cmds/idmap2/idmap2d/Idmap2Service.cpp - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2018 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 "idmap2d/Idmap2Service.h"

 #include <sys/stat.h>   // umask
 #include <sys/types.h>  // umask

 #include <cerrno>
 #include <cstring>
 #include <filesystem>
 #include <fstream>
 #include <limits>
 #include <memory>
 #include <ostream>
 #include <string>
 #include <utility>
 #include <vector>

 #include "android-base/macros.h"
 #include "android-base/stringprintf.h"
 #include "binder/IPCThreadState.h"
 #include "idmap2/BinaryStreamVisitor.h"
 #include "idmap2/FileUtils.h"
 #include "idmap2/Idmap.h"
 #include "idmap2/PrettyPrintVisitor.h"
 #include "idmap2/Result.h"
 #include "idmap2/SysTrace.h"
 #include <fcntl.h>

 using android::base::StringPrintf;
 using android::binder::Status;
 using android::idmap2::BinaryStreamVisitor;
 using android::idmap2::FabricatedOverlayContainer;
 using android::idmap2::Idmap;
 using android::idmap2::IdmapHeader;
 using android::idmap2::OverlayResourceContainer;
 using android::idmap2::PrettyPrintVisitor;
 using android::idmap2::TargetResourceContainer;
 using android::idmap2::utils::kIdmapCacheDir;
 using android::idmap2::utils::kIdmapFilePermissionMask;
 using android::idmap2::utils::RandomStringForPath;
 using android::idmap2::utils::UidHasWriteAccessToPath;

 using PolicyBitmask = android::ResTable_overlayable_policy_header::PolicyBitmask;

 namespace {

 constexpr const char* kFrameworkPath = "/system/framework/framework-res.apk";

 Status ok() {
   return Status::ok();
 }

 Status error(const std::string& msg) {
   LOG(ERROR) << msg;
   return Status::fromExceptionCode(Status::EX_NONE, msg.c_str());
 }

 PolicyBitmask ConvertAidlArgToPolicyBitmask(int32_t arg) {
   return static_cast<PolicyBitmask>(arg);
 }

 }  // namespace

 namespace android::os {

 Status Idmap2Service::getIdmapPath(const std::string& overlay_path,
                                    int32_t user_id ATTRIBUTE_UNUSED, std::string* _aidl_return) {
   assert(_aidl_return);
   SYSTRACE << "Idmap2Service::getIdmapPath " << overlay_path;
   *_aidl_return = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
   return ok();
 }

 Status Idmap2Service::removeIdmap(const std::string& overlay_path, int32_t user_id ATTRIBUTE_UNUSED,
                                   bool* _aidl_return) {
   assert(_aidl_return);
   SYSTRACE << "Idmap2Service::removeIdmap " << overlay_path;
   const uid_t uid = IPCThreadState::self()->getCallingUid();
   const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
   if (!UidHasWriteAccessToPath(uid, idmap_path)) {
     *_aidl_return = false;
     return error(base::StringPrintf("failed to unlink %s: calling uid %d lacks write access",
                                     idmap_path.c_str(), uid));
   }
   if (unlink(idmap_path.c_str()) != 0) {
     *_aidl_return = false;
     return error("failed to unlink " + idmap_path + ": " + strerror(errno));
   }
   *_aidl_return = true;
   return ok();
 }

