets. Used for ApkAssets::LoadEmpty.
 class EmptyAssetsProvider : public AssetsProvider {
  public:
   EmptyAssetsProvider() = default;
   ~EmptyAssetsProvider() override = default;

  protected:
   std::unique_ptr<Asset> OpenInternal(const std::string& /*path */,
                                       Asset::AccessMode /* mode */,
                                       bool* file_exists) const override {
     if (file_exists) {
       *file_exists = false;
     }
     return nullptr;
   }

  private:
   DISALLOW_COPY_AND_ASSIGN(EmptyAssetsProvider);
 };

 // AssetProvider implementation
 class MultiAssetsProvider : public AssetsProvider {
  public:
   ~MultiAssetsProvider() override = default;

   static std::unique_ptr<const AssetsProvider> Create(
       std::unique_ptr<const AssetsProvider> child, std::unique_ptr<const AssetsProvider> parent) {
     CHECK(parent != nullptr) << "parent provider must not be null";
     return (!child) ? std::move(parent)
                     : std::unique_ptr<const AssetsProvider>(new MultiAssetsProvider(
                         std::move(child), std::move(parent)));
   }

   bool ForEachFile(const std::string& root_path,
                    const std::function<void(const StringPiece&, FileType)>& f) const override {
     // TODO: Only call the function once for files defined in the parent and child
     return child_->ForEachFile(root_path, f) && parent_->ForEachFile(root_path, f);
   }

  protected:
   std::unique_ptr<Asset> OpenInternal(
       const std::string& path, Asset::AccessMode mode, bool* file_exists) const override {
     auto asset = child_->Open(path, mode, file_exists);
     return (asset) ? std::move(asset) : parent_->Open(path, mode, file_exists);
   }

  private:
   DISALLOW_COPY_AND_ASSIGN(MultiAssetsProvider);

   MultiAssetsProvider(std::unique_ptr<const AssetsProvider> child,
                       std::unique_ptr<const AssetsProvider> parent)
                       : child_(std::move(child)), parent_(std::move(parent)) { }

   std::unique_ptr<const AssetsProvider> child_;
   std::unique_ptr<const AssetsProvider> parent_;
 };

 // Opens the archive using the file path. Calling CloseArchive on the zip handle will close the
 // file.
 std::unique_ptr<const ApkAssets> ApkAssets::Load(
     const std::string& path, const package_property_t flags,
     std::unique_ptr<const AssetsProvider> override_asset) {
   auto assets = ZipAssetsProvider::Create(path);
   return (assets) ? LoadImpl(std::move(assets), path, flags, std::move(override_asset))
                   : nullptr;
 }

 // Opens the archive using the file file descriptor with the specified file offset and read length.
 // If the `assume_ownership` parameter is 'true' calling CloseArchive will close the file.
 std::unique_ptr<const ApkAssets> ApkAssets::LoadFromFd(
     unique_fd fd, const std::string& friendly_name, const package_property_t flags,
     std::unique_ptr<const AssetsProvider> override_asset, const off64_t offset,
     const off64_t length) {
   CHECK(length >= kUnknownLength) << "length must be greater than or equal to " << kUnknownLength;
   CHECK(length != kUnknownLength || offset == 0) << "offset must be 0 if length is "
                                                  << kUnknownLength;

   auto assets = ZipAssetsProvider::Create(std::move(fd), friendly_name, offset, length);
   return (assets) ? LoadImpl(std::move(assets), friendly_name, flags, std::move(override_asset))
                   : nullptr;
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadTable(
     const std::string& path, const package_property_t flags,
     std::unique_ptr<const AssetsProvider> override_asset) {

   auto assets = CreateAssetFromFile(path);
   return (assets) ? LoadTableImpl(std::move(assets), path, flags, std::move(override_asset))
                   : nullptr;
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadTableFromFd(
     unique_fd fd, const std::string& friendly_name, const package_property_t flags,
     std::unique_ptr<const AssetsProvider> override_asset, const off64_t offset,
     const off64_t length) {

