1 /*
2 * Copyright (C) 2010 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 #define LOG_TAG "JniConstants"
18
19 #include "JniConstants.h"
20
21 #include <atomic>
22 #include <mutex>
23 #include <stdlib.h>
24
25 #include <log/log.h>
26 #include <nativehelper/ScopedLocalRef.h>
27
28 namespace {
29
findClass(JNIEnv * env,const char * name)30 jclass findClass(JNIEnv* env, const char* name) {
31 ScopedLocalRef<jclass> localClass(env, env->FindClass(name));
32 jclass result = reinterpret_cast<jclass>(env->NewGlobalRef(localClass.get()));
33 if (result == NULL) {
34 ALOGE("failed to find class '%s'", name);
35 abort();
36 }
37 return result;
38 }
39
40 // Mutex protecting static variables
41 static std::mutex g_constants_mutex;
42
43 // Flag indicating whether cached constants are valid
44 static bool g_constants_valid = false;
45
46 // Mapping between C++ names and java class descriptors.
47 #define JCLASS_CONSTANTS_LIST(V) \
48 V(BooleanClass, "java/lang/Boolean") \
49 V(ByteBufferClass, "java/nio/ByteBuffer") \
50 V(DoubleClass, "java/lang/Double") \
51 V(ErrnoExceptionClass, "android/system/ErrnoException") \
52 V(FileDescriptorClass, "java/io/FileDescriptor") \
53 V(GaiExceptionClass, "android/system/GaiException") \
54 V(Inet6AddressClass, "java/net/Inet6Address") \
55 V(Inet6AddressHolderClass, "java/net/Inet6Address$Inet6AddressHolder") \
56 V(InetAddressClass, "java/net/InetAddress") \
57 V(InetAddressHolderClass, "java/net/InetAddress$InetAddressHolder") \
58 V(InetSocketAddressClass, "java/net/InetSocketAddress") \
59 V(InetSocketAddressHolderClass, "java/net/InetSocketAddress$InetSocketAddressHolder") \
60 V(IntegerClass, "java/lang/Integer") \
61 V(LocaleDataClass, "libcore/icu/LocaleData") \
62 V(LongClass, "java/lang/Long") \
63 V(NetlinkSocketAddressClass, "android/system/NetlinkSocketAddress") \
64 V(PacketSocketAddressClass, "android/system/PacketSocketAddress") \
65 V(VmSocketAddressClass, "android/system/VmSocketAddress") \
66 V(PrimitiveByteArrayClass, "[B") \
67 V(StringClass, "java/lang/String") \
68 V(StructAddrinfoClass, "android/system/StructAddrinfo") \
69 V(StructCmsghdrClass, "android/system/StructCmsghdr") \
70 V(StructGroupReqClass, "android/system/StructGroupReq") \
71 V(StructIfaddrsClass, "android/system/StructIfaddrs") \
72 V(StructLingerClass, "android/system/StructLinger") \
73 V(StructMsghdrClass, "android/system/StructMsghdr") \
74 V(StructPasswdClass, "android/system/StructPasswd") \
75 V(StructPollfdClass, "android/system/StructPollfd") \
76 V(StructStatClass, "android/system/StructStat") \
77 V(StructStatVfsClass, "android/system/StructStatVfs") \
78 V(StructTimevalClass, "android/system/StructTimeval") \
79 V(StructTimespecClass, "android/system/StructTimespec") \
80 V(StructUcredClass, "android/system/StructUcred") \
81 V(StructUtsnameClass, "android/system/StructUtsname") \
82 V(UnixSocketAddressClass, "android/system/UnixSocketAddress")
83
84 #define DECLARE_JCLASS_CONSTANT(cppname, _) jclass g_ ## cppname;
JCLASS_CONSTANTS_LIST(DECLARE_JCLASS_CONSTANT)85 JCLASS_CONSTANTS_LIST(DECLARE_JCLASS_CONSTANT)
86
87 // EnsureJniConstantsInitialized initializes cached constants. It should be
88 // called before returning a heap object from the cache to ensure cache is
89 // initialized. This pattern is only necessary because if a process finishes one
90 // runtime and starts another then JNI_OnLoad may not be called.
91 void EnsureJniConstantsInitialized(JNIEnv* env) {
92 std::lock_guard guard(g_constants_mutex);
93 if (g_constants_valid) {
94 return;
95 }
96
97 #define INITIALIZE_JCLASS_CONSTANT(cppname, javaname) g_ ## cppname = findClass(env, javaname);
98 JCLASS_CONSTANTS_LIST(INITIALIZE_JCLASS_CONSTANT)
99
100 g_constants_valid = true;
101 }
102
103 } // namespace
104
105 #define CONSTANT_GETTER(cppname, _) \
106 jclass JniConstants::Get ## cppname(JNIEnv* env) { \
107 EnsureJniConstantsInitialized(env); \
108 return g_ ## cppname; \
109 }
JCLASS_CONSTANTS_LIST(CONSTANT_GETTER)110 JCLASS_CONSTANTS_LIST(CONSTANT_GETTER)
111
112 void JniConstants::Initialize(JNIEnv* env) {
113 EnsureJniConstantsInitialized(env);
114 }
115
Invalidate()116 void JniConstants::Invalidate() {
117 // This method is called when a new runtime instance is created. There is no
118 // notification of a runtime instance being destroyed in the JNI interface
119 // so we piggyback on creation. Since only one runtime is supported at a
120 // time, we know the constants are invalid when JNI_CreateJavaVM() is
121 // called.
122 //
123 // Clean shutdown would require calling DeleteGlobalRef() for each of the
124 // class references, but JavaVM is unavailable because ART only calls this
125 // once all threads are unregistered.
126 std::lock_guard guard(g_constants_mutex);
127 g_constants_valid = false;
128 }
129