1 /* 2 * Copyright (C) 2019 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 LIBNATIVEHELPER_INCLUDE_NATIVEHELPER_LIBNATIVEHELPER_API_H_ 18 #define LIBNATIVEHELPER_INCLUDE_NATIVEHELPER_LIBNATIVEHELPER_API_H_ 19 20 #include <stddef.h> 21 22 #include "jni.h" 23 24 // This is the stable C API exported by libnativehelper. 25 26 #ifdef __cplusplus 27 extern "C" { 28 #endif // __cplusplus 29 30 /* ------------------------------------ C API for JNIHelp.h ------------------------------------- */ 31 32 /* 33 * Register one or more native methods with a particular class. "className" looks like 34 * "java/lang/String". Aborts on failure, returns 0 on success. 35 */ 36 int jniRegisterNativeMethods(C_JNIEnv* env, 37 const char* className, 38 const JNINativeMethod* gMethods, 39 int numMethods); 40 41 /* 42 * Throw an exception with the specified class and an optional message. 43 * 44 * The "className" argument will be passed directly to FindClass, which 45 * takes strings with slashes (e.g. "java/lang/Object"). 46 * 47 * If an exception is currently pending, we log a warning message and 48 * clear it. 49 * 50 * Returns 0 on success, nonzero if something failed (e.g. the exception 51 * class couldn't be found, so *an* exception will still be pending). 52 * 53 * Currently aborts the VM if it can't throw the exception. 54 */ 55 int jniThrowException(C_JNIEnv* env, const char* className, const char* msg); 56 57 /* 58 * Throw an exception with the specified class and formatted error message. 59 * 60 * The "className" argument will be passed directly to FindClass, which 61 * takes strings with slashes (e.g. "java/lang/Object"). 62 * 63 * If an exception is currently pending, we log a warning message and 64 * clear it. 65 * 66 * Returns 0 on success, nonzero if something failed (e.g. the exception 67 * class couldn't be found, so *an* exception will still be pending). 68 * 69 * Currently aborts the VM if it can't throw the exception. 70 */ 71 int jniThrowExceptionFmt(C_JNIEnv* env, const char* className, const char* fmt, va_list args); 72 73 /* 74 * Throw a java.lang.NullPointerException, with an optional message. 75 */ 76 int jniThrowNullPointerException(C_JNIEnv* env, const char* msg); 77 78 /* 79 * Throw a java.lang.RuntimeException, with an optional message. 80 */ 81 int jniThrowRuntimeException(C_JNIEnv* env, const char* msg); 82 83 /* 84 * Throw a java.io.IOException, generating the message from errno. 85 */ 86 int jniThrowIOException(C_JNIEnv* env, int errnum); 87 88 /* 89 * Return a pointer to a locale-dependent error string explaining errno 90 * value 'errnum'. The returned pointer may or may not be equal to 'buf'. 91 * This function is thread-safe (unlike strerror) and portable (unlike 92 * strerror_r). 93 */ 94 const char* jniStrError(int errnum, char* buf, size_t buflen); 95 96 /* 97 * Returns a new java.io.FileDescriptor for the given int fd. 98 */ 99 jobject jniCreateFileDescriptor(C_JNIEnv* env, int fd); 100 101 /* 102 * Returns the int fd from a java.io.FileDescriptor. 103 */ 104 int jniGetFDFromFileDescriptor(C_JNIEnv* env, jobject fileDescriptor); 105 106 /* 107 * Sets the int fd in a java.io.FileDescriptor. Throws java.lang.NullPointerException 108 * if fileDescriptor is null. 109 */ 110 void jniSetFileDescriptorOfFD(C_JNIEnv* env, jobject fileDescriptor, int value); 111 112 /* 113 * Returns the long ownerId from a java.io.FileDescriptor. 114 */ 115 jlong jniGetOwnerIdFromFileDescriptor(C_JNIEnv* env, jobject fileDescriptor); 116 117 /* 118 * Gets the managed heap array backing a java.nio.Buffer instance. 119 * 120 * Returns nullptr if there is no array backing. 121 * 122 * This method performs a JNI call to java.nio.NIOAccess.getBaseArray(). 123 */ 124 jarray jniGetNioBufferBaseArray(C_JNIEnv* env, jobject nioBuffer); 125 126 /* 127 * Gets the offset in bytes from the start of the managed heap array backing the buffer. 128 * 129 * Returns 0 if there is no array backing. 130 * 131 * This method performs a JNI call to java.nio.NIOAccess.getBaseArrayOffset(). 132 */ 133 jint jniGetNioBufferBaseArrayOffset(C_JNIEnv* env, jobject nioBuffer); 134 135 /* 136 * Gets field information from a java.nio.Buffer instance. 137 * 138 * Reads the |position|, |limit|, and |elementSizeShift| fields from the buffer instance. 139 * 140 * Returns the |address| field of the java.nio.Buffer instance which is only valid (non-zero) when 141 * the buffer is backed by a direct buffer. 142 */ 143 jlong jniGetNioBufferFields(C_JNIEnv* env, 144 jobject nioBuffer, 145 /*out*/jint* position, 146 /*out*/jint* limit, 147 /*out*/jint* elementSizeShift); 148 149 /* 150 * Gets the current position from a java.nio.Buffer as a pointer to memory in a fixed buffer. 