   auto assets = CreateAssetFromFd(std::move(fd), nullptr /* path */, offset, length);
   return (assets) ? LoadTableImpl(std::move(assets), friendly_name, flags,
                                   std::move(override_asset))
                   : nullptr;
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadOverlay(const std::string& idmap_path,
                                                         const package_property_t flags) {
   CHECK((flags & PROPERTY_LOADER) == 0U) << "Cannot load RROs through loaders";
   std::unique_ptr<Asset> idmap_asset = CreateAssetFromFile(idmap_path);
   if (idmap_asset == nullptr) {
     return {};
   }

   const StringPiece idmap_data(
       reinterpret_cast<const char*>(idmap_asset->getBuffer(true /*wordAligned*/)),
       static_cast<size_t>(idmap_asset->getLength()));
   std::unique_ptr<const LoadedIdmap> loaded_idmap = LoadedIdmap::Load(idmap_path, idmap_data);
   if (loaded_idmap == nullptr) {
     LOG(ERROR) << "failed to load IDMAP " << idmap_path;
     return {};
   }

   auto overlay_path = loaded_idmap->OverlayApkPath();
   auto assets = ZipAssetsProvider::Create(overlay_path);
   return (assets) ? LoadImpl(std::move(assets), overlay_path, flags | PROPERTY_OVERLAY,
                              nullptr /* override_asset */, std::move(idmap_asset),
                              std::move(loaded_idmap))
                   : nullptr;
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadFromDir(
     const std::string& path, const package_property_t flags,
     std::unique_ptr<const AssetsProvider> override_asset) {

   auto assets = DirectoryAssetsProvider::Create(path);
   return (assets) ? LoadImpl(std::move(assets), path, flags, std::move(override_asset))
                   : nullptr;
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadEmpty(
     const package_property_t flags, std::unique_ptr<const AssetsProvider> override_asset) {

   auto assets = (override_asset) ? std::move(override_asset)
                                  : std::unique_ptr<const AssetsProvider>(new EmptyAssetsProvider());
   std::unique_ptr<ApkAssets> loaded_apk(new ApkAssets(std::move(assets), "empty" /* path */,
                                                       -1 /* last_mod-time */, flags));
   loaded_apk->loaded_arsc_ = LoadedArsc::CreateEmpty();
   // Need to force a move for mingw32.
   return std::move(loaded_apk);
 }

 std::unique_ptr<Asset> ApkAssets::CreateAssetFromFile(const std::string& path) {
   unique_fd fd(base::utf8::open(path.c_str(), O_RDONLY | O_BINARY | O_CLOEXEC));
   if (!fd.ok()) {
     LOG(ERROR) << "Failed to open file '" << path << "': " << SystemErrorCodeToString(errno);
     return {};
   }

   return CreateAssetFromFd(std::move(fd), path.c_str());
 }

 std::unique_ptr<Asset> ApkAssets::CreateAssetFromFd(base::unique_fd fd,
                                                     const char* path,
                                                     off64_t offset,
                                                     off64_t length) {
   CHECK(length >= kUnknownLength) << "length must be greater than or equal to " << kUnknownLength;
   CHECK(length != kUnknownLength || offset == 0) << "offset must be 0 if length is "
                                                  << kUnknownLength;
   if (length == kUnknownLength) {
     length = lseek64(fd, 0, SEEK_END);
     if (length < 0) {
       LOG(ERROR) << "Failed to get size of file '" << ((path) ? path : "anon") << "': "
                  << SystemErrorCodeToString(errno);
       return {};
     }
   }

   incfs::IncFsFileMap file_map;
   if (!file_map.Create(fd, offset, static_cast<size_t>(length), path)) {
     LOG(ERROR) << "Failed to mmap file '" << ((path) ? path : "anon") << "': "
                << SystemErrorCodeToString(errno);
     return {};
   }

   // If `path` is set, do not pass ownership of the `fd` to the new Asset since
   // Asset::openFileDescriptor can use `path` to create new file descriptors.
   return Asset::createFromUncompressedMap(std::move(file_map),
                                           Asset::AccessMode::ACCESS_RANDOM,
                                           (path) ? base::unique_fd(-1) : std::move(fd));
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadImpl(
     std::unique_ptr<const AssetsProvider> assets, const std::string& path,
     package_property_t property_flags, std::unique_ptr<const AssetsProvider> override_assets,
     std::unique_ptr<Asset> idmap_asset, std::unique_ptr<const LoadedIdmap> idmap) {

   const time_t last_mod_time = getFileModDate(path.c_str());

