| /* |
| * Copyright (C) 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. |
| */ |
| |
| package android.os; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.annotation.SystemApi; |
| import android.annotation.TestApi; |
| import android.util.Log; |
| import android.util.MutableInt; |
| |
| import com.android.internal.annotations.GuardedBy; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| |
| |
| /** |
| * Gives access to the system properties store. The system properties |
| * store contains a list of string key-value pairs. |
| * |
| * {@hide} |
| */ |
| @SystemApi |
| @TestApi |
| public class SystemProperties { |
| private static final String TAG = "SystemProperties"; |
| private static final boolean TRACK_KEY_ACCESS = false; |
| |
| /** |
| * Android O removed the property name length limit, but com.amazon.kindle 7.8.1.5 |
| * uses reflection to read this whenever text is selected (http://b/36095274). |
| * @hide |
| */ |
| public static final int PROP_NAME_MAX = Integer.MAX_VALUE; |
| |
| /** @hide */ |
| public static final int PROP_VALUE_MAX = 91; |
| |
| @GuardedBy("sChangeCallbacks") |
| private static final ArrayList<Runnable> sChangeCallbacks = new ArrayList<Runnable>(); |
| |
| @GuardedBy("sRoReads") |
| private static final HashMap<String, MutableInt> sRoReads = |
| TRACK_KEY_ACCESS ? new HashMap<>() : null; |
| |
| private static void onKeyAccess(String key) { |
| if (!TRACK_KEY_ACCESS) return; |
| |
| if (key != null && key.startsWith("ro.")) { |
| synchronized (sRoReads) { |
| MutableInt numReads = sRoReads.getOrDefault(key, null); |
| if (numReads == null) { |
| numReads = new MutableInt(0); |
| sRoReads.put(key, numReads); |
| } |
| numReads.value++; |
| if (numReads.value > 3) { |
| Log.d(TAG, "Repeated read (count=" + numReads.value |
| + ") of a read-only system property '" + key + "'", |
| new Exception()); |
| } |
| } |
| } |
| } |
| |
| private static native String native_get(String key); |
| private static native String native_get(String key, String def); |
| private static native int native_get_int(String key, int def); |
| private static native long native_get_long(String key, long def); |
| private static native boolean native_get_boolean(String key, boolean def); |
| private static native void native_set(String key, String def); |
| private static native void native_add_change_callback(); |
| private static native void native_report_sysprop_change(); |
| |
| /** |
| * Get the String value for the given {@code key}. |
| * |
| * @param key the key to lookup |
| * @return an empty string if the {@code key} isn't found |
| * @hide |
| */ |
| @NonNull |
| @SystemApi |
| public static String get(@NonNull String key) { |
| if (TRACK_KEY_ACCESS) onKeyAccess(key); |
| return native_get(key); |
| } |
| |
| /** |
| * Get the String value for the given {@code key}. |
| * |
| * @param key the key to lookup |
| * @param def the default value in case the property is not set or empty |
| * @return if the {@code key} isn't found, return {@code def} if it isn't null, or an empty |
| * string otherwise |
| * @hide |
| */ |
| @NonNull |
| @SystemApi |
| @TestApi |
| public static String get(@NonNull String key, @Nullable String def) { |
| if (TRACK_KEY_ACCESS) onKeyAccess(key); |
| return native_get(key, def); |
| } |
| |
| /** |
| * Get the value for the given {@code key}, and return as an integer. |
| * |
| * @param key the key to lookup |
| * @param def a default value to return |
| * @return the key parsed as an integer, or def if the key isn't found or |
| * cannot be parsed |
| * @hide |
| */ |
| @SystemApi |
| public static int getInt(@NonNull String key, int def) { |
| if (TRACK_KEY_ACCESS) onKeyAccess(key); |
| return native_get_int(key, def); |
| } |
| |
| /** |
| * Get the value for the given {@code key}, and return as a long. |
| * |
| * @param key the key to lookup |
| * @param def a default value to return |
| * @return the key parsed as a long, or def if the key isn't found or |
| * cannot be parsed |
| * @hide |
| */ |
| @SystemApi |
| public static long getLong(@NonNull String key, long def) { |
| if (TRACK_KEY_ACCESS) onKeyAccess(key); |
| return native_get_long(key, def); |
| } |
| |
| /** |
| * Get the value for the given {@code key}, returned as a boolean. |
| * Values 'n', 'no', '0', 'false' or 'off' are considered false. |
| * Values 'y', 'yes', '1', 'true' or 'on' are considered true. |
| * (case sensitive). |
| * If the key does not exist, or has any other value, then the default |
| * result is returned. |
| * |
| * @param key the key to lookup |
| * @param def a default value to return |
| * @return the key parsed as a boolean, or def if the key isn't found or is |
| * not able to be parsed as a boolean. |
| * @hide |
| */ |
| @SystemApi |
| public static boolean getBoolean(@NonNull String key, boolean def) { |
| if (TRACK_KEY_ACCESS) onKeyAccess(key); |
| return native_get_boolean(key, def); |
| } |
| |
| /** |
| * Set the value for the given {@code key} to {@code val}. |
| * |
| * @throws IllegalArgumentException if the {@code val} exceeds 91 characters |
| * @hide |
| */ |
| public static void set(@NonNull String key, @Nullable String val) { |
| if (val != null && !val.startsWith("ro.") && val.length() > PROP_VALUE_MAX) { |
| throw new IllegalArgumentException("value of system property '" + key |
| + "' is longer than " + PROP_VALUE_MAX + " characters: " + val); |
| } |
| if (TRACK_KEY_ACCESS) onKeyAccess(key); |
| native_set(key, val); |
| } |
| |
| /** |
| * Add a callback that will be run whenever any system property changes. |
| * |
| * @param callback The {@link Runnable} that should be executed when a system property |
| * changes. |
| * @hide |
| */ |
| public static void addChangeCallback(@NonNull Runnable callback) { |
| synchronized (sChangeCallbacks) { |
| if (sChangeCallbacks.size() == 0) { |
| native_add_change_callback(); |
| } |
| sChangeCallbacks.add(callback); |
| } |
| } |
| |
| @SuppressWarnings("unused") // Called from native code. |
| private static void callChangeCallbacks() { |
| synchronized (sChangeCallbacks) { |
| //Log.i("foo", "Calling " + sChangeCallbacks.size() + " change callbacks!"); |
| if (sChangeCallbacks.size() == 0) { |
| return; |
| } |
| ArrayList<Runnable> callbacks = new ArrayList<Runnable>(sChangeCallbacks); |
| for (int i=0; i<callbacks.size(); i++) { |
| try { |
| callbacks.get(i).run(); |
| } catch (Throwable t) { |
| Log.wtf(TAG, "Exception in SystemProperties change callback", t); |
| // Ignore and try to go on. |
| } |
| } |
| } |
| } |
| |
| /** |
| * Notifies listeners that a system property has changed |
| * @hide |
| */ |
| public static void reportSyspropChanged() { |
| native_report_sysprop_change(); |
| } |
| |
| private SystemProperties() { |
| } |
| } |