| /* |
| * Copyright (c) 2018, 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.nio.zipfs; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| import java.nio.channels.ClosedChannelException; |
| import java.nio.channels.NonWritableChannelException; |
| import java.nio.channels.SeekableByteChannel; |
| import java.util.Arrays; |
| import java.util.concurrent.locks.ReadWriteLock; |
| import java.util.concurrent.locks.ReentrantReadWriteLock; |
| |
| public class ByteArrayChannel implements SeekableByteChannel { |
| |
| private final ReadWriteLock rwlock = new ReentrantReadWriteLock(); |
| private byte buf[]; |
| |
| /* |
| * The current position of this channel. |
| */ |
| private int pos; |
| |
| /* |
| * The index that is one greater than the last valid byte in the channel. |
| */ |
| private int last; |
| |
| private boolean closed; |
| private boolean readonly; |
| |
| /* |
| * Creates a {@code ByteArrayChannel} with size {@code sz}. |
| */ |
| ByteArrayChannel(int sz, boolean readonly) { |
| this.buf = new byte[sz]; |
| this.pos = this.last = 0; |
| this.readonly = readonly; |
| } |
| |
| /* |
| * Creates a ByteArrayChannel with its 'pos' at 0 and its 'last' at buf's end. |
| * Note: no defensive copy of the 'buf', used directly. |
| */ |
| ByteArrayChannel(byte[] buf, boolean readonly) { |
| this.buf = buf; |
| this.pos = 0; |
| this.last = buf.length; |
| this.readonly = readonly; |
| } |
| |
| @Override |
| public boolean isOpen() { |
| return !closed; |
| } |
| |
| @Override |
| public long position() throws IOException { |
| beginRead(); |
| try { |
| ensureOpen(); |
| return pos; |
| } finally { |
| endRead(); |
| } |
| } |
| |
| @Override |
| public SeekableByteChannel position(long pos) throws IOException { |
| beginWrite(); |
| try { |
| ensureOpen(); |
| if (pos < 0 || pos >= Integer.MAX_VALUE) |
| throw new IllegalArgumentException("Illegal position " + pos); |
| this.pos = Math.min((int)pos, last); |
| return this; |
| } finally { |
| endWrite(); |
| } |
| } |
| |
| @Override |
| public int read(ByteBuffer dst) throws IOException { |
| beginWrite(); |
| try { |
| ensureOpen(); |
| if (pos == last) |
| return -1; |
| int n = Math.min(dst.remaining(), last - pos); |
| dst.put(buf, pos, n); |
| pos += n; |
| return n; |
| } finally { |
| endWrite(); |
| } |
| } |
| |
| @Override |
| public SeekableByteChannel truncate(long size) throws IOException { |
| if (readonly) |
| throw new NonWritableChannelException(); |
| ensureOpen(); |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public int write(ByteBuffer src) throws IOException { |
| if (readonly) |
| throw new NonWritableChannelException(); |
| beginWrite(); |
| try { |
| ensureOpen(); |
| int n = src.remaining(); |
| ensureCapacity(pos + n); |
| src.get(buf, pos, n); |
| pos += n; |
| if (pos > last) { |
| last = pos; |
| } |
| return n; |
| } finally { |
| endWrite(); |
| } |
| } |
| |
| @Override |
| public long size() throws IOException { |
| beginRead(); |
| try { |
| ensureOpen(); |
| return last; |
| } finally { |
| endRead(); |
| } |
| } |
| |
| @Override |
| public void close() throws IOException { |
| if (closed) |
| return; |
| beginWrite(); |
| try { |
| closed = true; |
| buf = null; |
| pos = 0; |
| last = 0; |
| } finally { |
| endWrite(); |
| } |
| } |
| |
| /** |
| * Creates a newly allocated byte array. Its size is the current |
| * size of this channel and the valid contents of the buffer |
| * have been copied into it. |
| * |
| * @return the current contents of this channel, as a byte array. |
| */ |
| public byte[] toByteArray() { |
| beginRead(); |
| try { |
| // avoid copy if last == bytes.length? |
| return Arrays.copyOf(buf, last); |
| } finally { |
| endRead(); |
| } |
| } |
| |
| private void ensureOpen() throws IOException { |
| if (closed) |
| throw new ClosedChannelException(); |
| } |
| |
| private final void beginWrite() { |
| rwlock.writeLock().lock(); |
| } |
| |
| private final void endWrite() { |
| rwlock.writeLock().unlock(); |
| } |
| |
| private final void beginRead() { |
| rwlock.readLock().lock(); |
| } |
| |
| private final void endRead() { |
| rwlock.readLock().unlock(); |
| } |
| |
| private void ensureCapacity(int minCapacity) { |
| // overflow-conscious code |
| if (minCapacity - buf.length > 0) { |
| grow(minCapacity); |
| } |
| } |
| |
| /** |
| * The maximum size of array to allocate. |
| * Some VMs reserve some header words in an array. |
| * Attempts to allocate larger arrays may result in |
| * OutOfMemoryError: Requested array size exceeds VM limit |
| */ |
| private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; |
| |
| /** |
| * Increases the capacity to ensure that it can hold at least the |
| * number of elements specified by the minimum capacity argument. |
| * |
| * @param minCapacity the desired minimum capacity |
| */ |
| private void grow(int minCapacity) { |
| // overflow-conscious code |
| int oldCapacity = buf.length; |
| int newCapacity = oldCapacity << 1; |
| if (newCapacity - minCapacity < 0) |
| newCapacity = minCapacity; |
| if (newCapacity - MAX_ARRAY_SIZE > 0) |
| newCapacity = hugeCapacity(minCapacity); |
| buf = Arrays.copyOf(buf, newCapacity); |
| } |
| |
| private static int hugeCapacity(int minCapacity) { |
| if (minCapacity < 0) // overflow |
| throw new OutOfMemoryError(); |
| return (minCapacity > MAX_ARRAY_SIZE) ? |
| Integer.MAX_VALUE : |
| MAX_ARRAY_SIZE; |
| } |
| } |