libs/androidfw/AssetsProvider.cpp - android_frameworks_base - Gitiles

 /*
  * Copyright (C) 2021 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/AssetsProvider.h"

 #include <sys/stat.h>

 #include <android-base/errors.h>
 #include <android-base/stringprintf.h>
 #include <android-base/utf8.h>
 #include <ziparchive/zip_archive.h>

 namespace android {
 namespace {
 constexpr const char* kEmptyDebugString = "<empty>";
 } // namespace

 std::unique_ptr<Asset> AssetsProvider::Open(const std::string& path, Asset::AccessMode mode,
                                             bool* file_exists) const {
   return OpenInternal(path, mode, file_exists);
 }

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

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

 std::unique_ptr<Asset> AssetsProvider::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") << "': "
                  << base::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 != nullptr) ? path : "anon") << "': "
                << base::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 != nullptr) ? base::unique_fd(-1) : std::move(fd));
 }

 const std::string* ZipAssetsProvider::PathOrDebugName::GetPath() const {
   return is_path_ ? &value_ : nullptr;
 }

 const std::string& ZipAssetsProvider::PathOrDebugName::GetDebugName() const {
   return value_;
 }

 void ZipAssetsProvider::ZipCloser::operator()(ZipArchive* a) const {
   ::CloseArchive(a);
 }

 ZipAssetsProvider::ZipAssetsProvider(ZipArchiveHandle handle, PathOrDebugName&& path,
                                      package_property_t flags, time_t last_mod_time)
     : zip_handle_(handle),
       name_(std::move(path)),
       flags_(flags),
       last_mod_time_(last_mod_time) {}

 std::unique_ptr<ZipAssetsProvider> ZipAssetsProvider::Create(std::string path,
                                                              package_property_t flags,
                                                              base::unique_fd fd) {
   const auto released_fd = fd.ok() ? fd.release() : -1;
   ZipArchiveHandle handle;
   if (int32_t result = released_fd < 0 ? OpenArchive(path.c_str(), &handle)
                                        : OpenArchiveFd(released_fd, path.c_str(), &handle)) {
     LOG(ERROR) << "Failed to open APK '" << path << "': " << ::ErrorCodeString(result);
     CloseArchive(handle);
     return {};
   }

   struct stat sb{.st_mtime = -1};
   // Skip all up-to-date checks if the file won't ever change.
   if (!isReadonlyFilesystem(path.c_str())) {
     if ((released_fd < 0 ? stat(path.c_str(), &sb) : fstat(released_fd, &sb)) < 0) {
       // Stat requires execute permissions on all directories path to the file. If the process does
       // not have execute permissions on this file, allow the zip to be opened but IsUpToDate() will
       // always have to return true.
       PLOG(WARNING) << "Failed to stat file '" << path << "'";
     }
   }

   return std::unique_ptr<ZipAssetsProvider>(
       new ZipAssetsProvider(handle, PathOrDebugName::Path(std::move(path)), flags, sb.st_mtime));
 }

 std::unique_ptr<ZipAssetsProvider> ZipAssetsProvider::Create(base::unique_fd fd,
                                                              std::string friendly_name,
                                                              package_property_t flags,
                                                              off64_t offset,
                                                              off64_t len) {
   ZipArchiveHandle handle;
   const int released_fd = fd.release();
   const int32_t result = (len == AssetsProvider::kUnknownLength)
       ? ::OpenArchiveFd(released_fd, friendly_name.c_str(), &handle)
       : ::OpenArchiveFdRange(released_fd, friendly_name.c_str(), &handle, len, offset);

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

   struct stat sb{.st_mtime = -1};
   // Skip all up-to-date checks if the file won't ever change.
   if (!isReadonlyFilesystem(released_fd)) {
     if (fstat(released_fd, &sb) < 0) {
       // Stat requires execute permissions on all directories path to the file. If the process does
       // not have execute permissions on this file, allow the zip to be opened but IsUpToDate() will
       // always have to return true.
       LOG(WARNING) << "Failed to fstat file '" << friendly_name
                    << "': " << base::SystemErrorCodeToString(errno);
     }
   }

   return std::unique_ptr<ZipAssetsProvider>(new ZipAssetsProvider(
       handle, PathOrDebugName::DebugName(std::move(friendly_name)), flags, sb.st_mtime));
 }

