--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/Control.java Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,209 @@
+/*
+ * 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");
+ }
+}