/*

 * 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 java.security;

import java.util.Enumeration;

import java.util.Hashtable;

import java.util.NoSuchElementException;

import java.util.Map;

import java.util.HashMap;

import java.util.List;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.Collections;

import java.io.Serializable;

import java.io.ObjectStreamField;

import java.io.ObjectOutputStream;

import java.io.ObjectInputStream;

import java.io.IOException;

/**

 * This class represents a heterogeneous collection of Permissions. That is,

 * it contains different types of Permission objects, organized into

 * PermissionCollections. For example, if any

 * <code>java.io.FilePermission</code> objects are added to an instance of

 * this class, they are all stored in a single

 * PermissionCollection. It is the PermissionCollection returned by a call to

 * the <code>newPermissionCollection</code> method in the FilePermission class.

 * Similarly, any <code>java.lang.RuntimePermission</code> objects are

 * stored in the PermissionCollection returned by a call to the

 * <code>newPermissionCollection</code> method in the

 * RuntimePermission class. Thus, this class represents a collection of

 * PermissionCollections.

 *

 * <p>When the <code>add</code> method is called to add a Permission, the

 * Permission is stored in the appropriate PermissionCollection. If no such

 * collection exists yet, the Permission object's class is determined and the

 * <code>newPermissionCollection</code> method is called on that class to create

 * the PermissionCollection and add it to the Permissions object. If

 * <code>newPermissionCollection</code> returns null, then a default

 * PermissionCollection that uses a hashtable will be created and used. Each

 * hashtable entry stores a Permission object as both the key and the value.

 *

 * <p> Enumerations returned via the <code>elements</code> method are

 * not <em>fail-fast</em>.  Modifications to a collection should not be

 * performed while enumerating over that collection.

 *

 * @see Permission

 * @see PermissionCollection

 * @see AllPermission

 *

 *

 * @author Marianne Mueller

 * @author Roland Schemers

 *

 * @serial exclude

 */

public final class Permissions extends PermissionCollection

implements Serializable

{

    /**

     * Key is permissions Class, value is PermissionCollection for that class.

     * Not serialized; see serialization section at end of class.

     */

    private transient Map<Class<?>, PermissionCollection> permsMap;

    // optimization. keep track of whether unresolved permissions need to be

    // checked

    private transient boolean hasUnresolved = false;

    // optimization. keep track of the AllPermission collection

    // - package private for ProtectionDomain optimization

    PermissionCollection allPermission;

    /**

     * Creates a new Permissions object containing no PermissionCollections.

     */

    public Permissions() {

        permsMap = new HashMap<Class<?>, PermissionCollection>(11);

        allPermission = null;

    }

    /**

     * Adds a permission object to the PermissionCollection for the class the

     * permission belongs to. For example, if <i>permission</i> is a

     * FilePermission, it is added to the FilePermissionCollection stored

     * in this Permissions object.

     *

     * This method creates

     * a new PermissionCollection object (and adds the permission to it)

     * if an appropriate collection does not yet exist. <p>

     *

     * @param permission the Permission object to add.

     *

     * @exception SecurityException if this Permissions object is

     * marked as readonly.

     *

     * @see PermissionCollection#isReadOnly()

     */

    public void add(Permission permission) {

        if (isReadOnly())

            throw new SecurityException(

              "attempt to add a Permission to a readonly Permissions object");

        PermissionCollection pc;

        synchronized (this) {

            pc = getPermissionCollection(permission, true);

            pc.add(permission);

        }

        // No sync; staleness -> optimizations delayed, which is OK

        if (permission instanceof AllPermission) {

            allPermission = pc;

        }

        if (permission instanceof UnresolvedPermission) {

            hasUnresolved = true;

        }

    }

    /**

     * Checks to see if this object's PermissionCollection for permissions of

     * the specified permission's class implies the permissions

     * expressed in the <i>permission</i> object. Returns true if the

     * combination of permissions in the appropriate PermissionCollection

     * (e.g., a FilePermissionCollection for a FilePermission) together

     * imply the specified permission.

     *

     * <p>For example, suppose there is a FilePermissionCollection in this

     * Permissions object, and it contains one FilePermission that specifies

     * "read" access for  all files in all subdirectories of the "/tmp"

     * directory, and another FilePermission that specifies "write" access

     * for all files in the "/tmp/scratch/foo" directory.

     * Then if the <code>implies</code> method

     * is called with a permission specifying both "read" and "write" access

     * to files in the "/tmp/scratch/foo" directory, <code>true</code> is

     * returned.

     *

     * <p>Additionally, if this PermissionCollection contains the

     * AllPermission, this method will always return true.

     * <p>

     * @param permission the Permission object to check.

     *

     * @return true if "permission" is implied by the permissions in the

     * PermissionCollection it

     * belongs to, false if not.