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

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

     if (file_exists != nullptr) {
       *file_exists = true;
     }

     const int fd = GetFileDescriptor(zip_handle_.get());
     const off64_t fd_offset = GetFileDescriptorOffset(zip_handle_.get());
     const bool incremental_hardening = (flags_ & PROPERTY_DISABLE_INCREMENTAL_HARDENING) == 0U;
     incfs::IncFsFileMap asset_map;
     if (entry.method == kCompressDeflated) {
       if (!asset_map.Create(fd, entry.offset + fd_offset, entry.compressed_length,
                             name_.GetDebugName().c_str(), incremental_hardening)) {
         LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << name_.GetDebugName()
                    << "'";
         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 '" << name_.GetDebugName()
                    << "'";
         return {};
       }
       return asset;
     }

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

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

 bool ZipAssetsProvider::ForEachFile(
     const std::string& root_path,
     base::function_ref<void(StringPiece, FileType)> f) const {
     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)));
           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;
 }

 std::optional<uint32_t> ZipAssetsProvider::GetCrc(std::string_view path) const {
   ::ZipEntry entry;
   if (FindEntry(zip_handle_.get(), path, &entry) != 0) {
     return {};
   }
   return entry.crc32;
 }

 std::optional<std::string_view> ZipAssetsProvider::GetPath() const {
   if (name_.GetPath() != nullptr) {
     return *name_.GetPath();
   }
   return {};
 }

 const std::string& ZipAssetsProvider::GetDebugName() const {
   return name_.GetDebugName();
 }

 bool ZipAssetsProvider::IsUpToDate() const {
   if (last_mod_time_ == -1) {
     return true;
   }
   struct stat sb{};
   if (fstat(GetFileDescriptor(zip_handle_.get()), &sb) < 0) {
     // If fstat fails on the zip archive, return true so the zip archive the resource system does
     // attempt to refresh the ApkAsset.
     return true;
   }
   return last_mod_time_ == sb.st_mtime;
 }

 DirectoryAssetsProvider::DirectoryAssetsProvider(std::string&& path, time_t last_mod_time)
     : dir_(std::move(path)), last_mod_time_(last_mod_time) {}

 std::unique_ptr<DirectoryAssetsProvider> DirectoryAssetsProvider::Create(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;
   }

   if (path.back() != OS_PATH_SEPARATOR) {
     path += OS_PATH_SEPARATOR;
   }

   const bool isReadonly = isReadonlyFilesystem(path.c_str());
   return std::unique_ptr<DirectoryAssetsProvider>(
       new DirectoryAssetsProvider(std::move(path), isReadonly ? -1 : sb.st_mtime));
 }

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

   return CreateAssetFromFile(resolved_path);
 }

 bool DirectoryAssetsProvider::ForEachFile(
     const std::string& /* root_path */,
     base::function_ref<void(StringPiece, FileType)> /* f */) const {
   return true;
 }

 std::optional<std::string_view> DirectoryAssetsProvider::GetPath() const {
   return dir_;
 }

 const std::string& DirectoryAssetsProvider::GetDebugName() const {
   return dir_;
 }

 bool DirectoryAssetsProvider::IsUpToDate() const {
   if (last_mod_time_ == -1) {
     return true;
   }
   struct stat sb;
   if (stat(dir_.c_str(), &sb) < 0) {
     // If stat fails on the zip archive, return true so the zip archive the resource system does
     // attempt to refresh the ApkAsset.
     return true;
   }
   return last_mod_time_ == sb.st_mtime;
 }

 MultiAssetsProvider::MultiAssetsProvider(std::unique_ptr<AssetsProvider>&& primary,
                                          std::unique_ptr<AssetsProvider>&& secondary)
     : primary_(std::move(primary)), secondary_(std::move(secondary)) {
   debug_name_ = primary_->GetDebugName() + " and " + secondary_->GetDebugName();
   path_ = (primary_->GetDebugName() != kEmptyDebugString) ? primary_->GetPath()
                                                           : secondary_->GetPath();
 }

 std::unique_ptr<AssetsProvider> MultiAssetsProvider::Create(
     std::unique_ptr<AssetsProvider>&& primary, std::unique_ptr<AssetsProvider>&& secondary) {
   if (primary == nullptr || secondary == nullptr) {
     return nullptr;
   }
   return std::unique_ptr<MultiAssetsProvider>(new MultiAssetsProvider(std::move(primary),
                                                                       std::move(secondary)));
 }

