| /* |
| * 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. |
| */ |
| |
| #include "nativebridge/native_bridge.h" |
| |
| #include <cutils/log.h> |
| #include <dlfcn.h> |
| #include <stdio.h> |
| #include "utils/Mutex.h" |
| |
| |
| namespace android { |
| |
| static Mutex native_bridge_lock("native bridge lock"); |
| |
| // The symbol name exposed by native-bridge with the type of NativeBridgeCallbacks. |
| static constexpr const char* kNativeBridgeInterfaceSymbol = "NativeBridgeItf"; |
| |
| // The filename of the library we are supposed to load. |
| static const char* native_bridge_library_filename = nullptr; |
| |
| // Whether a native bridge is available (loaded and ready). |
| static bool available = false; |
| // Whether we have already initialized (or tried to). |
| static bool initialized = false; |
| // Whether we had an error at some point. |
| static bool had_error = false; |
| |
| static NativeBridgeCallbacks* callbacks = nullptr; |
| static const NativeBridgeRuntimeCallbacks* runtime_callbacks = nullptr; |
| |
| // Characters allowed in a native bridge filename. The first character must |
| // be in [a-zA-Z] (expected 'l' for "libx"). The rest must be in [a-zA-Z0-9._-]. |
| static bool CharacterAllowed(char c, bool first) { |
| if (first) { |
| return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z'); |
| } else { |
| return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || |
| (c == '.') || (c == '_') || (c == '-'); |
| } |
| } |
| |
| // We only allow simple names for the library. It is supposed to be a file in |
| // /system/lib or /vendor/lib. Only allow a small range of characters, that is |
| // names consisting of [a-zA-Z0-9._-] and starting with [a-zA-Z]. |
| bool NativeBridgeNameAcceptable(const char* nb_library_filename) { |
| const char* ptr = nb_library_filename; |
| if (*ptr == 0) { |
| // Emptry string. Allowed, means no native bridge. |
| return true; |
| } else { |
| // First character must be [a-zA-Z]. |
| if (!CharacterAllowed(*ptr, true)) { |
| // Found an invalid fist character, don't accept. |
| ALOGE("Native bridge library %s has been rejected for first character %c", nb_library_filename, *ptr); |
| return false; |
| } else { |
| // For the rest, be more liberal. |
| ptr++; |
| while (*ptr != 0) { |
| if (!CharacterAllowed(*ptr, false)) { |
| // Found an invalid character, don't accept. |
| ALOGE("Native bridge library %s has been rejected for %c", nb_library_filename, *ptr); |
| return false; |
| } |
| ptr++; |
| } |
| } |
| return true; |
| } |
| } |
| |
| void SetupNativeBridge(const char* nb_library_filename, |
| const NativeBridgeRuntimeCallbacks* runtime_cbs) { |
| Mutex::Autolock auto_lock(native_bridge_lock); |
| |
| if (initialized || native_bridge_library_filename != nullptr) { |
| // Setup has been called before. Ignore this call. |
| ALOGW("Called SetupNativeBridge for an already set up native bridge."); |
| // Note: counts as an error, even though the bridge may be functional. |
| had_error = true; |
| return; |
| } |
| |
| runtime_callbacks = runtime_cbs; |
| |
| if (nb_library_filename == nullptr) { |
| available = false; |
| initialized = true; |
| } else { |
| // Check whether it's an empty string. |
| if (*nb_library_filename == 0) { |
| available = false; |
| initialized = true; |
| } else if (!NativeBridgeNameAcceptable(nb_library_filename)) { |
| available = false; |
| initialized = true; |
| had_error = true; |
| } |
| |
| if (!initialized) { |
| // Didn't find a name error or empty string, assign it. |
| native_bridge_library_filename = nb_library_filename; |
| } |
| } |
| } |
| |
| static bool NativeBridgeInitialize() { |
| Mutex::Autolock auto_lock(native_bridge_lock); |
| |
| if (initialized) { |
| // Somebody did it before. |
| return available; |
| } |
| |
| available = false; |
| |
| if (native_bridge_library_filename == nullptr) { |
| // Called initialize without setup. dlopen has special semantics for nullptr input. |
| // So just call it a day here. This counts as an error. |
| initialized = true; |
| had_error = true; |
| return false; |
| } |
| |
| void* handle = dlopen(native_bridge_library_filename, RTLD_LAZY); |
| if (handle != nullptr) { |
| callbacks = reinterpret_cast<NativeBridgeCallbacks*>(dlsym(handle, |
| kNativeBridgeInterfaceSymbol)); |
| |
| if (callbacks != nullptr) { |
| available = callbacks->initialize(runtime_callbacks); |
| } |
| |
| if (!available) { |
| // If we fail initialization, this counts as an error. |
| had_error = true; |
| dlclose(handle); |
| } |
| } else { |
| // Being unable to open the library counts as an error. |
| had_error = true; |
| } |
| |
| initialized = true; |
| |
| return available; |
| } |
| |
| bool NativeBridgeError() { |
| return had_error; |
| } |
| |
| bool NativeBridgeAvailable() { |
| return NativeBridgeInitialize(); |
| } |
| |
| void* NativeBridgeLoadLibrary(const char* libpath, int flag) { |
| if (NativeBridgeInitialize()) { |
| return callbacks->loadLibrary(libpath, flag); |
| } |
| return nullptr; |
| } |
| |
| void* NativeBridgeGetTrampoline(void* handle, const char* name, const char* shorty, |
| uint32_t len) { |
| if (NativeBridgeInitialize()) { |
| return callbacks->getTrampoline(handle, name, shorty, len); |
| } |
| return nullptr; |
| } |
| |
| bool NativeBridgeIsSupported(const char* libpath) { |
| if (NativeBridgeInitialize()) { |
| return callbacks->isSupported(libpath); |
| } |
| return false; |
| } |
| |
| }; // namespace android |