   // Open the resource table via mmap unless it is compressed. This logic is taken care of by Open.
   bool resources_asset_exists = false;
   auto resources_asset_ = assets->Open(kResourcesArsc, Asset::AccessMode::ACCESS_BUFFER,
                                        &resources_asset_exists);

   assets = MultiAssetsProvider::Create(std::move(override_assets), std::move(assets));

   // Wrap the handle in a unique_ptr so it gets automatically closed.
   std::unique_ptr<ApkAssets>
       loaded_apk(new ApkAssets(std::move(assets), path, last_mod_time, property_flags));

   if (!resources_asset_exists) {
     loaded_apk->loaded_arsc_ = LoadedArsc::CreateEmpty();
     return std::move(loaded_apk);
   }

   loaded_apk->resources_asset_ = std::move(resources_asset_);
   if (!loaded_apk->resources_asset_) {
     LOG(ERROR) << "Failed to open '" << kResourcesArsc << "' in APK '" << path << "'.";
     return {};
   }

   // Must retain ownership of the IDMAP Asset so that all pointers to its mmapped data remain valid.
   loaded_apk->idmap_asset_ = std::move(idmap_asset);
   loaded_apk->loaded_idmap_ = std::move(idmap);

   const auto data = loaded_apk->resources_asset_->getIncFsBuffer(true /* aligned */);
   const size_t length = loaded_apk->resources_asset_->getLength();
   if (!data || length == 0) {
     LOG(ERROR) << "Failed to read '" << kResourcesArsc << "' data in APK '" << path << "'.";
     return {};
   }

   loaded_apk->loaded_arsc_ = LoadedArsc::Load(data, length, loaded_apk->loaded_idmap_.get(),
                                               property_flags);
   if (!loaded_apk->loaded_arsc_) {
     LOG(ERROR) << "Failed to load '" << kResourcesArsc << "' in APK '" << path << "'.";
     return {};
   }

   // Need to force a move for mingw32.
   return std::move(loaded_apk);
 }

 std::unique_ptr<const ApkAssets> ApkAssets::LoadTableImpl(
     std::unique_ptr<Asset> resources_asset, const std::string& path,
     package_property_t property_flags, std::unique_ptr<const AssetsProvider> override_assets) {

   const time_t last_mod_time = getFileModDate(path.c_str());

   auto assets = (override_assets) ? std::move(override_assets)
                                   : std::unique_ptr<AssetsProvider>(new EmptyAssetsProvider());

   std::unique_ptr<ApkAssets> loaded_apk(
       new ApkAssets(std::move(assets), path, last_mod_time, property_flags));
   loaded_apk->resources_asset_ = std::move(resources_asset);

   const auto data = loaded_apk->resources_asset_->getIncFsBuffer(true /* aligned */);
   const size_t length = loaded_apk->resources_asset_->getLength();
   if (!data || length == 0) {
     LOG(ERROR) << "Failed to read resources table data in '" << path << "'.";
     return {};
   }

   loaded_apk->loaded_arsc_ = LoadedArsc::Load(data, length, nullptr /* loaded_idmap */,
                                               property_flags);
   if (loaded_apk->loaded_arsc_ == nullptr) {
     LOG(ERROR) << "Failed to read resources table in '" << path << "'.";
     return {};
   }

   // Need to force a move for mingw32.
   return std::move(loaded_apk);
 }

 bool ApkAssets::IsUpToDate() const {
   if (IsLoader()) {
     // Loaders are invalidated by the app, not the system, so assume they are up to date.
     return true;
   }
   return (!loaded_idmap_ || loaded_idmap_->IsUpToDate()) &&
       last_mod_time_ == getFileModDate(path_.c_str());
 }

 }  // namespace android
	/*
	* 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.
	*/

	#include "androidfw/ApkAssets.h"

