Move native bridge library in system/core

Bug: 16884833

Change-Id: I73aab8e212860ba5aee9444d801806d3da326a41

3 files changed, 258 insertions, 0 deletions

diff --git a/include/nativebridge/native_bridge.h b/include/nativebridge/native_bridge.h
new file mode 100644
index 000000000..2415e6bc5
--- /dev/null
+++ b/include/nativebridge/native_bridge.h
@@ -0,0 +1,118 @@
+/*
+ * 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 "jni.h"
+#include <stdint.h>
+
+namespace android {
+
+struct NativeBridgeRuntimeCallbacks;
+
+// Initialize 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.
+void SetupNativeBridge(const char* native_bridge_library_filename,
+                       const NativeBridgeRuntimeCallbacks* runtime_callbacks);
+
+// Load a shared library that is supported by the native bridge.
+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 is valid and is for an ABI that is supported by native bridge.
+bool NativeBridgeIsSupported(const char* libpath);
+
+// Native bridge interfaces to runtime.
+struct NativeBridgeCallbacks {
+  // 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 iff initialization was successful.
+  bool (*initialize)(const NativeBridgeRuntimeCallbacks* runtime_cbs);
+
+  // 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
+  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
+  bool (*isSupported)(const char* libpath);
+};
+
+// 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);
+};
+
+};  // namespace android
+
+#endif  // NATIVE_BRIDGE_H_
diff --git a/libnativebridge/Android.mk b/libnativebridge/Android.mk
new file mode 100644
index 000000000..8209bc794
--- /dev/null
+++ b/libnativebridge/Android.mk
@@ -0,0 +1,34 @@
+LOCAL_PATH:= $(call my-dir)
+
+NATIVE_BRIDGE_COMMON_SRC_FILES := \
+  native_bridge.cc
+
+# Shared library for target
+# ========================================================
+include $(CLEAR_VARS)
+
+LOCAL_MODULE:= libnativebridge
+
+LOCAL_SRC_FILES:= $(NATIVE_BRIDGE_COMMON_SRC_FILES)
+LOCAL_CPP_EXTENSION := .cc
+LOCAL_CFLAGS := -Werror
+LOCAL_CPPFLAGS := -std=gnu++11
+LOCAL_LDFLAGS := -ldl
+LOCAL_MULTILIB := both
+
+include $(BUILD_SHARED_LIBRARY)
+
+# Shared library for host
+# ========================================================
+include $(CLEAR_VARS)
+
+LOCAL_MODULE:= libnativebridge
+
+LOCAL_SRC_FILES:= $(NATIVE_BRIDGE_COMMON_SRC_FILES)
+LOCAL_CPP_EXTENSION := .cc
+LOCAL_CFLAGS := -Werror
+LOCAL_CPPFLAGS := -std=gnu++11
+LOCAL_LDFLAGS := -ldl
+LOCAL_MULTILIB := both
+
+include $(BUILD_HOST_SHARED_LIBRARY)
diff --git a/libnativebridge/native_bridge.cc b/libnativebridge/native_bridge.cc
new file mode 100644
index 000000000..ad4ee73d6
--- /dev/null
+++ b/libnativebridge/native_bridge.cc
@@ -0,0 +1,106 @@
+/*
+ * 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 <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 path of the library we are supposed to load.
+static const char* native_bridge_library_path = 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;
+
+static NativeBridgeCallbacks* callbacks = nullptr;
+static const NativeBridgeRuntimeCallbacks* runtime_callbacks = nullptr;
+
+void SetupNativeBridge(const char* nb_library_path,
+                       const NativeBridgeRuntimeCallbacks* runtime_cbs) {
+  Mutex::Autolock auto_lock(native_bridge_lock);
+
+  native_bridge_library_path = nb_library_path;
+  runtime_callbacks = runtime_cbs;
+
+  if (native_bridge_library_path == nullptr) {
+    initialized = true;
+    available = false;
+  }
+}
+
+static bool NativeBridgeInitialize() {
+  Mutex::Autolock auto_lock(native_bridge_lock);
+
+  if (initialized) {
+    // Somebody did it before.
+    return available;
+  }
+
+  available = false;
+
+  void* handle = dlopen(native_bridge_library_path, RTLD_LAZY);
+  if (handle != nullptr) {
+    callbacks = reinterpret_cast<NativeBridgeCallbacks*>(dlsym(handle,
+                                                               kNativeBridgeInterfaceSymbol));
+
+    if (callbacks != nullptr) {
+      available = callbacks->initialize(runtime_callbacks);
+    }
+
+    if (!available) {
+      dlclose(handle);
+    }
+  }
+
+  initialized = true;
+
+  return available;
+}
+
+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