libnativebridge/include/nativebridge/native_bridge.h - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2014 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.
  */

 #ifndef NATIVE_BRIDGE_H_
 #define NATIVE_BRIDGE_H_

 #include <signal.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <sys/types.h>

 #include "jni.h"

 #ifdef __cplusplus
 namespace android {
 extern "C" {
 #endif  // __cplusplus

 struct NativeBridgeRuntimeCallbacks;
 struct NativeBridgeRuntimeValues;

 // Function pointer type for sigaction. This is mostly the signature of a signal handler, except
 // for the return type. The runtime needs to know whether the signal was handled or should be given
 // to the chain.
 typedef bool (*NativeBridgeSignalHandlerFn)(int, siginfo_t*, void*);

 // Open the native bridge, if any. Should be called by Runtime::Init(). A null library filename
 // signals that we do not want to load a native bridge.
 bool LoadNativeBridge(const char* native_bridge_library_filename,
                       const struct NativeBridgeRuntimeCallbacks* runtime_callbacks);

 // Quick check whether a native bridge will be needed. This is based off of the instruction set
 // of the process.
 bool NeedsNativeBridge(const char* instruction_set);

 // Do the early initialization part of the native bridge, if necessary. This should be done under
 // high privileges.
 bool PreInitializeNativeBridge(const char* app_data_dir, const char* instruction_set);

 // Initialize the native bridge, if any. Should be called by Runtime::DidForkFromZygote. The JNIEnv*
 // will be used to modify the app environment for the bridge.
 bool InitializeNativeBridge(JNIEnv* env, const char* instruction_set);

 // Unload the native bridge, if any. Should be called by Runtime::DidForkFromZygote.
 void UnloadNativeBridge();

 // Check whether a native bridge is available (opened or initialized). Requires a prior call to
 // LoadNativeBridge.
 bool NativeBridgeAvailable();

 // Check whether a native bridge is available (initialized). Requires a prior call to
 // LoadNativeBridge & InitializeNativeBridge.
 bool NativeBridgeInitialized();

 // Load a shared library that is supported by the native bridge.
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Use NativeBridgeLoadLibraryExt() instead in namespace scenario.
 void* NativeBridgeLoadLibrary(const char* libpath, int flag);

 // Get a native bridge trampoline for specified native method.
 void* NativeBridgeGetTrampoline(void* handle, const char* name, const char* shorty, uint32_t len);

 // True if native library paths are valid and is for an ABI that is supported by native bridge.
 // The *libpath* must point to a library.
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Use NativeBridgeIsPathSupported() instead in namespace scenario.
 bool NativeBridgeIsSupported(const char* libpath);

 // Returns the version number of the native bridge. This information is available after a
 // successful LoadNativeBridge() and before closing it, that is, as long as NativeBridgeAvailable()
 // returns true. Returns 0 otherwise.
 uint32_t NativeBridgeGetVersion();

 // Returns a signal handler that the bridge would like to be managed. Only valid for a native
 // bridge supporting the version 2 interface. Will return null if the bridge does not support
 // version 2, or if it doesn't have a signal handler it wants to be known.
 NativeBridgeSignalHandlerFn NativeBridgeGetSignalHandler(int signal);

 // Returns whether we have seen a native bridge error. This could happen because the library
 // was not found, rejected, could not be initialized and so on.
 //
 // This functionality is mainly for testing.
 bool NativeBridgeError();

 // Returns whether a given string is acceptable as a native bridge library filename.
 //
 // This functionality is exposed mainly for testing.
 bool NativeBridgeNameAcceptable(const char* native_bridge_library_filename);

 // Decrements the reference count on the dynamic library handler. If the reference count drops
 // to zero then the dynamic library is unloaded. Returns 0 on success and non-zero on error.
 int NativeBridgeUnloadLibrary(void* handle);

 // Get last error message of native bridge when fail to load library or search symbol.
 // This is reflection of dlerror() for native bridge.
 const char* NativeBridgeGetError();

 struct native_bridge_namespace_t;