	#include <algorithm>

	#include "android-base/errors.h"
	#include "android-base/file.h"
	#include "android-base/logging.h"
	#include "android-base/stringprintf.h"
	#include "android-base/unique_fd.h"
	#include "android-base/utf8.h"
	#include "utils/Compat.h"
	#include "ziparchive/zip_archive.h"

	#include "androidfw/Asset.h"
	#include "androidfw/Idmap.h"
	#include "androidfw/misc.h"
	#include "androidfw/Util.h"

	namespace android {

	using base::SystemErrorCodeToString;
	using base::unique_fd;

	static const std::string kResourcesArsc("resources.arsc");

	ApkAssets::ApkAssets(std::unique_ptr<const AssetsProvider> assets_provider,
	std::string path,
	time_t last_mod_time,
	package_property_t property_flags)
	: assets_provider_(std::move(assets_provider)),
	path_(std::move(path)),
	last_mod_time_(last_mod_time),
	property_flags_(property_flags) {
	}

	// Provides asset files from a zip file.
	class ZipAssetsProvider : public AssetsProvider {
	public:
	~ZipAssetsProvider() override = default;

	static std::unique_ptr<const AssetsProvider> Create(const std::string& path) {
	::ZipArchiveHandle unmanaged_handle;
	const int32_t result = ::OpenArchive(path.c_str(), &unmanaged_handle);
	if (result != 0) {
	LOG(ERROR) << "Failed to open APK '" << path << "' " << ::ErrorCodeString(result);
	::CloseArchive(unmanaged_handle);
	return {};
	}

	return std::unique_ptr<AssetsProvider>(new ZipAssetsProvider(path, path, unmanaged_handle));
	}

	static std::unique_ptr<const AssetsProvider> Create(
	unique_fd fd, const std::string& friendly_name, const off64_t offset = 0,
	const off64_t length = ApkAssets::kUnknownLength) {

	::ZipArchiveHandle unmanaged_handle;
	const int32_t result = (length == ApkAssets::kUnknownLength)
	? ::OpenArchiveFd(fd.release(), friendly_name.c_str(), &unmanaged_handle)
	: ::OpenArchiveFdRange(fd.release(), friendly_name.c_str(), &unmanaged_handle, length,
	offset);

	if (result != 0) {
	LOG(ERROR) << "Failed to open APK '" << friendly_name << "' through FD with offset " << offset
	<< " and length " << length << ": " << ::ErrorCodeString(result);
	::CloseArchive(unmanaged_handle);
	return {};
	}

	return std::unique_ptr<AssetsProvider>(new ZipAssetsProvider({}, friendly_name,
	unmanaged_handle));
	}

	// Iterate over all files and directories within the zip. The order of iteration is not
	// guaranteed to be the same as the order of elements in the central directory but is stable for a
	// given zip file.
	bool ForEachFile(const std::string& root_path,
	const std::function<void(const StringPiece&, FileType)>& f) const override {
	// If this is a resource loader from an .arsc, there will be no zip handle
	if (zip_handle_ == nullptr) {
	return false;
	}

	std::string root_path_full = root_path;
	if (root_path_full.back() != '/') {
	root_path_full += '/';
	}

	void* cookie;
	if (::StartIteration(zip_handle_.get(), &cookie, root_path_full, "") != 0) {
	return false;
	}

	std::string name;
	::ZipEntry entry{};

	// We need to hold back directories because many paths will contain them and we want to only
	// surface one.
	std::set<std::string> dirs{};

	int32_t result;
	while ((result = ::Next(cookie, &entry, &name)) == 0) {
	StringPiece full_file_path(name);
	StringPiece leaf_file_path = full_file_path.substr(root_path_full.size());

	if (!leaf_file_path.empty()) {
	auto iter = std::find(leaf_file_path.begin(), leaf_file_path.end(), '/');
	if (iter != leaf_file_path.end()) {
	std::string dir =
	leaf_file_path.substr(0, std::distance(leaf_file_path.begin(), iter)).to_string();
	dirs.insert(std::move(dir));
	} else {
	f(leaf_file_path, kFileTypeRegular);
	}
	}
	}
	::EndIteration(cookie);

	// Now present the unique directories.
	for (const std::string& dir : dirs) {
	f(dir, kFileTypeDirectory);
	}

