src.com.android.server.am.SettingsToPropertiesMapper Maven / Gradle / Ivy
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/*
* Copyright (C) 2018 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.
*/
package com.android.server.am;
import android.annotation.NonNull;
import android.content.ContentResolver;
import android.database.ContentObserver;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.os.SystemProperties;
import android.provider.DeviceConfig;
import android.provider.Settings;
import android.text.TextUtils;
import android.util.Slog;
import com.android.internal.annotations.VisibleForTesting;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.HashSet;
/**
* Maps system settings to system properties.
* The properties are dynamically updated when settings change.
* @hide
*/
public class SettingsToPropertiesMapper {
private static final String TAG = "SettingsToPropertiesMapper";
private static final String SYSTEM_PROPERTY_PREFIX = "persist.device_config.";
private static final String RESET_PERFORMED_PROPERTY = "device_config.reset_performed";
private static final String RESET_RECORD_FILE_PATH =
"/data/server_configurable_flags/reset_flags";
private static final String SYSTEM_PROPERTY_VALID_CHARACTERS_REGEX = "^[\\w\\.\\-@:]*$";
private static final String SYSTEM_PROPERTY_INVALID_SUBSTRING = "..";
private static final int SYSTEM_PROPERTY_MAX_LENGTH = 92;
// experiment flags added to Global.Settings(before new "Config" provider table is available)
// will be added under this category.
private static final String GLOBAL_SETTINGS_CATEGORY = "global_settings";
// Add the global setting you want to push to native level as experiment flag into this list.
//
// NOTE: please grant write permission system property prefix
// with format persist.device_config.global_settings.[flag_name] in system_server.te and grant
// read permission in the corresponding .te file your feature belongs to.
@VisibleForTesting
static final String[] sGlobalSettings = new String[] {
Settings.Global.NATIVE_FLAGS_HEALTH_CHECK_ENABLED,
};
// All the flags under the listed DeviceConfig scopes will be synced to native level.
//
// NOTE: please grant write permission system property prefix
// with format persist.device_config.[device_config_scope]. in system_server.te and grant read
// permission in the corresponding .te file your feature belongs to.
@VisibleForTesting
static final String[] sDeviceConfigScopes = new String[] {
DeviceConfig.NAMESPACE_ACTIVITY_MANAGER_NATIVE_BOOT,
DeviceConfig.NAMESPACE_CONFIGURATION,
DeviceConfig.NAMESPACE_CONNECTIVITY,
DeviceConfig.NAMESPACE_INPUT_NATIVE_BOOT,
DeviceConfig.NAMESPACE_INTELLIGENCE_CONTENT_SUGGESTIONS,
DeviceConfig.NAMESPACE_LMKD_NATIVE,
DeviceConfig.NAMESPACE_MEDIA_NATIVE,
DeviceConfig.NAMESPACE_NETD_NATIVE,
DeviceConfig.NAMESPACE_PROFCOLLECT_NATIVE_BOOT,
DeviceConfig.NAMESPACE_RUNTIME_NATIVE,
DeviceConfig.NAMESPACE_RUNTIME_NATIVE_BOOT,
DeviceConfig.NAMESPACE_STATSD_NATIVE,
DeviceConfig.NAMESPACE_STATSD_NATIVE_BOOT,
DeviceConfig.NAMESPACE_STORAGE_NATIVE_BOOT,
DeviceConfig.NAMESPACE_WINDOW_MANAGER_NATIVE_BOOT,
};
private final String[] mGlobalSettings;
private final String[] mDeviceConfigScopes;
private final ContentResolver mContentResolver;
@VisibleForTesting
protected SettingsToPropertiesMapper(ContentResolver contentResolver,
String[] globalSettings,
String[] deviceConfigScopes) {
mContentResolver = contentResolver;
mGlobalSettings = globalSettings;
mDeviceConfigScopes = deviceConfigScopes;
}
@VisibleForTesting
void updatePropertiesFromSettings() {
for (String globalSetting : mGlobalSettings) {
Uri settingUri = Settings.Global.getUriFor(globalSetting);
String propName = makePropertyName(GLOBAL_SETTINGS_CATEGORY, globalSetting);
if (settingUri == null) {
log("setting uri is null for globalSetting " + globalSetting);
continue;
}
if (propName == null) {
log("invalid prop name for globalSetting " + globalSetting);
continue;
}
ContentObserver co = new ContentObserver(null) {
@Override
public void onChange(boolean selfChange) {
updatePropertyFromSetting(globalSetting, propName);
}
};
// only updating on starting up when no native flags reset is performed during current
// booting.
