1 /*
2 * Copyright (C) 2013 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 "nativehelper/JniInvocation.h"
18
19 #ifdef _WIN32
20 #include <windows.h>
21 #else
22 #include <dlfcn.h>
23 #endif
24 #include <stdlib.h>
25 #include <string.h>
26
27 #include <cstddef>
28
29 #define LOG_TAG "JniInvocation"
30 #include <log/log.h>
31
32 #ifdef __ANDROID__
33 #include <sys/system_properties.h>
34 #endif
35
36 #include "android-base/errors.h"
37 #include "JniConstants.h"
38
39 namespace {
40
41 template <typename T>
UNUSED(const T &)42 void UNUSED(const T&) {}
43
IsDebuggable()44 bool IsDebuggable() {
45 #ifdef __ANDROID__
46 char debuggable[PROP_VALUE_MAX] = {0};
47 __system_property_get("ro.debuggable", debuggable);
48 return strcmp(debuggable, "1") == 0;
49 #else
50 return false;
51 #endif
52 }
53
GetLibrarySystemProperty(char * buffer)54 int GetLibrarySystemProperty(char* buffer) {
55 #ifdef __ANDROID__
56 return __system_property_get("persist.sys.dalvik.vm.lib.2", buffer);
57 #else
58 UNUSED(buffer);
59 return 0;
60 #endif
61 }
62
63 #ifdef _WIN32
64 #define FUNC_POINTER FARPROC
65 #else
66 #define FUNC_POINTER void*
67 #endif
68
OpenLibrary(const char * filename)69 void* OpenLibrary(const char* filename) {
70 #ifdef _WIN32
71 return LoadLibrary(filename);
72 #else
73 // Load with RTLD_NODELETE in order to ensure that libart.so is not unmapped when it is closed.
74 // This is due to the fact that it is possible that some threads might have yet to finish
75 // exiting even after JNI_DeleteJavaVM returns, which can lead to segfaults if the library is
76 // unloaded.
77 const int kDlopenFlags = RTLD_NOW | RTLD_NODELETE;
78 return dlopen(filename, kDlopenFlags);
79 #endif
80 }
81
CloseLibrary(void * handle)82 int CloseLibrary(void* handle) {
83 #ifdef _WIN32
84 return FreeLibrary(static_cast<HMODULE>(handle));
85 #else
86 return dlclose(handle);
87 #endif
88 }
89
GetSymbol(void * handle,const char * symbol)90 FUNC_POINTER GetSymbol(void* handle, const char* symbol) {
91 #ifdef _WIN32
92 return GetProcAddress(static_cast<HMODULE>(handle), symbol);
93 #else
94 return dlsym(handle, symbol);
95 #endif
96 }
97
GetError()98 std::string GetError() {
99 #ifdef _WIN32
100 return android::base::SystemErrorCodeToString(GetLastError());
101 #else
102 return std::string(dlerror());
103 #endif
104 }
105
106 } // namespace
107
108 struct JniInvocationImpl final {
109 public:
110 JniInvocationImpl();
111 ~JniInvocationImpl();
112
113 bool Init(const char* library);
114
115 // static const char* GetLibrary(const char* library, char* buffer);
116
117 static const char* GetLibrary(const char* library,
118 char* buffer,
119 bool (*is_debuggable)() = IsDebuggable,
120 int (*get_library_system_property)(char* buffer) = GetLibrarySystemProperty);
121
122 static JniInvocationImpl& GetJniInvocation();
123
124 jint JNI_GetDefaultJavaVMInitArgs(void* vmargs);
125 jint JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args);
126 jint JNI_GetCreatedJavaVMs(JavaVM** vms, jsize size, jsize* vm_count);
127
128 private:
129 JniInvocationImpl(const JniInvocationImpl&) = delete;
130 JniInvocationImpl& operator=(const JniInvocationImpl&) = delete;
131
132 bool FindSymbol(FUNC_POINTER* pointer, const char* symbol);
133
134 static JniInvocationImpl* jni_invocation_;
135
136 // Handle to library opened with dlopen(). Library exports
137 // JNI_GetDefaultJavaVMInitArgs, JNI_CreateJavaVM, JNI_GetCreatedJavaVMs.