 Status Idmap2Service::verifyIdmap(const std::string& target_path, const std::string& overlay_path,
                                   const std::string& overlay_name, int32_t fulfilled_policies,
                                   bool enforce_overlayable, int32_t user_id ATTRIBUTE_UNUSED,
                                   bool* _aidl_return) {
   SYSTRACE << "Idmap2Service::verifyIdmap " << overlay_path;
   assert(_aidl_return);

   const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
   std::ifstream fin(idmap_path);
   const std::unique_ptr<const IdmapHeader> header = IdmapHeader::FromBinaryStream(fin);
   fin.close();
   if (!header) {
     *_aidl_return = false;
     LOG(WARNING) << "failed to parse idmap header of '" << idmap_path << "'";
     return ok();
   }

   const auto target = GetTargetContainer(target_path);
   if (!target) {
     *_aidl_return = false;
     LOG(WARNING) << "failed to load target '" << target_path << "'";
     return ok();
   }

   const auto overlay = OverlayResourceContainer::FromPath(overlay_path);
   if (!overlay) {
     *_aidl_return = false;
     LOG(WARNING) << "failed to load overlay '" << overlay_path << "'";
     return ok();
   }

   auto up_to_date =
       header->IsUpToDate(*GetPointer(*target), **overlay, overlay_name,
                          ConvertAidlArgToPolicyBitmask(fulfilled_policies), enforce_overlayable);

   *_aidl_return = static_cast<bool>(up_to_date);
   if (!up_to_date) {
     LOG(WARNING) << "idmap '" << idmap_path
                  << "' not up to date : " << up_to_date.GetErrorMessage();
   }
   return ok();
 }

 Status Idmap2Service::createIdmap(const std::string& target_path, const std::string& overlay_path,
                                   const std::string& overlay_name, int32_t fulfilled_policies,
                                   bool enforce_overlayable, int32_t user_id ATTRIBUTE_UNUSED,
                                   std::optional<std::string>* _aidl_return) {
   assert(_aidl_return);
   SYSTRACE << "Idmap2Service::createIdmap " << target_path << " " << overlay_path;
   _aidl_return->reset();

   const PolicyBitmask policy_bitmask = ConvertAidlArgToPolicyBitmask(fulfilled_policies);

   const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
   const uid_t uid = IPCThreadState::self()->getCallingUid();
   if (!UidHasWriteAccessToPath(uid, idmap_path)) {
     return error(base::StringPrintf("will not write to %s: calling uid %d lacks write accesss",
                                     idmap_path.c_str(), uid));
   }

   // idmap files are mapped with mmap in libandroidfw. Deleting and recreating the idmap guarantees
   // that existing memory maps will continue to be valid and unaffected. The file must be deleted
   // before attempting to create the idmap, so that if idmap  creation fails, the overlay will no
   // longer be usable.
   unlink(idmap_path.c_str());

   const auto target = GetTargetContainer(target_path);
   if (!target) {
     return error("failed to load target '%s'" + target_path);
   }

   const auto overlay = OverlayResourceContainer::FromPath(overlay_path);
   if (!overlay) {
     return error("failed to load apk overlay '%s'" + overlay_path);
   }

   const auto idmap = Idmap::FromContainers(*GetPointer(*target), **overlay, overlay_name,
                                            policy_bitmask, enforce_overlayable);
   if (!idmap) {
     return error(idmap.GetErrorMessage());
   }

   umask(kIdmapFilePermissionMask);
   std::ofstream fout(idmap_path);
   if (fout.fail()) {
     return error("failed to open idmap path " + idmap_path);
   }

   BinaryStreamVisitor visitor(fout);
   (*idmap)->accept(&visitor);
   fout.close();
   if (fout.fail()) {
     unlink(idmap_path.c_str());
     return error("failed to write to idmap path " + idmap_path);
   }

   *_aidl_return = idmap_path;
   return ok();
 }

 idmap2::Result<Idmap2Service::TargetResourceContainerPtr> Idmap2Service::GetTargetContainer(
     const std::string& target_path) {
   if (target_path == kFrameworkPath) {
     if (framework_apk_cache_ == nullptr) {
       // Initialize the framework APK cache.
       auto target = TargetResourceContainer::FromPath(target_path);
       if (!target) {
         return target.GetError();
       }
       framework_apk_cache_ = std::move(*target);
     }
     return {framework_apk_cache_.get()};
   }

   auto target = TargetResourceContainer::FromPath(target_path);
   if (!target) {
     return target.GetError();
   }
   return {std::move(*target)};
 }