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

 bool MultiAssetsProvider::ForEachFile(
     const std::string& root_path,
     base::function_ref<void(StringPiece, FileType)> f) const {
   return primary_->ForEachFile(root_path, f) && secondary_->ForEachFile(root_path, f);
 }

 std::optional<std::string_view> MultiAssetsProvider::GetPath() const {
   return path_;
 }

 const std::string& MultiAssetsProvider::GetDebugName() const {
   return debug_name_;
 }

 bool MultiAssetsProvider::IsUpToDate() const {
   return primary_->IsUpToDate() && secondary_->IsUpToDate();
 }

 EmptyAssetsProvider::EmptyAssetsProvider(std::optional<std::string>&& path) :
     path_(std::move(path)) {}

 std::unique_ptr<AssetsProvider> EmptyAssetsProvider::Create() {
   return std::unique_ptr<EmptyAssetsProvider>(new EmptyAssetsProvider({}));
 }

 std::unique_ptr<AssetsProvider> EmptyAssetsProvider::Create(std::string path) {
   return std::unique_ptr<EmptyAssetsProvider>(new EmptyAssetsProvider(std::move(path)));
 }

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

 bool EmptyAssetsProvider::ForEachFile(
     const std::string& /* root_path */,
     base::function_ref<void(StringPiece, FileType)> /* f */) const {
   return true;
 }

 std::optional<std::string_view> EmptyAssetsProvider::GetPath() const {
   if (path_.has_value()) {
     return *path_;
   }
   return {};
 }

 const std::string& EmptyAssetsProvider::GetDebugName() const {
   if (path_.has_value()) {
     return *path_;
   }
   const static std::string kEmpty = kEmptyDebugString;
   return kEmpty;
 }

 bool EmptyAssetsProvider::IsUpToDate() const {
   return true;
 }

 }  // namespace android
	/*
	* Copyright (C) 2021 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/AssetsProvider.h"

	#include <sys/stat.h>

	#include <android-base/errors.h>
	#include <android-base/stringprintf.h>
	#include <android-base/utf8.h>
	#include <ziparchive/zip_archive.h>

	namespace android {
	namespace {
	constexpr const char* kEmptyDebugString = "<empty>";
	} // namespace

	std::unique_ptr<Asset> AssetsProvider::Open(const std::string& path, Asset::AccessMode mode,
	bool* file_exists) const {
	return OpenInternal(path, mode, file_exists);
	}

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

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

	std::unique_ptr<Asset> AssetsProvider::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") << "': "
	<< base::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 != nullptr) ? path : "anon") << "': "
	<< base::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 != nullptr) ? base::unique_fd(-1) : std::move(fd));
	}

	const std::string* ZipAssetsProvider::PathOrDebugName::GetPath() const {
	return is_path_ ? &value_ : nullptr;
	}

	const std::string& ZipAssetsProvider::PathOrDebugName::GetDebugName() const {
	return value_;
	}

	void ZipAssetsProvider::ZipCloser::operator()(ZipArchive* a) const {
	::CloseArchive(a);
	}

	ZipAssetsProvider::ZipAssetsProvider(ZipArchiveHandle handle, PathOrDebugName&& path,
	package_property_t flags, time_t last_mod_time)
	: zip_handle_(handle),
	name_(std::move(path)),
	flags_(flags),
	last_mod_time_(last_mod_time) {}

	std::unique_ptr<ZipAssetsProvider> ZipAssetsProvider::Create(std::string path,
	package_property_t flags,
	base::unique_fd fd) {
	const auto released_fd = fd.ok() ? fd.release() : -1;
	ZipArchiveHandle handle;
	if (int32_t result = released_fd < 0 ? OpenArchive(path.c_str(), &handle)
	: OpenArchiveFd(released_fd, path.c_str(), &handle)) {
	LOG(ERROR) << "Failed to open APK '" << path << "': " << ::ErrorCodeString(result);
	CloseArchive(handle);
	return {};
	}

