nativebridge.cc revision 855564b83db7b106d2995d0e784f1f4b62e52371 
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// A simple implementation of the native-bridge interface.
18
19#include <algorithm>
20#include <dlfcn.h>
21#include <vector>
22
23#include "jni.h"
24#include "stdio.h"
25#include "string.h"
26#include "unistd.h"
27
28#include "native_bridge.h"
29
30
31// Native bridge interfaces...
32
33struct NativeBridgeArtCallbacks {
34  const char* (*getMethodShorty)(JNIEnv* env, jmethodID mid);
35  int (*getNativeMethodCount)(JNIEnv* env, jclass clazz);
36  int (*getNativeMethods)(JNIEnv* env, jclass clazz, JNINativeMethod* methods,
37       uint32_t method_count);
38};
39
40struct NativeBridgeCallbacks {
41  bool (*initialize)(NativeBridgeArtCallbacks* art_cbs);
42  void* (*loadLibrary)(const char* libpath, int flag);
43  void* (*getTrampoline)(void* handle, const char* name, const char* shorty, uint32_t len);
44  bool (*isSupported)(const char* libpath);
45};
46
47
48
49static std::vector<void*> symbols;
50
51// NativeBridgeCallbacks implementations
52extern "C" bool native_bridge_initialize(NativeBridgeArtCallbacks* art_cbs) {
53  printf("Native bridge initialized.\n");
54  return true;
55}
56
57extern "C" void* native_bridge_loadLibrary(const char* libpath, int flag) {
58  size_t len = strlen(libpath);
59  char* tmp = new char[len + 10];
60  strncpy(tmp, libpath, len);
61  tmp[len - 3] = '2';
62  tmp[len - 2] = '.';
63  tmp[len - 1] = 's';
64  tmp[len] = 'o';
65  tmp[len + 1] = 0;
66  void* handle = dlopen(tmp, flag);
67  delete[] tmp;
68
69  if (handle == nullptr) {
70    printf("Handle = nullptr!\n");
71    printf("Was looking for %s.\n", libpath);
72    printf("Error = %s.\n", dlerror());
73    char cwd[1024];
74    if (getcwd(cwd, sizeof(cwd)) != nullptr) {
75      printf("Current working dir: %s\n", cwd);
76    }
77  }
78  return handle;
79}
80
81extern "C" void* native_bridge_getTrampoline(void* handle, const char* name, const char* shorty,
82                                             uint32_t len) {
83  printf("Getting trampoline.\n");
84
85  // The name here is actually the JNI name, so we can directly do the lookup.
86  void* sym = dlsym(handle, name);
87  if (sym != nullptr) {
88    symbols.push_back(sym);
89  }
90
91  // As libarttest is the same arch as the host, we can actually directly use the code and do not
92  // need to create a trampoline. :-)
93  return sym;
94}
95
96extern "C" bool native_bridge_isSupported(const char* libpath) {
97  printf("Checking for support.\n");
98
99  if (libpath == nullptr) {
100    return false;
101  }
102  // We don't want to hijack javacore. So we should get libarttest...
103  return strcmp(libpath, "libjavacore.so") != 0;
104}
105
106NativeBridgeCallbacks NativeBridgeItf {
107  .initialize = &native_bridge_initialize,
108  .loadLibrary = &native_bridge_loadLibrary,
109  .getTrampoline = &native_bridge_getTrampoline,
110  .isSupported = &native_bridge_isSupported
111};
112
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115