	// -1 is end of iteration, anything else is an error.
	return result == -1;
	}

	protected:
	std::unique_ptr<Asset> OpenInternal(
	const std::string& path, Asset::AccessMode mode, bool* file_exists) const override {
	if (file_exists) {
	*file_exists = false;
	}

	::ZipEntry entry;
	int32_t result = ::FindEntry(zip_handle_.get(), path, &entry);
	if (result != 0) {
	return {};
	}

	if (file_exists) {
	*file_exists = true;
	}

	const int fd = ::GetFileDescriptor(zip_handle_.get());
	const off64_t fd_offset = ::GetFileDescriptorOffset(zip_handle_.get());
	incfs::IncFsFileMap asset_map;
	if (entry.method == kCompressDeflated) {
	if (!asset_map.Create(fd, entry.offset + fd_offset, entry.compressed_length, GetPath())) {
	LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << friendly_name_ << "'";
	return {};
	}

	std::unique_ptr<Asset> asset =
	Asset::createFromCompressedMap(std::move(asset_map), entry.uncompressed_length, mode);
	if (asset == nullptr) {
	LOG(ERROR) << "Failed to decompress '" << path << "' in APK '" << friendly_name_ << "'";
	return {};
	}
	return asset;
	}

	if (!asset_map.Create(fd, entry.offset + fd_offset, entry.uncompressed_length, GetPath())) {
	LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << friendly_name_ << "'";
	return {};
	}

	unique_fd ufd;
	if (!GetPath()) {
	// If the `path` is not set, create a new `fd` for the new Asset to own in order to create
	// new file descriptors using Asset::openFileDescriptor. If the path is set, it will be used
	// to create new file descriptors.
	ufd = unique_fd(dup(fd));
	if (!ufd.ok()) {
	LOG(ERROR) << "Unable to dup fd '" << path << "' in APK '" << friendly_name_ << "'";
	return {};
	}
	}

	auto asset = Asset::createFromUncompressedMap(std::move(asset_map), mode, std::move(ufd));
	if (asset == nullptr) {
	LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << friendly_name_ << "'";
	return {};
	}
	return asset;
	}

	private:
	DISALLOW_COPY_AND_ASSIGN(ZipAssetsProvider);

	explicit ZipAssetsProvider(std::string path,
	std::string friendly_name,
	ZipArchiveHandle unmanaged_handle)
	: zip_handle_(unmanaged_handle, ::CloseArchive),
	path_(std::move(path)),
	friendly_name_(std::move(friendly_name)) { }

	const char* GetPath() const {
	return path_.empty() ? nullptr : path_.c_str();
	}

	using ZipArchivePtr = std::unique_ptr<ZipArchive, void (*)(ZipArchiveHandle)>;
	ZipArchivePtr zip_handle_;
	std::string path_;
	std::string friendly_name_;
	};

	class DirectoryAssetsProvider : AssetsProvider {
	public:
	~DirectoryAssetsProvider() override = default;

	static std::unique_ptr<const AssetsProvider> Create(const std::string& path) {
	struct stat sb{};
	const int result = stat(path.c_str(), &sb);
	if (result == -1) {
	LOG(ERROR) << "Failed to find directory '" << path << "'.";
	return nullptr;
	}

	if (!S_ISDIR(sb.st_mode)) {
	LOG(ERROR) << "Path '" << path << "' is not a directory.";
	return nullptr;
	}

	return std::unique_ptr<AssetsProvider>(new DirectoryAssetsProvider(path));
	}

	protected:
	std::unique_ptr<Asset> OpenInternal(
	const std::string& path, Asset::AccessMode /* mode /, bool file_exists) const override {
	const std::string resolved_path = ResolvePath(path);
	if (file_exists) {
	struct stat sb{};
	const int result = stat(resolved_path.c_str(), &sb);
	*file_exists = result != -1 && S_ISREG(sb.st_mode);
	}

	return ApkAssets::CreateAssetFromFile(resolved_path);
	}

	private:
	DISALLOW_COPY_AND_ASSIGN(DirectoryAssetsProvider);

	explicit DirectoryAssetsProvider(std::string path) : path_(std::move(path)) { }

	inline std::string ResolvePath(const std::string& path) const {
	return base::StringPrintf("%s%c%s", path_.c_str(), OS_PATH_SEPARATOR, path.c_str());
	}

	const std::string path_;
	};