 // True if native library paths are valid and is for an ABI that is supported by native bridge.
 // Different from NativeBridgeIsSupported(), the *path* here must be a directory containing
 // libraries of an ABI.
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Use NativeBridgeIsSupported() instead in non-namespace scenario.
 bool NativeBridgeIsPathSupported(const char* path);

 // Initializes anonymous namespace.
 // NativeBridge's peer of android_init_anonymous_namespace() of dynamic linker.
 //
 // The anonymous namespace is used in the case when a NativeBridge implementation
 // cannot identify the caller of dlopen/dlsym which happens for the code not loaded
 // by dynamic linker; for example calls from the mono-compiled code.
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Should not use in non-namespace scenario.
 bool NativeBridgeInitAnonymousNamespace(const char* public_ns_sonames,
                                         const char* anon_ns_library_path);

 // Create new namespace in which native libraries will be loaded.
 // NativeBridge's peer of android_create_namespace() of dynamic linker.
 //
 // The libraries in the namespace are searched by folowing order:
 // 1. ld_library_path (Think of this as namespace-local LD_LIBRARY_PATH)
 // 2. In directories specified by DT_RUNPATH of the "needed by" binary.
 // 3. deault_library_path (This of this as namespace-local default library path)
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Should not use in non-namespace scenario.
 struct native_bridge_namespace_t* NativeBridgeCreateNamespace(
     const char* name, const char* ld_library_path, const char* default_library_path, uint64_t type,
     const char* permitted_when_isolated_path, struct native_bridge_namespace_t* parent_ns);

 // Creates a link which shares some libraries from one namespace to another.
 // NativeBridge's peer of android_link_namespaces() of dynamic linker.
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Should not use in non-namespace scenario.
 bool NativeBridgeLinkNamespaces(struct native_bridge_namespace_t* from,
                                 struct native_bridge_namespace_t* to,
                                 const char* shared_libs_sonames);

 // Load a shared library with namespace key that is supported by the native bridge.
 // NativeBridge's peer of android_dlopen_ext() of dynamic linker, only supports namespace
 // extension.
 //
 // Starting with v3, NativeBridge has two scenarios: with/without namespace.
 // Use NativeBridgeLoadLibrary() instead in non-namespace scenario.
 void* NativeBridgeLoadLibraryExt(const char* libpath, int flag,
                                  struct native_bridge_namespace_t* ns);

 // Returns exported namespace by the name. This is a reflection of
 // android_get_exported_namespace function. Introduced in v5.
 struct native_bridge_namespace_t* NativeBridgeGetExportedNamespace(const char* name);

 // Native bridge interfaces to runtime.
 struct NativeBridgeCallbacks {
   // Version number of the interface.
   uint32_t version;

   // Initialize native bridge. Native bridge's internal implementation must ensure MT safety and
   // that the native bridge is initialized only once. Thus it is OK to call this interface for an
   // already initialized native bridge.
   //
   // Parameters:
   //   runtime_cbs [IN] the pointer to NativeBridgeRuntimeCallbacks.
   // Returns:
   //   true if initialization was successful.
   bool (*initialize)(const struct NativeBridgeRuntimeCallbacks* runtime_cbs,
                      const char* private_dir, const char* instruction_set);

   // Load a shared library that is supported by the native bridge.
   //
   // Parameters:
   //   libpath [IN] path to the shared library
   //   flag [IN] the stardard RTLD_XXX defined in bionic dlfcn.h
   // Returns:
   //   The opaque handle of the shared library if sucessful, otherwise NULL
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Use loadLibraryExt instead in namespace scenario.
   void* (*loadLibrary)(const char* libpath, int flag);

   // Get a native bridge trampoline for specified native method. The trampoline has same
   // sigature as the native method.
   //
   // Parameters:
   //   handle [IN] the handle returned from loadLibrary
   //   shorty [IN] short descriptor of native method
   //   len [IN] length of shorty
   // Returns:
   //   address of trampoline if successful, otherwise NULL
   void* (*getTrampoline)(void* handle, const char* name, const char* shorty, uint32_t len);

