2 * Copyright (C) 2006 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
18 * JNI helper functions.
20 #define LOG_TAG "JNIHelp"
22 #include "utils/Log.h"
28 * Register native JNI-callable methods.
30 * "className" looks like "java/lang/String".
32 int jniRegisterNativeMethods(JNIEnv* env, const char* className,
33 const JNINativeMethod* gMethods, int numMethods)
37 LOGV("Registering %s natives\n", className);
38 clazz = (*env)->FindClass(env, className);
40 LOGE("Native registration unable to find class '%s'\n", className);
43 if ((*env)->RegisterNatives(env, clazz, gMethods, numMethods) < 0) {
44 LOGE("RegisterNatives failed for '%s'\n", className);
51 * Get a human-readable summary of an exception object. The buffer will
52 * be populated with the "binary" class name and, if present, the
55 static void getExceptionSummary(JNIEnv* env, jthrowable excep, char* buf,
61 /* get the name of the exception's class; none of these should fail */
62 jclass clazz = (*env)->GetObjectClass(env, excep); // exception's class
63 jclass jlc = (*env)->GetObjectClass(env, clazz); // java.lang.Class
64 jmethodID getNameMethod =
65 (*env)->GetMethodID(env, jlc, "getName", "()Ljava/lang/String;");
66 jstring className = (*env)->CallObjectMethod(env, clazz, getNameMethod);
68 /* get printable string */
69 const char* nameStr = (*env)->GetStringUTFChars(env, className, NULL);
70 if (nameStr == NULL) {
71 snprintf(buf, bufLen, "%s", "out of memory generating summary");
72 (*env)->ExceptionClear(env); // clear OOM
76 /* if the exception has a message string, get that */
77 jmethodID getThrowableMessage =
78 (*env)->GetMethodID(env, clazz, "getMessage", "()Ljava/lang/String;");
79 jstring message = (*env)->CallObjectMethod(env, excep, getThrowableMessage);
81 if (message != NULL) {
82 const char* messageStr = (*env)->GetStringUTFChars(env, message, NULL);
83 snprintf(buf, bufLen, "%s: %s", nameStr, messageStr);
84 if (messageStr != NULL)
85 (*env)->ReleaseStringUTFChars(env, message, messageStr);
87 (*env)->ExceptionClear(env); // clear OOM
89 strncpy(buf, nameStr, bufLen);
93 (*env)->ReleaseStringUTFChars(env, className, nameStr);
97 * Throw an exception with the specified class and an optional message.
99 * If an exception is currently pending, we log a warning message and
102 * Returns 0 if the specified exception was successfully thrown. (Some
103 * sort of exception will always be pending when this returns.)
105 int jniThrowException(JNIEnv* env, const char* className, const char* msg)
107 jclass exceptionClass;
109 if ((*env)->ExceptionCheck(env)) {
110 /* TODO: consider creating the new exception with this as "cause" */
113 jthrowable excep = (*env)->ExceptionOccurred(env);
114 (*env)->ExceptionClear(env);
115 getExceptionSummary(env, excep, buf, sizeof(buf));
116 LOGW("Discarding pending exception (%s) to throw %s\n",
120 exceptionClass = (*env)->FindClass(env, className);
121 if (exceptionClass == NULL) {
122 LOGE("Unable to find exception class %s\n", className);
123 /* ClassNotFoundException now pending */
127 if ((*env)->ThrowNew(env, exceptionClass, msg) != JNI_OK) {
128 LOGE("Failed throwing '%s' '%s'\n", className, msg);
129 /* an exception, most likely OOM, will now be pending */
136 * Throw a java.lang.RuntimeException, with an optional message.
138 int jniThrowRuntimeException(JNIEnv* env, const char* msg)
140 return jniThrowException(env, "java/lang/RuntimeException", msg);
144 * Throw a java.io.IOException, generating the message from errno.
146 int jniThrowIOException(JNIEnv* env, int errnum)
149 const char* message = jniStrError(errnum, buffer, sizeof(buffer));
150 return jniThrowException(env, "java/io/IOException", message);
153 const char* jniStrError(int errnum, char* buf, size_t buflen)
155 // note: glibc has a nonstandard strerror_r that returns char* rather
157 // char *strerror_r(int errnum, char *buf, size_t n);
158 char* ret = (char*) strerror_r(errnum, buf, buflen);
159 if (((int)ret) == 0) {
160 //POSIX strerror_r, success
162 } else if (((int)ret) == -1) {
163 //POSIX strerror_r, failure
164 // (Strictly, POSIX only guarantees a value other than 0. The safest
165 // way to implement this function is to use C++ and overload on the
166 // type of strerror_r to accurately distinguish GNU from POSIX. But
167 // realistic implementations will always return -1.)
168 snprintf(buf, buflen, "errno %d", errnum);
171 //glibc strerror_r returning a string