 Status Idmap2Service::createFabricatedOverlay(
     const os::FabricatedOverlayInternal& overlay,
     std::optional<os::FabricatedOverlayInfo>* _aidl_return) {
   idmap2::FabricatedOverlay::Builder builder(overlay.packageName, overlay.overlayName,
                                              overlay.targetPackageName);
   if (!overlay.targetOverlayable.empty()) {
     builder.SetOverlayable(overlay.targetOverlayable);
   }

   for (const auto& res : overlay.entries) {
     if (res.dataType == Res_value::TYPE_STRING) {
       builder.SetResourceValue(res.resourceName, res.dataType, res.stringData.value(),
             res.configuration.value_or(std::string()));
     } else if (res.binaryData.has_value()) {
       builder.SetResourceValue(res.resourceName, res.binaryData->get(),
             res.configuration.value_or(std::string()));
     } else {
       builder.SetResourceValue(res.resourceName, res.dataType, res.data,
             res.configuration.value_or(std::string()));
     }
   }

   // Generate the file path of the fabricated overlay and ensure it does not collide with an
   // existing path. Re-registering a fabricated overlay will always result in an updated path.
   std::string path;
   std::string file_name;
   do {
     constexpr size_t kSuffixLength = 4;
     const std::string random_suffix = RandomStringForPath(kSuffixLength);
     file_name = StringPrintf("%s-%s-%s.frro", overlay.packageName.c_str(),
                              overlay.overlayName.c_str(), random_suffix.c_str());
     path = StringPrintf("%s/%s", kIdmapCacheDir, file_name.c_str());

     // Invoking std::filesystem::exists with a file name greater than 255 characters will cause this
     // process to abort since the name exceeds the maximum file name size.
     const size_t kMaxFileNameLength = 255;
     if (file_name.size() > kMaxFileNameLength) {
       return error(
           base::StringPrintf("fabricated overlay file name '%s' longer than %zu characters",
                              file_name.c_str(), kMaxFileNameLength));
     }
   } while (std::filesystem::exists(path));
   builder.setFrroPath(path);

   const uid_t uid = IPCThreadState::self()->getCallingUid();
   if (!UidHasWriteAccessToPath(uid, path)) {
     return error(base::StringPrintf("will not write to %s: calling uid %d lacks write access",
                                     path.c_str(), uid));
   }

   const auto frro = builder.Build();
   if (!frro) {
     return error(StringPrintf("failed to serialize '%s:%s': %s", overlay.packageName.c_str(),
                               overlay.overlayName.c_str(), frro.GetErrorMessage().c_str()));
   }
   // Persist the fabricated overlay.
   umask(kIdmapFilePermissionMask);
   std::ofstream fout(path);
   if (fout.fail()) {
     return error("failed to open frro path " + path);
   }
   auto result = frro->ToBinaryStream(fout);
   if (!result) {
     unlink(path.c_str());
     return error("failed to write to frro path " + path + ": " + result.GetErrorMessage());
   }
   if (fout.fail()) {
     unlink(path.c_str());
     return error("failed to write to frro path " + path);
   }

   os::FabricatedOverlayInfo out_info;
   out_info.packageName = overlay.packageName;
   out_info.overlayName = overlay.overlayName;
   out_info.targetPackageName = overlay.targetPackageName;
   out_info.targetOverlayable = overlay.targetOverlayable;
   out_info.path = path;
   *_aidl_return = out_info;
   return ok();
 }

 Status Idmap2Service::acquireFabricatedOverlayIterator(int32_t* _aidl_return) {
   std::lock_guard l(frro_iter_mutex_);
   if (frro_iter_.has_value()) {
     LOG(WARNING) << "active ffro iterator was not previously released";
   }
   frro_iter_ = std::filesystem::directory_iterator(kIdmapCacheDir);
   if (frro_iter_id_ == std::numeric_limits<int32_t>::max()) {
     frro_iter_id_ = 0;
   } else {
     ++frro_iter_id_;
   }
   *_aidl_return = frro_iter_id_;
   return ok();
 }