   // Check whether native library is valid and is for an ABI that is supported by native bridge.
   //
   // Parameters:
   //   libpath [IN] path to the shared library
   // Returns:
   //   TRUE if library is supported by native bridge, FALSE otherwise
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Use isPathSupported instead in namespace scenario.
   bool (*isSupported)(const char* libpath);

   // Provide environment values required by the app running with native bridge according to the
   // instruction set.
   //
   // Parameters:
   //   instruction_set [IN] the instruction set of the app
   // Returns:
   //   NULL if not supported by native bridge.
   //   Otherwise, return all environment values to be set after fork.
   const struct NativeBridgeRuntimeValues* (*getAppEnv)(const char* instruction_set);

   // Added callbacks in version 2.

   // Check whether the bridge is compatible with the given version. A bridge may decide not to be
   // forwards- or backwards-compatible, and libnativebridge will then stop using it.
   //
   // Parameters:
   //   bridge_version [IN] the version of libnativebridge.
   // Returns:
   //   true if the native bridge supports the given version of libnativebridge.
   bool (*isCompatibleWith)(uint32_t bridge_version);

   // A callback to retrieve a native bridge's signal handler for the specified signal. The runtime
   // will ensure that the signal handler is being called after the runtime's own handler, but before
   // all chained handlers. The native bridge should not try to install the handler by itself, as
   // that will potentially lead to cycles.
   //
   // Parameters:
   //   signal [IN] the signal for which the handler is asked for. Currently, only SIGSEGV is
   //                 supported by the runtime.
   // Returns:
   //   NULL if the native bridge doesn't use a handler or doesn't want it to be managed by the
   //   runtime.
   //   Otherwise, a pointer to the signal handler.
   NativeBridgeSignalHandlerFn (*getSignalHandler)(int signal);

   // Added callbacks in version 3.

   // Decrements the reference count on the dynamic library handler. If the reference count drops
   // to zero then the dynamic library is unloaded.
   //
   // Parameters:
   //   handle [IN] the handler of a dynamic library.
   //
   // Returns:
   //   0 on success, and nonzero on error.
   int (*unloadLibrary)(void* handle);

   // Dump the last failure message of native bridge when fail to load library or search symbol.
   //
   // Parameters:
   //
   // Returns:
   //   A string describing the most recent error that occurred when load library
   //   or lookup symbol via native bridge.
   const char* (*getError)();

   // Check whether library paths are supported by native bridge.
   //
   // Parameters:
   //   library_path [IN] search paths for native libraries (directories separated by ':')
   // Returns:
   //   TRUE if libraries within search paths are supported by native bridge, FALSE otherwise
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Use isSupported instead in non-namespace scenario.
   bool (*isPathSupported)(const char* library_path);

   // Initializes anonymous namespace at native bridge side.
   // NativeBridge's peer of android_init_anonymous_namespace() of dynamic linker.
   //
   // The anonymous namespace is used in the case when a NativeBridge implementation
   // cannot identify the caller of dlopen/dlsym which happens for the code not loaded
   // by dynamic linker; for example calls from the mono-compiled code.
   //
   // Parameters:
   //   public_ns_sonames [IN] the name of "public" libraries.
   //   anon_ns_library_path [IN] the library search path of (anonymous) namespace.
   // Returns:
   //   true if the pass is ok.
   //   Otherwise, false.
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Should not use in non-namespace scenario.
   bool (*initAnonymousNamespace)(const char* public_ns_sonames, const char* anon_ns_library_path);

