| /* |
| * 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.Build; |
| import android.os.SystemProperties; |
| import android.provider.Settings; |
| import android.text.TextUtils; |
| import android.util.Slog; |
| import android.view.ThreadedRenderer; |
| |
| import com.android.internal.annotations.VisibleForTesting; |
| import com.android.internal.util.Preconditions; |
| |
| /** |
| * Maps global system settings to system properties. |
| * <p>The properties are dynamically updated when settings change. |
| */ |
| class GlobalSettingsToPropertiesMapper { |
| |
| private static final String TAG = "GlobalSettingsToPropertiesMapper"; |
| |
| // List mapping entries in the following format: |
| // {Settings.Global.SETTING_NAME, "system_property_name"} |
| // Important: Property being added should be whitelisted by SELinux policy or have one of the |
| // already whitelisted prefixes in system_server.te, e.g. sys. |
| private static final String[][] sGlobalSettingsMapping = new String[][] { |
| {Settings.Global.SYS_VDSO, "sys.vdso"}, |
| {Settings.Global.FPS_DEVISOR, ThreadedRenderer.DEBUG_FPS_DIVISOR}, |
| {Settings.Global.DISPLAY_PANEL_LPM, "sys.display_panel_lpm"}, |
| {Settings.Global.SYS_UIDCPUPOWER, "sys.uidcpupower"}, |
| {Settings.Global.SYS_TRACED, "sys.traced.enable_override"}, |
| }; |
| |
| |
| private final ContentResolver mContentResolver; |
| private final String[][] mGlobalSettingsMapping; |
| |
| @VisibleForTesting |
| GlobalSettingsToPropertiesMapper(ContentResolver contentResolver, |
| String[][] globalSettingsMapping) { |
| mContentResolver = contentResolver; |
| mGlobalSettingsMapping = globalSettingsMapping; |
| } |
| |
| void updatePropertiesFromGlobalSettings() { |
| for (String[] entry : mGlobalSettingsMapping) { |
| final String settingName = entry[0]; |
| final String propName = entry[1]; |
| Uri settingUri = Settings.Global.getUriFor(settingName); |
| Preconditions.checkNotNull(settingUri, "Setting " + settingName + " not found"); |
| ContentObserver co = new ContentObserver(null) { |
| @Override |
| public void onChange(boolean selfChange) { |
| updatePropertyFromSetting(settingName, propName); |
| } |
| }; |
| updatePropertyFromSetting(settingName, propName); |
| mContentResolver.registerContentObserver(settingUri, false, co); |
| } |
| } |
| |
| public static void start(ContentResolver contentResolver) { |
| new GlobalSettingsToPropertiesMapper(contentResolver, sGlobalSettingsMapping) |
| .updatePropertiesFromGlobalSettings(); |
| } |
| |
| private String getGlobalSetting(String name) { |
| return Settings.Global.getString(mContentResolver, name); |
| } |
| |
| 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 = ""; |
| } |
| 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. |
| if (Build.IS_DEBUGGABLE) { |
| Slog.wtf(TAG, "Unable to set property " + key + " value '" + value + "'", e); |
| } else { |
| Slog.e(TAG, "Unable to set property " + key + " value '" + value + "'", e); |
| } |
| } |
| } |
| |
| @VisibleForTesting |
| protected String systemPropertiesGet(String key) { |
| return SystemProperties.get(key); |
| } |
| |
| @VisibleForTesting |
| protected void systemPropertiesSet(String key, String value) { |
| SystemProperties.set(key, value); |
| } |
| |
| @VisibleForTesting |
| void updatePropertyFromSetting(String settingName, String propName) { |
| String settingValue = getGlobalSetting(settingName); |
| setProperty(propName, settingValue); |
| } |
| } |