 Status Idmap2Service::releaseFabricatedOverlayIterator(int32_t iteratorId) {
   std::lock_guard l(frro_iter_mutex_);
   if (!frro_iter_.has_value()) {
     LOG(WARNING) << "no active ffro iterator to release";
   } else if (frro_iter_id_ != iteratorId) {
     LOG(WARNING) << "incorrect iterator id in a call to release";
   } else {
     frro_iter_.reset();
   }
   return ok();
 }

 Status Idmap2Service::nextFabricatedOverlayInfos(int32_t iteratorId,
     std::vector<os::FabricatedOverlayInfo>* _aidl_return) {
   std::lock_guard l(frro_iter_mutex_);

   constexpr size_t kMaxEntryCount = 100;
   if (!frro_iter_.has_value()) {
     return error("no active frro iterator");
   } else if (frro_iter_id_ != iteratorId) {
     return error("incorrect iterator id in a call to next");
   }

   size_t count = 0;
   auto& entry_iter = *frro_iter_;
   auto entry_iter_end = end(*frro_iter_);
   for (; entry_iter != entry_iter_end && count < kMaxEntryCount; ++entry_iter) {
     auto& entry = *entry_iter;
     if (!entry.is_regular_file() || !android::IsFabricatedOverlay(entry.path().native())) {
       continue;
     }

     const auto overlay = FabricatedOverlayContainer::FromPath(entry.path().native());
     if (!overlay) {
       LOG(WARNING) << "Failed to open '" << entry.path() << "': " << overlay.GetErrorMessage();
       continue;
     }

     auto info = (*overlay)->GetManifestInfo();
     os::FabricatedOverlayInfo out_info;
     out_info.packageName = std::move(info.package_name);
     out_info.overlayName = std::move(info.name);
     out_info.targetPackageName = std::move(info.target_package);
     out_info.targetOverlayable = std::move(info.target_name);
     out_info.path = entry.path();
     _aidl_return->emplace_back(std::move(out_info));
     count++;
   }
   return ok();
 }

 binder::Status Idmap2Service::deleteFabricatedOverlay(const std::string& overlay_path,
                                                       bool* _aidl_return) {
   SYSTRACE << "Idmap2Service::deleteFabricatedOverlay " << overlay_path;
   const uid_t uid = IPCThreadState::self()->getCallingUid();

   if (!UidHasWriteAccessToPath(uid, overlay_path)) {
     *_aidl_return = false;
     return error(base::StringPrintf("failed to unlink %s: calling uid %d lacks write access",
                                     overlay_path.c_str(), uid));
   }

   const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
   if (!UidHasWriteAccessToPath(uid, idmap_path)) {
     *_aidl_return = false;
     return error(base::StringPrintf("failed to unlink %s: calling uid %d lacks write access",
                                     idmap_path.c_str(), uid));
   }

   if (unlink(overlay_path.c_str()) != 0) {
     *_aidl_return = false;
     return error("failed to unlink " + overlay_path + ": " + strerror(errno));
   }

   if (unlink(idmap_path.c_str()) != 0) {
     *_aidl_return = false;
     return error("failed to unlink " + idmap_path + ": " + strerror(errno));
   }

   *_aidl_return = true;
   return ok();
 }

 binder::Status Idmap2Service::dumpIdmap(const std::string& overlay_path,
                                         std::string* _aidl_return) {
   assert(_aidl_return);

   const auto idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
   std::ifstream fin(idmap_path);
   const auto idmap = Idmap::FromBinaryStream(fin);
   fin.close();
   if (!idmap) {
     return error(idmap.GetErrorMessage());
   }

   std::stringstream stream;
   PrettyPrintVisitor visitor(stream);
   (*idmap)->accept(&visitor);
   *_aidl_return = stream.str();

   return ok();
 }

 }  // namespace android::os
	/*
	* Copyright (C) 2018 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 "idmap2d/Idmap2Service.h"