	struct stat sb{.st_mtime = -1};
	// Skip all up-to-date checks if the file won't ever change.
	if (!isReadonlyFilesystem(path.c_str())) {
	if ((released_fd < 0 ? stat(path.c_str(), &sb) : fstat(released_fd, &sb)) < 0) {
	// Stat requires execute permissions on all directories path to the file. If the process does
	// not have execute permissions on this file, allow the zip to be opened but IsUpToDate() will
	// always have to return true.
	PLOG(WARNING) << "Failed to stat file '" << path << "'";
	}
	}

	return std::unique_ptr<ZipAssetsProvider>(
	new ZipAssetsProvider(handle, PathOrDebugName::Path(std::move(path)), flags, sb.st_mtime));
	}

	std::unique_ptr<ZipAssetsProvider> ZipAssetsProvider::Create(base::unique_fd fd,
	std::string friendly_name,
	package_property_t flags,
	off64_t offset,
	off64_t len) {
	ZipArchiveHandle handle;
	const int released_fd = fd.release();
	const int32_t result = (len == AssetsProvider::kUnknownLength)
	? ::OpenArchiveFd(released_fd, friendly_name.c_str(), &handle)
	: ::OpenArchiveFdRange(released_fd, friendly_name.c_str(), &handle, len, offset);

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

	struct stat sb{.st_mtime = -1};
	// Skip all up-to-date checks if the file won't ever change.
	if (!isReadonlyFilesystem(released_fd)) {
	if (fstat(released_fd, &sb) < 0) {
	// Stat requires execute permissions on all directories path to the file. If the process does
	// not have execute permissions on this file, allow the zip to be opened but IsUpToDate() will
	// always have to return true.
	LOG(WARNING) << "Failed to fstat file '" << friendly_name
	<< "': " << base::SystemErrorCodeToString(errno);
	}
	}

	return std::unique_ptr<ZipAssetsProvider>(new ZipAssetsProvider(
	handle, PathOrDebugName::DebugName(std::move(friendly_name)), flags, sb.st_mtime));
	}

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

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

	if (file_exists != nullptr) {
	*file_exists = true;
	}

	const int fd = GetFileDescriptor(zip_handle_.get());
	const off64_t fd_offset = GetFileDescriptorOffset(zip_handle_.get());
	const bool incremental_hardening = (flags_ & PROPERTY_DISABLE_INCREMENTAL_HARDENING) == 0U;
	incfs::IncFsFileMap asset_map;
	if (entry.method == kCompressDeflated) {
	if (!asset_map.Create(fd, entry.offset + fd_offset, entry.compressed_length,
	name_.GetDebugName().c_str(), incremental_hardening)) {
	LOG(ERROR) << "Failed to mmap file '" << path << "' in APK '" << name_.GetDebugName()
	<< "'";
	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 '" << name_.GetDebugName()
	<< "'";
	return {};
	}
	return asset;
	}

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

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

	bool ZipAssetsProvider::ForEachFile(
	const std::string& root_path,
	base::function_ref<void(StringPiece, FileType)> f) const {
	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)));
	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;
	}

	std::optional<uint32_t> ZipAssetsProvider::GetCrc(std::string_view path) const {
	::ZipEntry entry;
	if (FindEntry(zip_handle_.get(), path, &entry) != 0) {
	return {};
	}
	return entry.crc32;
	}

	std::optional<std::string_view> ZipAssetsProvider::GetPath() const {
	if (name_.GetPath() != nullptr) {
	return *name_.GetPath();
	}
	return {};
	}

	const std::string& ZipAssetsProvider::GetDebugName() const {
	return name_.GetDebugName();
	}

	bool ZipAssetsProvider::IsUpToDate() const {
	if (last_mod_time_ == -1) {
	return true;
	}
	struct stat sb{};
	if (fstat(GetFileDescriptor(zip_handle_.get()), &sb) < 0) {
	// If fstat fails on the zip archive, return true so the zip archive the resource system does
	// attempt to refresh the ApkAsset.
	return true;
	}
	return last_mod_time_ == sb.st_mtime;
	}

