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- /*
- * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
- * Copyright (C) 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.storage.file;
-
- import java.io.File;
- import java.io.FileInputStream;
- import java.io.FileNotFoundException;
- import java.io.IOException;
- import java.text.MessageFormat;
- import java.util.Iterator;
-
- import org.eclipse.jgit.JGitText;
- import org.eclipse.jgit.errors.MissingObjectException;
- import org.eclipse.jgit.lib.AnyObjectId;
- import org.eclipse.jgit.lib.MutableObjectId;
- import org.eclipse.jgit.lib.ObjectId;
- import org.eclipse.jgit.util.IO;
- import org.eclipse.jgit.util.NB;
-
- /**
- * Access path to locate objects by {@link ObjectId} in a {@link PackFile}.
- * <p>
- * Indexes are strictly redundant information in that we can rebuild all of the
- * data held in the index file from the on disk representation of the pack file
- * itself, but it is faster to access for random requests because data is stored
- * by ObjectId.
- * </p>
- */
- public abstract class PackIndex implements Iterable<PackIndex.MutableEntry> {
- /**
- * Open an existing pack <code>.idx</code> file for reading.
- * <p>
- * The format of the file will be automatically detected and a proper access
- * implementation for that format will be constructed and returned to the
- * caller. The file may or may not be held open by the returned instance.
- * </p>
- *
- * @param idxFile
- * existing pack .idx to read.
- * @return access implementation for the requested file.
- * @throws FileNotFoundException
- * the file does not exist.
- * @throws IOException
- * the file exists but could not be read due to security errors,
- * unrecognized data version, or unexpected data corruption.
- */
- public static PackIndex open(final File idxFile) throws IOException {
- final FileInputStream fd = new FileInputStream(idxFile);
- try {
- final byte[] hdr = new byte[8];
- IO.readFully(fd, hdr, 0, hdr.length);
- if (isTOC(hdr)) {
- final int v = NB.decodeInt32(hdr, 4);
- switch (v) {
- case 2:
- return new PackIndexV2(fd);
- default:
- throw new IOException(MessageFormat.format(JGitText.get().unsupportedPackIndexVersion, v));
- }
- }
- return new PackIndexV1(fd, hdr);
- } catch (IOException ioe) {
- final String path = idxFile.getAbsolutePath();
- final IOException err;
- err = new IOException(MessageFormat.format(JGitText.get().unreadablePackIndex, path));
- err.initCause(ioe);
- throw err;
- } finally {
- try {
- fd.close();
- } catch (IOException err2) {
- // ignore
- }
- }
- }
-
- private static boolean isTOC(final byte[] h) {
- final byte[] toc = PackIndexWriter.TOC;
- for (int i = 0; i < toc.length; i++)
- if (h[i] != toc[i])
- return false;
- return true;
- }
-
- /** Footer checksum applied on the bottom of the pack file. */
- protected byte[] packChecksum;
-
- /**
- * Determine if an object is contained within the pack file.
- *
- * @param id
- * the object to look for. Must not be null.
- * @return true if the object is listed in this index; false otherwise.
- */
- public boolean hasObject(final AnyObjectId id) {
- return findOffset(id) != -1;
- }
-
- /**
- * Provide iterator that gives access to index entries. Note, that iterator
- * returns reference to mutable object, the same reference in each call -
- * for performance reason. If client needs immutable objects, it must copy
- * returned object on its own.
- * <p>
- * Iterator returns objects in SHA-1 lexicographical order.
- * </p>
- *
- * @return iterator over pack index entries
- */
- public abstract Iterator<MutableEntry> iterator();
-
- /**
- * Obtain the total number of objects described by this index.
- *
- * @return number of objects in this index, and likewise in the associated
- * pack that this index was generated from.
- */
- abstract long getObjectCount();
-
- /**
- * Obtain the total number of objects needing 64 bit offsets.
- *
- * @return number of objects in this index using a 64 bit offset; that is an
- * object positioned after the 2 GB position within the file.
- */
- abstract long getOffset64Count();
-
- /**
- * Get ObjectId for the n-th object entry returned by {@link #iterator()}.
