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/*
* Copyright (C) 2010, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.pgm.debug;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Collections;
import java.util.zip.InflaterInputStream;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
import org.eclipse.jgit.internal.storage.pack.BinaryDelta;
import org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs;
import org.eclipse.jgit.internal.storage.pack.ObjectToPack;
import org.eclipse.jgit.internal.storage.pack.PackOutputStream;
import org.eclipse.jgit.internal.storage.pack.PackWriter;
import org.eclipse.jgit.internal.storage.pack.StoredObjectRepresentation;
import org.eclipse.jgit.lib.NullProgressMonitor;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.pgm.Command;
import org.eclipse.jgit.pgm.TextBuiltin;
import org.eclipse.jgit.revwalk.RevObject;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.util.TemporaryBuffer;
import org.kohsuke.args4j.Argument;
@Command(usage = "usage_ShowPackDelta")
class ShowPackDelta extends TextBuiltin {
@Argument(index = 0)
private ObjectId objectId;
/** {@inheritDoc} */
@Override
protected void run() throws Exception {
ObjectReader reader = db.newObjectReader();
RevObject obj;
try (RevWalk rw = new RevWalk(reader)) {
obj = rw.parseAny(objectId);
}
byte[] delta = getDelta(reader, obj);
// We're crossing our fingers that this will be a delta. Double
// check the size field in the header, it should match.
//
long size = reader.getObjectSize(obj, obj.getType());
try {
if (BinaryDelta.getResultSize(delta) != size)
throw die("Object " + obj.name() + " is not a delta"); //$NON-NLS-1$ //$NON-NLS-2$
} catch (ArrayIndexOutOfBoundsException bad) {
throw die("Object " + obj.name() + " is not a delta", bad); //$NON-NLS-1$ //$NON-NLS-2$
}
outw.println(BinaryDelta.format(delta));
}
private static byte[] getDelta(ObjectReader reader, RevObject obj)
throws IOException, MissingObjectException,
StoredObjectRepresentationNotAvailableException {
ObjectReuseAsIs asis = (ObjectReuseAsIs) reader;
ObjectToPack target = asis.newObjectToPack(obj, obj.getType());
PackWriter pw = new PackWriter(reader) {
@Override
public void select(ObjectToPack otp, StoredObjectRepresentation next) {
otp.select(next);
}
};
ByteArrayOutputStream buf = new ByteArrayOutputStream();
asis.selectObjectRepresentation(pw, NullProgressMonitor.INSTANCE,
Collections.singleton(target));
asis.copyObjectAsIs(new PackOutputStream(NullProgressMonitor.INSTANCE,
buf, pw), target, true);
// At this point the object header has no delta information,
// because it was output as though it were a whole object.
// Skip over the header and inflate.
//
byte[] bufArray = buf.toByteArray();
int ptr = 0;
while ((bufArray[ptr] & 0x80) != 0)
ptr++;
ptr++;
try (TemporaryBuffer.Heap raw = new TemporaryBuffer.Heap(
bufArray.length);
InflaterInputStream inf = new InflaterInputStream(
new ByteArrayInputStream(bufArray, ptr,
bufArray.length))) {
raw.copy(inf);
return raw.toByteArray();
}
}
}
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