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mpv/misc/jni.c

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/*
* JNI utility functions
*
* Copyright (c) 2015-2016 Matthieu Bouron <matthieu.bouron stupeflix.com>
*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libavcodec/jni.h>
#include <libavutil/mem.h>
#include <libavutil/bprint.h>
#include <pthread.h>
#include <stdlib.h>
#include "jni.h"
static JavaVM *java_vm;
static pthread_key_t current_env;
static pthread_once_t once = PTHREAD_ONCE_INIT;
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
static void jni_detach_env(void *data)
{
if (java_vm) {
(*java_vm)->DetachCurrentThread(java_vm);
}
}
static void jni_create_pthread_key(void)
{
pthread_key_create(&current_env, jni_detach_env);
}
JNIEnv *mp_jni_get_env(struct mp_log *log)
{
int ret = 0;
JNIEnv *env = NULL;
pthread_mutex_lock(&lock);
if (java_vm == NULL) {
java_vm = av_jni_get_java_vm(NULL);
}
if (!java_vm) {
mp_err(log, "No Java virtual machine has been registered\n");
goto done;
}
pthread_once(&once, jni_create_pthread_key);
if ((env = pthread_getspecific(current_env)) != NULL) {
goto done;
}
ret = (*java_vm)->GetEnv(java_vm, (void **)&env, JNI_VERSION_1_6);
switch(ret) {
case JNI_EDETACHED:
if ((*java_vm)->AttachCurrentThread(java_vm, &env, NULL) != 0) {
mp_err(log, "Failed to attach the JNI environment to the current thread\n");
env = NULL;
} else {
pthread_setspecific(current_env, env);
}
break;
case JNI_OK:
break;
case JNI_EVERSION:
mp_err(log, "The specified JNI version is not supported\n");
break;
default:
mp_err(log, "Failed to get the JNI environment attached to this thread\n");
break;
}
done:
pthread_mutex_unlock(&lock);
return env;
}
char *mp_jni_jstring_to_utf_chars(JNIEnv *env, jstring string, struct mp_log *log)
{
char *ret = NULL;
const char *utf_chars = NULL;
jboolean copy = 0;
if (!string) {
return NULL;
}
utf_chars = (*env)->GetStringUTFChars(env, string, &copy);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "String.getStringUTFChars() threw an exception\n");
return NULL;
}
ret = av_strdup(utf_chars);
(*env)->ReleaseStringUTFChars(env, string, utf_chars);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "String.releaseStringUTFChars() threw an exception\n");
return NULL;
}
return ret;
}
jstring mp_jni_utf_chars_to_jstring(JNIEnv *env, const char *utf_chars, struct mp_log *log)
{
jstring ret;
ret = (*env)->NewStringUTF(env, utf_chars);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "NewStringUTF() threw an exception\n");
return NULL;
}
return ret;
}
int mp_jni_exception_get_summary(JNIEnv *env, jthrowable exception, char **error, struct mp_log *log)
{
int ret = 0;
AVBPrint bp;
char *name = NULL;
char *message = NULL;
jclass class_class = NULL;
jmethodID get_name_id = NULL;
jclass exception_class = NULL;
jmethodID get_message_id = NULL;
jstring string = NULL;
av_bprint_init(&bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
exception_class = (*env)->GetObjectClass(env, exception);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "Could not find Throwable class\n");
ret = -1;
goto done;
}
class_class = (*env)->GetObjectClass(env, exception_class);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "Could not find Throwable class's class\n");
ret = -1;
goto done;
}
get_name_id = (*env)->GetMethodID(env, class_class, "getName", "()Ljava/lang/String;");
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "Could not find method Class.getName()\n");
ret = -1;
goto done;
}
string = (*env)->CallObjectMethod(env, exception_class, get_name_id);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "Class.getName() threw an exception\n");
ret = -1;
goto done;
}
if (string) {
name = mp_jni_jstring_to_utf_chars(env, string, log);
(*env)->DeleteLocalRef(env, string);
string = NULL;
}
get_message_id = (*env)->GetMethodID(env, exception_class, "getMessage", "()Ljava/lang/String;");
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "Could not find method java/lang/Throwable.getMessage()\n");
ret = -1;
goto done;
}
string = (*env)->CallObjectMethod(env, exception, get_message_id);
if ((*env)->ExceptionCheck(env)) {
(*env)->ExceptionClear(env);
mp_err(log, "Throwable.getMessage() threw an exception\n");
ret = -1;
goto done;
}
if (string) {
message = mp_jni_jstring_to_utf_chars(env, string, log);
(*env)->DeleteLocalRef(env, string);
string = NULL;
}
if (name && message) {
av_bprintf(&bp, "%s: %s", name, message);
} else if (name && !message) {
av_bprintf(&bp, "%s occurred", name);
} else if (!name && message) {
av_bprintf(&bp, "Exception: %s", message);
} else {
