libnativeloader/library_namespaces.cpp - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2019 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.
  */

 #if defined(ART_TARGET_ANDROID)

 #define LOG_TAG "nativeloader"

 #include "library_namespaces.h"

 #include <dirent.h>
 #include <dlfcn.h>
 #include <stdio.h>

 #include <algorithm>
 #include <optional>
 #include <regex>
 #include <string>
 #include <string_view>
 #include <vector>

 #include "android-base/file.h"
 #include "android-base/logging.h"
 #include "android-base/macros.h"
 #include "android-base/result.h"
 #include "android-base/stringprintf.h"
 #include "android-base/strings.h"
 #include "nativehelper/scoped_utf_chars.h"
 #include "nativeloader/dlext_namespaces.h"
 #include "public_libraries.h"
 #include "utils.h"

 namespace android::nativeloader {

 namespace {

 using ::android::base::Error;

 constexpr const char* kApexPath = "/apex/";

 // clns-XX is a linker namespace that is created for normal apps installed in
 // the data partition. To be specific, it is created for the app classloader.
 // When System.load() is called from a Java class that is loaded from the
 // classloader, the clns namespace associated with that classloader is selected
 // for dlopen. The namespace is configured so that its search path is set to the
 // app-local JNI directory and it is linked to the system namespace with the
 // names of libs listed in the public.libraries.txt and other public libraries.
 // This way an app can only load its own JNI libraries along with the public
 // libs.
 constexpr const char* kClassloaderNamespaceName = "clns";
 // Same thing for unbundled APKs in the vendor partition.
 constexpr const char* kVendorClassloaderNamespaceName = "vendor-clns";
 // Same thing for unbundled APKs in the product partition.
 constexpr const char* kProductClassloaderNamespaceName = "product-clns";
 // If the namespace is shared then add this suffix to help identify it in debug
 // messages. A shared namespace (cf. ANDROID_NAMESPACE_TYPE_SHARED) has
 // inherited all the libraries of the parent classloader namespace, or the
 // system namespace for the main app classloader. It is used to give full access
 // to the platform libraries for apps bundled in the system image, including
 // their later updates installed in /data.
 constexpr const char* kSharedNamespaceSuffix = "-shared";

 // (http://b/27588281) This is a workaround for apps using custom classloaders and calling
 // System.load() with an absolute path which is outside of the classloader library search path.
 // This list includes all directories app is allowed to access this way.
 constexpr const char* kAlwaysPermittedDirectories = "/data:/mnt/expand";

 constexpr const char* kVendorLibPath = "/vendor/" LIB;
 // TODO(mast): It's unlikely that both paths are necessary for kProductLibPath
 // below, because they can't be two separate directories - either one has to be
 // a symlink to the other.
 constexpr const char* kProductLibPath = "/product/" LIB ":/system/product/" LIB;

 const std::regex kVendorPathRegex("(/system)?/vendor/.*");
 const std::regex kProductPathRegex("(/system)?/product/.*");

 jobject GetParentClassLoader(JNIEnv* env, jobject class_loader) {
   jclass class_loader_class = env->FindClass("java/lang/ClassLoader");
   jmethodID get_parent =
       env->GetMethodID(class_loader_class, "getParent", "()Ljava/lang/ClassLoader;");

   return env->CallObjectMethod(class_loader, get_parent);
 }

 }  // namespace

 ApiDomain GetApiDomainFromPath(const std::string_view path) {
   if (std::regex_match(path.begin(), path.end(), kVendorPathRegex)) {
     return API_DOMAIN_VENDOR;
   }
   if (is_product_treblelized() && std::regex_match(path.begin(), path.end(), kProductPathRegex)) {
     return API_DOMAIN_PRODUCT;
   }
   return API_DOMAIN_DEFAULT;
 }

 // Returns the API domain for a ':'-separated list of paths, or an error if they
 // match more than one.
 Result<ApiDomain> GetApiDomainFromPathList(const std::string& path_list) {
   ApiDomain result = API_DOMAIN_DEFAULT;
   size_t start_pos = 0;
   while (true) {
     size_t end_pos = path_list.find(':', start_pos);
     ApiDomain api_domain =
         GetApiDomainFromPath(std::string_view(path_list).substr(start_pos, end_pos));
     // Allow mixing API_DOMAIN_DEFAULT with any other domain. That's a bit lax,
     // since the default e.g. includes /data, which strictly speaking is a
     // separate domain. However, we keep it this way to not risk compat issues
     // until we actually need all domains.
     if (api_domain != API_DOMAIN_DEFAULT) {
       if (result != API_DOMAIN_DEFAULT && result != api_domain) {
         return Error() << "Path list crosses partition boundaries: " << path_list;
       }
       result = api_domain;
     }
     if (end_pos == std::string::npos) {
       break;
     }
     start_pos = end_pos + 1;
   }
   return result;
 }

 void LibraryNamespaces::Initialize() {
   // Once public namespace is initialized there is no
   // point in running this code - it will have no effect
   // on the current list of public libraries.
   if (initialized_) {
     return;
   }

