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 * Copyright (c) 2019, 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
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package sun.security.util;

import java.io.File;
import java.io.FilePermission;
import java.io.IOException;
import java.net.URL;
import java.security.CodeSource;
import java.security.Permission;
import java.security.PermissionCollection;
import java.util.Enumeration;

This PermissionCollection implementation delegates to another PermissionCollection, taking care to lazily add the permission needed to read from the given CodeSource at first use, i.e., when either of elements, implies or toString is called, or when the collection is serialized. /**
 * This {@code PermissionCollection} implementation delegates to another
 * {@code PermissionCollection}, taking care to lazily add the permission needed
 * to read from the given {@code CodeSource} at first use, i.e., when either of
 * {@link #elements}, {@link #implies} or {@link #toString} is called, or when
 * the collection is serialized.
 */
public final class LazyCodeSourcePermissionCollection
        extends PermissionCollection
{
    private static final long serialVersionUID = -6727011328946861783L;
    private final PermissionCollection perms;
    private final CodeSource cs;
    private volatile boolean permissionAdded;

    public LazyCodeSourcePermissionCollection(PermissionCollection perms,
                                              CodeSource cs) {
        this.perms = perms;
        this.cs = cs;
    }

    private void ensureAdded() {
        if (!permissionAdded) {
            synchronized(perms) {
                if (permissionAdded)
                    return;

                // open connection to determine the permission needed
                URL location = cs.getLocation();
                if (location != null) {
                    try {
                        Permission p = location.openConnection().getPermission();
                        if (p != null) {
                            // for directories then need recursive access
                            if (p instanceof FilePermission) {
                                String path = p.getName();
                                if (path.endsWith(File.separator)) {
                                    path += "-";
                                    p = new FilePermission(path,
                                            SecurityConstants.FILE_READ_ACTION);
                                }
                            }
                            perms.add(p);
                        }
                    } catch (IOException ioe) {
                    }
                }
                if (isReadOnly()) {
                    perms.setReadOnly();
                }
                permissionAdded = true;
            }
        }
    }

    @Override
    public void add(Permission permission) {
        if (isReadOnly())
            throw new SecurityException(
                    "attempt to add a Permission to a readonly PermissionCollection");
        perms.add(permission);
    }

    @Override
    public boolean implies(Permission permission) {
        ensureAdded();
        return perms.implies(permission);
    }

    @Override
    public Enumeration<Permission> elements() {
        ensureAdded();
        return perms.elements();
    }

    @Override
    public String toString() {
        ensureAdded();
        return perms.toString();
    }

    
On serialization, initialize and replace with the underlying
permissions. This removes the laziness on deserialization.
/**
     * On serialization, initialize and replace with the underlying
     * permissions. This removes the laziness on deserialization.
     */
    private Object writeReplace() {
        ensureAdded();
        return perms;
    }
}