blob: 49c4f94194ae271d4104405635ea55172349297e [file] [log] [blame]
/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#if defined(__ANDROID__)
/* libnativehelper is built by NDK 19 in one variant, which doesn't yet have the GNU strerror_r. */
#undef _GNU_SOURCE
#endif
#define LOG_TAG "JNIHelp"
#include "JniConstants.h"
#include "JNIHelp.h"
#include "ALog-priv.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <string>
/**
* Equivalent to ScopedLocalRef, but for C_JNIEnv instead. (And slightly more powerful.)
*/
template<typename T>
class scoped_local_ref {
public:
scoped_local_ref(C_JNIEnv* env, T localRef = NULL)
: mEnv(env), mLocalRef(localRef)
{
}
~scoped_local_ref() {
reset();
}
void reset(T localRef = NULL) {
if (mLocalRef != NULL) {
(*mEnv)->DeleteLocalRef(reinterpret_cast<JNIEnv*>(mEnv), mLocalRef);
mLocalRef = localRef;
}
}
T get() const {
return mLocalRef;
}
private:
C_JNIEnv* const mEnv;
T mLocalRef;
DISALLOW_COPY_AND_ASSIGN(scoped_local_ref);
};
static jclass findClass(C_JNIEnv* env, const char* className) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
return (*env)->FindClass(e, className);
}
extern "C" int jniRegisterNativeMethods(C_JNIEnv* env, const char* className,
const JNINativeMethod* gMethods, int numMethods)
{
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
ALOGV("Registering %s's %d native methods...", className, numMethods);
scoped_local_ref<jclass> c(env, findClass(env, className));
if (c.get() == NULL) {
char* msg;
asprintf(&msg, "Native registration unable to find class '%s'; aborting...", className);
e->FatalError(msg);
}
if ((*env)->RegisterNatives(e, c.get(), gMethods, numMethods) < 0) {
char* msg;
asprintf(&msg, "RegisterNatives failed for '%s'; aborting...", className);
e->FatalError(msg);
}
return 0;
}
/*
* Returns a human-readable summary of an exception object. The buffer will
* be populated with the "binary" class name and, if present, the
* exception message.
*/
static bool getExceptionSummary(C_JNIEnv* env, jthrowable exception, std::string& result) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
/* get the name of the exception's class */
scoped_local_ref<jclass> exceptionClass(env, (*env)->GetObjectClass(e, exception)); // can't fail
scoped_local_ref<jclass> classClass(env,
(*env)->GetObjectClass(e, exceptionClass.get())); // java.lang.Class, can't fail
jmethodID classGetNameMethod =
(*env)->GetMethodID(e, classClass.get(), "getName", "()Ljava/lang/String;");
scoped_local_ref<jstring> classNameStr(env,
(jstring) (*env)->CallObjectMethod(e, exceptionClass.get(), classGetNameMethod));
if (classNameStr.get() == NULL) {
(*env)->ExceptionClear(e);
result = "<error getting class name>";
return false;
}
const char* classNameChars = (*env)->GetStringUTFChars(e, classNameStr.get(), NULL);
if (classNameChars == NULL) {
(*env)->ExceptionClear(e);
result = "<error getting class name UTF-8>";
return false;
}
result += classNameChars;
(*env)->ReleaseStringUTFChars(e, classNameStr.get(), classNameChars);
/* if the exception has a detail message, get that */
jmethodID getMessage =
(*env)->GetMethodID(e, exceptionClass.get(), "getMessage", "()Ljava/lang/String;");
scoped_local_ref<jstring> messageStr(env,
(jstring) (*env)->CallObjectMethod(e, exception, getMessage));
if (messageStr.get() == NULL) {
return true;
}
result += ": ";
const char* messageChars = (*env)->GetStringUTFChars(e, messageStr.get(), NULL);
if (messageChars != NULL) {
result += messageChars;
(*env)->ReleaseStringUTFChars(e, messageStr.get(), messageChars);
} else {
result += "<error getting message>";
(*env)->ExceptionClear(e); // clear OOM
}
return true;
}
/*
* Returns an exception (with stack trace) as a string.