     */

    public boolean implies(Permission permission) {

        // No sync; staleness -> skip optimization, which is OK

        if (allPermission != null) {

            return true; // AllPermission has already been added

        } else {

            synchronized (this) {

                PermissionCollection pc = getPermissionCollection(permission,

                    false);

                if (pc != null) {

                    return pc.implies(permission);

                } else {

                    // none found

                    return false;

                }

            }

        }

    }

    /**

     * Returns an enumeration of all the Permission objects in all the

     * PermissionCollections in this Permissions object.

     *

     * @return an enumeration of all the Permissions.

     */

    public Enumeration<Permission> elements() {

        // go through each Permissions in the hash table

        // and call their elements() function.

        synchronized (this) {

            return new PermissionsEnumerator(permsMap.values().iterator());

        }

    }

    /**

     * Gets the PermissionCollection in this Permissions object for

     * permissions whose type is the same as that of <i>p</i>.

     * For example, if <i>p</i> is a FilePermission,

     * the FilePermissionCollection

     * stored in this Permissions object will be returned.

     *

     * If createEmpty is true,

     * this method creates a new PermissionCollection object for the specified

     * type of permission objects if one does not yet exist.

     * To do so, it first calls the <code>newPermissionCollection</code> method

     * on <i>p</i>.  Subclasses of class Permission

     * override that method if they need to store their permissions in a

     * particular PermissionCollection object in order to provide the

     * correct semantics when the <code>PermissionCollection.implies</code>

     * method is called.

     * If the call returns a PermissionCollection, that collection is stored

     * in this Permissions object. If the call returns null and createEmpty

     * is true, then

     * this method instantiates and stores a default PermissionCollection

     * that uses a hashtable to store its permission objects.

     *

     * createEmpty is ignored when creating empty PermissionCollection

     * for unresolved permissions because of the overhead of determining the

     * PermissionCollection to use.

     *

     * createEmpty should be set to false when this method is invoked from

     * implies() because it incurs the additional overhead of creating and

     * adding an empty PermissionCollection that will just return false.

     * It should be set to true when invoked from add().

     */

    private PermissionCollection getPermissionCollection(Permission p,

        boolean createEmpty) {

        Class c = p.getClass();

        PermissionCollection pc = permsMap.get(c);

        if (!hasUnresolved && !createEmpty) {

            return pc;

        } else if (pc == null) {

            // Check for unresolved permissions

            pc = (hasUnresolved ? getUnresolvedPermissions(p) : null);

            // if still null, create a new collection

            if (pc == null && createEmpty) {

                pc = p.newPermissionCollection();

                // still no PermissionCollection?

                // We'll give them a PermissionsHash.

                if (pc == null)

                    pc = new PermissionsHash();

            }

            if (pc != null) {

                permsMap.put(c, pc);

            }

        }

        return pc;

    }

    /**

     * Resolves any unresolved permissions of type p.

     *

     * @param p the type of unresolved permission to resolve

     *

     * @return PermissionCollection containing the unresolved permissions,

     *  or null if there were no unresolved permissions of type p.

     *

     */

    private PermissionCollection getUnresolvedPermissions(Permission p)

    {

        // Called from within synchronized method so permsMap doesn't need lock

        UnresolvedPermissionCollection uc =

        (UnresolvedPermissionCollection) permsMap.get(UnresolvedPermission.class);

        // we have no unresolved permissions if uc is null

        if (uc == null)

            return null;

        List<UnresolvedPermission> unresolvedPerms =

                                        uc.getUnresolvedPermissions(p);

        // we have no unresolved permissions of this type if unresolvedPerms is null

        if (unresolvedPerms == null)

            return null;

        java.security.cert.Certificate certs[] = null;

        Object signers[] = p.getClass().getSigners();

        int n = 0;

        if (signers != null) {

            for (int j=0; j < signers.length; j++) {

                if (signers[j] instanceof java.security.cert.Certificate) {

                    n++;

                }

            }

            certs = new java.security.cert.Certificate[n];

            n = 0;

            for (int j=0; j < signers.length; j++) {

                if (signers[j] instanceof java.security.cert.Certificate) {

                    certs[n++] = (java.security.cert.Certificate)signers[j];

                }

            }

        }

        PermissionCollection pc = null;

        synchronized (unresolvedPerms) {

            int len = unresolvedPerms.size();

            for (int i = 0; i < len; i++) {

                UnresolvedPermission up = unresolvedPerms.get(i);

                Permission perm = up.resolve(p, certs);

                if (perm != null) {

                    if (pc == null) {

                        pc = p.newPermissionCollection();

                        if (pc == null)

                            pc = new PermissionsHash();

                    }

                    pc.add(perm);

                }

            }

        }

        return pc;

    }

    private static final long serialVersionUID = 4858622370623524688L;

    // Need to maintain serialization interoperability with earlier releases,

    // which had the serializable field:

    // private Hashtable perms;

    /**

     * @serialField perms java.util.Hashtable

     *     A table of the Permission classes and PermissionCollections.