   // Load the preloadable public libraries. Since libnativeloader is in the
   // com_android_art namespace, use OpenSystemLibrary rather than dlopen to
   // ensure the libraries are loaded in the system namespace.
   //
   // TODO(dimitry): this is a bit misleading since we do not know
   // if the vendor public library is going to be opened from /vendor/lib
   // we might as well end up loading them from /system/lib or /product/lib
   // For now we rely on CTS test to catch things like this but
   // it should probably be addressed in the future.
   for (const std::string& soname : android::base::Split(preloadable_public_libraries(), ":")) {
     void* handle = OpenSystemLibrary(soname.c_str(), RTLD_NOW | RTLD_NODELETE);
     LOG_ALWAYS_FATAL_IF(handle == nullptr,
                         "Error preloading public library %s: %s", soname.c_str(), dlerror());
   }
 }

 // "ALL" is a magic name that allows all public libraries even when the
 // target SDK is > 30. Currently this is used for (Java) shared libraries
 // which don't use <uses-native-library>
 // TODO(b/142191088) remove this hack
 static constexpr const char LIBRARY_ALL[] = "ALL";

 // Returns the colon-separated list of library names by filtering uses_libraries from
 // public_libraries. The returned names will actually be available to the app. If the app is pre-S
 // (<= 30), the filtering is not done; the entire public_libraries are provided.
 static const std::string filter_public_libraries(
     uint32_t target_sdk_version, const std::vector<std::string>& uses_libraries,
     const std::string& public_libraries) {
   // Apps targeting Android 11 or earlier gets all public libraries
   if (target_sdk_version <= 30) {
     return public_libraries;
   }
   if (std::find(uses_libraries.begin(), uses_libraries.end(), LIBRARY_ALL) !=
       uses_libraries.end()) {
     return public_libraries;
   }
   std::vector<std::string> filtered;
   std::vector<std::string> orig = android::base::Split(public_libraries, ":");
   for (const std::string& lib : uses_libraries) {
     if (std::find(orig.begin(), orig.end(), lib) != orig.end()) {
       filtered.emplace_back(lib);
     }
   }
   return android::base::Join(filtered, ":");
 }

 Result<NativeLoaderNamespace*> LibraryNamespaces::Create(JNIEnv* env,
                                                          uint32_t target_sdk_version,
                                                          jobject class_loader,
                                                          ApiDomain api_domain,
                                                          bool is_shared,
                                                          const std::string& dex_path,
                                                          jstring library_path_j,
                                                          jstring permitted_path_j,
                                                          jstring uses_library_list_j) {
   std::string library_path;  // empty string by default.

   if (library_path_j != nullptr) {
     ScopedUtfChars library_path_utf_chars(env, library_path_j);
     library_path = library_path_utf_chars.c_str();
   }

   std::vector<std::string> uses_libraries;
   if (uses_library_list_j != nullptr) {
     ScopedUtfChars names(env, uses_library_list_j);
     uses_libraries = android::base::Split(names.c_str(), ":");
   } else {
     // uses_library_list_j could be nullptr when System.loadLibrary is called
     // from a custom classloader. In that case, we don't know the list of public
     // libraries because we don't know which apk the classloader is for. Only
     // choices we can have are 1) allowing all public libs (as before), or 2)
     // not allowing all but NDK libs. Here we take #1 because #2 would surprise
     // developers unnecessarily.
     // TODO(b/142191088) finalize the policy here. We could either 1) allow all
     // public libs, 2) disallow any lib, or 3) use the libs that were granted to
     // the first (i.e. app main) classloader.
     uses_libraries.emplace_back(LIBRARY_ALL);
   }

   // (http://b/27588281) This is a workaround for apps using custom
   // classloaders and calling System.load() with an absolute path which
   // is outside of the classloader library search path.
   //
   // This part effectively allows such a classloader to access anything
   // under /data and /mnt/expand
   std::string permitted_path = kAlwaysPermittedDirectories;

   if (permitted_path_j != nullptr) {
     ScopedUtfChars path(env, permitted_path_j);
     if (path.c_str() != nullptr && path.size() > 0) {
       permitted_path = permitted_path + ":" + path.c_str();
     }
   }

   LOG_ALWAYS_FATAL_IF(FindNamespaceByClassLoader(env, class_loader) != nullptr,
                       "There is already a namespace associated with this classloader");

   std::string system_exposed_libraries = default_public_libraries();
   std::string namespace_name = kClassloaderNamespaceName;
   ApiDomain unbundled_app_domain = API_DOMAIN_DEFAULT;
   const char* api_domain_msg = "other apk";  // Only for debug logging.

   if (!is_shared) {
     if (api_domain == API_DOMAIN_VENDOR) {
       unbundled_app_domain = API_DOMAIN_VENDOR;
       api_domain_msg = "unbundled vendor apk";

       // For vendor apks, give access to the vendor libs even though they are
       // treated as unbundled; the libs and apks are still bundled together in the
       // vendor partition.
       library_path = library_path + ':' + kVendorLibPath;
       permitted_path = permitted_path + ':' + kVendorLibPath;