138 void* handle_;
139 jint (*JNI_GetDefaultJavaVMInitArgs_)(void*);
140 jint (*JNI_CreateJavaVM_)(JavaVM**, JNIEnv**, void*);
141 jint (*JNI_GetCreatedJavaVMs_)(JavaVM**, jsize, jsize*);
142
143 friend class JNIInvocation_Debuggable_Test;
144 friend class JNIInvocation_NonDebuggable_Test;
145 };
146
147 // Check JniInvocationImpl size is same as fields, e.g. no vtable present.
148 static_assert(sizeof(JniInvocationImpl) == 4 * sizeof(uintptr_t));
149
150 JniInvocationImpl* JniInvocationImpl::jni_invocation_ = NULL;
151
JniInvocationImpl()152 JniInvocationImpl::JniInvocationImpl() :
153 handle_(NULL),
154 JNI_GetDefaultJavaVMInitArgs_(NULL),
155 JNI_CreateJavaVM_(NULL),
156 JNI_GetCreatedJavaVMs_(NULL) {
157 LOG_ALWAYS_FATAL_IF(jni_invocation_ != NULL, "JniInvocation instance already initialized");
158 jni_invocation_ = this;
159 }
160
~JniInvocationImpl()161 JniInvocationImpl::~JniInvocationImpl() {
162 jni_invocation_ = NULL;
163 if (handle_ != NULL) {
164 CloseLibrary(handle_);
165 }
166 }
167
168 static const char* kLibraryFallback = "libart.so";
169
GetLibrary(const char * library,char * buffer,bool (* is_debuggable)(),int (* get_library_system_property)(char * buffer))170 const char* JniInvocationImpl::GetLibrary(const char* library,
171 char* buffer,
172 bool (*is_debuggable)(),
173 int (*get_library_system_property)(char* buffer)) {
174 #ifdef __ANDROID__
175 const char* default_library;
176
177 if (!is_debuggable()) {
178 // Not a debuggable build.
179 // Do not allow arbitrary library. Ignore the library parameter. This
180 // will also ignore the default library, but initialize to fallback
181 // for cleanliness.
182 library = kLibraryFallback;
183 default_library = kLibraryFallback;
184 } else {
185 // Debuggable build.
186 // Accept the library parameter. For the case it is NULL, load the default
187 // library from the system property.
188 if (buffer != NULL) {
189 if (get_library_system_property(buffer) > 0) {
190 default_library = buffer;
191 } else {
192 default_library = kLibraryFallback;
193 }
194 } else {
195 // No buffer given, just use default fallback.
196 default_library = kLibraryFallback;
197 }
198 }
199 #else
200 UNUSED(buffer);
201 UNUSED(is_debuggable);
202 UNUSED(get_library_system_property);
203 const char* default_library = kLibraryFallback;
204 #endif
205 if (library == NULL) {
206 library = default_library;
207 }
208
209 return library;
210 }
211
Init(const char * library)212 bool JniInvocationImpl::Init(const char* library) {
213 #ifdef __ANDROID__
214 char buffer[PROP_VALUE_MAX];
215 #else
216 char* buffer = NULL;
217 #endif
218 library = GetLibrary(library, buffer);
219 handle_ = OpenLibrary(library);
220 if (handle_ == NULL) {
221 if (strcmp(library, kLibraryFallback) == 0) {
222 // Nothing else to try.
