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/* //device/libs/android_runtime/android_os_SystemProperties.cpp
**
** Copyright 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.
*/
#define LOG_TAG "SysPropJNI"
#include "android-base/logging.h"
#include "android-base/properties.h"
#include "cutils/properties.h"
#include "utils/misc.h"
#include <utils/Log.h>
#include "jni.h"
#include "core_jni_helpers.h"
#include <nativehelper/JNIHelp.h>
#include <nativehelper/ScopedPrimitiveArray.h>
#include <nativehelper/ScopedUtfChars.h>
namespace android
{
namespace {
template <typename T, typename Handler>
T ConvertKeyAndForward(JNIEnv *env, jstring keyJ, T defJ, Handler handler) {
std::string key;
{
// Scope the String access. If the handler can throw an exception,
// releasing the string characters late would trigger an abort.
ScopedUtfChars key_utf(env, keyJ);
if (key_utf.c_str() == nullptr) {
return defJ;
}
key = key_utf.c_str(); // This will make a copy, but we can't avoid
// with the existing interface in
// android::base.
}
return handler(key, defJ);
}
jstring SystemProperties_getSS(JNIEnv *env, jclass clazz, jstring keyJ,
jstring defJ)
{
// Using ConvertKeyAndForward is sub-optimal for copying the key string,
// but improves reuse and reasoning over code.
auto handler = [&](const std::string& key, jstring defJ) {
std::string prop_val = android::base::GetProperty(key, "");
if (!prop_val.empty()) {
return env->NewStringUTF(prop_val.c_str());
};
if (defJ != nullptr) {
return defJ;
}
// This function is specified to never return null (or have an
// exception pending).
return env->NewStringUTF("");
};
return ConvertKeyAndForward(env, keyJ, defJ, handler);
}
jstring SystemProperties_getS(JNIEnv *env, jclass clazz, jstring keyJ)
{
return SystemProperties_getSS(env, clazz, keyJ, nullptr);
}
template <typename T>
T SystemProperties_get_integral(JNIEnv *env, jclass, jstring keyJ,
T defJ)
{
auto handler = [](const std::string& key, T defV) {
return android::base::GetIntProperty<T>(key, defV);
};
return ConvertKeyAndForward(env, keyJ, defJ, handler);
}
jboolean SystemProperties_get_boolean(JNIEnv *env, jclass, jstring keyJ,
jboolean defJ)
{
auto handler = [](const std::string& key, jboolean defV) -> jboolean {
bool result = android::base::GetBoolProperty(key, defV);
return result ? JNI_TRUE : JNI_FALSE;
};
return ConvertKeyAndForward(env, keyJ, defJ, handler);
}
void SystemProperties_set(JNIEnv *env, jobject clazz, jstring keyJ,
jstring valJ)
{
auto handler = [&](const std::string& key, bool) {
std::string val;
if (valJ != nullptr) {
ScopedUtfChars key_utf(env, valJ);
val = key_utf.c_str();
}
return android::base::SetProperty(key, val);
};
if (!ConvertKeyAndForward(env, keyJ, true, handler)) {
// Must have been a failure in SetProperty.
jniThrowException(env, "java/lang/RuntimeException",
"failed to set system property");
}
}
JavaVM* sVM = nullptr;
jclass sClazz = nullptr;
jmethodID sCallChangeCallbacks;
void do_report_sysprop_change() {
//ALOGI("Java SystemProperties: VM=%p, Clazz=%p", sVM, sClazz);
if (sVM != nullptr && sClazz != nullptr) {
JNIEnv* env;
if (sVM->GetEnv((void **)&env, JNI_VERSION_1_4) >= 0) {
//ALOGI("Java SystemProperties: calling %p", sCallChangeCallbacks);
env->CallStaticVoidMethod(sClazz, sCallChangeCallbacks);
// There should not be any exceptions. But we must guarantee
// there are none on return.
if (env->ExceptionCheck()) {
env->ExceptionClear();
LOG(ERROR) << "Exception pending after sysprop_change!";
}
}
}
}
void SystemProperties_add_change_callback(JNIEnv *env, jobject clazz)
{
// This is called with the Java lock held.
if (sVM == nullptr) {
env->GetJavaVM(&sVM);
}
if (sClazz == nullptr) {
sClazz = (jclass) env->NewGlobalRef(clazz);
sCallChangeCallbacks = env->GetStaticMethodID(sClazz, "callChangeCallbacks", "()V");
add_sysprop_change_callback(do_report_sysprop_change, -10000);
}
}
void SystemProperties_report_sysprop_change(JNIEnv /**env*/, jobject /*clazz*/)
{
report_sysprop_change();
}
} // namespace
int register_android_os_SystemProperties(JNIEnv *env)
{
const JNINativeMethod method_table[] = {
{ "native_get", "(Ljava/lang/String;)Ljava/lang/String;",
(void*) SystemProperties_getS },
{ "native_get",
"(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;",
(void*) SystemProperties_getSS },
{ "native_get_int", "(Ljava/lang/String;I)I",
(void*) SystemProperties_get_integral<jint> },
{ "native_get_long", "(Ljava/lang/String;J)J",
(void*) SystemProperties_get_integral<jlong> },
{ "native_get_boolean", "(Ljava/lang/String;Z)Z",
(void*) SystemProperties_get_boolean },
{ "native_set", "(Ljava/lang/String;Ljava/lang/String;)V",
(void*) SystemProperties_set },
{ "native_add_change_callback", "()V",
(void*) SystemProperties_add_change_callback },
{ "native_report_sysprop_change", "()V",
(void*) SystemProperties_report_sysprop_change },
};
return RegisterMethodsOrDie(env, "android/os/SystemProperties",
method_table, NELEM(method_table));
}
};
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