mp_warn(log, "Could not retrieve exception name and message\n");
av_bprintf(&bp, "Exception occurred");
}
ret = av_bprint_finalize(&bp, error);
done:
av_free(name);
av_free(message);
if (class_class) {
(*env)->DeleteLocalRef(env, class_class);
}
if (exception_class) {
(*env)->DeleteLocalRef(env, exception_class);
}
if (string) {
(*env)->DeleteLocalRef(env, string);
}
return ret;
}
int mp_jni_exception_check(JNIEnv *env, int logging, struct mp_log *log)
{
int ret;
jthrowable exception;
char *message = NULL;
if (!(*(env))->ExceptionCheck((env))) {
return 0;
}
if (!logging) {
(*(env))->ExceptionClear((env));
return -1;
}
exception = (*env)->ExceptionOccurred(env);
(*(env))->ExceptionClear((env));
if ((ret = mp_jni_exception_get_summary(env, exception, &message, log)) < 0) {
(*env)->DeleteLocalRef(env, exception);
return ret;
}
(*env)->DeleteLocalRef(env, exception);
mp_err(log, "%s\n", message);
av_free(message);
return -1;
}
int mp_jni_init_jfields(JNIEnv *env, void *jfields, const struct MPJniField *jfields_mapping, int global, struct mp_log *log)
{
int i, ret = 0;
jclass last_clazz = NULL;
for (i = 0; jfields_mapping[i].name; i++) {
int mandatory = jfields_mapping[i].mandatory;
enum MPJniFieldType type = jfields_mapping[i].type;
if (type == MP_JNI_CLASS) {
jclass clazz;
last_clazz = NULL;
clazz = (*env)->FindClass(env, jfields_mapping[i].name);
if ((ret = mp_jni_exception_check(env, mandatory, log)) < 0 && mandatory) {
goto done;
}
last_clazz = *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset) =
global ? (*env)->NewGlobalRef(env, clazz) : clazz;
if (global) {
(*env)->DeleteLocalRef(env, clazz);
}
} else {
if (!last_clazz) {
ret = -1;
break;
}
switch(type) {
case MP_JNI_FIELD: {
jfieldID field_id = (*env)->GetFieldID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
if ((ret = mp_jni_exception_check(env, mandatory, log)) < 0 && mandatory) {
goto done;
}
*(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = field_id;
break;
}
case MP_JNI_STATIC_FIELD_AS_INT:
case MP_JNI_STATIC_FIELD: {
jfieldID field_id = (*env)->GetStaticFieldID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
if ((ret = mp_jni_exception_check(env, mandatory, log)) < 0 && mandatory) {
goto done;
}
if (type == MP_JNI_STATIC_FIELD_AS_INT) {
if (field_id) {
jint value = (*env)->GetStaticIntField(env, last_clazz, field_id);
if ((ret = mp_jni_exception_check(env, mandatory, log)) < 0 && mandatory) {
goto done;
}
*(jint*)((uint8_t*)jfields + jfields_mapping[i].offset) = value;
}
} else {
*(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = field_id;
}
break;
}
case MP_JNI_METHOD: {
jmethodID method_id = (*env)->GetMethodID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
if ((ret = mp_jni_exception_check(env, mandatory, log)) < 0 && mandatory) {
goto done;
}
*(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = method_id;
break;
}
case MP_JNI_STATIC_METHOD: {
jmethodID method_id = (*env)->GetStaticMethodID(env, last_clazz, jfields_mapping[i].method, jfields_mapping[i].signature);
if ((ret = mp_jni_exception_check(env, mandatory, log)) < 0 && mandatory) {
goto done;
}
*(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = method_id;
break;
}
default:
mp_err(log, "Unknown JNI field type\n");
ret = -1;
goto done;
}
ret = 0;
}
}
done:
if (ret < 0) {
/* reset jfields in case of failure so it does not leak references */
mp_jni_reset_jfields(env, jfields, jfields_mapping, global, log);
}
return ret;
}
int mp_jni_reset_jfields(JNIEnv *env, void *jfields, const struct MPJniField *jfields_mapping, int global, struct mp_log *log)
{
int i;
for (i = 0; jfields_mapping[i].name; i++) {
enum MPJniFieldType type = jfields_mapping[i].type;
switch(type) {
case MP_JNI_CLASS: {
jclass clazz = *(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset);
if (!clazz)
continue;
if (global) {
(*env)->DeleteGlobalRef(env, clazz);
} else {
(*env)->DeleteLocalRef(env, clazz);
}
*(jclass*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
break;
}
case MP_JNI_FIELD: {
*(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
break;
}
case MP_JNI_STATIC_FIELD: {
*(jfieldID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
break;
}
case MP_JNI_STATIC_FIELD_AS_INT: {
*(jint*)((uint8_t*)jfields + jfields_mapping[i].offset) = 0;
break;
}
case MP_JNI_METHOD: {
*(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
break;
}
case MP_JNI_STATIC_METHOD: {
*(jmethodID*)((uint8_t*)jfields + jfields_mapping[i].offset) = NULL;
break;
}
default:
mp_err(log, "Unknown JNI field type\n");
}
}
return 0;
}
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