native_bridge.cc revision 4914fcd91bcd75400c0e023974158912f077464c 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "nativebridge/native_bridge.h"
18
19#include <dlfcn.h>
20#include <stdio.h>
21#include "utils/Mutex.h"
22
23
24namespace android {
25
26static Mutex native_bridge_lock("native bridge lock");
27
28// The symbol name exposed by native-bridge with the type of NativeBridgeCallbacks.
29static constexpr const char* kNativeBridgeInterfaceSymbol = "NativeBridgeItf";
30
31// The path of the library we are supposed to load.
32static const char* native_bridge_library_path = nullptr;
33
34// Whether a native bridge is available (loaded and ready).
35static bool available = false;
36// Whether we have already initialized (or tried to).
37static bool initialized = false;
38
39static NativeBridgeCallbacks* callbacks = nullptr;
40static const NativeBridgeRuntimeCallbacks* runtime_callbacks = nullptr;
41
42void SetupNativeBridge(const char* nb_library_path,
43                       const NativeBridgeRuntimeCallbacks* runtime_cbs) {
44  Mutex::Autolock auto_lock(native_bridge_lock);
45
46  native_bridge_library_path = nb_library_path;
47  runtime_callbacks = runtime_cbs;
48
49  if (native_bridge_library_path == nullptr) {
50    initialized = true;
51    available = false;
52  }
53}
54
55static bool NativeBridgeInitialize() {
56  Mutex::Autolock auto_lock(native_bridge_lock);
57
58  if (initialized) {
59    // Somebody did it before.
60    return available;
61  }
62
63  available = false;
64
65  void* handle = dlopen(native_bridge_library_path, RTLD_LAZY);
66  if (handle != nullptr) {
67    callbacks = reinterpret_cast<NativeBridgeCallbacks*>(dlsym(handle,
68                                                               kNativeBridgeInterfaceSymbol));
69
70    if (callbacks != nullptr) {
71      available = callbacks->initialize(runtime_callbacks);
72    }
73
74    if (!available) {
75      dlclose(handle);
76    }
77  }
78
79  initialized = true;
80
81  return available;
82}
83
84void* NativeBridgeLoadLibrary(const char* libpath, int flag) {
85  if (NativeBridgeInitialize()) {
86    return callbacks->loadLibrary(libpath, flag);
87  }
88  return nullptr;
89}
90
91void* NativeBridgeGetTrampoline(void* handle, const char* name, const char* shorty,
92                                uint32_t len) {
93  if (NativeBridgeInitialize()) {
94    return callbacks->getTrampoline(handle, name, shorty, len);
95  }
96  return nullptr;
97}
98
99bool NativeBridgeIsSupported(const char* libpath) {
100  if (NativeBridgeInitialize()) {
101    return callbacks->isSupported(libpath);
102  }
103  return false;
104}
105
106};  // namespace android
107