       // Also give access to LLNDK libraries since they are available to vendor.
       system_exposed_libraries = system_exposed_libraries + ':' + llndk_libraries_vendor();

       // Different name is useful for debugging
       namespace_name = kVendorClassloaderNamespaceName;
     } else if (api_domain == API_DOMAIN_PRODUCT) {
       unbundled_app_domain = API_DOMAIN_PRODUCT;
       api_domain_msg = "unbundled product apk";

       // Like for vendor apks, give access to the product libs since they are
       // bundled together in the same partition.
       library_path = library_path + ':' + kProductLibPath;
       permitted_path = permitted_path + ':' + kProductLibPath;

       // Also give access to LLNDK libraries since they are available to product.
       system_exposed_libraries = system_exposed_libraries + ':' + llndk_libraries_product();

       // Different name is useful for debugging
       namespace_name = kProductClassloaderNamespaceName;
     }
   }

   if (is_shared) {
     // Show in the name that the namespace was created as shared, for debugging
     // purposes.
     namespace_name = namespace_name + kSharedNamespaceSuffix;
   }

   // Append a unique number to the namespace name, to tell them apart when
   // debugging linker issues, e.g. with debug.ld.all set to "dlopen,dlerror".
   static int clns_count = 0;
   namespace_name = android::base::StringPrintf("%s-%d", namespace_name.c_str(), ++clns_count);

   ALOGD(
       "Configuring %s for %s %s. target_sdk_version=%u, uses_libraries=%s, library_path=%s, "
       "permitted_path=%s",
       namespace_name.c_str(),
       api_domain_msg,
       dex_path.c_str(),
       static_cast<unsigned>(target_sdk_version),
       android::base::Join(uses_libraries, ':').c_str(),
       library_path.c_str(),
       permitted_path.c_str());

   if (unbundled_app_domain != API_DOMAIN_VENDOR) {
     // Extended public libraries are NOT available to unbundled vendor apks, but
     // they are to other apps, including those in system, system_ext, and
     // product partitions. The reason is that when GSI is used, the system
     // partition may get replaced, and then vendor apps may fail. It's fine for
     // product apps, because that partition isn't mounted in GSI tests.
     const std::string libs =
         filter_public_libraries(target_sdk_version, uses_libraries, extended_public_libraries());
     if (!libs.empty()) {
       ALOGD("Extending system_exposed_libraries: %s", libs.c_str());
       system_exposed_libraries = system_exposed_libraries + ':' + libs;
     }
   }

   // Create the app namespace
   NativeLoaderNamespace* parent_ns = FindParentNamespaceByClassLoader(env, class_loader);
   // Heuristic: the first classloader with non-empty library_path is assumed to
   // be the main classloader for app
   // TODO(b/139178525) remove this heuristic by determining this in LoadedApk (or its
   // friends) and then passing it down to here.
   bool is_main_classloader = app_main_namespace_ == nullptr && !library_path.empty();
   // Policy: the namespace for the main classloader is also used as the
   // anonymous namespace.
   bool also_used_as_anonymous = is_main_classloader;
   // Note: this function is executed with g_namespaces_mutex held, thus no
   // racing here.
   Result<NativeLoaderNamespace> app_ns =
       NativeLoaderNamespace::Create(namespace_name,
                                     library_path,
                                     permitted_path,
                                     parent_ns,
                                     is_shared,
                                     target_sdk_version < 24 /* is_exempt_list_enabled */,
                                     also_used_as_anonymous);
   if (!app_ns.ok()) {
     return app_ns.error();
   }
   // ... and link to other namespaces to allow access to some public libraries
   bool is_bridged = app_ns->IsBridged();

   Result<NativeLoaderNamespace> system_ns = NativeLoaderNamespace::GetSystemNamespace(is_bridged);
   if (!system_ns.ok()) {
     return system_ns.error();
   }

   Result<void> linked = app_ns->Link(&system_ns.value(), system_exposed_libraries);
   if (!linked.ok()) {
     return linked.error();
   }

   for (const auto&[apex_ns_name, public_libs] : apex_public_libraries()) {
     Result<NativeLoaderNamespace> ns =
         NativeLoaderNamespace::GetExportedNamespace(apex_ns_name, is_bridged);
     // Even if APEX namespace is visible, it may not be available to bridged.
     if (ns.ok()) {
       linked = app_ns->Link(&ns.value(), public_libs);
       if (!linked.ok()) {
         return linked.error();
       }
     }
   }

   // Give access to VNDK-SP libraries from the 'vndk' namespace for unbundled vendor apps.
   if (unbundled_app_domain == API_DOMAIN_VENDOR && !vndksp_libraries_vendor().empty()) {
     Result<NativeLoaderNamespace> vndk_ns =
         NativeLoaderNamespace::GetExportedNamespace(kVndkNamespaceName, is_bridged);
     if (vndk_ns.ok()) {
       linked = app_ns->Link(&vndk_ns.value(), vndksp_libraries_vendor());
       if (!linked.ok()) {
         return linked.error();
       }
     }
   }