     * @serialField allPermission java.security.PermissionCollection

     */

    private static final ObjectStreamField[] serialPersistentFields = {

        new ObjectStreamField("perms", Hashtable.class),

        new ObjectStreamField("allPermission", PermissionCollection.class),

    };

    /**

     * @serialData Default fields.

     */

    /*

     * Writes the contents of the permsMap field out as a Hashtable for

     * serialization compatibility with earlier releases. allPermission

     * unchanged.

     */

    private void writeObject(ObjectOutputStream out) throws IOException {

        // Don't call out.defaultWriteObject()

        // Copy perms into a Hashtable

        Hashtable<Class<?>, PermissionCollection> perms =

            new Hashtable<>(permsMap.size()*2); // no sync; estimate

        synchronized (this) {

            perms.putAll(permsMap);

        }

        // Write out serializable fields

        ObjectOutputStream.PutField pfields = out.putFields();

        pfields.put("allPermission", allPermission); // no sync; staleness OK

        pfields.put("perms", perms);

        out.writeFields();

    }

    /*

     * Reads in a Hashtable of Class/PermissionCollections and saves them in the

     * permsMap field. Reads in allPermission.

     */

    private void readObject(ObjectInputStream in) throws IOException,

    ClassNotFoundException {

        // Don't call defaultReadObject()

        // Read in serialized fields

        ObjectInputStream.GetField gfields = in.readFields();

        // Get allPermission

        allPermission = (PermissionCollection) gfields.get("allPermission", null);

        // Get permissions

        Hashtable<Class<?>, PermissionCollection> perms =

            (Hashtable<Class<?>, PermissionCollection>)gfields.get("perms", null);

        permsMap = new HashMap<Class<?>, PermissionCollection>(perms.size()*2);

        permsMap.putAll(perms);

        // Set hasUnresolved

        UnresolvedPermissionCollection uc =

        (UnresolvedPermissionCollection) permsMap.get(UnresolvedPermission.class);

        hasUnresolved = (uc != null && uc.elements().hasMoreElements());

    }

}

final class PermissionsEnumerator implements Enumeration<Permission> {

    // all the perms

    private Iterator<PermissionCollection> perms;

    // the current set

    private Enumeration<Permission> permset;

    PermissionsEnumerator(Iterator<PermissionCollection> e) {

        perms = e;

        permset = getNextEnumWithMore();

    }

    // No need to synchronize; caller should sync on object as required

    public boolean hasMoreElements() {

        // if we enter with permissionimpl null, we know

        // there are no more left.

        if (permset == null)

            return  false;

        // try to see if there are any left in the current one

        if (permset.hasMoreElements())

            return true;

        // get the next one that has something in it...

        permset = getNextEnumWithMore();

        // if it is null, we are done!

        return (permset != null);

    }

    // No need to synchronize; caller should sync on object as required

    public Permission nextElement() {

        // hasMoreElements will update permset to the next permset

        // with something in it...

        if (hasMoreElements()) {

            return permset.nextElement();

        } else {

            throw new NoSuchElementException("PermissionsEnumerator");

        }

    }

    private Enumeration<Permission> getNextEnumWithMore() {

        while (perms.hasNext()) {

            PermissionCollection pc = perms.next();

            Enumeration<Permission> next =pc.elements();

            if (next.hasMoreElements())

                return next;

        }

        return null;

    }

}

/**

 * A PermissionsHash stores a homogeneous set of permissions in a hashtable.

 *

 * @see Permission

 * @see Permissions

 *

 *

 * @author Roland Schemers

 *

 * @serial include

 */

final class PermissionsHash extends PermissionCollection

implements Serializable

{

    /**

     * Key and value are (same) permissions objects.

     * Not serialized; see serialization section at end of class.

     */

    private transient Map<Permission, Permission> permsMap;

    /**

     * Create an empty PermissionsHash object.

     */

    PermissionsHash() {

        permsMap = new HashMap<Permission, Permission>(11);

    }

    /**

     * Adds a permission to the PermissionsHash.

     *

     * @param permission the Permission object to add.

     */

    public void add(Permission permission) {

        synchronized (this) {

            permsMap.put(permission, permission);

        }

    }

    /**

     * Check and see if this set of permissions implies the permissions

     * expressed in "permission".

     *

     * @param permission the Permission object to compare

     *

     * @return true if "permission" is a proper subset of a permission in

     * the set, false if not.

     */

    public boolean implies(Permission permission) {

        // attempt a fast lookup and implies. If that fails

        // then enumerate through all the permissions.

        synchronized (this) {

            Permission p = permsMap.get(permission);

            // If permission is found, then p.equals(permission)

            if (p == null) {

                for (Permission p_ : permsMap.values()) {

                    if (p_.implies(permission))

                        return true;

                }

                return false;

            } else {