if (!isNativeFlagsResetPerformed()) {
updatePropertyFromSetting(globalSetting, propName);
}
mContentResolver.registerContentObserver(settingUri, false, co);
}
for (String deviceConfigScope : mDeviceConfigScopes) {
DeviceConfig.addOnPropertiesChangedListener(
deviceConfigScope,
AsyncTask.THREAD_POOL_EXECUTOR,
(DeviceConfig.Properties properties) -> {
String scope = properties.getNamespace();
for (String key : properties.getKeyset()) {
String propertyName = makePropertyName(scope, key);
if (propertyName == null) {
log("unable to construct system property for " + scope + "/"
+ key);
return;
}
setProperty(propertyName, properties.getString(key, null));
}
});
}
}
public static SettingsToPropertiesMapper start(ContentResolver contentResolver) {
SettingsToPropertiesMapper mapper = new SettingsToPropertiesMapper(
contentResolver, sGlobalSettings, sDeviceConfigScopes);
mapper.updatePropertiesFromSettings();
return mapper;
}
/**
* If native level flags reset has been performed as an attempt to recover from a crash loop
* during current device booting.
* @return
*/
public static boolean isNativeFlagsResetPerformed() {
String value = SystemProperties.get(RESET_PERFORMED_PROPERTY);
return "true".equals(value);
}
/**
* return an array of native flag categories under which flags got reset during current device
* booting.
* @return
*/
public static @NonNull String[] getResetNativeCategories() {
if (!isNativeFlagsResetPerformed()) {
return new String[0];
}
String content = getResetFlagsFileContent();
if (TextUtils.isEmpty(content)) {
return new String[0];
}
String[] property_names = content.split(";");
HashSet categories = new HashSet<>();
for (String property_name : property_names) {
String[] segments = property_name.split("\\.");
if (segments.length < 3) {
log("failed to extract category name from property " + property_name);
continue;
}
categories.add(segments[2]);
}
return categories.toArray(new String[0]);
}
/**
* system property name constructing rule: "persist.device_config.[category_name].[flag_name]".
* If the name contains invalid characters or substrings for system property name,
* will return null.
* @param categoryName
* @param flagName
* @return
*/
@VisibleForTesting
static String makePropertyName(String categoryName, String flagName) {
String propertyName = SYSTEM_PROPERTY_PREFIX + categoryName + "." + flagName;
if (!propertyName.matches(SYSTEM_PROPERTY_VALID_CHARACTERS_REGEX)
|| propertyName.contains(SYSTEM_PROPERTY_INVALID_SUBSTRING)) {
return null;
}
return propertyName;
}
private void setProperty(String key, String value) {
// Check if need to clear the property
if (value == null) {
// It's impossible to remove system property, therefore we check previous value to
// avoid setting an empty string if the property wasn't set.
if (TextUtils.isEmpty(SystemProperties.get(key))) {
return;
}
value = "";
} else if (value.length() > SYSTEM_PROPERTY_MAX_LENGTH) {
log(value + " exceeds system property max length.");
return;
}
try {
SystemProperties.set(key, value);
} catch (Exception e) {
// Failure to set a property can be caused by SELinux denial. This usually indicates
// that the property wasn't allowlisted in sepolicy.
// No need to report it on all user devices, only on debug builds.
log("Unable to set property " + key + " value '" + value + "'", e);
}
}
private static void log(String msg, Exception e) {
if (Build.IS_DEBUGGABLE) {
Slog.wtf(TAG, msg, e);
} else {
Slog.e(TAG, msg, e);
}
}
private static void log(String msg) {
if (Build.IS_DEBUGGABLE) {
Slog.wtf(TAG, msg);
} else {
Slog.e(TAG, msg);
}
}
@VisibleForTesting
static String getResetFlagsFileContent() {
String content = null;
try {
File reset_flag_file = new File(RESET_RECORD_FILE_PATH);
BufferedReader br = new BufferedReader(new FileReader(reset_flag_file));
content = br.readLine();
br.close();
} catch (IOException ioe) {
log("failed to read file " + RESET_RECORD_FILE_PATH, ioe);
}
return content;
}
@VisibleForTesting
void updatePropertyFromSetting(String settingName, String propName) {
String settingValue = Settings.Global.getString(mContentResolver, settingName);
setProperty(propName, settingValue);
}
}