   // Give access to VNDK-SP libraries from the 'vndk_product' namespace for unbundled product apps.
   if (unbundled_app_domain == API_DOMAIN_PRODUCT && !vndksp_libraries_product().empty()) {
     Result<NativeLoaderNamespace> vndk_ns =
         NativeLoaderNamespace::GetExportedNamespace(kVndkProductNamespaceName, is_bridged);
     if (vndk_ns.ok()) {
       linked = app_ns->Link(&vndk_ns.value(), vndksp_libraries_product());
       if (!linked.ok()) {
         return linked.error();
       }
     }
   }

   for (const std::string& each_jar_path : android::base::Split(dex_path, ":")) {
     std::optional<std::string> apex_ns_name = FindApexNamespaceName(each_jar_path);
     if (apex_ns_name.has_value()) {
       const std::string& jni_libs = apex_jni_libraries(apex_ns_name.value());
       if (jni_libs != "") {
         Result<NativeLoaderNamespace> apex_ns =
             NativeLoaderNamespace::GetExportedNamespace(apex_ns_name.value(), is_bridged);
         if (apex_ns.ok()) {
           linked = app_ns->Link(&apex_ns.value(), jni_libs);
           if (!linked.ok()) {
             return linked.error();
           }
         }
       }
     }
   }

   const std::string vendor_libs =
       filter_public_libraries(target_sdk_version, uses_libraries, vendor_public_libraries());
   if (!vendor_libs.empty()) {
     Result<NativeLoaderNamespace> vendor_ns =
         NativeLoaderNamespace::GetExportedNamespace(kVendorNamespaceName, is_bridged);
     // when vendor_ns is not configured, link to the system namespace
     Result<NativeLoaderNamespace> target_ns = vendor_ns.ok() ? vendor_ns : system_ns;
     if (target_ns.ok()) {
       linked = app_ns->Link(&target_ns.value(), vendor_libs);
       if (!linked.ok()) {
         return linked.error();
       }
     }
   }

   const std::string product_libs =
       filter_public_libraries(target_sdk_version, uses_libraries, product_public_libraries());
   if (!product_libs.empty()) {
     Result<NativeLoaderNamespace> target_ns = system_ns;
     if (is_product_treblelized()) {
       target_ns = NativeLoaderNamespace::GetExportedNamespace(kProductNamespaceName, is_bridged);
     }
     if (target_ns.ok()) {
       linked = app_ns->Link(&target_ns.value(), product_libs);
       if (!linked.ok()) {
         return linked.error();
       }
     } else {
       // The linkerconfig must have a problem on defining the product namespace in the system
       // section. Skip linking product namespace. This will not affect most of the apps. Only the
       // apps that requires the product public libraries will fail.
       ALOGW("Namespace for product libs not found: %s", target_ns.error().message().c_str());
     }
   }

   std::pair<jweak, NativeLoaderNamespace>& emplaced =
       namespaces_.emplace_back(std::make_pair(env->NewWeakGlobalRef(class_loader), *app_ns));
   if (is_main_classloader) {
     app_main_namespace_ = &emplaced.second;
   }
   return &emplaced.second;
 }

 NativeLoaderNamespace* LibraryNamespaces::FindNamespaceByClassLoader(JNIEnv* env,
                                                                      jobject class_loader) {
   auto it = std::find_if(namespaces_.begin(), namespaces_.end(),
                          [&](const std::pair<jweak, NativeLoaderNamespace>& value) {
                            return env->IsSameObject(value.first, class_loader);
                          });
   if (it != namespaces_.end()) {
     return &it->second;
   }

   return nullptr;
 }

 NativeLoaderNamespace* LibraryNamespaces::FindParentNamespaceByClassLoader(JNIEnv* env,
                                                                            jobject class_loader) {
   jobject parent_class_loader = GetParentClassLoader(env, class_loader);

   while (parent_class_loader != nullptr) {
     NativeLoaderNamespace* ns;
     if ((ns = FindNamespaceByClassLoader(env, parent_class_loader)) != nullptr) {
       return ns;
     }

     parent_class_loader = GetParentClassLoader(env, parent_class_loader);
   }

   return nullptr;
 }

 std::optional<std::string> FindApexNamespaceName(const std::string& location) {
   // Lots of implicit assumptions here: we expect `location` to be of the form:
   // /apex/modulename/...
   //
   // And we extract from it 'modulename', and then apply mangling rule to get namespace name for it.
   if (android::base::StartsWith(location, kApexPath)) {
     size_t start_index = strlen(kApexPath);
     size_t slash_index = location.find_first_of('/', start_index);
     LOG_ALWAYS_FATAL_IF((slash_index == std::string::npos),
                         "Error finding namespace of apex: no slash in path %s", location.c_str());
     std::string name = location.substr(start_index, slash_index - start_index);
     std::replace(name.begin(), name.end(), '.', '_');
     return name;
   }
   return std::nullopt;
 }

