/*
 * 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.
 */
/*
 * $Id$
 */

package org.apache.xpath.functions;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;

/**
 * This class is duplicated for each Xalan-Java subpackage so keep it in sync.
 * It is package private and therefore is not exposed as part of the Xalan-Java
 * API.
 *
 * Security related methods that only work on J2SE 1.2 and newer.
 */
final class SecuritySupport {

    static ClassLoader getContextClassLoader() {
        return (ClassLoader)
                AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                ClassLoader cl = null;
                try {
                    cl = Thread.currentThread().getContextClassLoader();
                } catch (SecurityException ex) { }
                return cl;
            }
        });
    }

    static ClassLoader getSystemClassLoader() {
        return (ClassLoader)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    ClassLoader cl = null;
                    try {
                        cl = ClassLoader.getSystemClassLoader();
                    } catch (SecurityException ex) {}
                    return cl;
                }
            });
    }

    static ClassLoader getParentClassLoader(final ClassLoader cl) {
        return (ClassLoader)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    ClassLoader parent = null;
                    try {
                        parent = cl.getParent();
                    } catch (SecurityException ex) {}

                    // eliminate loops in case of the boot
                    // ClassLoader returning itself as a parent
                    return (parent == cl) ? null : parent;
                }
            });
    }

    static String getSystemProperty(final String propName) {
        return (String)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    return System.getProperty(propName);
                }
            });
    }

    static FileInputStream getFileInputStream(final File file)
        throws FileNotFoundException
    {
        try {
            return (FileInputStream)
                AccessController.doPrivileged(new PrivilegedExceptionAction() {
                    public Object run() throws FileNotFoundException {
                        return new FileInputStream(file);
                    }
                });
        } catch (PrivilegedActionException e) {
            throw (FileNotFoundException)e.getException();
        }
    }

    static InputStream getResourceAsStream(final ClassLoader cl,
                                           final String name)
    {
        return (InputStream)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    InputStream ris;
                    if (cl == null) {
                        ris = ClassLoader.getSystemResourceAsStream(name);
                    } else {
                        ris = cl.getResourceAsStream(name);
                    }
                    return ris;
                }
            });
    }
    
    static boolean getFileExists(final File f) {
    return ((Boolean)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    return f.exists() ? Boolean.TRUE : Boolean.FALSE;
                }
            })).booleanValue();
    }
    
    static long getLastModified(final File f) {
    return ((Long)
            AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    return new Long(f.lastModified());
                }
            })).longValue();
    }
    
    private SecuritySupport () {}
}