   // Create new namespace in which native libraries will be loaded.
   // NativeBridge's peer of android_create_namespace() of dynamic linker.
   //
   // Parameters:
   //   name [IN] the name of the namespace.
   //   ld_library_path [IN] the first set of library search paths of the namespace.
   //   default_library_path [IN] the second set of library search path of the namespace.
   //   type [IN] the attribute of the namespace.
   //   permitted_when_isolated_path [IN] the permitted path for isolated namespace(if it is).
   //   parent_ns [IN] the pointer of the parent namespace to be inherited from.
   // Returns:
   //   native_bridge_namespace_t* for created namespace or nullptr in the case of error.
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Should not use in non-namespace scenario.
   struct native_bridge_namespace_t* (*createNamespace)(const char* name,
                                                        const char* ld_library_path,
                                                        const char* default_library_path,
                                                        uint64_t type,
                                                        const char* permitted_when_isolated_path,
                                                        struct native_bridge_namespace_t* parent_ns);

   // Creates a link which shares some libraries from one namespace to another.
   // NativeBridge's peer of android_link_namespaces() of dynamic linker.
   //
   // Parameters:
   //   from [IN] the namespace where libraries are accessed.
   //   to [IN] the namespace where libraries are loaded.
   //   shared_libs_sonames [IN] the libraries to be shared.
   //
   // Returns:
   //   Whether successed or not.
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Should not use in non-namespace scenario.
   bool (*linkNamespaces)(struct native_bridge_namespace_t* from,
                          struct native_bridge_namespace_t* to, const char* shared_libs_sonames);

   // Load a shared library within a namespace.
   // NativeBridge's peer of android_dlopen_ext() of dynamic linker, only supports namespace
   // extension.
   //
   // Parameters:
   //   libpath [IN] path to the shared library
   //   flag [IN] the stardard RTLD_XXX defined in bionic dlfcn.h
   //   ns [IN] the pointer of the namespace in which the library should be loaded.
   // Returns:
   //   The opaque handle of the shared library if sucessful, otherwise NULL
   //
   // Starting with v3, NativeBridge has two scenarios: with/without namespace.
   // Use loadLibrary instead in non-namespace scenario.
   void* (*loadLibraryExt)(const char* libpath, int flag, struct native_bridge_namespace_t* ns);

   // Get native bridge version of vendor namespace.
   // The vendor namespace is the namespace used to load vendor public libraries.
   // With O release this namespace can be different from the default namespace.
   // For the devices without enable vendor namespaces this function should return null
   //
   // Returns:
   //   vendor namespace or null if it was not set up for the device
   //
   // Starting with v5 (Android Q) this function is no longer used.
   // Use getExportedNamespace() below.
   struct native_bridge_namespace_t* (*getVendorNamespace)();

   // Get native bridge version of exported namespace. Peer of
   // android_get_exported_namespace(const char*) function.
   //
   // Returns:
   //   exported namespace or null if it was not set up for the device
   struct native_bridge_namespace_t* (*getExportedNamespace)(const char* name);
 };

 // Runtime interfaces to native bridge.
 struct NativeBridgeRuntimeCallbacks {
   // Get shorty of a Java method. The shorty is supposed to be persistent in memory.
   //
   // Parameters:
   //   env [IN] pointer to JNIenv.
   //   mid [IN] Java methodID.
   // Returns:
   //   short descriptor for method.
   const char* (*getMethodShorty)(JNIEnv* env, jmethodID mid);

   // Get number of native methods for specified class.
   //
   // Parameters:
   //   env [IN] pointer to JNIenv.
   //   clazz [IN] Java class object.
   // Returns:
   //   number of native methods.
   uint32_t (*getNativeMethodCount)(JNIEnv* env, jclass clazz);

   // Get at most 'method_count' native methods for specified class 'clazz'. Results are outputed
   // via 'methods' [OUT]. The signature pointer in JNINativeMethod is reused as the method shorty.
   //
   // Parameters:
   //   env [IN] pointer to JNIenv.
   //   clazz [IN] Java class object.
   //   methods [OUT] array of method with the name, shorty, and fnPtr.
   //   method_count [IN] max number of elements in methods.
   // Returns:
   //   number of method it actually wrote to methods.
   uint32_t (*getNativeMethods)(JNIEnv* env, jclass clazz, JNINativeMethod* methods,
                                uint32_t method_count);
 };