	#include <sys/stat.h> // umask
	#include <sys/types.h> // umask

	#include <cerrno>
	#include <cstring>
	#include <filesystem>
	#include <fstream>
	#include <limits>
	#include <memory>
	#include <ostream>
	#include <string>
	#include <utility>
	#include <vector>

	#include "android-base/macros.h"
	#include "android-base/stringprintf.h"
	#include "binder/IPCThreadState.h"
	#include "idmap2/BinaryStreamVisitor.h"
	#include "idmap2/FileUtils.h"
	#include "idmap2/Idmap.h"
	#include "idmap2/PrettyPrintVisitor.h"
	#include "idmap2/Result.h"
	#include "idmap2/SysTrace.h"
	#include <fcntl.h>

	using android::base::StringPrintf;
	using android::binder::Status;
	using android::idmap2::BinaryStreamVisitor;
	using android::idmap2::FabricatedOverlayContainer;
	using android::idmap2::Idmap;
	using android::idmap2::IdmapHeader;
	using android::idmap2::OverlayResourceContainer;
	using android::idmap2::PrettyPrintVisitor;
	using android::idmap2::TargetResourceContainer;
	using android::idmap2::utils::kIdmapCacheDir;
	using android::idmap2::utils::kIdmapFilePermissionMask;
	using android::idmap2::utils::RandomStringForPath;
	using android::idmap2::utils::UidHasWriteAccessToPath;

	using PolicyBitmask = android::ResTable_overlayable_policy_header::PolicyBitmask;

	namespace {

	constexpr const char* kFrameworkPath = "/system/framework/framework-res.apk";

	Status ok() {
	return Status::ok();
	}

	Status error(const std::string& msg) {
	LOG(ERROR) << msg;
	return Status::fromExceptionCode(Status::EX_NONE, msg.c_str());
	}

	PolicyBitmask ConvertAidlArgToPolicyBitmask(int32_t arg) {
	return static_cast<PolicyBitmask>(arg);
	}

	} // namespace

	namespace android::os {

	Status Idmap2Service::getIdmapPath(const std::string& overlay_path,
	int32_t user_id ATTRIBUTE_UNUSED, std::string* _aidl_return) {
	assert(_aidl_return);
	SYSTRACE << "Idmap2Service::getIdmapPath " << overlay_path;
	*_aidl_return = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
	return ok();
	}

	Status Idmap2Service::removeIdmap(const std::string& overlay_path, int32_t user_id ATTRIBUTE_UNUSED,
	bool* _aidl_return) {
	assert(_aidl_return);
	SYSTRACE << "Idmap2Service::removeIdmap " << overlay_path;
	const uid_t uid = IPCThreadState::self()->getCallingUid();
	const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
	if (!UidHasWriteAccessToPath(uid, idmap_path)) {
	*_aidl_return = false;
	return error(base::StringPrintf("failed to unlink %s: calling uid %d lacks write access",
	idmap_path.c_str(), uid));
	}
	if (unlink(idmap_path.c_str()) != 0) {
	*_aidl_return = false;
	return error("failed to unlink " + idmap_path + ": " + strerror(errno));
	}
	*_aidl_return = true;
	return ok();
	}

