// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package org.chromium.components.policy;
import android.content.Context;
import android.content.SharedPreferences;
import android.util.Pair;
import androidx.annotation.VisibleForTesting;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.chromium.base.ContextUtils;
import org.chromium.base.ResettersForTesting;
import org.chromium.base.StrictModeContext;
import org.chromium.base.ThreadUtils;
import java.util.List;
import java.util.Map;
/**
* Manage policy cache that will be used during browser launch stage.
*
* Policy loading is async on Android and caching policy values makes them
* available during launch stage even before native library is ready.
*/
public class PolicyCache {
@VisibleForTesting static final String POLICY_PREF = "Components.Policy";
private static PolicyCache sInstance;
public enum Type {
Integer,
Boolean,
String,
List,
Dict,
}
private boolean mReadable = true;
private SharedPreferences mSharedPreferences;
private ThreadUtils.ThreadChecker mThreadChecker = new ThreadUtils.ThreadChecker();
/**
* Creates and returns SharedPreferences instance that is used to cache policy
* value.
*
* @return The SharedPreferences instance that is used for policy caching. Returns null if
* application context is not available.
*/
private SharedPreferences getSharedPreferences() {
assert mReadable;
mThreadChecker.assertOnValidThread();
if (mSharedPreferences == null) {
Context context = ContextUtils.getApplicationContext();
// Policy cache is not accessiable without application context.
if (context == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
mSharedPreferences =
context.getSharedPreferences(POLICY_PREF, Context.MODE_PRIVATE);
}
}
return mSharedPreferences;
}
private SharedPreferences.Editor getSharedPreferencesEditor() {
mThreadChecker.assertOnValidThread();
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
return ContextUtils.getApplicationContext()
.getSharedPreferences(POLICY_PREF, Context.MODE_PRIVATE)
.edit();
}
}
public static PolicyCache get() {
var ret = sInstance;
if (ret == null) {
ret = new PolicyCache();
sInstance = ret;
ResettersForTesting.register(() -> sInstance = null);
}
return ret;
}
/**
* @param policy The name of policy.
* @return The value of cached integer policy, null if there is no valid
* cached policy.
*/
public Integer getIntValue(String policy) {
SharedPreferences sharedPreferences = getSharedPreferences();
if (sharedPreferences == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
if (!sharedPreferences.contains(policy)) return null;
return sharedPreferences.getInt(policy, 0);
}
}
/**
* @param policy The name of policy.
* @return The value of cached boolean policy, null if there is no valid
* cached policy.
*/
public Boolean getBooleanValue(String policy) {
SharedPreferences sharedPreferences = getSharedPreferences();
if (sharedPreferences == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
if (!sharedPreferences.contains(policy)) return null;
return sharedPreferences.getBoolean(policy, false);
}
}
/**
* @param policy The name of policy.
* @return The value of cached string policy, null if there is no valid
* cached policy.
*/
public String getStringValue(String policy) {
SharedPreferences sharedPreferences = getSharedPreferences();
if (sharedPreferences == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
if (!sharedPreferences.contains(policy)) return null;
return sharedPreferences.getString(policy, null);
}
}
/**
* @param policy The name of policy.
* @return The value of cached list policy, null if there is no valid
* cached policy.
*/
public JSONArray getListValue(String policy) {
SharedPreferences sharedPreferences = getSharedPreferences();
if (sharedPreferences == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
if (!sharedPreferences.contains(policy)) return null;
try {
return new JSONArray(sharedPreferences.getString(policy, null));
} catch (JSONException e) {
return null;
}
}
}
/**
* @param policy The name of policy.
* @return The value of cached dictionary policy, null if there is no valid
* cached policy.
*/
public JSONObject getDictValue(String policy) {
SharedPreferences sharedPreferences = getSharedPreferences();
if (sharedPreferences == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
if (!sharedPreferences.contains(policy)) return null;
try {
return new JSONObject(sharedPreferences.getString(policy, null));
} catch (JSONException e) {
return null;
}
}
}
/** @return All cached policies. */
public Map<String, ?> getAllPolicies() {
SharedPreferences sharedPreferences = getSharedPreferences();
if (sharedPreferences == null) return null;
try (StrictModeContext ignored = StrictModeContext.allowDiskReads()) {
return sharedPreferences.getAll();
}
}
public boolean isReadable() {
return mReadable;
}
/**
* @param policyMap The latest policy value bundle.
* @param policyNames The list of policies that needs to be cached if available.
* Caches the policies that are available in both |policyNames| and
* |policyMap|. It also disables {@link PolicyCache} reading.
*/
public void cachePolicies(PolicyMap policyMap, List<Pair<String, Type>> policyNames) {
// TODO(zmin): support policy level while caching policy.
SharedPreferences.Editor sharedPreferencesEditor = getSharedPreferencesEditor();
sharedPreferencesEditor.clear();
for (Pair<String, Type> policy : policyNames) {
String policyName = policy.first;
switch (policy.second) {
case Integer:
{
Integer value = policyMap.getIntValue(policyName);
if (value != null) {
sharedPreferencesEditor.putInt(policyName, value.intValue());
}
break;
}
case Boolean:
{
Boolean value = policyMap.getBooleanValue(policyName);
if (value != null) {
sharedPreferencesEditor.putBoolean(policyName, value.booleanValue());
}
break;
}
case String:
{
String value = policyMap.getStringValue(policyName);
if (value != null) {
sharedPreferencesEditor.putString(policyName, value);
}
break;
}
// List and Dict policy values are stored in the native library
// as base::Value and converted to JSON string to passed through
// the JNI. It's stored to the SharedPreferences as String and
// will be converted to JSON object when being read.
case List:
{
String value = policyMap.getListValueAsString(policyName);
if (value != null) {
sharedPreferencesEditor.putString(policyName, value);
}
break;
}
case Dict:
{
String value = policyMap.getDictValueAsString(policyName);
if (value != null) {
sharedPreferencesEditor.putString(policyName, value);
}
break;
}
}
}
// Update sharedPreferences. The first round of updating during launch
// will use the main thread.
try (StrictModeContext ignored = StrictModeContext.allowDiskWrites()) {
sharedPreferencesEditor.apply();
}
// Policy Service is up and there is no need to get policy from here anymore.
enableWriteOnlyMode();
}
/** Delete all entries from the cache. */
public void reset() {
SharedPreferences.Editor sharedPreferencesEditor = getSharedPreferencesEditor();
sharedPreferencesEditor.clear();
sharedPreferencesEditor.apply();
}
private void enableWriteOnlyMode() {
mSharedPreferences = null;
mReadable = false;
}
public void setReadableForTesting(boolean readable) {
mReadable = readable;
}
}
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