 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace android
 #endif  // __cplusplus

 #endif  // NATIVE_BRIDGE_H_
	/*
	* Copyright (C) 2014 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.
	*/

	#ifndef NATIVE_BRIDGE_H_
	#define NATIVE_BRIDGE_H_

	#include <signal.h>
	#include <stdbool.h>
	#include <stdint.h>
	#include <sys/types.h>

	#include "jni.h"

	#ifdef __cplusplus
	namespace android {
	extern "C" {
	#endif // __cplusplus

	struct NativeBridgeRuntimeCallbacks;
	struct NativeBridgeRuntimeValues;

	// Function pointer type for sigaction. This is mostly the signature of a signal handler, except
	// for the return type. The runtime needs to know whether the signal was handled or should be given
	// to the chain.
	typedef bool (NativeBridgeSignalHandlerFn)(int, siginfo_t, void*);

	// Open the native bridge, if any. Should be called by Runtime::Init(). A null library filename
	// signals that we do not want to load a native bridge.
	bool LoadNativeBridge(const char* native_bridge_library_filename,
	const struct NativeBridgeRuntimeCallbacks* runtime_callbacks);

	// Quick check whether a native bridge will be needed. This is based off of the instruction set
	// of the process.
	bool NeedsNativeBridge(const char* instruction_set);

	// Do the early initialization part of the native bridge, if necessary. This should be done under
	// high privileges.
	bool PreInitializeNativeBridge(const char* app_data_dir, const char* instruction_set);

	// Initialize the native bridge, if any. Should be called by Runtime::DidForkFromZygote. The JNIEnv*
	// will be used to modify the app environment for the bridge.
	bool InitializeNativeBridge(JNIEnv* env, const char* instruction_set);

	// Unload the native bridge, if any. Should be called by Runtime::DidForkFromZygote.
	void UnloadNativeBridge();

	// Check whether a native bridge is available (opened or initialized). Requires a prior call to
	// LoadNativeBridge.
	bool NativeBridgeAvailable();

	// Check whether a native bridge is available (initialized). Requires a prior call to
	// LoadNativeBridge & InitializeNativeBridge.
	bool NativeBridgeInitialized();

	// Load a shared library that is supported by the native bridge.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use NativeBridgeLoadLibraryExt() instead in namespace scenario.
	void* NativeBridgeLoadLibrary(const char* libpath, int flag);

	// Get a native bridge trampoline for specified native method.
	void* NativeBridgeGetTrampoline(void* handle, const char* name, const char* shorty, uint32_t len);

	// True if native library paths are valid and is for an ABI that is supported by native bridge.
	// The libpath must point to a library.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use NativeBridgeIsPathSupported() instead in namespace scenario.
	bool NativeBridgeIsSupported(const char* libpath);

	// Returns the version number of the native bridge. This information is available after a
	// successful LoadNativeBridge() and before closing it, that is, as long as NativeBridgeAvailable()
	// returns true. Returns 0 otherwise.
	uint32_t NativeBridgeGetVersion();

	// Returns a signal handler that the bridge would like to be managed. Only valid for a native
	// bridge supporting the version 2 interface. Will return null if the bridge does not support
	// version 2, or if it doesn't have a signal handler it wants to be known.
	NativeBridgeSignalHandlerFn NativeBridgeGetSignalHandler(int signal);

	// Returns whether we have seen a native bridge error. This could happen because the library
	// was not found, rejected, could not be initialized and so on.
	//
	// This functionality is mainly for testing.
	bool NativeBridgeError();

	// Returns whether a given string is acceptable as a native bridge library filename.
	//
	// This functionality is exposed mainly for testing.
	bool NativeBridgeNameAcceptable(const char* native_bridge_library_filename);

	// Decrements the reference count on the dynamic library handler. If the reference count drops
	// to zero then the dynamic library is unloaded. Returns 0 on success and non-zero on error.
	int NativeBridgeUnloadLibrary(void* handle);

