| /* |
| * 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.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. |
| * <p>The properties are dynamically updated when settings change. |
| */ |
| 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[] { |
| }; |
| |
| 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.addOnPropertyChangedListener( |
| deviceConfigScope, |
| AsyncTask.THREAD_POOL_EXECUTOR, |
| (String scope, String name, String value) -> { |
| String propertyName = makePropertyName(scope, name); |
| if (propertyName == null) { |
| log("unable to construct system property for " + scope + "/" + name); |
| return; |
| } |
| setProperty(propertyName, value); |
| }); |
| } |
| } |
| |
| 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 boolean isNativeFlagsResetPerformed() { |
| String value = systemPropertiesGet(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 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<String> 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(systemPropertiesGet(key))) { |
| return; |
| } |
| value = ""; |
| } else if (value.length() > SYSTEM_PROPERTY_MAX_LENGTH) { |
| log(value + " exceeds system property max length."); |
| return; |
| } |
| |
| try { |
| systemPropertiesSet(key, value); |
| } catch (Exception e) { |
| // Failure to set a property can be caused by SELinux denial. This usually indicates |
| // that the property wasn't whitelisted 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 |
| protected String systemPropertiesGet(String key) { |
| return SystemProperties.get(key); |
| } |
| |
| @VisibleForTesting |
| protected void systemPropertiesSet(String key, String value) { |
| SystemProperties.set(key, value); |
| } |
| |
| @VisibleForTesting |
| protected 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); |
| } |
| } |