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      1 /*
      2  * Copyright (C) 2007 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 /*
     18  * JNI helper functions.
     19  *
     20  * This file may be included by C or C++ code, which is trouble because jni.h
     21  * uses different typedefs for JNIEnv in each language.
     22  *
     23  * TODO: remove C support.
     24  */
     25 #ifndef NATIVEHELPER_JNIHELP_H_
     26 #define NATIVEHELPER_JNIHELP_H_
     27 
     28 #include "jni.h"
     29 #include <errno.h>
     30 #include <unistd.h>
     31 
     32 #ifndef NELEM
     33 # define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))
     34 #endif
     35 
     36 #ifdef __cplusplus
     37 extern "C" {
     38 #endif
     39 
     40 /*
     41  * Register one or more native methods with a particular class.
     42  * "className" looks like "java/lang/String". Aborts on failure.
     43  * TODO: fix all callers and change the return type to void.
     44  */
     45 int jniRegisterNativeMethods(C_JNIEnv* env, const char* className, const JNINativeMethod* gMethods, int numMethods);
     46 
     47 /*
     48  * Throw an exception with the specified class and an optional message.
     49  *
     50  * The "className" argument will be passed directly to FindClass, which
     51  * takes strings with slashes (e.g. "java/lang/Object").
     52  *
     53  * If an exception is currently pending, we log a warning message and
     54  * clear it.
     55  *
     56  * Returns 0 on success, nonzero if something failed (e.g. the exception
     57  * class couldn't be found, so *an* exception will still be pending).
     58  *
     59  * Currently aborts the VM if it can't throw the exception.
     60  */
     61 int jniThrowException(C_JNIEnv* env, const char* className, const char* msg);
     62 
     63 /*
     64  * Throw a java.lang.NullPointerException, with an optional message.
     65  */
     66 int jniThrowNullPointerException(C_JNIEnv* env, const char* msg);
     67 
     68 /*
     69  * Throw a java.lang.RuntimeException, with an optional message.
     70  */
     71 int jniThrowRuntimeException(C_JNIEnv* env, const char* msg);
     72 
     73 /*
     74  * Throw a java.io.IOException, generating the message from errno.
     75  */
     76 int jniThrowIOException(C_JNIEnv* env, int errnum);
     77 
     78 /*
     79  * Return a pointer to a locale-dependent error string explaining errno
     80  * value 'errnum'. The returned pointer may or may not be equal to 'buf'.
     81  * This function is thread-safe (unlike strerror) and portable (unlike
     82  * strerror_r).
     83  */
     84 const char* jniStrError(int errnum, char* buf, size_t buflen);
     85 
     86 /*
     87  * Returns a new java.io.FileDescriptor for the given int fd.
     88  */
     89 jobject jniCreateFileDescriptor(C_JNIEnv* env, int fd);
     90 
     91 /*
     92  * Returns the int fd from a java.io.FileDescriptor.
     93  */
     94 int jniGetFDFromFileDescriptor(C_JNIEnv* env, jobject fileDescriptor);
     95 
     96 /*
     97  * Sets the int fd in a java.io.FileDescriptor.
     98  */
     99 void jniSetFileDescriptorOfFD(C_JNIEnv* env, jobject fileDescriptor, int value);
    100 
    101 /*
    102  * Returns the reference from a java.lang.ref.Reference.
    103  */
    104 jobject jniGetReferent(C_JNIEnv* env, jobject ref);
    105 
    106 /*
    107  * Log a message and an exception.
    108  * If exception is NULL, logs the current exception in the JNI environment.
    109  */
    110 void jniLogException(C_JNIEnv* env, int priority, const char* tag, jthrowable exception);
    111 
    112 #ifdef __cplusplus
    113 }
    114 #endif
    115 
    116 
    117 /*
    118  * For C++ code, we provide inlines that map to the C functions.  g++ always
    119  * inlines these, even on non-optimized builds.
    120  */
    121 #if defined(__cplusplus)
    122 inline int jniRegisterNativeMethods(JNIEnv* env, const char* className, const JNINativeMethod* gMethods, int numMethods) {
    123     return jniRegisterNativeMethods(&env->functions, className, gMethods, numMethods);
    124 }
    125 
    126 inline int jniThrowException(JNIEnv* env, const char* className, const char* msg) {
    127     return jniThrowException(&env->functions, className, msg);
    128 }
    129 
    130 extern "C" int jniThrowExceptionFmt(C_JNIEnv* env, const char* className, const char* fmt, va_list args);
    131 
    132 /*
    133  * Equivalent to jniThrowException but with a printf-like format string and
    134  * variable-length argument list. This is only available in C++.
    135  */
    136 inline int jniThrowExceptionFmt(JNIEnv* env, const char* className, const char* fmt, ...) {
    137     va_list args;
    138     va_start(args, fmt);
    139     return jniThrowExceptionFmt(&env->functions, className, fmt, args);
    140     va_end(args);
    141 }
    142 
    143 inline int jniThrowNullPointerException(JNIEnv* env, const char* msg) {
    144     return jniThrowNullPointerException(&env->functions, msg);
    145 }
    146 
    147 inline int jniThrowRuntimeException(JNIEnv* env, const char* msg) {
    148     return jniThrowRuntimeException(&env->functions, msg);
    149 }
    150 
    151 inline int jniThrowIOException(JNIEnv* env, int errnum) {
    152     return jniThrowIOException(&env->functions, errnum);
    153 }
    154 
    155 inline jobject jniCreateFileDescriptor(JNIEnv* env, int fd) {
    156     return jniCreateFileDescriptor(&env->functions, fd);
    157 }
    158 
    159 inline int jniGetFDFromFileDescriptor(JNIEnv* env, jobject fileDescriptor) {
    160     return jniGetFDFromFileDescriptor(&env->functions, fileDescriptor);
    161 }
    162 
    163 inline void jniSetFileDescriptorOfFD(JNIEnv* env, jobject fileDescriptor, int value) {
    164     jniSetFileDescriptorOfFD(&env->functions, fileDescriptor, value);
    165 }
    166 
    167 inline jobject jniGetReferent(JNIEnv* env, jobject ref) {
    168     return jniGetReferent(&env->functions, ref);
    169 }
    170 
    171 inline void jniLogException(JNIEnv* env, int priority, const char* tag, jthrowable exception = NULL) {
    172     jniLogException(&env->functions, priority, tag, exception);
    173 }
    174 
    175 #endif
    176 
    177 /*
    178  * TEMP_FAILURE_RETRY is defined by some, but not all, versions of
    179  * <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
    180  * not already defined, then define it here.
    181  */
    182 #ifndef TEMP_FAILURE_RETRY
    183 /* Used to retry syscalls that can return EINTR. */
    184 #define TEMP_FAILURE_RETRY(exp) ({         \
    185     typeof (exp) _rc;                      \
    186     do {                                   \
    187         _rc = (exp);                       \
    188     } while (_rc == -1 && errno == EINTR); \
    189     _rc; })
    190 #endif
    191 
    192 #endif  /* NATIVEHELPER_JNIHELP_H_ */
    193