	// AssetProvider implementation that does not provide any assets. Used for ApkAssets::LoadEmpty.
	class EmptyAssetsProvider : public AssetsProvider {
	public:
	EmptyAssetsProvider() = default;
	~EmptyAssetsProvider() override = default;

	protected:
	std::unique_ptr<Asset> OpenInternal(const std::string& /path /,
	Asset::AccessMode /* mode */,
	bool* file_exists) const override {
	if (file_exists) {
	*file_exists = false;
	}
	return nullptr;
	}

	private:
	DISALLOW_COPY_AND_ASSIGN(EmptyAssetsProvider);
	};

	// AssetProvider implementation
	class MultiAssetsProvider : public AssetsProvider {
	public:
	~MultiAssetsProvider() override = default;

	static std::unique_ptr<const AssetsProvider> Create(
	std::unique_ptr<const AssetsProvider> child, std::unique_ptr<const AssetsProvider> parent) {
	CHECK(parent != nullptr) << "parent provider must not be null";
	return (!child) ? std::move(parent)
	: std::unique_ptr<const AssetsProvider>(new MultiAssetsProvider(
	std::move(child), std::move(parent)));
	}

	bool ForEachFile(const std::string& root_path,
	const std::function<void(const StringPiece&, FileType)>& f) const override {
	// TODO: Only call the function once for files defined in the parent and child
	return child_->ForEachFile(root_path, f) && parent_->ForEachFile(root_path, f);
	}

	protected:
	std::unique_ptr<Asset> OpenInternal(
	const std::string& path, Asset::AccessMode mode, bool* file_exists) const override {
	auto asset = child_->Open(path, mode, file_exists);
	return (asset) ? std::move(asset) : parent_->Open(path, mode, file_exists);
	}

	private:
	DISALLOW_COPY_AND_ASSIGN(MultiAssetsProvider);

	MultiAssetsProvider(std::unique_ptr<const AssetsProvider> child,
	std::unique_ptr<const AssetsProvider> parent)
	: child_(std::move(child)), parent_(std::move(parent)) { }

	std::unique_ptr<const AssetsProvider> child_;
	std::unique_ptr<const AssetsProvider> parent_;
	};

	// Opens the archive using the file path. Calling CloseArchive on the zip handle will close the
	// file.
	std::unique_ptr<const ApkAssets> ApkAssets::Load(
	const std::string& path, const package_property_t flags,
	std::unique_ptr<const AssetsProvider> override_asset) {
	auto assets = ZipAssetsProvider::Create(path);
	return (assets) ? LoadImpl(std::move(assets), path, flags, std::move(override_asset))
	: nullptr;
	}

	// Opens the archive using the file file descriptor with the specified file offset and read length.
	// If the `assume_ownership` parameter is 'true' calling CloseArchive will close the file.
	std::unique_ptr<const ApkAssets> ApkAssets::LoadFromFd(
	unique_fd fd, const std::string& friendly_name, const package_property_t flags,
	std::unique_ptr<const AssetsProvider> override_asset, const off64_t offset,
	const off64_t length) {
	CHECK(length >= kUnknownLength) << "length must be greater than or equal to " << kUnknownLength;
	CHECK(length != kUnknownLength \|\| offset == 0) << "offset must be 0 if length is "
	<< kUnknownLength;

	auto assets = ZipAssetsProvider::Create(std::move(fd), friendly_name, offset, length);
	return (assets) ? LoadImpl(std::move(assets), friendly_name, flags, std::move(override_asset))
	: nullptr;
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadTable(
	const std::string& path, const package_property_t flags,
	std::unique_ptr<const AssetsProvider> override_asset) {

	auto assets = CreateAssetFromFile(path);
	return (assets) ? LoadTableImpl(std::move(assets), path, flags, std::move(override_asset))
	: nullptr;
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadTableFromFd(
	unique_fd fd, const std::string& friendly_name, const package_property_t flags,
	std::unique_ptr<const AssetsProvider> override_asset, const off64_t offset,
	const off64_t length) {

