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- /*
- * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
- * 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.util.zip.DataFormatException;
- import java.util.zip.Inflater;
-
- /**
- * A window of data currently stored within a cache.
- * <p>
- * All bytes in the window can be assumed to be "immediately available", that is
- * they are very likely already in memory, unless the operating system's memory
- * is very low and has paged part of this process out to disk. Therefore copying
- * bytes from a window is very inexpensive.
- * </p>
- */
- abstract class ByteWindow {
- protected final PackFile pack;
-
- protected final long start;
-
- protected final long end;
-
- protected ByteWindow(final PackFile p, final long s, final int n) {
- pack = p;
- start = s;
- end = start + n;
- }
-
- final int size() {
- return (int) (end - start);
- }
-
- final boolean contains(final PackFile neededFile, final long neededPos) {
- return pack == neededFile && start <= neededPos && neededPos < end;
- }
-
- /**
- * Copy bytes from the window to a caller supplied buffer.
- *
- * @param pos
- * offset within the file to start copying 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.
- */
- final int copy(long pos, byte[] dstbuf, int dstoff, int cnt) {
- return copy((int) (pos - start), dstbuf, dstoff, cnt);
- }
-
- /**
- * Copy bytes from the window to a caller supplied buffer.
- *
- * @param pos
- * offset within the window to start copying 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.
- */
- protected abstract int copy(int pos, byte[] dstbuf, int dstoff, int cnt);
-
- /**
- * Pump bytes into the supplied inflater as input.
- *
- * @param pos
- * offset within the file to start supplying input from.
- * @param dstbuf
- * destination buffer the inflater should output decompressed
- * data to.
- * @param dstoff
- * current offset within <code>dstbuf</code> to inflate into.
- * @param inf
- * the inflater to feed input to. The caller is responsible for
- * initializing the inflater as multiple windows may need to
- * supply data to the same inflater to completely decompress
- * something.
- * @return updated <code>dstoff</code> based on the number of bytes
- * successfully copied into <code>dstbuf</code> by
- * <code>inf</code>. If the inflater is not yet finished then
- * another window's data must still be supplied as input to finish
- * decompression.
- * @throws DataFormatException
- * the inflater encountered an invalid chunk of data. Data
- * stream corruption is likely.
- */
- final int inflate(long pos, byte[] dstbuf, int dstoff, Inflater inf)
- throws DataFormatException {
- return inflate((int) (pos - start), dstbuf, dstoff, inf);
- }
-
- /**
- * Pump bytes into the supplied inflater as input.
- *
- * @param pos
- * offset within the window to start supplying input from.
- * @param dstbuf
- * destination buffer the inflater should output decompressed
- * data to.
- * @param dstoff
- * current offset within <code>dstbuf</code> to inflate into.
- * @param inf
- * the inflater to feed input to. The caller is responsible for
- * initializing the inflater as multiple windows may need to
- * supply data to the same inflater to completely decompress
- * something.
- * @return updated <code>dstoff</code> based on the number of bytes
- * successfully copied into <code>dstbuf</code> by
- * <code>inf</code>. If the inflater is not yet finished then
- * another window's data must still be supplied as input to finish
- * decompression.
- * @throws DataFormatException
- * the inflater encountered an invalid chunk of data. Data
- * stream corruption is likely.
- */
- protected abstract int inflate(int pos, byte[] dstbuf, int dstoff,
- Inflater inf) throws DataFormatException;
-
- protected static final byte[] verifyGarbageBuffer = new byte[2048];
-
- final void inflateVerify(final long pos, final Inflater inf)
- throws DataFormatException {
- inflateVerify((int) (pos - start), inf);
- }
-
- protected abstract void inflateVerify(int pos, Inflater inf)
- throws DataFormatException;
- }
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