	Status Idmap2Service::verifyIdmap(const std::string& target_path, const std::string& overlay_path,
	const std::string& overlay_name, int32_t fulfilled_policies,
	bool enforce_overlayable, int32_t user_id ATTRIBUTE_UNUSED,
	bool* _aidl_return) {
	SYSTRACE << "Idmap2Service::verifyIdmap " << overlay_path;
	assert(_aidl_return);

	const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
	std::ifstream fin(idmap_path);
	const std::unique_ptr<const IdmapHeader> header = IdmapHeader::FromBinaryStream(fin);
	fin.close();
	if (!header) {
	*_aidl_return = false;
	LOG(WARNING) << "failed to parse idmap header of '" << idmap_path << "'";
	return ok();
	}

	const auto target = GetTargetContainer(target_path);
	if (!target) {
	*_aidl_return = false;
	LOG(WARNING) << "failed to load target '" << target_path << "'";
	return ok();
	}

	const auto overlay = OverlayResourceContainer::FromPath(overlay_path);
	if (!overlay) {
	*_aidl_return = false;
	LOG(WARNING) << "failed to load overlay '" << overlay_path << "'";
	return ok();
	}

	auto up_to_date =
	header->IsUpToDate(GetPointer(target), **overlay, overlay_name,
	ConvertAidlArgToPolicyBitmask(fulfilled_policies), enforce_overlayable);

	*_aidl_return = static_cast<bool>(up_to_date);
	if (!up_to_date) {
	LOG(WARNING) << "idmap '" << idmap_path
	<< "' not up to date : " << up_to_date.GetErrorMessage();
	}
	return ok();
	}

	Status Idmap2Service::createIdmap(const std::string& target_path, const std::string& overlay_path,
	const std::string& overlay_name, int32_t fulfilled_policies,
	bool enforce_overlayable, int32_t user_id ATTRIBUTE_UNUSED,
	std::optional<std::string>* _aidl_return) {
	assert(_aidl_return);
	SYSTRACE << "Idmap2Service::createIdmap " << target_path << " " << overlay_path;
	_aidl_return->reset();

	const PolicyBitmask policy_bitmask = ConvertAidlArgToPolicyBitmask(fulfilled_policies);

	const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
	const uid_t uid = IPCThreadState::self()->getCallingUid();
	if (!UidHasWriteAccessToPath(uid, idmap_path)) {
	return error(base::StringPrintf("will not write to %s: calling uid %d lacks write accesss",
	idmap_path.c_str(), uid));
	}

	// idmap files are mapped with mmap in libandroidfw. Deleting and recreating the idmap guarantees
	// that existing memory maps will continue to be valid and unaffected. The file must be deleted
	// before attempting to create the idmap, so that if idmap creation fails, the overlay will no
	// longer be usable.
	unlink(idmap_path.c_str());

	const auto target = GetTargetContainer(target_path);
	if (!target) {
	return error("failed to load target '%s'" + target_path);
	}

	const auto overlay = OverlayResourceContainer::FromPath(overlay_path);
	if (!overlay) {
	return error("failed to load apk overlay '%s'" + overlay_path);
	}

	const auto idmap = Idmap::FromContainers(GetPointer(target), **overlay, overlay_name,
	policy_bitmask, enforce_overlayable);
	if (!idmap) {
	return error(idmap.GetErrorMessage());
	}

	umask(kIdmapFilePermissionMask);
	std::ofstream fout(idmap_path);
	if (fout.fail()) {
	return error("failed to open idmap path " + idmap_path);
	}

	BinaryStreamVisitor visitor(fout);
	(*idmap)->accept(&visitor);
	fout.close();
	if (fout.fail()) {
	unlink(idmap_path.c_str());
	return error("failed to write to idmap path " + idmap_path);
	}

	*_aidl_return = idmap_path;
	return ok();
	}

	idmap2::Result<Idmap2Service::TargetResourceContainerPtr> Idmap2Service::GetTargetContainer(
	const std::string& target_path) {
	if (target_path == kFrameworkPath) {
	if (framework_apk_cache_ == nullptr) {
	// Initialize the framework APK cache.
	auto target = TargetResourceContainer::FromPath(target_path);
	if (!target) {
	return target.GetError();
	}
	framework_apk_cache_ = std::move(*target);
	}
	return {framework_apk_cache_.get()};
	}

	auto target = TargetResourceContainer::FromPath(target_path);
	if (!target) {
	return target.GetError();
	}
	return {std::move(*target)};
	}