	auto assets = CreateAssetFromFd(std::move(fd), nullptr /* path */, offset, length);
	return (assets) ? LoadTableImpl(std::move(assets), friendly_name, flags,
	std::move(override_asset))
	: nullptr;
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadOverlay(const std::string& idmap_path,
	const package_property_t flags) {
	CHECK((flags & PROPERTY_LOADER) == 0U) << "Cannot load RROs through loaders";
	std::unique_ptr<Asset> idmap_asset = CreateAssetFromFile(idmap_path);
	if (idmap_asset == nullptr) {
	return {};
	}

	const StringPiece idmap_data(
	reinterpret_cast<const char>(idmap_asset->getBuffer(true /wordAligned*/)),
	static_cast<size_t>(idmap_asset->getLength()));
	std::unique_ptr<const LoadedIdmap> loaded_idmap = LoadedIdmap::Load(idmap_path, idmap_data);
	if (loaded_idmap == nullptr) {
	LOG(ERROR) << "failed to load IDMAP " << idmap_path;
	return {};
	}

	auto overlay_path = loaded_idmap->OverlayApkPath();
	auto assets = ZipAssetsProvider::Create(overlay_path);
	return (assets) ? LoadImpl(std::move(assets), overlay_path, flags \| PROPERTY_OVERLAY,
	nullptr /* override_asset */, std::move(idmap_asset),
	std::move(loaded_idmap))
	: nullptr;
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadFromDir(
	const std::string& path, const package_property_t flags,
	std::unique_ptr<const AssetsProvider> override_asset) {

	auto assets = DirectoryAssetsProvider::Create(path);
	return (assets) ? LoadImpl(std::move(assets), path, flags, std::move(override_asset))
	: nullptr;
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadEmpty(
	const package_property_t flags, std::unique_ptr<const AssetsProvider> override_asset) {

	auto assets = (override_asset) ? std::move(override_asset)
	: std::unique_ptr<const AssetsProvider>(new EmptyAssetsProvider());
	std::unique_ptr<ApkAssets> loaded_apk(new ApkAssets(std::move(assets), "empty" /* path */,
	-1 /* last_mod-time */, flags));
	loaded_apk->loaded_arsc_ = LoadedArsc::CreateEmpty();
	// Need to force a move for mingw32.
	return std::move(loaded_apk);
	}

	std::unique_ptr<Asset> ApkAssets::CreateAssetFromFile(const std::string& path) {
	unique_fd fd(base::utf8::open(path.c_str(), O_RDONLY \| O_BINARY \| O_CLOEXEC));
	if (!fd.ok()) {
	LOG(ERROR) << "Failed to open file '" << path << "': " << SystemErrorCodeToString(errno);
	return {};
	}

	return CreateAssetFromFd(std::move(fd), path.c_str());
	}

	std::unique_ptr<Asset> ApkAssets::CreateAssetFromFd(base::unique_fd fd,
	const char* path,
	off64_t offset,
	off64_t length) {
	CHECK(length >= kUnknownLength) << "length must be greater than or equal to " << kUnknownLength;
	CHECK(length != kUnknownLength \|\| offset == 0) << "offset must be 0 if length is "
	<< kUnknownLength;
	if (length == kUnknownLength) {
	length = lseek64(fd, 0, SEEK_END);
	if (length < 0) {
	LOG(ERROR) << "Failed to get size of file '" << ((path) ? path : "anon") << "': "
	<< SystemErrorCodeToString(errno);
	return {};
	}
	}

	incfs::IncFsFileMap file_map;
	if (!file_map.Create(fd, offset, static_cast<size_t>(length), path)) {
	LOG(ERROR) << "Failed to mmap file '" << ((path) ? path : "anon") << "': "
	<< SystemErrorCodeToString(errno);
	return {};
	}