	// Get last error message of native bridge when fail to load library or search symbol.
	// This is reflection of dlerror() for native bridge.
	const char* NativeBridgeGetError();

	struct native_bridge_namespace_t;

	// True if native library paths are valid and is for an ABI that is supported by native bridge.
	// Different from NativeBridgeIsSupported(), the path here must be a directory containing
	// libraries of an ABI.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use NativeBridgeIsSupported() instead in non-namespace scenario.
	bool NativeBridgeIsPathSupported(const char* path);

	// Initializes anonymous namespace.
	// NativeBridge's peer of android_init_anonymous_namespace() of dynamic linker.
	//
	// The anonymous namespace is used in the case when a NativeBridge implementation
	// cannot identify the caller of dlopen/dlsym which happens for the code not loaded
	// by dynamic linker; for example calls from the mono-compiled code.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Should not use in non-namespace scenario.
	bool NativeBridgeInitAnonymousNamespace(const char* public_ns_sonames,
	const char* anon_ns_library_path);

	// Create new namespace in which native libraries will be loaded.
	// NativeBridge's peer of android_create_namespace() of dynamic linker.
	//
	// The libraries in the namespace are searched by folowing order:
	// 1. ld_library_path (Think of this as namespace-local LD_LIBRARY_PATH)
	// 2. In directories specified by DT_RUNPATH of the "needed by" binary.
	// 3. deault_library_path (This of this as namespace-local default library path)
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Should not use in non-namespace scenario.
	struct native_bridge_namespace_t* NativeBridgeCreateNamespace(
	const char* name, const char* ld_library_path, const char* default_library_path, uint64_t type,
	const char* permitted_when_isolated_path, struct native_bridge_namespace_t* parent_ns);

	// Creates a link which shares some libraries from one namespace to another.
	// NativeBridge's peer of android_link_namespaces() of dynamic linker.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Should not use in non-namespace scenario.
	bool NativeBridgeLinkNamespaces(struct native_bridge_namespace_t* from,
	struct native_bridge_namespace_t* to,
	const char* shared_libs_sonames);

	// Load a shared library with namespace key that is supported by the native bridge.
	// NativeBridge's peer of android_dlopen_ext() of dynamic linker, only supports namespace
	// extension.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use NativeBridgeLoadLibrary() instead in non-namespace scenario.
	void* NativeBridgeLoadLibraryExt(const char* libpath, int flag,
	struct native_bridge_namespace_t* ns);

	// Returns exported namespace by the name. This is a reflection of
	// android_get_exported_namespace function. Introduced in v5.
	struct native_bridge_namespace_t* NativeBridgeGetExportedNamespace(const char* name);

	// Native bridge interfaces to runtime.
	struct NativeBridgeCallbacks {
	// Version number of the interface.
	uint32_t version;

	// Initialize native bridge. Native bridge's internal implementation must ensure MT safety and
	// that the native bridge is initialized only once. Thus it is OK to call this interface for an
	// already initialized native bridge.
	//
	// Parameters:
	// runtime_cbs [IN] the pointer to NativeBridgeRuntimeCallbacks.
	// Returns:
	// true if initialization was successful.
	bool (initialize)(const struct NativeBridgeRuntimeCallbacks runtime_cbs,
	const char* private_dir, const char* instruction_set);

	// Load a shared library that is supported by the native bridge.
	//
	// Parameters:
	// libpath [IN] path to the shared library
	// flag [IN] the stardard RTLD_XXX defined in bionic dlfcn.h
	// Returns:
	// The opaque handle of the shared library if sucessful, otherwise NULL
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use loadLibraryExt instead in namespace scenario.
	void* (loadLibrary)(const char libpath, int flag);

	// Get a native bridge trampoline for specified native method. The trampoline has same
	// sigature as the native method.
	//
	// Parameters:
	// handle [IN] the handle returned from loadLibrary
	// shorty [IN] short descriptor of native method
	// len [IN] length of shorty
	// Returns:
	// address of trampoline if successful, otherwise NULL
	void* (getTrampoline)(void handle, const char* name, const char* shorty, uint32_t len);