	Status Idmap2Service::createFabricatedOverlay(
	const os::FabricatedOverlayInternal& overlay,
	std::optional<os::FabricatedOverlayInfo>* _aidl_return) {
	idmap2::FabricatedOverlay::Builder builder(overlay.packageName, overlay.overlayName,
	overlay.targetPackageName);
	if (!overlay.targetOverlayable.empty()) {
	builder.SetOverlayable(overlay.targetOverlayable);
	}

	for (const auto& res : overlay.entries) {
	if (res.dataType == Res_value::TYPE_STRING) {
	builder.SetResourceValue(res.resourceName, res.dataType, res.stringData.value(),
	res.configuration.value_or(std::string()));
	} else if (res.binaryData.has_value()) {
	builder.SetResourceValue(res.resourceName, res.binaryData->get(),
	res.configuration.value_or(std::string()));
	} else {
	builder.SetResourceValue(res.resourceName, res.dataType, res.data,
	res.configuration.value_or(std::string()));
	}
	}

	// Generate the file path of the fabricated overlay and ensure it does not collide with an
	// existing path. Re-registering a fabricated overlay will always result in an updated path.
	std::string path;
	std::string file_name;
	do {
	constexpr size_t kSuffixLength = 4;
	const std::string random_suffix = RandomStringForPath(kSuffixLength);
	file_name = StringPrintf("%s-%s-%s.frro", overlay.packageName.c_str(),
	overlay.overlayName.c_str(), random_suffix.c_str());
	path = StringPrintf("%s/%s", kIdmapCacheDir, file_name.c_str());

	// Invoking std::filesystem::exists with a file name greater than 255 characters will cause this
	// process to abort since the name exceeds the maximum file name size.
	const size_t kMaxFileNameLength = 255;
	if (file_name.size() > kMaxFileNameLength) {
	return error(
	base::StringPrintf("fabricated overlay file name '%s' longer than %zu characters",
	file_name.c_str(), kMaxFileNameLength));
	}
	} while (std::filesystem::exists(path));
	builder.setFrroPath(path);

	const uid_t uid = IPCThreadState::self()->getCallingUid();
	if (!UidHasWriteAccessToPath(uid, path)) {
	return error(base::StringPrintf("will not write to %s: calling uid %d lacks write access",
	path.c_str(), uid));
	}

	const auto frro = builder.Build();
	if (!frro) {
	return error(StringPrintf("failed to serialize '%s:%s': %s", overlay.packageName.c_str(),
	overlay.overlayName.c_str(), frro.GetErrorMessage().c_str()));
	}
	// Persist the fabricated overlay.
	umask(kIdmapFilePermissionMask);
	std::ofstream fout(path);
	if (fout.fail()) {
	return error("failed to open frro path " + path);
	}
	auto result = frro->ToBinaryStream(fout);
	if (!result) {
	unlink(path.c_str());
	return error("failed to write to frro path " + path + ": " + result.GetErrorMessage());
	}
	if (fout.fail()) {
	unlink(path.c_str());
	return error("failed to write to frro path " + path);
	}

	os::FabricatedOverlayInfo out_info;
	out_info.packageName = overlay.packageName;
	out_info.overlayName = overlay.overlayName;
	out_info.targetPackageName = overlay.targetPackageName;
	out_info.targetOverlayable = overlay.targetOverlayable;
	out_info.path = path;
	*_aidl_return = out_info;
	return ok();
	}

	Status Idmap2Service::acquireFabricatedOverlayIterator(int32_t* _aidl_return) {
	std::lock_guard l(frro_iter_mutex_);
	if (frro_iter_.has_value()) {
	LOG(WARNING) << "active ffro iterator was not previously released";
	}
	frro_iter_ = std::filesystem::directory_iterator(kIdmapCacheDir);
	if (frro_iter_id_ == std::numeric_limits<int32_t>::max()) {
	frro_iter_id_ = 0;
	} else {
	++frro_iter_id_;
	}
	*_aidl_return = frro_iter_id_;
	return ok();
	}