	// If `path` is set, do not pass ownership of the `fd` to the new Asset since
	// Asset::openFileDescriptor can use `path` to create new file descriptors.
	return Asset::createFromUncompressedMap(std::move(file_map),
	Asset::AccessMode::ACCESS_RANDOM,
	(path) ? base::unique_fd(-1) : std::move(fd));
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadImpl(
	std::unique_ptr<const AssetsProvider> assets, const std::string& path,
	package_property_t property_flags, std::unique_ptr<const AssetsProvider> override_assets,
	std::unique_ptr<Asset> idmap_asset, std::unique_ptr<const LoadedIdmap> idmap) {

	const time_t last_mod_time = getFileModDate(path.c_str());

	// Open the resource table via mmap unless it is compressed. This logic is taken care of by Open.
	bool resources_asset_exists = false;
	auto resources_asset_ = assets->Open(kResourcesArsc, Asset::AccessMode::ACCESS_BUFFER,
	&resources_asset_exists);

	assets = MultiAssetsProvider::Create(std::move(override_assets), std::move(assets));

	// Wrap the handle in a unique_ptr so it gets automatically closed.
	std::unique_ptr<ApkAssets>
	loaded_apk(new ApkAssets(std::move(assets), path, last_mod_time, property_flags));

	if (!resources_asset_exists) {
	loaded_apk->loaded_arsc_ = LoadedArsc::CreateEmpty();
	return std::move(loaded_apk);
	}

	loaded_apk->resources_asset_ = std::move(resources_asset_);
	if (!loaded_apk->resources_asset_) {
	LOG(ERROR) << "Failed to open '" << kResourcesArsc << "' in APK '" << path << "'.";
	return {};
	}

	// Must retain ownership of the IDMAP Asset so that all pointers to its mmapped data remain valid.
	loaded_apk->idmap_asset_ = std::move(idmap_asset);
	loaded_apk->loaded_idmap_ = std::move(idmap);

	const auto data = loaded_apk->resources_asset_->getIncFsBuffer(true /* aligned */);
	const size_t length = loaded_apk->resources_asset_->getLength();
	if (!data \|\| length == 0) {
	LOG(ERROR) << "Failed to read '" << kResourcesArsc << "' data in APK '" << path << "'.";
	return {};
	}

	loaded_apk->loaded_arsc_ = LoadedArsc::Load(data, length, loaded_apk->loaded_idmap_.get(),
	property_flags);
	if (!loaded_apk->loaded_arsc_) {
	LOG(ERROR) << "Failed to load '" << kResourcesArsc << "' in APK '" << path << "'.";
	return {};
	}

	// Need to force a move for mingw32.
	return std::move(loaded_apk);
	}

	std::unique_ptr<const ApkAssets> ApkAssets::LoadTableImpl(
	std::unique_ptr<Asset> resources_asset, const std::string& path,
	package_property_t property_flags, std::unique_ptr<const AssetsProvider> override_assets) {

	const time_t last_mod_time = getFileModDate(path.c_str());

	auto assets = (override_assets) ? std::move(override_assets)
	: std::unique_ptr<AssetsProvider>(new EmptyAssetsProvider());

	std::unique_ptr<ApkAssets> loaded_apk(
	new ApkAssets(std::move(assets), path, last_mod_time, property_flags));
	loaded_apk->resources_asset_ = std::move(resources_asset);

	const auto data = loaded_apk->resources_asset_->getIncFsBuffer(true /* aligned */);
	const size_t length = loaded_apk->resources_asset_->getLength();
	if (!data \|\| length == 0) {
	LOG(ERROR) << "Failed to read resources table data in '" << path << "'.";
	return {};
	}

	loaded_apk->loaded_arsc_ = LoadedArsc::Load(data, length, nullptr /* loaded_idmap */,
	property_flags);
	if (loaded_apk->loaded_arsc_ == nullptr) {
	LOG(ERROR) << "Failed to read resources table in '" << path << "'.";
	return {};
	}

	// Need to force a move for mingw32.
	return std::move(loaded_apk);
	}

	bool ApkAssets::IsUpToDate() const {
	if (IsLoader()) {
	// Loaders are invalidated by the app, not the system, so assume they are up to date.
	return true;
	}
	return (!loaded_idmap_ \|\| loaded_idmap_->IsUpToDate()) &&
	last_mod_time_ == getFileModDate(path_.c_str());
	}

	} // namespace android