org.osgi.service.event.TopicPermission Maven / Gradle / Ivy
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/*
* Copyright (c) OSGi Alliance (2005, 2009). All Rights Reserved.
*
* 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 org.osgi.service.event;
import java.io.IOException;
import java.security.Permission;
import java.security.PermissionCollection;
import java.util.Enumeration;
import java.util.Hashtable;
/**
* A bundle's authority to publish or subscribe to event on a topic.
*
*
* A topic is a slash-separated string that defines a topic.
*
* For example:
*
*
* org / osgi / service / foo / FooEvent / ACTION
*
*
*
* TopicPermission has two actions: publish and
* subscribe.
*
* @ThreadSafe
* @version $Revision: 6381 $
*/
public final class TopicPermission extends Permission {
static final long serialVersionUID = -5855563886961618300L;
/**
* The action string publish.
*/
public final static String PUBLISH = "publish";
/**
* The action string subscribe.
*/
public final static String SUBSCRIBE = "subscribe";
private final static int ACTION_PUBLISH = 0x00000001;
private final static int ACTION_SUBSCRIBE = 0x00000002;
private final static int ACTION_ALL = ACTION_PUBLISH
| ACTION_SUBSCRIBE;
private final static int ACTION_NONE = 0;
/**
* The actions mask.
*/
private transient int action_mask;
/**
* prefix if the name is wildcarded.
*/
private transient volatile String prefix;
/**
* The actions in canonical form.
*
* @serial
*/
private volatile String actions = null;
/**
* Defines the authority to publich and/or subscribe to a topic within the
* EventAdmin service.
*
* The name is specified as a slash-separated string. Wildcards may be used.
* For example:
*
*
* org/osgi/service/fooFooEvent/ACTION
* com/isv/*
* *
*
*
*
* A bundle that needs to publish events on a topic must have the
* appropriate TopicPermission for that topic; similarly, a
* bundle that needs to subscribe to events on a topic must have the
* appropriate TopicPermssion for that topic.
*
*
* @param name Topic name.
* @param actions publish,subscribe (canonical
* order).
*/
public TopicPermission(String name, String actions) {
this(name, parseActions(actions));
}
/**
* Package private constructor used by TopicPermissionCollection.
*
* @param name class name
* @param mask action mask
*/
TopicPermission(String name, int mask) {
super(name);
setTransients(mask);
}
/**
* Called by constructors and when deserialized.
*
* @param name topic name
* @param mask action mask
*/
private synchronized void setTransients(final int mask) {
final String name = getName();
if ((name == null) || name.length() == 0) {
throw new IllegalArgumentException("invalid name");
}
if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
throw new IllegalArgumentException("invalid action string");
}
action_mask = mask;
if (name.equals("*")) {
prefix = "";
}
else {
if (name.endsWith("/*")) {
prefix = name.substring(0, name.length() - 1);
}
else {
prefix = null;
}
}
}
/**
* Returns the current action mask.
*
* Used by the TopicPermissionCollection class.
*
* @return Current action mask.
*/
synchronized int getActionsMask() {
return action_mask;
}
/**
* Parse action string into action mask.
*
* @param actions Action string.
* @return action mask.
*/
private static int parseActions(final String actions) {
boolean seencomma = false;
int mask = ACTION_NONE;
if (actions == null) {
return mask;
}
char[] a = actions.toCharArray();
int i = a.length - 1;
if (i < 0)
return mask;
while (i != -1) {
char c;
// skip whitespace
while ((i != -1)
&& ((c = a[i]) == ' ' || c == '\r' || c == '\n'
|| c == '\f' || c == '\t'))
i--;
// check for the known strings
int matchlen;
if (i >= 8 && (a[i - 8] == 's' || a[i - 8] == 'S')
&& (a[i - 7] == 'u' || a[i - 7] == 'U')
&& (a[i - 6] == 'b' || a[i - 6] == 'B')
&& (a[i - 5] == 's' || a[i - 5] == 'S')
&& (a[i - 4] == 'c' || a[i - 4] == 'C')
&& (a[i - 3] == 'r' || a[i - 3] == 'R')
&& (a[i - 2] == 'i' || a[i - 2] == 'I')
&& (a[i - 1] == 'b' || a[i - 1] == 'B')
&& (a[i] == 'e' || a[i] == 'E')) {
matchlen = 9;
mask |= ACTION_SUBSCRIBE;
}
else
if (i >= 6 && (a[i - 6] == 'p' || a[i - 6] == 'P')
&& (a[i - 5] == 'u' || a[i - 5] == 'U')
&& (a[i - 4] == 'b' || a[i - 4] == 'B')
&& (a[i - 3] == 'l' || a[i - 3] == 'L')
&& (a[i - 2] == 'i' || a[i - 2] == 'I')
&& (a[i - 1] == 's' || a[i - 1] == 'S')
&& (a[i] == 'h' || a[i] == 'H')) {
matchlen = 7;
mask |= ACTION_PUBLISH;
}
else {
// parse error
throw new IllegalArgumentException("invalid permission: "
+ actions);
}
// make sure we didn't just match the tail of a word
// like "ackbarfpublish". Also, skip to the comma.
