/*

 * Copyright (c) 1998, 2009, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.internal.loader;

import java.io.EOFException;

import java.net.URL;

import java.io.IOException;

import java.io.InterruptedIOException;

import java.io.InputStream;

import java.security.CodeSigner;

import java.util.jar.Manifest;

import java.nio.ByteBuffer;

import java.util.Arrays;

import sun.nio.ByteBuffered;

/**

 * This class is used to represent a Resource that has been loaded

 * from the class path.

 *

 * @author  David Connelly

 * @since   1.2

 */

public abstract class Resource {

    /**

     * Returns the name of the Resource.

     */

    public abstract String getName();

    /**

     * Returns the URL of the Resource.

     */

    public abstract URL getURL();

    /**

     * Returns the CodeSource URL for the Resource.

     */

    public abstract URL getCodeSourceURL();

    /**

     * Returns an InputStream for reading the Resource data.

     */

    public abstract InputStream getInputStream() throws IOException;

    /**

     * Returns the length of the Resource data, or -1 if unknown.

     */

    public abstract int getContentLength() throws IOException;

    private InputStream cis;

    /* Cache result in case getBytes is called after getByteBuffer. */

    private synchronized InputStream cachedInputStream() throws IOException {

        if (cis == null) {

            cis = getInputStream();

        }

        return cis;

    }

    /**

     * Returns the Resource data as an array of bytes.

     */

    public byte[] getBytes() throws IOException {

        byte[] b;

        // Get stream before content length so that a FileNotFoundException

        // can propagate upwards without being caught too early

        InputStream in = cachedInputStream();

        // This code has been uglified to protect against interrupts.

        // Even if a thread has been interrupted when loading resources,

        // the IO should not abort, so must carefully retry, failing only

        // if the retry leads to some other IO exception.

        boolean isInterrupted = Thread.interrupted();

        int len;

        for (;;) {

            try {

                len = getContentLength();

                break;

            } catch (InterruptedIOException iioe) {

                Thread.interrupted();

                isInterrupted = true;

            }

        }

        try {

            b = new byte[0];

            if (len == -1) len = Integer.MAX_VALUE;

            int pos = 0;

            while (pos < len) {

                int bytesToRead;

                if (pos >= b.length) { // Only expand when there's no room

                    bytesToRead = Math.min(len - pos, b.length + 1024);

                    if (b.length < pos + bytesToRead) {

                        b = Arrays.copyOf(b, pos + bytesToRead);

                    }

                } else {

                    bytesToRead = b.length - pos;

                }

                int cc = 0;

                try {

                    cc = in.read(b, pos, bytesToRead);

                } catch (InterruptedIOException iioe) {

                    Thread.interrupted();

                    isInterrupted = true;

                }

                if (cc < 0) {

                    if (len != Integer.MAX_VALUE) {

                        throw new EOFException("Detect premature EOF");

                    } else {

                        if (b.length != pos) {

                            b = Arrays.copyOf(b, pos);

                        }

                        break;

                    }

                }

                pos += cc;

            }

        } finally {

            try {

                in.close();

            } catch (InterruptedIOException iioe) {

                isInterrupted = true;

            } catch (IOException ignore) {}

            if (isInterrupted) {

                Thread.currentThread().interrupt();

            }

        }

        return b;

    }

    /**

     * Returns the Resource data as a ByteBuffer, but only if the input stream

     * was implemented on top of a ByteBuffer. Return {@code null} otherwise.

     * @return Resource data or null.

     */

    public ByteBuffer getByteBuffer() throws IOException {

        InputStream in = cachedInputStream();

        if (in instanceof ByteBuffered) {

            return ((ByteBuffered)in).getByteBuffer();

        }

        return null;

    }

    /**

     * Returns the Manifest for the Resource, or null if none.

     */

    public Manifest getManifest() throws IOException {

        return null;

    }

    /**

     * Returns theCertificates for the Resource, or null if none.

     */

    public java.security.cert.Certificate[] getCertificates() {

        return null;

    }

    /**

     * Returns the code signers for the Resource, or null if none.

     */

    public CodeSigner[] getCodeSigners() {

        return null;

    }

}