| /* |
| * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package jdk.jfr.internal; |
| |
| import java.io.IOException; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.security.AccessControlContext; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.Objects; |
| import java.util.Set; |
| |
| // User must never be able to subclass directly. |
| // |
| // Never put Control or Setting Control in a collections |
| // so overridable versions of hashCode or equals are |
| // executed in the wrong context. TODO: wrap this class |
| // in SsecureControl directly when it is instantiated and |
| // forward calls using AccessControlContext |
| abstract public class Control { |
| private final AccessControlContext context; |
| private final static int CACHE_SIZE = 5; |
| private final Set<?>[] cachedUnions = new HashSet<?>[CACHE_SIZE]; |
| private final String[] cachedValues = new String[CACHE_SIZE]; |
| private String defaultValue; |
| private String lastValue; |
| |
| // called by exposed subclass in external API |
| public Control(AccessControlContext acc) { |
| Objects.requireNonNull(acc); |
| this.context = acc; |
| |
| } |
| |
| // only to be called by trusted VM code |
| public Control(String defaultValue) { |
| this.defaultValue = defaultValue; |
| this.context = null; |
| } |
| |
| // For user code to override, must never be called from jdk.jfr.internal |
| // for user defined settings |
| public abstract String combine(Set<String> values); |
| |
| // For user code to override, must never be called from jdk.jfr.internal |
| // for user defined settings |
| public abstract void setValue(String value); |
| |
| // For user code to override, must never be called from jdk.jfr.internal |
| // for user defined settings |
| public abstract String getValue(); |
| |
| // Package private, user code should not have access to this method |
| final void apply(Set<String> values) { |
| setValueSafe(findCombineSafe(values)); |
| } |
| |
| // Package private, user code should not have access to this method. |
| // Only called during event registration |
| final void setDefault() { |
| if (defaultValue == null) { |
| defaultValue = getValueSafe(); |
| } |
| apply(defaultValue); |
| } |
| |
| final String getValueSafe() { |
| if (context == null) { |
| // VM events requires no access control context |
| return getValue(); |
| } else { |
| return AccessController.doPrivileged(new PrivilegedAction<String>() { |
| @Override |
| public String run() { |
| try { |
| return getValue(); |
| } catch (Throwable t) { |
| // Prevent malicious user to propagate exception callback in the wrong context |
| Logger.log(LogTag.JFR_SETTING, LogLevel.WARN, "Exception occured when trying to get value for " + getClass()); |
| } |
| return defaultValue != null ? defaultValue : ""; // Need to return something |
| } |
| }, context); |
| } |
| } |
| |
| private void apply(String value) { |
| if (lastValue != null && Objects.equals(value, lastValue)) { |
| return; |
| } |
| setValueSafe(value); |
| } |
| |
| final void setValueSafe(String value) { |
| if (context == null) { |
| // VM events requires no access control context |
| try { |
| setValue(value); |
| } catch (Throwable t) { |
| Logger.log(LogTag.JFR_SETTING, LogLevel.WARN, "Exception occured when setting value \"" + value + "\" for " + getClass()); |
| } |
| } else { |
| AccessController.doPrivileged(new PrivilegedAction<Void>() { |
| @Override |
| public Void run() { |
| try { |
| setValue(value); |
| } catch (Throwable t) { |
| // Prevent malicious user to propagate exception callback in the wrong context |
| Logger.log(LogTag.JFR_SETTING, LogLevel.WARN, "Exception occured when setting value \"" + value + "\" for " + getClass()); |
| } |
| return null; |
| } |
| }, context); |
| } |
| lastValue = value; |
| } |
| |
| |
| private String combineSafe(Set<String> values) { |
| if (context == null) { |
| // VM events requires no access control context |
| return combine(values); |
| } |
| return AccessController.doPrivileged(new PrivilegedAction<String>() { |
| @Override |
| public String run() { |
| try { |
| combine(Collections.unmodifiableSet(values)); |
| } catch (Throwable t) { |
| // Prevent malicious user to propagate exception callback in the wrong context |
| Logger.log(LogTag.JFR_SETTING, LogLevel.WARN, "Exception occured when combining " + values + " for " + getClass()); |
| } |
| return null; |
| } |
| }, context); |
| } |
| |
| private final String findCombineSafe(Set<String> values) { |
| if (values.size() == 1) { |
| return values.iterator().next(); |
| } |
| for (int i = 0; i < CACHE_SIZE; i++) { |
| if (Objects.equals(cachedUnions[i], values)) { |
| return cachedValues[i]; |
| } |
| } |
| String result = combineSafe(values); |
| for (int i = 0; i < CACHE_SIZE - 1; i++) { |
| cachedUnions[i + 1] = cachedUnions[i]; |
| cachedValues[i + 1] = cachedValues[i]; |
| } |
| cachedValues[0] = result; |
| cachedUnions[0] = values; |
| return result; |
| } |
| |
| |
| // package private, user code should not have access to this method |
| final String getDefaultValue() { |
| return defaultValue; |
| } |
| |
| // package private, user code should not have access to this method |
| final String getLastValue() { |
| return lastValue; |
| } |
| |
| // Precaution to prevent a malicious user from instantiating instances |
| // of a control where the context has not been set up. |
| @Override |
| public final Object clone() throws java.lang.CloneNotSupportedException { |
| throw new CloneNotSupportedException(); |
| } |
| |
| private final void writeObject(ObjectOutputStream out) throws IOException { |
| throw new IOException("Object cannot be serialized"); |
| } |
| |
| private final void readObject(ObjectInputStream in) throws IOException { |
| throw new IOException("Class cannot be deserialized"); |
| } |
| } |