/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * 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 com.sun.org.apache.bcel.internal.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FilenameFilter;
import java.lang.ClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.ListResourceBundle;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

/**
 * This class is duplicated for each subpackage so keep it in sync. It is
 * package private and therefore is not exposed as part of any API.
 *
 * @xerces.internal
 */
public final class SecuritySupport {

    private static final SecuritySupport securitySupport = new SecuritySupport();

    /**
     * Return an instance of this class.
     */
    public static SecuritySupport getInstance() {
        return 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;
            }
        });
    }

    public 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();
        }
    }

    /**
     * Gets a resource bundle using the specified base name, the default locale,
     * and the caller's class loader.
     *
     * @param bundle the base name of the resource bundle, a fully qualified
     * class name
     * @return a resource bundle for the given base name and the default locale
     */
    public static ListResourceBundle getResourceBundle(String bundle) {
        return getResourceBundle(bundle, Locale.getDefault());
    }

    /**
     * Gets a resource bundle using the specified base name and locale, and the
     * caller's class loader.
     *
     * @param bundle the base name of the resource bundle, a fully qualified
     * class name
     * @param locale the locale for which a resource bundle is desired
     * @return a resource bundle for the given base name and locale
     */
    public static ListResourceBundle getResourceBundle(final String bundle, final Locale locale) {
        return AccessController.doPrivileged(new PrivilegedAction<ListResourceBundle>() {
            public ListResourceBundle run() {
                try {
                    return (ListResourceBundle) ResourceBundle.getBundle(bundle, locale);
                } catch (MissingResourceException e) {
                    try {
                        return (ListResourceBundle) ResourceBundle.getBundle(bundle, new Locale("en", "US"));
                    } catch (MissingResourceException e2) {
                        throw new MissingResourceException(
                                "Could not load any resource bundle by " + bundle, bundle, "");
                    }
                }
            }
        });
    }

    public static String[] getFileList(final File f, final FilenameFilter filter) {
        return ((String[]) AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                return f.list(filter);
            }
        }));
    }

    public 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();
    }


    /**
     * Figure out which ClassLoader to use.
     */
    public static ClassLoader findClassLoader()
    {
        if (System.getSecurityManager()!=null) {
            //this will ensure bootclassloader is used
            return null;
        } else {
            return SecuritySupport.class.getClassLoader();
        }
    } // findClassLoader():ClassLoader

    private SecuritySupport() {
    }
}
