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Apache Commons Daemon software provides an alternative invocation mechanism for unix-daemon-like Java code.
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.daemon;
import java.security.Permission;
import java.util.StringTokenizer;
/**
* Represents the permissions to control and query the status of
* a Daemon. A DaemonPermission consists of a
* target name and a list of actions associated with it.
*
* In this specification version the only available target name for this
* permission is "control", but further releases may add more target
* names to fine-tune the access that needs to be granted to the caller.
*
*
* Actions are defined by a string of comma-separated values, as shown in the
* table below. The empty string implies no permission at all, while the
* special "*" value implies all permissions for the given
* name:
*
*
*
*
* Target"Name
* Action
* Description
*
*
* "control"
* "start"
*
* The permission to call the start() method in an instance
* of a DaemonController interface.
*
*
*
* "stop"
*
* The permission to call the stop() method in an instance
* of a DaemonController interface.
*
*
*
* "shutdown"
*
* The permission to call the shutdown() method in an instance
* of a DaemonController interface.
*
*
*
* "reload"
*
* The permission to call the reload() method in an instance
* of a DaemonController interface.
*
*
*
* "*"
*
* The special wildcard action implies all above-mentioned action. This is
* equal to construct a permission with the "start, stop, shutdown,
* reload" list of actions.
*
*
*
*
*
* @author Pier Fumagalli
* @version $Id: DaemonPermission.java 1204010 2011-11-19 16:15:23Z ggregory $
*/
public final class DaemonPermission extends Permission
{
/* ====================================================================
* Constants.
*/
/**
* The target name when associated with control actions
* ("control").
*/
protected static final String CONTROL = "control";
/**
* The target type when associated with control actions.
*/
protected static final int TYPE_CONTROL = 1;
/**
* The action name associated with the permission to call the
* DaemonController.start() method.
*/
protected static final String CONTROL_START = "start";
/**
* The action name associated with the permission to call the
* DaemonController.stop() method.
*/
protected static final String CONTROL_STOP = "stop";
/**
* The action name associated with the permission to call the
* DaemonController.shutdown() method.
*/
protected static final String CONTROL_SHUTDOWN = "shutdown";
/**
* The action name associated with the permission to call the
* DaemonController.reload() method.
*/
protected static final String CONTROL_RELOAD = "reload";
/**
* The action mask associated with the permission to call the
* DaemonController.start() method.
*/
protected static final int MASK_CONTROL_START = 0x01;
/**
* The action mask associated with the permission to call the
* DaemonController.stop() method.
*/
protected static final int MASK_CONTROL_STOP = 0x02;
/**
* The action mask associated with the permission to call the
* DaemonController.shutdown() method.
*/
protected static final int MASK_CONTROL_SHUTDOWN = 0x04;
/**
* The action mask associated with the permission to call the
* DaemonController.reload() method.
*/
protected static final int MASK_CONTROL_RELOAD = 0x08;
/**
* The "wildcard" action implying all actions for the given
* target name.
*/
protected static final String WILDCARD = "*";
/* ====================================================================
* Instance variables
*/
/** The type of this permission object. */
private transient int type = 0;
/** The permission mask associated with this permission object. */
private transient int mask = 0;
/** The String representation of this permission object. */
private transient String desc = null;
/* ====================================================================
* Constructors
*/
/**
* Creates a new DaemonPermission instance with a specified
* permission name.
*
* This constructor will create a new DaemonPermission
* instance that will not grant any permission to the caller.
*
* @param target The target name of this permission.
* @exception IllegalArgumentException If the specified target name is not
* supported.
*/
public DaemonPermission(String target)
throws IllegalArgumentException
{
// Setup the target name of this permission object.
super(target);
// Check if the permission target name was specified
if (target == null)
throw new IllegalArgumentException("Null permission name");
// Check if this is a "control" permission and set up accordingly.
if (CONTROL.equalsIgnoreCase(target)) {
type = TYPE_CONTROL;
return;
}
// If we got here, we have an invalid permission name.
throw new IllegalArgumentException("Invalid permission name \"" +
target + "\" specified");
}
/**
* Creates a new DaemonPermission instance with a specified
* permission name and a specified list of actions.
*
*
*
* @param target The target name of this permission.
* @param actions The list of actions permitted by this permission.
* @exception IllegalArgumentException If the specified target name is not
* supported, or the specified list of actions includes an
* invalid value.
