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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 {
if (inf == null)
inf = InflaterCache.get();
else
inf.reset();
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 {
if (inf == null)
inf = InflaterCache.get();
else
inf.reset();
for (;;) {
pin(pack, position);
window.inflateVerify(position, inf);
if (inf.finished())
return;
position = window.end;
}
}
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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