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 #ifndef GRAPHICS_JNI_HELPERS
18 #define GRAPHICS_JNI_HELPERS
19
20 #include <log/log.h>
21 #include <nativehelper/JNIPlatformHelp.h>
22 #include <nativehelper/scoped_local_ref.h>
23 #include <nativehelper/scoped_utf_chars.h>
24 #include <string>
25
26 // Host targets (layoutlib) do not differentiate between regular and critical native methods,
27 // and they need all the JNI methods to have JNIEnv* and jclass/jobject as their first two arguments.
28 // The following macro allows to have those arguments when compiling for host while omitting them when
29 // compiling for Android.
30 #ifdef __ANDROID__
31 #define CRITICAL_JNI_PARAMS
32 #define CRITICAL_JNI_PARAMS_COMMA
33 #else
34 #define CRITICAL_JNI_PARAMS JNIEnv*, jclass
35 #define CRITICAL_JNI_PARAMS_COMMA JNIEnv*, jclass,
36 #endif
37
38 namespace android {
39
40 // Defines some helpful functions.
41
FindClassOrDie(JNIEnv * env,const char * class_name)42 static inline jclass FindClassOrDie(JNIEnv* env, const char* class_name) {
43 jclass clazz = env->FindClass(class_name);
44 LOG_ALWAYS_FATAL_IF(clazz == NULL, "Unable to find class %s", class_name);
45 return clazz;
46 }
47
GetFieldIDOrDie(JNIEnv * env,jclass clazz,const char * field_name,const char * field_signature)48 static inline jfieldID GetFieldIDOrDie(JNIEnv* env, jclass clazz, const char* field_name,
49 const char* field_signature) {
50 jfieldID res = env->GetFieldID(clazz, field_name, field_signature);
51 LOG_ALWAYS_FATAL_IF(res == NULL, "Unable to find static field %s", field_name);
52 return res;
53 }
54
GetMethodIDOrDie(JNIEnv * env,jclass clazz,const char * method_name,const char * method_signature)55 static inline jmethodID GetMethodIDOrDie(JNIEnv* env, jclass clazz, const char* method_name,
56 const char* method_signature) {
57 jmethodID res = env->GetMethodID(clazz, method_name, method_signature);
58 LOG_ALWAYS_FATAL_IF(res == NULL, "Unable to find method %s", method_name);
59 return res;
60 }
61
GetStaticFieldIDOrDie(JNIEnv * env,jclass clazz,const char * field_name,const char * field_signature)62 static inline jfieldID GetStaticFieldIDOrDie(JNIEnv* env, jclass clazz, const char* field_name,
63 const char* field_signature) {
64 jfieldID res = env->GetStaticFieldID(clazz, field_name, field_signature);
65 LOG_ALWAYS_FATAL_IF(res == NULL, "Unable to find static field %s", field_name);
66 return res;
67 }
68
GetStaticMethodIDOrDie(JNIEnv * env,jclass clazz,const char * method_name,const char * method_signature)69 static inline jmethodID GetStaticMethodIDOrDie(JNIEnv* env, jclass clazz, const char* method_name,
70 const char* method_signature) {
71 jmethodID res = env->GetStaticMethodID(clazz, method_name, method_signature);
72 LOG_ALWAYS_FATAL_IF(res == NULL, "Unable to find static method %s", method_name);
73 return res;
74 }
75
76 template <typename T>
MakeGlobalRefOrDie(JNIEnv * env,T in)77 static inline T MakeGlobalRefOrDie(JNIEnv* env, T in) {
78 jobject res = env->NewGlobalRef(in);
79 LOG_ALWAYS_FATAL_IF(res == NULL, "Unable to create global reference.");
80 return static_cast<T>(res);
81 }
82
83 // Inline variable that specifies the method binding format.
84 // The expected format is 'XX${method}XX', where ${method} represents the original method name.
85 // This variable is shared across all translation units. This is treated as a global variable as
86 // per C++ 17.
87 inline std::string jniMethodFormat;
88
setJniMethodFormat(std::string value)89 inline static void setJniMethodFormat(std::string value) {
90 jniMethodFormat = value;
91 }
92
93 // Register the native methods, potenially applying the jniMethodFormat if it has been set.
jniRegisterMaybeRenamedNativeMethods(JNIEnv * env,const char * className,const JNINativeMethod * gMethods,int numMethods)94 static inline int jniRegisterMaybeRenamedNativeMethods(JNIEnv* env, const char* className,
95 const JNINativeMethod* gMethods,
96 int numMethods) {
97 if (jniMethodFormat.empty()) {
98 return jniRegisterNativeMethods(env, className, gMethods, numMethods);
99 }
100
101 // Make a copy of gMethods with reformatted method names.
102 JNINativeMethod* modifiedMethods = new JNINativeMethod[numMethods];
103 LOG_ALWAYS_FATAL_IF(!modifiedMethods, "Failed to allocate a copy of the JNI methods");
104
105 size_t methodNamePos = jniMethodFormat.find("${method}");
106 LOG_ALWAYS_FATAL_IF(methodNamePos == std::string::npos,
107 "Invalid jniMethodFormat: could not find '${method}' in pattern");
108
109 for (int i = 0; i < numMethods; i++) {
110 modifiedMethods[i] = gMethods[i];
111 std::string modifiedName = jniMethodFormat;
112 modifiedName.replace(methodNamePos, 9, gMethods[i].name);
113 char* modifiedNameChars = new char[modifiedName.length() + 1];
114 LOG_ALWAYS_FATAL_IF(!modifiedNameChars, "Failed to allocate the new method name");
115 std::strcpy(modifiedNameChars, modifiedName.c_str());
116 modifiedMethods[i].name = modifiedNameChars;
117 }
118 int res = jniRegisterNativeMethods(env, className, modifiedMethods, numMethods);
119 for (int i = 0; i < numMethods; i++) {
120 delete[] modifiedMethods[i].name;
121 }
122 delete[] modifiedMethods;
123 return res;
124 }
125
RegisterMethodsOrDie(JNIEnv * env,const char * className,const JNINativeMethod * gMethods,int numMethods)126 static inline int RegisterMethodsOrDie(JNIEnv* env, const char* className,
127 const JNINativeMethod* gMethods, int numMethods) {
128 int res = jniRegisterMaybeRenamedNativeMethods(env, className, gMethods, numMethods);
129 LOG_ALWAYS_FATAL_IF(res < 0, "Unable to register native methods.");
130 return res;
131 }
132
133 /**
134 * Read the specified field from jobject, and convert to std::string.
135 * If the field cannot be obtained, return defaultValue.
136 */
getStringField(JNIEnv * env,jobject obj,jfieldID fieldId,const char * defaultValue)137 static inline std::string getStringField(JNIEnv* env, jobject obj, jfieldID fieldId,
138 const char* defaultValue) {
139 ScopedLocalRef<jstring> strObj(env, jstring(env->GetObjectField(obj, fieldId)));
140 if (strObj != nullptr) {
141 ScopedUtfChars chars(env, strObj.get());
142 return std::string(chars.c_str());
143 }
144 return std::string(defaultValue);
145 }
146
147 } // namespace android
148
149 #endif // GRAPHICS_JNI_HELPERS
150