342 lines
11 KiB
C++
342 lines
11 KiB
C++
/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#define LOG_TAG "JNIHelp"
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#include "JniConstants.h"
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#include "JNIHelp.h"
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#include "ALog-priv.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <string>
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/**
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* Equivalent to ScopedLocalRef, but for C_JNIEnv instead. (And slightly more powerful.)
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*/
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template<typename T>
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class scoped_local_ref {
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public:
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scoped_local_ref(C_JNIEnv* env, T localRef = NULL)
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: mEnv(env), mLocalRef(localRef)
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{
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}
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~scoped_local_ref() {
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reset();
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}
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void reset(T localRef = NULL) {
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if (mLocalRef != NULL) {
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(*mEnv)->DeleteLocalRef(reinterpret_cast<JNIEnv*>(mEnv), mLocalRef);
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mLocalRef = localRef;
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}
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}
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T get() const {
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return mLocalRef;
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}
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private:
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C_JNIEnv* mEnv;
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T mLocalRef;
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// Disallow copy and assignment.
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scoped_local_ref(const scoped_local_ref&);
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void operator=(const scoped_local_ref&);
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};
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static jclass findClass(C_JNIEnv* env, const char* className) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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return (*env)->FindClass(e, className);
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}
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extern "C" int jniRegisterNativeMethods(C_JNIEnv* env, const char* className,
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const JNINativeMethod* gMethods, int numMethods)
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{
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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ALOGV("Registering %s's %d native methods...", className, numMethods);
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scoped_local_ref<jclass> c(env, findClass(env, className));
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if (c.get() == NULL) {
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char* msg;
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asprintf(&msg, "Native registration unable to find class '%s'; aborting...", className);
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e->FatalError(msg);
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}
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if ((*env)->RegisterNatives(e, c.get(), gMethods, numMethods) < 0) {
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char* msg;
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asprintf(&msg, "RegisterNatives failed for '%s'; aborting...", className);
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e->FatalError(msg);
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}
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return 0;
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}
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/*
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* Returns a human-readable summary of an exception object. The buffer will
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* be populated with the "binary" class name and, if present, the
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* exception message.
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*/
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static bool getExceptionSummary(C_JNIEnv* env, jthrowable exception, std::string& result) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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/* get the name of the exception's class */
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scoped_local_ref<jclass> exceptionClass(env, (*env)->GetObjectClass(e, exception)); // can't fail
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scoped_local_ref<jclass> classClass(env,
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(*env)->GetObjectClass(e, exceptionClass.get())); // java.lang.Class, can't fail
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jmethodID classGetNameMethod =
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(*env)->GetMethodID(e, classClass.get(), "getName", "()Ljava/lang/String;");
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scoped_local_ref<jstring> classNameStr(env,
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(jstring) (*env)->CallObjectMethod(e, exceptionClass.get(), classGetNameMethod));
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if (classNameStr.get() == NULL) {
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(*env)->ExceptionClear(e);
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result = "<error getting class name>";
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return false;
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}
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const char* classNameChars = (*env)->GetStringUTFChars(e, classNameStr.get(), NULL);
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if (classNameChars == NULL) {
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(*env)->ExceptionClear(e);
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result = "<error getting class name UTF-8>";
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return false;
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}
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result += classNameChars;
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(*env)->ReleaseStringUTFChars(e, classNameStr.get(), classNameChars);
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/* if the exception has a detail message, get that */
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jmethodID getMessage =
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(*env)->GetMethodID(e, exceptionClass.get(), "getMessage", "()Ljava/lang/String;");
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scoped_local_ref<jstring> messageStr(env,
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(jstring) (*env)->CallObjectMethod(e, exception, getMessage));
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if (messageStr.get() == NULL) {
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return true;
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}
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result += ": ";
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const char* messageChars = (*env)->GetStringUTFChars(e, messageStr.get(), NULL);
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if (messageChars != NULL) {
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result += messageChars;
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(*env)->ReleaseStringUTFChars(e, messageStr.get(), messageChars);
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} else {
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result += "<error getting message>";
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(*env)->ExceptionClear(e); // clear OOM
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}
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return true;
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}
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/*
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* Returns an exception (with stack trace) as a string.