- * <p>
- * This method is a constant-time replacement for the following loop:
- *
- * <pre>
- * Iterator<MutableEntry> eItr = index.iterator();
- * int curPosition = 0;
- * while (eItr.hasNext() && curPosition++ < nthPosition)
- * eItr.next();
- * ObjectId result = eItr.next().toObjectId();
- * </pre>
- *
- * @param nthPosition
- * position within the traversal of {@link #iterator()} that the
- * caller needs the object for. The first returned
- * {@link MutableEntry} is 0, the second is 1, etc.
- * @return the ObjectId for the corresponding entry.
- */
- abstract ObjectId getObjectId(long nthPosition);
-
- /**
- * Get ObjectId for the n-th object entry returned by {@link #iterator()}.
- * <p>
- * This method is a constant-time replacement for the following loop:
- *
- * <pre>
- * Iterator<MutableEntry> eItr = index.iterator();
- * int curPosition = 0;
- * while (eItr.hasNext() && curPosition++ < nthPosition)
- * eItr.next();
- * ObjectId result = eItr.next().toObjectId();
- * </pre>
- *
- * @param nthPosition
- * unsigned 32 bit position within the traversal of
- * {@link #iterator()} that the caller needs the object for. The
- * first returned {@link MutableEntry} is 0, the second is 1,
- * etc. Positions past 2**31-1 are negative, but still valid.
- * @return the ObjectId for the corresponding entry.
- */
- final ObjectId getObjectId(final int nthPosition) {
- if (nthPosition >= 0)
- return getObjectId((long) nthPosition);
- final int u31 = nthPosition >>> 1;
- final int one = nthPosition & 1;
- return getObjectId(((long) u31) << 1 | one);
- }
-
- /**
- * Locate the file offset position for the requested object.
- *
- * @param objId
- * name of the object to locate within the pack.
- * @return offset of the object's header and compressed content; -1 if the
- * object does not exist in this index and is thus not stored in the
- * associated pack.
- */
- abstract long findOffset(AnyObjectId objId);
-
- /**
- * Retrieve stored CRC32 checksum of the requested object raw-data
- * (including header).
- *
- * @param objId
- * id of object to look for
- * @return CRC32 checksum of specified object (at 32 less significant bits)
- * @throws MissingObjectException
- * when requested ObjectId was not found in this index
- * @throws UnsupportedOperationException
- * when this index doesn't support CRC32 checksum
- */
- abstract long findCRC32(AnyObjectId objId) throws MissingObjectException,
- UnsupportedOperationException;
-
- /**
- * Check whether this index supports (has) CRC32 checksums for objects.
- *
- * @return true if CRC32 is stored, false otherwise
- */
- abstract boolean hasCRC32Support();
-
- /**
- * Represent mutable entry of pack index consisting of object id and offset
- * in pack (both mutable).
- *
- */
- public static class MutableEntry {
- final MutableObjectId idBuffer = new MutableObjectId();
-
- long offset;
-
- /**
- * Returns offset for this index object entry
- *
- * @return offset of this object in a pack file
- */
- public long getOffset() {
- return offset;
- }
-
- /** @return hex string describing the object id of this entry. */
- public String name() {
- ensureId();
- return idBuffer.name();
- }
-
- /** @return a copy of the object id. */
- public ObjectId toObjectId() {
- ensureId();
- return idBuffer.toObjectId();
- }
-
- /** @return a complete copy of this entry, that won't modify */
- public MutableEntry cloneEntry() {
- final MutableEntry r = new MutableEntry();
- ensureId();
- r.idBuffer.fromObjectId(idBuffer);
- r.offset = offset;
- return r;
- }
-
- void ensureId() {
- // Override in implementations.
- }
- }
-
- abstract class EntriesIterator implements Iterator<MutableEntry> {
- protected final MutableEntry entry = initEntry();
-
- protected long returnedNumber = 0;
-
- protected abstract MutableEntry initEntry();
-
- public boolean hasNext() {
- return returnedNumber < getObjectCount();
- }
-
- /**
- * Implementation must update {@link #returnedNumber} before returning
- * element.
- */
- public abstract MutableEntry next();
-
- public void remove() {
- throw new UnsupportedOperationException();
- }
- }
- }
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