	// Check whether native library is valid and is for an ABI that is supported by native bridge.
	//
	// Parameters:
	// libpath [IN] path to the shared library
	// Returns:
	// TRUE if library is supported by native bridge, FALSE otherwise
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use isPathSupported instead in namespace scenario.
	bool (isSupported)(const char libpath);

	// Provide environment values required by the app running with native bridge according to the
	// instruction set.
	//
	// Parameters:
	// instruction_set [IN] the instruction set of the app
	// Returns:
	// NULL if not supported by native bridge.
	// Otherwise, return all environment values to be set after fork.
	const struct NativeBridgeRuntimeValues* (getAppEnv)(const char instruction_set);

	// Added callbacks in version 2.

	// Check whether the bridge is compatible with the given version. A bridge may decide not to be
	// forwards- or backwards-compatible, and libnativebridge will then stop using it.
	//
	// Parameters:
	// bridge_version [IN] the version of libnativebridge.
	// Returns:
	// true if the native bridge supports the given version of libnativebridge.
	bool (*isCompatibleWith)(uint32_t bridge_version);

	// A callback to retrieve a native bridge's signal handler for the specified signal. The runtime
	// will ensure that the signal handler is being called after the runtime's own handler, but before
	// all chained handlers. The native bridge should not try to install the handler by itself, as
	// that will potentially lead to cycles.
	//
	// Parameters:
	// signal [IN] the signal for which the handler is asked for. Currently, only SIGSEGV is
	// supported by the runtime.
	// Returns:
	// NULL if the native bridge doesn't use a handler or doesn't want it to be managed by the
	// runtime.
	// Otherwise, a pointer to the signal handler.
	NativeBridgeSignalHandlerFn (*getSignalHandler)(int signal);

	// Added callbacks in version 3.

	// Decrements the reference count on the dynamic library handler. If the reference count drops
	// to zero then the dynamic library is unloaded.
	//
	// Parameters:
	// handle [IN] the handler of a dynamic library.
	//
	// Returns:
	// 0 on success, and nonzero on error.
	int (unloadLibrary)(void handle);

	// Dump the last failure message of native bridge when fail to load library or search symbol.
	//
	// Parameters:
	//
	// Returns:
	// A string describing the most recent error that occurred when load library
	// or lookup symbol via native bridge.
	const char* (*getError)();

	// Check whether library paths are supported by native bridge.
	//
	// Parameters:
	// library_path [IN] search paths for native libraries (directories separated by ':')
	// Returns:
	// TRUE if libraries within search paths are supported by native bridge, FALSE otherwise
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use isSupported instead in non-namespace scenario.
	bool (isPathSupported)(const char library_path);

	// Initializes anonymous namespace at native bridge side.
	// NativeBridge's peer of android_init_anonymous_namespace() of dynamic linker.
	//
	// The anonymous namespace is used in the case when a NativeBridge implementation
	// cannot identify the caller of dlopen/dlsym which happens for the code not loaded
	// by dynamic linker; for example calls from the mono-compiled code.
	//
	// Parameters:
	// public_ns_sonames [IN] the name of "public" libraries.
	// anon_ns_library_path [IN] the library search path of (anonymous) namespace.
	// Returns:
	// true if the pass is ok.
	// Otherwise, false.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Should not use in non-namespace scenario.
	bool (initAnonymousNamespace)(const char public_ns_sonames, const char* anon_ns_library_path);