	DirectoryAssetsProvider::DirectoryAssetsProvider(std::string&& path, time_t last_mod_time)
	: dir_(std::move(path)), last_mod_time_(last_mod_time) {}

	std::unique_ptr<DirectoryAssetsProvider> DirectoryAssetsProvider::Create(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;
	}

	if (path.back() != OS_PATH_SEPARATOR) {
	path += OS_PATH_SEPARATOR;
	}

	const bool isReadonly = isReadonlyFilesystem(path.c_str());
	return std::unique_ptr<DirectoryAssetsProvider>(
	new DirectoryAssetsProvider(std::move(path), isReadonly ? -1 : sb.st_mtime));
	}

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

	return CreateAssetFromFile(resolved_path);
	}

	bool DirectoryAssetsProvider::ForEachFile(
	const std::string& /* root_path */,
	base::function_ref<void(StringPiece, FileType)> /* f */) const {
	return true;
	}

	std::optional<std::string_view> DirectoryAssetsProvider::GetPath() const {
	return dir_;
	}

	const std::string& DirectoryAssetsProvider::GetDebugName() const {
	return dir_;
	}

	bool DirectoryAssetsProvider::IsUpToDate() const {
	if (last_mod_time_ == -1) {
	return true;
	}
	struct stat sb;
	if (stat(dir_.c_str(), &sb) < 0) {
	// If stat fails on the zip archive, return true so the zip archive the resource system does
	// attempt to refresh the ApkAsset.
	return true;
	}
	return last_mod_time_ == sb.st_mtime;
	}

	MultiAssetsProvider::MultiAssetsProvider(std::unique_ptr<AssetsProvider>&& primary,
	std::unique_ptr<AssetsProvider>&& secondary)
	: primary_(std::move(primary)), secondary_(std::move(secondary)) {
	debug_name_ = primary_->GetDebugName() + " and " + secondary_->GetDebugName();
	path_ = (primary_->GetDebugName() != kEmptyDebugString) ? primary_->GetPath()
	: secondary_->GetPath();
	}

	std::unique_ptr<AssetsProvider> MultiAssetsProvider::Create(
	std::unique_ptr<AssetsProvider>&& primary, std::unique_ptr<AssetsProvider>&& secondary) {
	if (primary == nullptr \|\| secondary == nullptr) {
	return nullptr;
	}
	return std::unique_ptr<MultiAssetsProvider>(new MultiAssetsProvider(std::move(primary),
	std::move(secondary)));
	}

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

	bool MultiAssetsProvider::ForEachFile(
	const std::string& root_path,
	base::function_ref<void(StringPiece, FileType)> f) const {
	return primary_->ForEachFile(root_path, f) && secondary_->ForEachFile(root_path, f);
	}

	std::optional<std::string_view> MultiAssetsProvider::GetPath() const {
	return path_;
	}

	const std::string& MultiAssetsProvider::GetDebugName() const {
	return debug_name_;
	}

	bool MultiAssetsProvider::IsUpToDate() const {
	return primary_->IsUpToDate() && secondary_->IsUpToDate();
	}

	EmptyAssetsProvider::EmptyAssetsProvider(std::optional<std::string>&& path) :
	path_(std::move(path)) {}

	std::unique_ptr<AssetsProvider> EmptyAssetsProvider::Create() {
	return std::unique_ptr<EmptyAssetsProvider>(new EmptyAssetsProvider({}));
	}

	std::unique_ptr<AssetsProvider> EmptyAssetsProvider::Create(std::string path) {
	return std::unique_ptr<EmptyAssetsProvider>(new EmptyAssetsProvider(std::move(path)));
	}

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

	bool EmptyAssetsProvider::ForEachFile(
	const std::string& /* root_path */,
	base::function_ref<void(StringPiece, FileType)> /* f */) const {
	return true;
	}

	std::optional<std::string_view> EmptyAssetsProvider::GetPath() const {
	if (path_.has_value()) {
	return *path_;
	}
	return {};
	}

	const std::string& EmptyAssetsProvider::GetDebugName() const {
	if (path_.has_value()) {
	return *path_;
	}
	const static std::string kEmpty = kEmptyDebugString;
	return kEmpty;
	}

	bool EmptyAssetsProvider::IsUpToDate() const {
	return true;
	}

	} // namespace android