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- /*
- * Copyright (C) 2008-2009, Google Inc.
- * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org>
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.lib;
-
- import java.io.IOException;
- import java.util.zip.DataFormatException;
- import java.util.zip.Inflater;
-
- /** Active handle to a ByteWindow. */
- public final class WindowCursor {
- /** Temporary buffer large enough for at least one raw object id. */
- final byte[] tempId = new byte[Constants.OBJECT_ID_LENGTH];
-
- private Inflater inf;
-
- private ByteWindow window;
-
- /**
- * Copy bytes from the window to a caller supplied buffer.
- *
- * @param pack
- * the file the desired window is stored within.
- * @param position
- * position within the file to read from.
- * @param dstbuf
- * destination buffer to copy into.
- * @param dstoff
- * offset within <code>dstbuf</code> to start copying into.
- * @param cnt
- * number of bytes to copy. This value may exceed the number of
- * bytes remaining in the window starting at offset
- * <code>pos</code>.
- * @return number of bytes actually copied; this may be less than
- * <code>cnt</code> if <code>cnt</code> exceeded the number of
- * bytes available.
- * @throws IOException
- * this cursor does not match the provider or id and the proper
- * window could not be acquired through the provider's cache.
- */
- int copy(final PackFile pack, long position, final byte[] dstbuf,
- int dstoff, final int cnt) throws IOException {
- final long length = pack.length;
- int need = cnt;
- while (need > 0 && position < length) {
- pin(pack, position);
- final int r = window.copy(position, dstbuf, dstoff, need);
- position += r;
- dstoff += r;
- need -= r;
- }
- return cnt - need;
- }
-
- /**
- * Pump bytes into the supplied inflater as input.
- *
- * @param pack
- * the file the desired window is stored within.
- * @param position
- * position within the file to read from.
- * @param dstbuf
- * destination buffer the inflater should output decompressed
- * data to.
- * @param dstoff
- * current offset within <code>dstbuf</code> to inflate into.
- * @return updated <code>dstoff</code> based on the number of bytes
- * successfully inflated into <code>dstbuf</code>.
- * @throws IOException
- * this cursor does not match the provider or id and the proper
- * window could not be acquired through the provider's cache.
- * @throws DataFormatException
- * the inflater encountered an invalid chunk of data. Data
- * stream corruption is likely.
- */
- int inflate(final PackFile pack, long position, final byte[] dstbuf,
- int dstoff) throws IOException, DataFormatException {
- prepareInflater();
- for (;;) {
- pin(pack, position);
- dstoff = window.inflate(position, dstbuf, dstoff, inf);
- if (inf.finished())
- return dstoff;
- position = window.end;
- }
- }
-
- void inflateVerify(final PackFile pack, long position)
- throws IOException, DataFormatException {
- prepareInflater();
- for (;;) {
- pin(pack, position);
- window.inflateVerify(position, inf);
- if (inf.finished())
- return;
- position = window.end;
- }
- }
-
- private void prepareInflater() {
- if (inf == null)
- inf = InflaterCache.get();
- else
- inf.reset();
- }
-
- private void pin(final PackFile pack, final long position)
- throws IOException {
- final ByteWindow w = window;
- if (w == null || !w.contains(pack, position)) {
- // If memory is low, we may need what is in our window field to
- // be cleaned up by the GC during the get for the next window.
- // So we always clear it, even though we are just going to set
- // it again.
- //
- window = null;
- window = WindowCache.get(pack, position);
- }
- }
-
- /** Release the current window cursor. */
- public void release() {
- window = null;
- try {
- InflaterCache.release(inf);
- } finally {
- inf = null;
- }
- }
-
- /**
- * @param curs cursor to release; may be null.
- * @return always null.
- */
- public static WindowCursor release(final WindowCursor curs) {
- if (curs != null)
- curs.release();
- return null;
- }
- }
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