*/
static bool getStackTrace(C_JNIEnv* env, jthrowable exception, std::string& result) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
scoped_local_ref<jclass> stringWriterClass(env, findClass(env, "java/io/StringWriter"));
if (stringWriterClass.get() == NULL) {
return false;
}
jmethodID stringWriterCtor = (*env)->GetMethodID(e, stringWriterClass.get(), "<init>", "()V");
jmethodID stringWriterToStringMethod =
(*env)->GetMethodID(e, stringWriterClass.get(), "toString", "()Ljava/lang/String;");
scoped_local_ref<jclass> printWriterClass(env, findClass(env, "java/io/PrintWriter"));
if (printWriterClass.get() == NULL) {
return false;
}
jmethodID printWriterCtor =
(*env)->GetMethodID(e, printWriterClass.get(), "<init>", "(Ljava/io/Writer;)V");
scoped_local_ref<jobject> stringWriter(env,
(*env)->NewObject(e, stringWriterClass.get(), stringWriterCtor));
if (stringWriter.get() == NULL) {
return false;
}
scoped_local_ref<jobject> printWriter(env,
(*env)->NewObject(e, printWriterClass.get(), printWriterCtor, stringWriter.get()));
if (printWriter.get() == NULL) {
return false;
}
scoped_local_ref<jclass> exceptionClass(env, (*env)->GetObjectClass(e, exception)); // can't fail
jmethodID printStackTraceMethod =
(*env)->GetMethodID(e, exceptionClass.get(), "printStackTrace", "(Ljava/io/PrintWriter;)V");
(*env)->CallVoidMethod(e, exception, printStackTraceMethod, printWriter.get());
if ((*env)->ExceptionCheck(e)) {
return false;
}
scoped_local_ref<jstring> messageStr(env,
(jstring) (*env)->CallObjectMethod(e, stringWriter.get(), stringWriterToStringMethod));
if (messageStr.get() == NULL) {
return false;
}
const char* utfChars = (*env)->GetStringUTFChars(e, messageStr.get(), NULL);
if (utfChars == NULL) {
return false;
}
result = utfChars;
(*env)->ReleaseStringUTFChars(e, messageStr.get(), utfChars);
return true;
}
extern "C" int jniThrowException(C_JNIEnv* env, const char* className, const char* msg) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
if ((*env)->ExceptionCheck(e)) {
/* TODO: consider creating the new exception with this as "cause" */
scoped_local_ref<jthrowable> exception(env, (*env)->ExceptionOccurred(e));
(*env)->ExceptionClear(e);
if (exception.get() != NULL) {
std::string text;
getExceptionSummary(env, exception.get(), text);
ALOGW("Discarding pending exception (%s) to throw %s", text.c_str(), className);
}
}
scoped_local_ref<jclass> exceptionClass(env, findClass(env, className));
if (exceptionClass.get() == NULL) {
ALOGE("Unable to find exception class %s", className);
/* ClassNotFoundException now pending */
return -1;
}
if ((*env)->ThrowNew(e, exceptionClass.get(), msg) != JNI_OK) {
ALOGE("Failed throwing '%s' '%s'", className, msg);
/* an exception, most likely OOM, will now be pending */
return -1;
}
return 0;
}
int jniThrowExceptionFmt(C_JNIEnv* env, const char* className, const char* fmt, va_list args) {
char msgBuf[512];
vsnprintf(msgBuf, sizeof(msgBuf), fmt, args);
return jniThrowException(env, className, msgBuf);
}
int jniThrowNullPointerException(C_JNIEnv* env, const char* msg) {
return jniThrowException(env, "java/lang/NullPointerException", msg);
}
int jniThrowRuntimeException(C_JNIEnv* env, const char* msg) {
return jniThrowException(env, "java/lang/RuntimeException", msg);
}
int jniThrowIOException(C_JNIEnv* env, int errnum) {
char buffer[80];
const char* message = jniStrError(errnum, buffer, sizeof(buffer));
return jniThrowException(env, "java/io/IOException", message);
}
static std::string jniGetStackTrace(C_JNIEnv* env, jthrowable exception) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
scoped_local_ref<jthrowable> currentException(env, (*env)->ExceptionOccurred(e));
if (exception == NULL) {
exception = currentException.get();
if (exception == NULL) {
return "<no pending exception>";
}
}
if (currentException.get() != NULL) {
(*env)->ExceptionClear(e);
}
std::string trace;
if (!getStackTrace(env, exception, trace)) {
(*env)->ExceptionClear(e);
getExceptionSummary(env, exception, trace);
}
if (currentException.get() != NULL) {
(*env)->Throw(e, currentException.get()); // rethrow
}
return trace;
}
void jniLogException(C_JNIEnv* env, int priority, const char* tag, jthrowable exception) {
std::string trace(jniGetStackTrace(env, exception));
__android_log_write(priority, tag, trace.c_str());
}
const char* jniStrError(int errnum, char* buf, size_t buflen) {
#if __GLIBC__
// Note: glibc has a nonstandard strerror_r that returns char* rather than POSIX's int.
// char *strerror_r(int errnum, char *buf, size_t n);
return strerror_r(errnum, buf, buflen);
#else
int rc = strerror_r(errnum, buf, buflen);
if (rc != 0) {
// (POSIX only guarantees a value other than 0. The safest
// way to implement this function is to use C++ and overload on the
// type of strerror_r to accurately distinguish GNU from POSIX.)
snprintf(buf, buflen, "errno %d", errnum);
}
return buf;
#endif
}
jobject jniCreateFileDescriptor(C_JNIEnv* env, int fd) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
static jmethodID ctor = e->GetMethodID(JniConstants::fileDescriptorClass, "<init>", "()V");
jobject fileDescriptor = (*env)->NewObject(e, JniConstants::fileDescriptorClass, ctor);
// NOTE: NewObject ensures that an OutOfMemoryError will be seen by the Java
// caller if the alloc fails, so we just return NULL when that happens.
if (fileDescriptor != NULL) {
jniSetFileDescriptorOfFD(env, fileDescriptor, fd);
}
return fileDescriptor;
}
int jniGetFDFromFileDescriptor(C_JNIEnv* env, jobject fileDescriptor) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
static jfieldID fid = e->GetFieldID(JniConstants::fileDescriptorClass, "descriptor", "I");
if (fileDescriptor != NULL) {
return (*env)->GetIntField(e, fileDescriptor, fid);
} else {
return -1;
}
}
void jniSetFileDescriptorOfFD(C_JNIEnv* env, jobject fileDescriptor, int value) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
static jfieldID fid = e->GetFieldID(JniConstants::fileDescriptorClass, "descriptor", "I");
(*env)->SetIntField(e, fileDescriptor, fid, value);
}
jobject jniGetReferent(C_JNIEnv* env, jobject ref) {
JNIEnv* e = reinterpret_cast<JNIEnv*>(env);
static jmethodID get = e->GetMethodID(JniConstants::referenceClass, "get", "()Ljava/lang/Object;");
return (*env)->CallObjectMethod(e, ref, get);
}