223 ALOGE("Failed to dlopen %s: %s", library, GetError().c_str());
224 return false;
225 }
226 // Note that this is enough to get something like the zygote
227 // running, we can't property_set here to fix this for the future
228 // because we are root and not the system user. See
229 // RuntimeInit.commonInit for where we fix up the property to
230 // avoid future fallbacks. http://b/11463182
231 ALOGW("Falling back from %s to %s after dlopen error: %s",
232 library, kLibraryFallback, GetError().c_str());
233 library = kLibraryFallback;
234 handle_ = OpenLibrary(library);
235 if (handle_ == NULL) {
236 ALOGE("Failed to dlopen %s: %s", library, GetError().c_str());
237 return false;
238 }
239 }
240 if (!FindSymbol(reinterpret_cast<FUNC_POINTER*>(&JNI_GetDefaultJavaVMInitArgs_),
241 "JNI_GetDefaultJavaVMInitArgs")) {
242 return false;
243 }
244 if (!FindSymbol(reinterpret_cast<FUNC_POINTER*>(&JNI_CreateJavaVM_),
245 "JNI_CreateJavaVM")) {
246 return false;
247 }
248 if (!FindSymbol(reinterpret_cast<FUNC_POINTER*>(&JNI_GetCreatedJavaVMs_),
249 "JNI_GetCreatedJavaVMs")) {
250 return false;
251 }
252 return true;
253 }
254
JNI_GetDefaultJavaVMInitArgs(void * vmargs)255 jint JniInvocationImpl::JNI_GetDefaultJavaVMInitArgs(void* vmargs) {
256 return JNI_GetDefaultJavaVMInitArgs_(vmargs);
257 }
258
JNI_CreateJavaVM(JavaVM ** p_vm,JNIEnv ** p_env,void * vm_args)259 jint JniInvocationImpl::JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args) {
260 return JNI_CreateJavaVM_(p_vm, p_env, vm_args);
261 }
262
JNI_GetCreatedJavaVMs(JavaVM ** vms,jsize size,jsize * vm_count)263 jint JniInvocationImpl::JNI_GetCreatedJavaVMs(JavaVM** vms, jsize size, jsize* vm_count) {
264 return JNI_GetCreatedJavaVMs_(vms, size, vm_count);
265 }
266
FindSymbol(FUNC_POINTER * pointer,const char * symbol)267 bool JniInvocationImpl::FindSymbol(FUNC_POINTER* pointer, const char* symbol) {
268 *pointer = GetSymbol(handle_, symbol);
269 if (*pointer == NULL) {
270 ALOGE("Failed to find symbol %s: %s\n", symbol, GetError().c_str());
271 CloseLibrary(handle_);
272 handle_ = NULL;
273 return false;
274 }
275 return true;
276 }
277
GetJniInvocation()278 JniInvocationImpl& JniInvocationImpl::GetJniInvocation() {
279 LOG_ALWAYS_FATAL_IF(jni_invocation_ == NULL,
280 "Failed to create JniInvocation instance before using JNI invocation API");
281 return *jni_invocation_;
282 }
283
JNI_GetDefaultJavaVMInitArgs(void * vm_args)284 MODULE_API jint JNI_GetDefaultJavaVMInitArgs(void* vm_args) {
285 return JniInvocationImpl::GetJniInvocation().JNI_GetDefaultJavaVMInitArgs(vm_args);
286 }
287
JNI_CreateJavaVM(JavaVM ** p_vm,JNIEnv ** p_env,void * vm_args)288 MODULE_API jint JNI_CreateJavaVM(JavaVM** p_vm, JNIEnv** p_env, void* vm_args) {
289 // Ensure any cached heap objects from previous VM instances are
290 // invalidated. There is no notification here that a VM is destroyed. These
291 // cached objects limit us to one VM instance per process.
292 JniConstants::Uninitialize();
293 return JniInvocationImpl::GetJniInvocation().JNI_CreateJavaVM(p_vm, p_env, vm_args);
294 }
295
JNI_GetCreatedJavaVMs(JavaVM ** vms,jsize size,jsize * vm_count)296 MODULE_API jint JNI_GetCreatedJavaVMs(JavaVM** vms, jsize size, jsize* vm_count) {
297 return JniInvocationImpl::GetJniInvocation().JNI_GetCreatedJavaVMs(vms, size, vm_count);
298 }
299
JniInvocationCreate()300 MODULE_API JniInvocationImpl* JniInvocationCreate() {
301 return new JniInvocationImpl();
302 }
303
JniInvocationDestroy(JniInvocationImpl * instance)304 MODULE_API void JniInvocationDestroy(JniInvocationImpl* instance) {
305 delete instance;
306 }
307
JniInvocationInit(JniInvocationImpl * instance,const char * library)308 MODULE_API int JniInvocationInit(JniInvocationImpl* instance, const char* library) {
309 return instance->Init(library) ? 1 : 0;
310 }
311
JniInvocationGetLibrary(const char * library,char * buffer)312 MODULE_API const char* JniInvocationGetLibrary(const char* library, char* buffer) {
313 return JniInvocationImpl::GetLibrary(library, buffer);
314 }
315
GetLibrary(const char * library,char * buffer,bool (* is_debuggable)(),int (* get_library_system_property)(char * buffer))316 MODULE_API const char* JniInvocation::GetLibrary(const char* library,
317 char* buffer,
318 bool (*is_debuggable)(),
319 int (*get_library_system_property)(char* buffer)) {
320 return JniInvocationImpl::GetLibrary(library, buffer, is_debuggable, get_library_system_property);
321 }
322