 }  // namespace android::nativeloader

 #endif  // defined(ART_TARGET_ANDROID)
	/*
	* Copyright (C) 2019 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.
	*/

	#if defined(ART_TARGET_ANDROID)

	#define LOG_TAG "nativeloader"

	#include "library_namespaces.h"

	#include <dirent.h>
	#include <dlfcn.h>
	#include <stdio.h>

	#include <algorithm>
	#include <optional>
	#include <regex>
	#include <string>
	#include <string_view>
	#include <vector>

	#include "android-base/file.h"
	#include "android-base/logging.h"
	#include "android-base/macros.h"
	#include "android-base/result.h"
	#include "android-base/stringprintf.h"
	#include "android-base/strings.h"
	#include "nativehelper/scoped_utf_chars.h"
	#include "nativeloader/dlext_namespaces.h"
	#include "public_libraries.h"
	#include "utils.h"

	namespace android::nativeloader {

	namespace {

	using ::android::base::Error;

	constexpr const char* kApexPath = "/apex/";

	// clns-XX is a linker namespace that is created for normal apps installed in
	// the data partition. To be specific, it is created for the app classloader.
	// When System.load() is called from a Java class that is loaded from the
	// classloader, the clns namespace associated with that classloader is selected
	// for dlopen. The namespace is configured so that its search path is set to the
	// app-local JNI directory and it is linked to the system namespace with the
	// names of libs listed in the public.libraries.txt and other public libraries.
	// This way an app can only load its own JNI libraries along with the public
	// libs.
	constexpr const char* kClassloaderNamespaceName = "clns";
	// Same thing for unbundled APKs in the vendor partition.
	constexpr const char* kVendorClassloaderNamespaceName = "vendor-clns";
	// Same thing for unbundled APKs in the product partition.
	constexpr const char* kProductClassloaderNamespaceName = "product-clns";
	// If the namespace is shared then add this suffix to help identify it in debug
	// messages. A shared namespace (cf. ANDROID_NAMESPACE_TYPE_SHARED) has
	// inherited all the libraries of the parent classloader namespace, or the
	// system namespace for the main app classloader. It is used to give full access
	// to the platform libraries for apps bundled in the system image, including
	// their later updates installed in /data.
	constexpr const char* kSharedNamespaceSuffix = "-shared";

	// (http://b/27588281) This is a workaround for apps using custom classloaders and calling
	// System.load() with an absolute path which is outside of the classloader library search path.
	// This list includes all directories app is allowed to access this way.
	constexpr const char* kAlwaysPermittedDirectories = "/data:/mnt/expand";

	constexpr const char* kVendorLibPath = "/vendor/" LIB;
	// TODO(mast): It's unlikely that both paths are necessary for kProductLibPath
	// below, because they can't be two separate directories - either one has to be
	// a symlink to the other.
	constexpr const char* kProductLibPath = "/product/" LIB ":/system/product/" LIB;

	const std::regex kVendorPathRegex("(/system)?/vendor/.*");
	const std::regex kProductPathRegex("(/system)?/product/.*");

	jobject GetParentClassLoader(JNIEnv* env, jobject class_loader) {
	jclass class_loader_class = env->FindClass("java/lang/ClassLoader");
	jmethodID get_parent =
	env->GetMethodID(class_loader_class, "getParent", "()Ljava/lang/ClassLoader;");

	return env->CallObjectMethod(class_loader, get_parent);
	}

	} // namespace

	ApiDomain GetApiDomainFromPath(const std::string_view path) {
	if (std::regex_match(path.begin(), path.end(), kVendorPathRegex)) {
	return API_DOMAIN_VENDOR;
	}
	if (is_product_treblelized() && std::regex_match(path.begin(), path.end(), kProductPathRegex)) {
	return API_DOMAIN_PRODUCT;
	}
	return API_DOMAIN_DEFAULT;
	}

	// Returns the API domain for a ':'-separated list of paths, or an error if they
	// match more than one.
	Result<ApiDomain> GetApiDomainFromPathList(const std::string& path_list) {
	ApiDomain result = API_DOMAIN_DEFAULT;
	size_t start_pos = 0;
	while (true) {
	size_t end_pos = path_list.find(':', start_pos);
	ApiDomain api_domain =
	GetApiDomainFromPath(std::string_view(path_list).substr(start_pos, end_pos));
	// Allow mixing API_DOMAIN_DEFAULT with any other domain. That's a bit lax,
	// since the default e.g. includes /data, which strictly speaking is a
	// separate domain. However, we keep it this way to not risk compat issues
	// until we actually need all domains.
	if (api_domain != API_DOMAIN_DEFAULT) {
	if (result != API_DOMAIN_DEFAULT && result != api_domain) {
	return Error() << "Path list crosses partition boundaries: " << path_list;
	}
	result = api_domain;
	}
	if (end_pos == std::string::npos) {
	break;
	}
	start_pos = end_pos + 1;
	}
	return result;
	}

	void LibraryNamespaces::Initialize() {
	// Once public namespace is initialized there is no
	// point in running this code - it will have no effect
	// on the current list of public libraries.
	if (initialized_) {
	return;
	}