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*/
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static bool getStackTrace(C_JNIEnv* env, jthrowable exception, std::string& result) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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scoped_local_ref<jclass> stringWriterClass(env, findClass(env, "java/io/StringWriter"));
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if (stringWriterClass.get() == NULL) {
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return false;
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}
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jmethodID stringWriterCtor = (*env)->GetMethodID(e, stringWriterClass.get(), "<init>", "()V");
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jmethodID stringWriterToStringMethod =
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(*env)->GetMethodID(e, stringWriterClass.get(), "toString", "()Ljava/lang/String;");
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scoped_local_ref<jclass> printWriterClass(env, findClass(env, "java/io/PrintWriter"));
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if (printWriterClass.get() == NULL) {
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return false;
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}
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jmethodID printWriterCtor =
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(*env)->GetMethodID(e, printWriterClass.get(), "<init>", "(Ljava/io/Writer;)V");
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scoped_local_ref<jobject> stringWriter(env,
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(*env)->NewObject(e, stringWriterClass.get(), stringWriterCtor));
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if (stringWriter.get() == NULL) {
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return false;
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}
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jobject printWriter =
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(*env)->NewObject(e, printWriterClass.get(), printWriterCtor, stringWriter.get());
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if (printWriter == NULL) {
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return false;
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}
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scoped_local_ref<jclass> exceptionClass(env, (*env)->GetObjectClass(e, exception)); // can't fail
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jmethodID printStackTraceMethod =
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(*env)->GetMethodID(e, exceptionClass.get(), "printStackTrace", "(Ljava/io/PrintWriter;)V");
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(*env)->CallVoidMethod(e, exception, printStackTraceMethod, printWriter);
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if ((*env)->ExceptionCheck(e)) {
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return false;
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}
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scoped_local_ref<jstring> messageStr(env,
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(jstring) (*env)->CallObjectMethod(e, stringWriter.get(), stringWriterToStringMethod));
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if (messageStr.get() == NULL) {
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return false;
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}
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const char* utfChars = (*env)->GetStringUTFChars(e, messageStr.get(), NULL);
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if (utfChars == NULL) {
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return false;
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}
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result = utfChars;
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(*env)->ReleaseStringUTFChars(e, messageStr.get(), utfChars);
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return true;
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}
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extern "C" int jniThrowException(C_JNIEnv* env, const char* className, const char* msg) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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if ((*env)->ExceptionCheck(e)) {
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/* TODO: consider creating the new exception with this as "cause" */
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scoped_local_ref<jthrowable> exception(env, (*env)->ExceptionOccurred(e));
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(*env)->ExceptionClear(e);
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if (exception.get() != NULL) {
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std::string text;
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getExceptionSummary(env, exception.get(), text);
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ALOGW("Discarding pending exception (%s) to throw %s", text.c_str(), className);
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}
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}
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scoped_local_ref<jclass> exceptionClass(env, findClass(env, className));
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if (exceptionClass.get() == NULL) {
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ALOGE("Unable to find exception class %s", className);
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/* ClassNotFoundException now pending */
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return -1;
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}
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if ((*env)->ThrowNew(e, exceptionClass.get(), msg) != JNI_OK) {
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ALOGE("Failed throwing '%s' '%s'", className, msg);
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/* an exception, most likely OOM, will now be pending */
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return -1;
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}
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return 0;
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}
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int jniThrowExceptionFmt(C_JNIEnv* env, const char* className, const char* fmt, va_list args) {
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char msgBuf[512];
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vsnprintf(msgBuf, sizeof(msgBuf), fmt, args);
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return jniThrowException(env, className, msgBuf);
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}
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int jniThrowNullPointerException(C_JNIEnv* env, const char* msg) {
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return jniThrowException(env, "java/lang/NullPointerException", msg);
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}
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int jniThrowRuntimeException(C_JNIEnv* env, const char* msg) {
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return jniThrowException(env, "java/lang/RuntimeException", msg);
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}
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int jniThrowIOException(C_JNIEnv* env, int errnum) {
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char buffer[80];
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const char* message = jniStrError(errnum, buffer, sizeof(buffer));
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return jniThrowException(env, "java/io/IOException", message);
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}
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static std::string jniGetStackTrace(C_JNIEnv* env, jthrowable exception) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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scoped_local_ref<jthrowable> currentException(env, (*env)->ExceptionOccurred(e));
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if (exception == NULL) {
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exception = currentException.get();
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if (exception == NULL) {
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return "<no pending exception>";
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}
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}
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if (currentException.get() != NULL) {
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(*env)->ExceptionClear(e);
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}
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std::string trace;
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if (!getStackTrace(env, exception, trace)) {
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(*env)->ExceptionClear(e);
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getExceptionSummary(env, exception, trace);
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}
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if (currentException.get() != NULL) {
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(*env)->Throw(e, currentException.get()); // rethrow
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}
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return trace;
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}
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void jniLogException(C_JNIEnv* env, int priority, const char* tag, jthrowable exception) {
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std::string trace(jniGetStackTrace(env, exception));
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__android_log_write(priority, tag, trace.c_str());
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}
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const char* jniStrError(int errnum, char* buf, size_t buflen) {
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#if __GLIBC__
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// Note: glibc has a nonstandard strerror_r that returns char* rather than POSIX's int.
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// char *strerror_r(int errnum, char *buf, size_t n);
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return strerror_r(errnum, buf, buflen);
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#else
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int rc = strerror_r(errnum, buf, buflen);
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if (rc != 0) {
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// (POSIX only guarantees a value other than 0. The safest
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// way to implement this function is to use C++ and overload on the
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// type of strerror_r to accurately distinguish GNU from POSIX.)
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snprintf(buf, buflen, "errno %d", errnum);
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}
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return buf;
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#endif
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}
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jobject jniCreateFileDescriptor(C_JNIEnv* env, int fd) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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static jmethodID ctor = e->GetMethodID(JniConstants::fileDescriptorClass, "<init>", "()V");
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jobject fileDescriptor = (*env)->NewObject(e, JniConstants::fileDescriptorClass, ctor);
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// NOTE: NewObject ensures that an OutOfMemoryError will be seen by the Java
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// caller if the alloc fails, so we just return NULL when that happens.
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if (fileDescriptor != NULL) {
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jniSetFileDescriptorOfFD(env, fileDescriptor, fd);
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}
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return fileDescriptor;
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}
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int jniGetFDFromFileDescriptor(C_JNIEnv* env, jobject fileDescriptor) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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static jfieldID fid = e->GetFieldID(JniConstants::fileDescriptorClass, "descriptor", "I");
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if (fileDescriptor != NULL) {
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return (*env)->GetIntField(e, fileDescriptor, fid);
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} else {
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return -1;
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}
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}
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void jniSetFileDescriptorOfFD(C_JNIEnv* env, jobject fileDescriptor, int value) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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static jfieldID fid = e->GetFieldID(JniConstants::fileDescriptorClass, "descriptor", "I");
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(*env)->SetIntField(e, fileDescriptor, fid, value);
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}
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jobject jniGetReferent(C_JNIEnv* env, jobject ref) {
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JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
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static jmethodID get = e->GetMethodID(JniConstants::referenceClass, "get", "()Ljava/lang/Object;");
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return (*env)->CallObjectMethod(e, ref, get);
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}
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