	// Create new namespace in which native libraries will be loaded.
	// NativeBridge's peer of android_create_namespace() of dynamic linker.
	//
	// Parameters:
	// name [IN] the name of the namespace.
	// ld_library_path [IN] the first set of library search paths of the namespace.
	// default_library_path [IN] the second set of library search path of the namespace.
	// type [IN] the attribute of the namespace.
	// permitted_when_isolated_path [IN] the permitted path for isolated namespace(if it is).
	// parent_ns [IN] the pointer of the parent namespace to be inherited from.
	// Returns:
	// native_bridge_namespace_t* for created namespace or nullptr in the case of error.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Should not use in non-namespace scenario.
	struct native_bridge_namespace_t* (createNamespace)(const char name,
	const char* ld_library_path,
	const char* default_library_path,
	uint64_t type,
	const char* permitted_when_isolated_path,
	struct native_bridge_namespace_t* parent_ns);

	// Creates a link which shares some libraries from one namespace to another.
	// NativeBridge's peer of android_link_namespaces() of dynamic linker.
	//
	// Parameters:
	// from [IN] the namespace where libraries are accessed.
	// to [IN] the namespace where libraries are loaded.
	// shared_libs_sonames [IN] the libraries to be shared.
	//
	// Returns:
	// Whether successed or not.
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Should not use in non-namespace scenario.
	bool (linkNamespaces)(struct native_bridge_namespace_t from,
	struct native_bridge_namespace_t* to, const char* shared_libs_sonames);

	// Load a shared library within a namespace.
	// NativeBridge's peer of android_dlopen_ext() of dynamic linker, only supports namespace
	// extension.
	//
	// Parameters:
	// libpath [IN] path to the shared library
	// flag [IN] the stardard RTLD_XXX defined in bionic dlfcn.h
	// ns [IN] the pointer of the namespace in which the library should be loaded.
	// Returns:
	// The opaque handle of the shared library if sucessful, otherwise NULL
	//
	// Starting with v3, NativeBridge has two scenarios: with/without namespace.
	// Use loadLibrary instead in non-namespace scenario.
	void* (loadLibraryExt)(const char libpath, int flag, struct native_bridge_namespace_t* ns);

	// Get native bridge version of vendor namespace.
	// The vendor namespace is the namespace used to load vendor public libraries.
	// With O release this namespace can be different from the default namespace.
	// For the devices without enable vendor namespaces this function should return null
	//
	// Returns:
	// vendor namespace or null if it was not set up for the device
	//
	// Starting with v5 (Android Q) this function is no longer used.
	// Use getExportedNamespace() below.
	struct native_bridge_namespace_t* (*getVendorNamespace)();

	// Get native bridge version of exported namespace. Peer of
	// android_get_exported_namespace(const char*) function.
	//
	// Returns:
	// exported namespace or null if it was not set up for the device
	struct native_bridge_namespace_t* (getExportedNamespace)(const char name);
	};

	// Runtime interfaces to native bridge.
	struct NativeBridgeRuntimeCallbacks {
	// Get shorty of a Java method. The shorty is supposed to be persistent in memory.
	//
	// Parameters:
	// env [IN] pointer to JNIenv.
	// mid [IN] Java methodID.
	// Returns:
	// short descriptor for method.
	const char* (getMethodShorty)(JNIEnv env, jmethodID mid);

	// Get number of native methods for specified class.
	//
	// Parameters:
	// env [IN] pointer to JNIenv.
	// clazz [IN] Java class object.
	// Returns:
	// number of native methods.
	uint32_t (getNativeMethodCount)(JNIEnv env, jclass clazz);

	// Get at most 'method_count' native methods for specified class 'clazz'. Results are outputed
	// via 'methods' [OUT]. The signature pointer in JNINativeMethod is reused as the method shorty.
	//
	// Parameters:
	// env [IN] pointer to JNIenv.
	// clazz [IN] Java class object.
	// methods [OUT] array of method with the name, shorty, and fnPtr.
	// method_count [IN] max number of elements in methods.
	// Returns:
	// number of method it actually wrote to methods.
	uint32_t (getNativeMethods)(JNIEnv env, jclass clazz, JNINativeMethod* methods,
	uint32_t method_count);
	};

	#ifdef __cplusplus
	} // extern "C"
	} // namespace android
	#endif // __cplusplus

	#endif // NATIVE_BRIDGE_H_