*/
public DaemonPermission(String target, String actions)
throws IllegalArgumentException
{
// Setup this instance's target name.
this(target);
// Create the appropriate mask if this is a control permission.
if (this.type == TYPE_CONTROL) {
this.mask = this.createControlMask(actions);
return;
}
}
/* ====================================================================
* Public methods
*/
/**
* Returns the list of actions permitted by this instance of
* DaemonPermission in its canonical form.
*
* @return The canonicalized list of actions.
*/
public String getActions()
{
if (this.type == TYPE_CONTROL) {
return this.createControlActions(this.mask);
}
return "";
}
/**
* Returns the hash code for this DaemonPermission instance.
*
* @return An hash code value.
*/
public int hashCode()
{
this.setupDescription();
return this.desc.hashCode();
}
/**
* Checks if a specified object equals DaemonPermission.
*
* @return true or false wether the specified object equals
* this DaemonPermission instance or not.
*/
public boolean equals(Object object)
{
if (object == this)
return true;
if (!(object instanceof DaemonPermission))
return false;
DaemonPermission that = (DaemonPermission) object;
if (this.type != that.type)
return false;
return this.mask == that.mask;
}
/**
* Checks if this DaemonPermission implies another
* Permission.
*
* @return true or false wether the specified permission
* is implied by this DaemonPermission instance or
* not.
*/
public boolean implies(Permission permission)
{
if (permission == this)
return true;
if (!(permission instanceof DaemonPermission))
return false;
DaemonPermission that = (DaemonPermission) permission;
if (this.type != that.type)
return false;
return (this.mask & that.mask) == that.mask;
}
/**
* Returns a String representation of this instance.
*
* @return A String representing this
* DaemonPermission instance.
*/
public String toString()
{
this.setupDescription();
return this.desc;
}
/* ====================================================================
* Private methods
*/
/**
* Creates a String description for this permission instance.
*/
private void setupDescription()
{
if (this.desc != null)
return;
StringBuffer buf = new StringBuffer();
buf.append(this.getClass().getName());
buf.append('[');
switch (this.type) {
case TYPE_CONTROL:
buf.append(CONTROL);
break;
default:
buf.append("UNKNOWN");
break;
}
buf.append(':');
buf.append(this.getActions());
buf.append(']');
this.desc = buf.toString();
}
/**
* Creates a permission mask for a given control actions string.
*/
private int createControlMask(String actions)
throws IllegalArgumentException
{
if (actions == null)
return 0;
int mask = 0;
StringTokenizer tok = new StringTokenizer(actions, ",", false);
while (tok.hasMoreTokens()) {
String val = tok.nextToken().trim();
if (WILDCARD.equals(val)) {
return MASK_CONTROL_START | MASK_CONTROL_STOP |
MASK_CONTROL_SHUTDOWN | MASK_CONTROL_RELOAD;
}
else if (CONTROL_START.equalsIgnoreCase(val)) {
mask = mask | MASK_CONTROL_START;
}
else if (CONTROL_STOP.equalsIgnoreCase(val)) {
mask = mask | MASK_CONTROL_STOP;
}
else if (CONTROL_SHUTDOWN.equalsIgnoreCase(val)) {
mask = mask | MASK_CONTROL_SHUTDOWN;
}
else if (CONTROL_RELOAD.equalsIgnoreCase(val)) {
mask = mask | MASK_CONTROL_RELOAD;
}
else {
throw new IllegalArgumentException("Invalid action name \"" +
val + "\" specified");
}
}
return mask;
}
/** Creates a actions list for a given control permission mask. */
private String createControlActions(int mask)
{
StringBuffer buf = new StringBuffer();
boolean sep = false;
if ((mask & MASK_CONTROL_START) == MASK_CONTROL_START) {
sep = true;
buf.append(CONTROL_START);
}
if ((mask & MASK_CONTROL_STOP) == MASK_CONTROL_STOP) {
if (sep)
buf.append(",");
else
sep = true;
buf.append(CONTROL_STOP);
}
if ((mask & MASK_CONTROL_SHUTDOWN) == MASK_CONTROL_SHUTDOWN) {
if (sep)
buf.append(",");
else
sep = true;
buf.append(CONTROL_SHUTDOWN);
}
if ((mask & MASK_CONTROL_RELOAD) == MASK_CONTROL_RELOAD) {
if (sep)
buf.append(",");
else
sep = true;
buf.append(CONTROL_RELOAD);
}
return buf.toString();
}
}