	Status Idmap2Service::releaseFabricatedOverlayIterator(int32_t iteratorId) {
	std::lock_guard l(frro_iter_mutex_);
	if (!frro_iter_.has_value()) {
	LOG(WARNING) << "no active ffro iterator to release";
	} else if (frro_iter_id_ != iteratorId) {
	LOG(WARNING) << "incorrect iterator id in a call to release";
	} else {
	frro_iter_.reset();
	}
	return ok();
	}

	Status Idmap2Service::nextFabricatedOverlayInfos(int32_t iteratorId,
	std::vector<os::FabricatedOverlayInfo>* _aidl_return) {
	std::lock_guard l(frro_iter_mutex_);

	constexpr size_t kMaxEntryCount = 100;
	if (!frro_iter_.has_value()) {
	return error("no active frro iterator");
	} else if (frro_iter_id_ != iteratorId) {
	return error("incorrect iterator id in a call to next");
	}

	size_t count = 0;
	auto& entry_iter = *frro_iter_;
	auto entry_iter_end = end(*frro_iter_);
	for (; entry_iter != entry_iter_end && count < kMaxEntryCount; ++entry_iter) {
	auto& entry = *entry_iter;
	if (!entry.is_regular_file() \|\| !android::IsFabricatedOverlay(entry.path().native())) {
	continue;
	}

	const auto overlay = FabricatedOverlayContainer::FromPath(entry.path().native());
	if (!overlay) {
	LOG(WARNING) << "Failed to open '" << entry.path() << "': " << overlay.GetErrorMessage();
	continue;
	}

	auto info = (*overlay)->GetManifestInfo();
	os::FabricatedOverlayInfo out_info;
	out_info.packageName = std::move(info.package_name);
	out_info.overlayName = std::move(info.name);
	out_info.targetPackageName = std::move(info.target_package);
	out_info.targetOverlayable = std::move(info.target_name);
	out_info.path = entry.path();
	_aidl_return->emplace_back(std::move(out_info));
	count++;
	}
	return ok();
	}

	binder::Status Idmap2Service::deleteFabricatedOverlay(const std::string& overlay_path,
	bool* _aidl_return) {
	SYSTRACE << "Idmap2Service::deleteFabricatedOverlay " << overlay_path;
	const uid_t uid = IPCThreadState::self()->getCallingUid();

	if (!UidHasWriteAccessToPath(uid, overlay_path)) {
	*_aidl_return = false;
	return error(base::StringPrintf("failed to unlink %s: calling uid %d lacks write access",
	overlay_path.c_str(), uid));
	}

	const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
	if (!UidHasWriteAccessToPath(uid, idmap_path)) {
	*_aidl_return = false;
	return error(base::StringPrintf("failed to unlink %s: calling uid %d lacks write access",
	idmap_path.c_str(), uid));
	}

	if (unlink(overlay_path.c_str()) != 0) {
	*_aidl_return = false;
	return error("failed to unlink " + overlay_path + ": " + strerror(errno));
	}

	if (unlink(idmap_path.c_str()) != 0) {
	*_aidl_return = false;
	return error("failed to unlink " + idmap_path + ": " + strerror(errno));
	}

	*_aidl_return = true;
	return ok();
	}

	binder::Status Idmap2Service::dumpIdmap(const std::string& overlay_path,
	std::string* _aidl_return) {
	assert(_aidl_return);

	const auto idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_path);
	std::ifstream fin(idmap_path);
	const auto idmap = Idmap::FromBinaryStream(fin);
	fin.close();
	if (!idmap) {
	return error(idmap.GetErrorMessage());
	}

	std::stringstream stream;
	PrettyPrintVisitor visitor(stream);
	(*idmap)->accept(&visitor);
	*_aidl_return = stream.str();

	return ok();
	}

	} // namespace android::os