seencomma = false;
while (i >= matchlen && !seencomma) {
switch (a[i - matchlen]) {
case ',' :
seencomma = true;
/* FALLTHROUGH */
case ' ' :
case '\r' :
case '\n' :
case '\f' :
case '\t' :
break;
default :
throw new IllegalArgumentException(
"invalid permission: " + actions);
}
i--;
}
// point i at the location of the comma minus one (or -1).
i -= matchlen;
}
if (seencomma) {
throw new IllegalArgumentException("invalid permission: " + actions);
}
return mask;
}
/**
* Determines if the specified permission is implied by this object.
*
*
* This method checks that the topic name of the target is implied by the
* topic name of this object. The list of TopicPermission
* actions must either match or allow for the list of the target object to
* imply the target TopicPermission action.
*
*
* x/y/*,"publish" -> x/y/z,"publish" is true
* *,"subscribe" -> x/y,"subscribe" is true
* *,"publish" -> x/y,"subscribe" is false
* x/y,"publish" -> x/y/z,"publish" is false
*
*
* @param p The target permission to interrogate.
* @return true if the specified TopicPermission
* action is implied by this object; false otherwise.
*/
public boolean implies(Permission p) {
if (p instanceof TopicPermission) {
TopicPermission requested = (TopicPermission) p;
int requestedMask = requested.getActionsMask();
if ((getActionsMask() & requestedMask) == requestedMask) {
String requestedName = requested.getName();
String pre = prefix;
if (pre != null) {
return requestedName.startsWith(pre);
}
return requestedName.equals(getName());
}
}
return false;
}
/**
* Returns the canonical string representation of the
* TopicPermission actions.
*
*
* Always returns present TopicPermission actions in the
* following order: publish,subscribe.
*
* @return Canonical string representation of the
* TopicPermission actions.
*/
public String getActions() {
String result = actions;
if (result == null) {
StringBuffer sb = new StringBuffer();
boolean comma = false;
int mask = getActionsMask();
if ((mask & ACTION_PUBLISH) == ACTION_PUBLISH) {
sb.append(PUBLISH);
comma = true;
}
if ((mask & ACTION_SUBSCRIBE) == ACTION_SUBSCRIBE) {
if (comma)
sb.append(',');
sb.append(SUBSCRIBE);
}
actions = result = sb.toString();
}
return result;
}
/**
* Returns a new PermissionCollection object suitable for
* storing TopicPermission objects.
*
* @return A new PermissionCollection object.
*/
public PermissionCollection newPermissionCollection() {
return new TopicPermissionCollection();
}
/**
* Determines the equality of two TopicPermission objects.
*
* This method checks that specified TopicPermission has the
* same topic name and actions as this TopicPermission object.
*
* @param obj The object to test for equality with this
* TopicPermission object.
* @return true if obj is a
* TopicPermission, and has the same topic name and
* actions as this TopicPermission object;
* false otherwise.
*/
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof TopicPermission)) {
return false;
}
TopicPermission tp = (TopicPermission) obj;
return (getActionsMask() == tp.getActionsMask())
&& getName().equals(tp.getName());
}
/**
* Returns the hash code value for this object.
*
* @return A hash code value for this object.
