ConcurrentResource.java
/*
** Module : ConcurrentResourceResource.java
** Abstract : plugin to manage access to concurrent resources
**
** Copyright (c) 2020-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- ----------------------------Description-----------------------------------
** 001 GES 20200130 Created the first version.
** 002 HC 20230427 Added support for file system rights.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program 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 Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
** You must preserve all legal notices or author attributions in the covered
** work or Appropriate Legal Notices displayed by works containing the covered
** work. You may not remove from the covered work any author or developer
** credit already included within the covered work.
**
** 1. No License To Use Trademarks.
**
** This license does not grant any license or rights to use the trademarks
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** name Golden Code, FWD, or the names of any author or contributor, for
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** versions of the covered work must be marked in a reasonable way to make it
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** attribution required in this license.
*/
package com.goldencode.p2j.concurrent;
import com.goldencode.p2j.security.*;
import com.goldencode.p2j.directory.*;
import com.goldencode.util.*;
import java.util.*;
/**
* Implements the "ConcurrentResource" resource. Access to such resources have rights which can
* be represented by a small set of flags:
* <ul>
* <li> create - a runtime instance of the resource can be created
* <li> delete - an existing runtime instance can be destroyed
* <li> read - the state or data associated with an existing runtime instance can be accessed
* <li> write - the state or data associated with an existing runtime instance can be modified
* <li> denied - no access is allowed (overrides any other access flags)
* </ul>
* <p>
* Rights objects for this resource are made of one bitfield with 8 bits. The first four bits
* correspond to the create, delete, read and write respectively. There are 3 reserved bits.
* The last bit is for explicit denial of access. When printed, they are shown as
* {@code CDRW...N}.
* <p>
* Resource names will be namespaced using the subclass' resource type name. The naming approach
* is {@code /resource_type_name/instance_name}. Each different instance of a particular
* resource type will share the same type name but must have a unique, non-empty instance name.
*/
public class ConcurrentResource
extends BitFlagsResource
{
/** All valid resource names. */
private static Set<String> names = new HashSet<String>();
static
{
names.add("event_semaphore");
}
/**
* Default constructor.
*/
public ConcurrentResource()
{
}
/**
* Obtains the set of all possible valid resource type names.
*
* @return The set of valid resource type names.
*/
public Set<String> resourceTypeName()
{
return Collections.unmodifiableSet(names);
}
/**
* Returns the plugin resource type name as a string.
*
* @return The plugin resource type name.
*/
public String getTypeName()
{
return "ConcurrentResource";
}
/**
* Instantiates a plugin's class that implements the <code>Rights</code> interface, using
* the array of objects representing a set of access rights fields.
*
* @param rights
* The objects needed to create an access rights instance.
*
* @return The newly created rights instance.
*/
public Rights getRightsInstance(Object[] rights)
{
return new ConcurrentRights(BitSetHelper.fromBitField((BitField)rights[0]));
}
/**
* Checks whether a given string is a valid resource name for this resource type.
* <p>
* Valid names are of the form {@code /resource_type_name/instance_name} where instance_name
* is a non-empty string which has no whitespace and which uniquely identifies a given
* resource instance and where resource_type_name is shared across all resources of the same
* type. Resource names are NOT case sensitive.
*
* @param resource
* The possible name to validate.
*
* @return <code>true</code> if the name is syntactically correct
*/
public boolean isInstanceNameValid(String resource)
{
if (resource == null || resource.length() == 0)
return false;
Set<String> names = resourceTypeName();
if (resource.charAt(0) != '/')
return false;
int resEnd = resource.indexOf('/', 1);
int insBegin = resEnd + 1;
// no ending slash OR an empty resource name OR an empty instance name
if (resEnd == -1 || resEnd == 1 || insBegin == resource.length())
return false;
String resName = resource.substring(1, resEnd).toLowerCase();
if (!names.contains(resName))
return false;
String iname = resource.substring(insBegin);
if (StringHelper.containsWhitespace(iname))
return false;
return true;
}
}