/*
 * Copyright (c) 1994, 2020, 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.net.www;

import java.io.*;
import java.util.concurrent.locks.ReentrantLock;
import sun.net.ProgressSource;
import sun.net.www.http.ChunkedInputStream;


public class MeteredStream extends FilterInputStream {

    // Instance variables.
    /* if expected != -1, after we've read >= expected, we're "closed" and return -1
     * from subsequest read() 's
     */
    protected boolean closed = false;
    protected long expected;
    protected long count = 0;
    protected long markedCount = 0;
    protected int markLimit = -1;
    protected ProgressSource pi;
    private final ReentrantLock readLock = new ReentrantLock();

    public MeteredStream(InputStream is, ProgressSource pi, long expected)
    {
        super(is);

        this.pi = pi;
        this.expected = expected;

        if (pi != null) {
            pi.updateProgress(0, expected);
        }
    }

    private final void justRead(long n) throws IOException {
        assert isLockHeldByCurrentThread();

        if (n == -1) {

            /*
             * don't close automatically when mark is set and is valid;
             * cannot reset() after close()
             */
            if (!isMarked()) {
                close();
            }
            return;
        }

        count += n;

        /**
         * If read beyond the markLimit, invalidate the mark
         */
        if (count - markedCount > markLimit) {
            markLimit = -1;
        }

        if (pi != null)
            pi.updateProgress(count, expected);

        if (isMarked()) {
            return;
        }

        // if expected length is known, we could determine if
        // read overrun.
        if (expected > 0)   {
            if (count >= expected) {
                close();
            }
        }
    }

    
Returns true if the mark is valid, false otherwise
/** * Returns true if the mark is valid, false otherwise */
private boolean isMarked() { assert isLockHeldByCurrentThread(); if (markLimit < 0) { return false; } // mark is set, but is not valid anymore if (count - markedCount > markLimit) { return false; } // mark still holds return true; } public int read() throws java.io.IOException { lock(); try { if (closed) return -1; int c = in.read(); if (c != -1) { justRead(1); } else { justRead(c); } return c; } finally { unlock(); } } public int read(byte b[], int off, int len) throws java.io.IOException { lock(); try { if (closed) return -1; int n = in.read(b, off, len); justRead(n); return n; } finally { unlock(); } } public long skip(long n) throws IOException { lock(); try { // REMIND: what does skip do on EOF???? if (closed) return 0; if (in instanceof ChunkedInputStream) { n = in.skip(n); } else { // just skip min(n, num_bytes_left) long min = (n > expected - count) ? expected - count : n; n = in.skip(min); } justRead(n); return n; } finally { unlock(); } } public void close() throws IOException { lock(); try { if (closed) return; if (pi != null) pi.finishTracking(); closed = true; in.close(); } finally { unlock(); } } public int available() throws IOException { lock(); try { return closed ? 0 : in.available(); } finally { unlock(); } } public void mark(int readLimit) { lock(); try { if (closed) return; super.mark(readLimit); /* * mark the count to restore upon reset */ markedCount = count; markLimit = readLimit; } finally { unlock(); } } public void reset() throws IOException { lock(); try { if (closed) return; if (!isMarked()) { throw new IOException("Resetting to an invalid mark"); } count = markedCount; super.reset(); } finally { unlock(); } } public boolean markSupported() { lock(); try { if (closed) return false; return super.markSupported(); } finally { unlock(); } } public final void lock() { readLock.lock(); } public final void unlock() { readLock.unlock(); } public final boolean isLockHeldByCurrentThread() { return readLock.isHeldByCurrentThread(); } @SuppressWarnings("deprecation") protected void finalize() throws Throwable { try { close(); if (pi != null) pi.close(); } finally { // Call super class super.finalize(); } } }