*/
public int hashCode() {
int h = 31 * 17 + getName().hashCode();
h = 31 * h + getActions().hashCode();
return h;
}
/**
* WriteObject is called to save the state of this permission object to a
* stream. The actions are serialized, and the superclass takes care of the
* name.
*/
private synchronized void writeObject(java.io.ObjectOutputStream s)
throws IOException {
// Write out the actions. The superclass takes care of the name
// call getActions to make sure actions field is initialized
if (actions == null)
getActions();
s.defaultWriteObject();
}
/**
* readObject is called to restore the state of this permission from a
* stream.
*/
private synchronized void readObject(java.io.ObjectInputStream s)
throws IOException, ClassNotFoundException {
// Read in the action, then initialize the rest
s.defaultReadObject();
setTransients(parseActions(actions));
}
}
/**
* Stores a set of TopicPermission permissions.
*
* @see java.security.Permission
* @see java.security.Permissions
* @see java.security.PermissionCollection
*/
final class TopicPermissionCollection extends PermissionCollection {
static final long serialVersionUID = -614647783533924048L;
/**
* Table of permissions.
*
* @serial
* @GuardedBy this
*/
private final Hashtable permissions;
/**
* Boolean saying if "*" is in the collection.
*
* @serial
* @GuardedBy this
*/
private boolean all_allowed;
/**
* Create an empty TopicPermissions object.
*
*/
public TopicPermissionCollection() {
permissions = new Hashtable();
all_allowed = false;
}
/**
* Adds a permission to the TopicPermission objects. The key
* for the hash is the name.
*
* @param permission The TopicPermission object to add.
*
* @throws IllegalArgumentException If the permission is not a
* TopicPermission instance.
*
* @throws SecurityException If this TopicPermissionCollection
* object has been marked read-only.
*/
public void add(final Permission permission) {
if (!(permission instanceof TopicPermission)) {
throw new IllegalArgumentException("invalid permission: "
+ permission);
}
if (isReadOnly()) {
throw new SecurityException("attempt to add a Permission to a "
+ "readonly PermissionCollection");
}
final TopicPermission tp = (TopicPermission) permission;
final String name = tp.getName();
final int newMask = tp.getActionsMask();
synchronized (this) {
final TopicPermission existing = (TopicPermission) permissions
.get(name);
if (existing != null) {
final int oldMask = existing.getActionsMask();
if (oldMask != newMask) {
permissions.put(name, new TopicPermission(name, oldMask
| newMask));
}
}
else {
permissions.put(name, tp);
}
if (!all_allowed) {
if (name.equals("*"))
all_allowed = true;
}
}
}
/**
* Determines if the specified permissions implies the permissions expressed
* in permission.
*
* @param permission The Permission object to compare with this
* TopicPermission object.
*
* @return true if permission is a proper subset
* of a permission in the set; false otherwise.
*/
public boolean implies(final Permission permission) {
if (!(permission instanceof TopicPermission)) {
return false;
}
final TopicPermission requested = (TopicPermission) permission;
String name = requested.getName();
final int desired = requested.getActionsMask();
int effective = 0;
TopicPermission x;
// short circuit if the "*" Permission was added
synchronized (this) {
if (all_allowed) {
x = (TopicPermission) permissions.get("*");
if (x != null) {
effective |= x.getActionsMask();
if ((effective & desired) == desired) {
return true;
}
}
}
x = (TopicPermission) permissions.get(name);
}
// strategy:
// Check for full match first. Then work our way up the
// name looking for matches on a/b/*
if (x != null) {
// we have a direct hit!
effective |= x.getActionsMask();
if ((effective & desired) == desired) {
return true;
}
}
// work our way up the tree...
int last;
int offset = name.length() - 1;
while ((last = name.lastIndexOf("/", offset)) != -1) {
name = name.substring(0, last + 1) + "*";
synchronized (this) {
x = (TopicPermission) permissions.get(name);
}
if (x != null) {
effective |= x.getActionsMask();
if ((effective & desired) == desired) {
return true;
}
}
offset = last - 1;
}
// we don't have to check for "*" as it was already checked
// at the top (all_allowed), so we just return false
return false;
}
/**
* Returns an enumeration of all TopicPermission objects in the
* container.
*
* @return Enumeration of all TopicPermission objects.
*/
public Enumeration elements() {
return permissions.elements();
}
}