	// Load the preloadable public libraries. Since libnativeloader is in the
	// com_android_art namespace, use OpenSystemLibrary rather than dlopen to
	// ensure the libraries are loaded in the system namespace.
	//
	// TODO(dimitry): this is a bit misleading since we do not know
	// if the vendor public library is going to be opened from /vendor/lib
	// we might as well end up loading them from /system/lib or /product/lib
	// For now we rely on CTS test to catch things like this but
	// it should probably be addressed in the future.
	for (const std::string& soname : android::base::Split(preloadable_public_libraries(), ":")) {
	void* handle = OpenSystemLibrary(soname.c_str(), RTLD_NOW \| RTLD_NODELETE);
	LOG_ALWAYS_FATAL_IF(handle == nullptr,
	"Error preloading public library %s: %s", soname.c_str(), dlerror());
	}
	}

	// "ALL" is a magic name that allows all public libraries even when the
	// target SDK is > 30. Currently this is used for (Java) shared libraries
	// which don't use <uses-native-library>
	// TODO(b/142191088) remove this hack
	static constexpr const char LIBRARY_ALL[] = "ALL";

	// Returns the colon-separated list of library names by filtering uses_libraries from
	// public_libraries. The returned names will actually be available to the app. If the app is pre-S
	// (<= 30), the filtering is not done; the entire public_libraries are provided.
	static const std::string filter_public_libraries(
	uint32_t target_sdk_version, const std::vector<std::string>& uses_libraries,
	const std::string& public_libraries) {
	// Apps targeting Android 11 or earlier gets all public libraries
	if (target_sdk_version <= 30) {
	return public_libraries;
	}
	if (std::find(uses_libraries.begin(), uses_libraries.end(), LIBRARY_ALL) !=
	uses_libraries.end()) {
	return public_libraries;
	}
	std::vector<std::string> filtered;
	std::vector<std::string> orig = android::base::Split(public_libraries, ":");
	for (const std::string& lib : uses_libraries) {
	if (std::find(orig.begin(), orig.end(), lib) != orig.end()) {
	filtered.emplace_back(lib);
	}
	}
	return android::base::Join(filtered, ":");
	}

	Result<NativeLoaderNamespace> LibraryNamespaces::Create(JNIEnv env,
	uint32_t target_sdk_version,
	jobject class_loader,
	ApiDomain api_domain,
	bool is_shared,
	const std::string& dex_path,
	jstring library_path_j,
	jstring permitted_path_j,
	jstring uses_library_list_j) {
	std::string library_path; // empty string by default.

	if (library_path_j != nullptr) {
	ScopedUtfChars library_path_utf_chars(env, library_path_j);
	library_path = library_path_utf_chars.c_str();
	}

	std::vector<std::string> uses_libraries;
	if (uses_library_list_j != nullptr) {
	ScopedUtfChars names(env, uses_library_list_j);
	uses_libraries = android::base::Split(names.c_str(), ":");
	} else {
	// uses_library_list_j could be nullptr when System.loadLibrary is called
	// from a custom classloader. In that case, we don't know the list of public
	// libraries because we don't know which apk the classloader is for. Only
	// choices we can have are 1) allowing all public libs (as before), or 2)
	// not allowing all but NDK libs. Here we take #1 because #2 would surprise
	// developers unnecessarily.
	// TODO(b/142191088) finalize the policy here. We could either 1) allow all
	// public libs, 2) disallow any lib, or 3) use the libs that were granted to
	// the first (i.e. app main) classloader.
	uses_libraries.emplace_back(LIBRARY_ALL);
	}

	// (http://b/27588281) This is a workaround for apps using custom
	// classloaders and calling System.load() with an absolute path which
	// is outside of the classloader library search path.
	//
	// This part effectively allows such a classloader to access anything
	// under /data and /mnt/expand
	std::string permitted_path = kAlwaysPermittedDirectories;

	if (permitted_path_j != nullptr) {
	ScopedUtfChars path(env, permitted_path_j);
	if (path.c_str() != nullptr && path.size() > 0) {
	permitted_path = permitted_path + ":" + path.c_str();
	}
	}

	LOG_ALWAYS_FATAL_IF(FindNamespaceByClassLoader(env, class_loader) != nullptr,
	"There is already a namespace associated with this classloader");

	std::string system_exposed_libraries = default_public_libraries();
	std::string namespace_name = kClassloaderNamespaceName;
	ApiDomain unbundled_app_domain = API_DOMAIN_DEFAULT;
	const char* api_domain_msg = "other apk"; // Only for debug logging.

	if (!is_shared) {
	if (api_domain == API_DOMAIN_VENDOR) {
	unbundled_app_domain = API_DOMAIN_VENDOR;
	api_domain_msg = "unbundled vendor apk";

	// For vendor apks, give access to the vendor libs even though they are
	// treated as unbundled; the libs and apks are still bundled together in the
	// vendor partition.
	library_path = library_path + ':' + kVendorLibPath;
	permitted_path = permitted_path + ':' + kVendorLibPath;

