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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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