151 * 152 * Returns 0 if |nioBuffer| is not backed by a direct buffer. 153 * 154 * This method reads the |address|, |position|, and |elementSizeShift| fields from the 155 * java.nio.Buffer instance to calculate the pointer address for the current position. 156 */ 157 jlong jniGetNioBufferPointer(C_JNIEnv* env, jobject nioBuffer); 158 159 /* 160 * Returns the reference from a java.lang.ref.Reference. 161 */ 162 jobject jniGetReferent(C_JNIEnv* env, jobject ref); 163 164 /* 165 * Returns a Java String object created from UTF-16 data either from jchar or, 166 * if called from C++11, char16_t (a bitwise identical distinct type). 167 */ 168 jstring jniCreateString(C_JNIEnv* env, const jchar* unicodeChars, jsize len); 169 170 /* 171 * Log a message and an exception. 172 * If exception is NULL, logs the current exception in the JNI environment. 173 */ 174 void jniLogException(C_JNIEnv* env, int priority, const char* tag, jthrowable exception); 175 176 /* 177 * Clear the cache of constants libnativehelper is using. 178 */ 179 void jniUninitializeConstants(); 180 181 /* ---------------------------------- C API for JniInvocation.h --------------------------------- */ 182 183 /* 184 * The JNI invocation API exists to allow a choice of library responsible for managing virtual 185 * machines. 186 */ 187 188 /* 189 * Opaque structure used to hold JNI invocation internal state. 190 */ 191 struct JniInvocationImpl; 192 193 /* 194 * Creates an instance of a JniInvocationImpl. 195 */ 196 struct JniInvocationImpl* JniInvocationCreate(); 197 198 /* 199 * Associates a library with a JniInvocationImpl instance. The library should export C symbols for 200 * JNI_GetDefaultJavaVMInitArgs, JNI_CreateJavaVM and JNI_GetDefaultJavaVMInitArgs. 201 * 202 * The specified |library| should be the filename of a shared library. The |library| is opened with 203 * dlopen(3). 204 * 205 * If there is an error opening the specified |library|, then function will fallback to the 206 * default library "libart.so". If the fallback library is successfully used then a warning is 207 * written to the Android log buffer. Use of the fallback library is not considered an error. 208 * 209 * If the fallback library cannot be opened or the expected symbols are not found in the library 210 * opened, then an error message is written to the Android log buffer and the function returns 0. 211 * 212 * Returns 1 on success, 0 otherwise. 213 */ 214 int JniInvocationInit(struct JniInvocationImpl* instance, const char* library); 215 216 /* 217 * Release resources associated with JniInvocationImpl instance. 218 */ 219 void JniInvocationDestroy(struct JniInvocationImpl* instance); 220 221 /* 222 * Gets the default library for JNI invocation. The default library is "libart.so". This value may 223 * be overridden for debuggable builds using the persist.sys.dalvik.vm.lib.2 system property. 224 * 225 * The |library| argument is the preferred library to use on debuggable builds (when 226 * ro.debuggable=1). If the |library| argument is nullptr, then the system preferred value will be 227 * queried from persist.sys.dalvik.vm.lib.2 if the caller has provided |buffer| argument. 228 * 229 * The |buffer| argument is used for reading system properties in debuggable builds. It is 230 * optional, but should be provisioned to be PROP_VALUE_MAX bytes if provided to ensure it is 231 * large enough to hold a system property. 232 * 233 * Returns the filename of the invocation library determined from the inputs and system 234 * properties. The returned value may be |library|, |buffer|, or a pointer to a string constant 235 * "libart.so". 236 */ 237 const char* JniInvocationGetLibrary(const char* library, char* buffer); 238 239 /* ---------------------------------- C API for toStringArray.h --------------------------------- */ 240 241 /* 242 * Allocates a new array for java/lang/String instances with space for |count| elements. Elements 243 * are initially null. 244 * 245 * Returns a new array on success or nullptr in case of failure. This method raises an 246 * OutOfMemoryError exception if allocation fails. 247 */ 248 jobjectArray newStringArray(JNIEnv* env, size_t count); 249 250 /* 251 * Converts an array of C strings into a managed array of Java strings. The size of the C array is 252 * determined by the presence of a final element containing a nullptr. 253 * 254 * Returns a new array on success or nullptr in case of failure. This method raises an 255 * OutOfMemoryError exception if allocation fails. 256 */ 257 jobjectArray toStringArray(JNIEnv* env, const char* const* strings); 258 259 #ifdef __cplusplus 260 } 261 #endif // __cplusplus 262 263 #endif // LIBNATIVEHELPER_INCLUDE_NATIVEHELPER_LIBNATIVEHELPER_API_H_ 264