	// Also give access to LLNDK libraries since they are available to vendor.
	system_exposed_libraries = system_exposed_libraries + ':' + llndk_libraries_vendor();

	// Different name is useful for debugging
	namespace_name = kVendorClassloaderNamespaceName;
	} else if (api_domain == API_DOMAIN_PRODUCT) {
	unbundled_app_domain = API_DOMAIN_PRODUCT;
	api_domain_msg = "unbundled product apk";

	// Like for vendor apks, give access to the product libs since they are
	// bundled together in the same partition.
	library_path = library_path + ':' + kProductLibPath;
	permitted_path = permitted_path + ':' + kProductLibPath;

	// Also give access to LLNDK libraries since they are available to product.
	system_exposed_libraries = system_exposed_libraries + ':' + llndk_libraries_product();

	// Different name is useful for debugging
	namespace_name = kProductClassloaderNamespaceName;
	}
	}

	if (is_shared) {
	// Show in the name that the namespace was created as shared, for debugging
	// purposes.
	namespace_name = namespace_name + kSharedNamespaceSuffix;
	}

	// Append a unique number to the namespace name, to tell them apart when
	// debugging linker issues, e.g. with debug.ld.all set to "dlopen,dlerror".
	static int clns_count = 0;
	namespace_name = android::base::StringPrintf("%s-%d", namespace_name.c_str(), ++clns_count);

	ALOGD(
	"Configuring %s for %s %s. target_sdk_version=%u, uses_libraries=%s, library_path=%s, "
	"permitted_path=%s",
	namespace_name.c_str(),
	api_domain_msg,
	dex_path.c_str(),
	static_cast<unsigned>(target_sdk_version),
	android::base::Join(uses_libraries, ':').c_str(),
	library_path.c_str(),
	permitted_path.c_str());

	if (unbundled_app_domain != API_DOMAIN_VENDOR) {
	// Extended public libraries are NOT available to unbundled vendor apks, but
	// they are to other apps, including those in system, system_ext, and
	// product partitions. The reason is that when GSI is used, the system
	// partition may get replaced, and then vendor apps may fail. It's fine for
	// product apps, because that partition isn't mounted in GSI tests.
	const std::string libs =
	filter_public_libraries(target_sdk_version, uses_libraries, extended_public_libraries());
	if (!libs.empty()) {
	ALOGD("Extending system_exposed_libraries: %s", libs.c_str());
	system_exposed_libraries = system_exposed_libraries + ':' + libs;
	}
	}

	// Create the app namespace
	NativeLoaderNamespace* parent_ns = FindParentNamespaceByClassLoader(env, class_loader);
	// Heuristic: the first classloader with non-empty library_path is assumed to
	// be the main classloader for app
	// TODO(b/139178525) remove this heuristic by determining this in LoadedApk (or its
	// friends) and then passing it down to here.
	bool is_main_classloader = app_main_namespace_ == nullptr && !library_path.empty();
	// Policy: the namespace for the main classloader is also used as the
	// anonymous namespace.
	bool also_used_as_anonymous = is_main_classloader;
	// Note: this function is executed with g_namespaces_mutex held, thus no
	// racing here.
	Result<NativeLoaderNamespace> app_ns =
	NativeLoaderNamespace::Create(namespace_name,
	library_path,
	permitted_path,
	parent_ns,
	is_shared,
	target_sdk_version < 24 /* is_exempt_list_enabled */,
	also_used_as_anonymous);
	if (!app_ns.ok()) {
	return app_ns.error();
	}
	// ... and link to other namespaces to allow access to some public libraries
	bool is_bridged = app_ns->IsBridged();

	Result<NativeLoaderNamespace> system_ns = NativeLoaderNamespace::GetSystemNamespace(is_bridged);
	if (!system_ns.ok()) {
	return system_ns.error();
	}

	Result<void> linked = app_ns->Link(&system_ns.value(), system_exposed_libraries);
	if (!linked.ok()) {
	return linked.error();
	}

	for (const auto&[apex_ns_name, public_libs] : apex_public_libraries()) {
	Result<NativeLoaderNamespace> ns =
	NativeLoaderNamespace::GetExportedNamespace(apex_ns_name, is_bridged);
	// Even if APEX namespace is visible, it may not be available to bridged.
	if (ns.ok()) {
	linked = app_ns->Link(&ns.value(), public_libs);
	if (!linked.ok()) {
	return linked.error();
	}
	}
	}

	// Give access to VNDK-SP libraries from the 'vndk' namespace for unbundled vendor apps.
	if (unbundled_app_domain == API_DOMAIN_VENDOR && !vndksp_libraries_vendor().empty()) {
	Result<NativeLoaderNamespace> vndk_ns =
	NativeLoaderNamespace::GetExportedNamespace(kVndkNamespaceName, is_bridged);
	if (vndk_ns.ok()) {
	linked = app_ns->Link(&vndk_ns.value(), vndksp_libraries_vendor());
	if (!linked.ok()) {
	return linked.error();
	}
	}
	}

	// Give access to VNDK-SP libraries from the 'vndk_product' namespace for unbundled product apps.
	if (unbundled_app_domain == API_DOMAIN_PRODUCT && !vndksp_libraries_product().empty()) {
	Result<NativeLoaderNamespace> vndk_ns =
	NativeLoaderNamespace::GetExportedNamespace(kVndkProductNamespaceName, is_bridged);
	if (vndk_ns.ok()) {
	linked = app_ns->Link(&vndk_ns.value(), vndksp_libraries_product());
	if (!linked.ok()) {
	return linked.error();
	}
	}
	}

	for (const std::string& each_jar_path : android::base::Split(dex_path, ":")) {
	std::optional<std::string> apex_ns_name = FindApexNamespaceName(each_jar_path);
	if (apex_ns_name.has_value()) {
	const std::string& jni_libs = apex_jni_libraries(apex_ns_name.value());
	if (jni_libs != "") {
	Result<NativeLoaderNamespace> apex_ns =
	NativeLoaderNamespace::GetExportedNamespace(apex_ns_name.value(), is_bridged);
	if (apex_ns.ok()) {
	linked = app_ns->Link(&apex_ns.value(), jni_libs);
	if (!linked.ok()) {
	return linked.error();
	}
	}
	}
	}
	}

	const std::string vendor_libs =
	filter_public_libraries(target_sdk_version, uses_libraries, vendor_public_libraries());
	if (!vendor_libs.empty()) {
	Result<NativeLoaderNamespace> vendor_ns =
	NativeLoaderNamespace::GetExportedNamespace(kVendorNamespaceName, is_bridged);
	// when vendor_ns is not configured, link to the system namespace
	Result<NativeLoaderNamespace> target_ns = vendor_ns.ok() ? vendor_ns : system_ns;
	if (target_ns.ok()) {
	linked = app_ns->Link(&target_ns.value(), vendor_libs);
	if (!linked.ok()) {
	return linked.error();
	}
	}
	}

	const std::string product_libs =
	filter_public_libraries(target_sdk_version, uses_libraries, product_public_libraries());
	if (!product_libs.empty()) {
	Result<NativeLoaderNamespace> target_ns = system_ns;
	if (is_product_treblelized()) {
	target_ns = NativeLoaderNamespace::GetExportedNamespace(kProductNamespaceName, is_bridged);
	}
	if (target_ns.ok()) {
	linked = app_ns->Link(&target_ns.value(), product_libs);
	if (!linked.ok()) {
	return linked.error();
	}
	} else {
	// The linkerconfig must have a problem on defining the product namespace in the system
	// section. Skip linking product namespace. This will not affect most of the apps. Only the
	// apps that requires the product public libraries will fail.
	ALOGW("Namespace for product libs not found: %s", target_ns.error().message().c_str());
	}
	}

	std::pair<jweak, NativeLoaderNamespace>& emplaced =
	namespaces_.emplace_back(std::make_pair(env->NewWeakGlobalRef(class_loader), *app_ns));
	if (is_main_classloader) {
	app_main_namespace_ = &emplaced.second;
	}
	return &emplaced.second;
	}

	NativeLoaderNamespace* LibraryNamespaces::FindNamespaceByClassLoader(JNIEnv* env,
	jobject class_loader) {
	auto it = std::find_if(namespaces_.begin(), namespaces_.end(),
	[&](const std::pair<jweak, NativeLoaderNamespace>& value) {
	return env->IsSameObject(value.first, class_loader);
	});
	if (it != namespaces_.end()) {
	return &it->second;
	}

	return nullptr;
	}

	NativeLoaderNamespace* LibraryNamespaces::FindParentNamespaceByClassLoader(JNIEnv* env,
	jobject class_loader) {
	jobject parent_class_loader = GetParentClassLoader(env, class_loader);

	while (parent_class_loader != nullptr) {
	NativeLoaderNamespace* ns;
	if ((ns = FindNamespaceByClassLoader(env, parent_class_loader)) != nullptr) {
	return ns;
	}

	parent_class_loader = GetParentClassLoader(env, parent_class_loader);
	}

	return nullptr;
	}

	std::optional<std::string> FindApexNamespaceName(const std::string& location) {
	// Lots of implicit assumptions here: we expect `location` to be of the form:
	// /apex/modulename/...
	//
	// And we extract from it 'modulename', and then apply mangling rule to get namespace name for it.
	if (android::base::StartsWith(location, kApexPath)) {
	size_t start_index = strlen(kApexPath);
	size_t slash_index = location.find_first_of('/', start_index);
	LOG_ALWAYS_FATAL_IF((slash_index == std::string::npos),
	"Error finding namespace of apex: no slash in path %s", location.c_str());
	std::string name = location.substr(start_index, slash_index - start_index);
	std::replace(name.begin(), name.end(), '.', '_');
	return name;
	}
	return std::nullopt;
	}

	} // namespace android::nativeloader

	#endif // defined(ART_TARGET_ANDROID)