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- /*
- * Copyright (C) 2016, Google Inc.
- * 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.internal.storage.reftree;
-
- import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
- import static org.eclipse.jgit.lib.Constants.R_REFS;
- import static org.eclipse.jgit.lib.Constants.encode;
- import static org.eclipse.jgit.lib.FileMode.TYPE_GITLINK;
- import static org.eclipse.jgit.lib.FileMode.TYPE_SYMLINK;
- import static org.eclipse.jgit.lib.FileMode.TYPE_TREE;
- import static org.eclipse.jgit.lib.Ref.Storage.NEW;
- import static org.eclipse.jgit.lib.Ref.Storage.PACKED;
- import static org.eclipse.jgit.lib.RefDatabase.MAX_SYMBOLIC_REF_DEPTH;
-
- import java.io.IOException;
-
- import org.eclipse.jgit.annotations.Nullable;
- import org.eclipse.jgit.errors.IncorrectObjectTypeException;
- import org.eclipse.jgit.lib.AnyObjectId;
- import org.eclipse.jgit.lib.ObjectId;
- import org.eclipse.jgit.lib.ObjectIdRef;
- import org.eclipse.jgit.lib.ObjectReader;
- import org.eclipse.jgit.lib.Ref;
- import org.eclipse.jgit.lib.Repository;
- import org.eclipse.jgit.lib.SymbolicRef;
- import org.eclipse.jgit.revwalk.RevTree;
- import org.eclipse.jgit.revwalk.RevWalk;
- import org.eclipse.jgit.treewalk.AbstractTreeIterator;
- import org.eclipse.jgit.treewalk.CanonicalTreeParser;
- import org.eclipse.jgit.treewalk.TreeWalk;
- import org.eclipse.jgit.util.Paths;
- import org.eclipse.jgit.util.RawParseUtils;
- import org.eclipse.jgit.util.RefList;
-
- /** A tree parser that extracts references from a {@link RefTree}. */
- class Scanner {
- private static final int MAX_SYMLINK_BYTES = 10 << 10;
- private static final byte[] BINARY_R_REFS = encode(R_REFS);
- private static final byte[] REFS_DOT_DOT = encode("refs/.."); //$NON-NLS-1$
-
- static class Result {
- final ObjectId refTreeId;
- final RefList<Ref> all;
- final RefList<Ref> sym;
-
- Result(ObjectId id, RefList<Ref> all, RefList<Ref> sym) {
- this.refTreeId = id;
- this.all = all;
- this.sym = sym;
- }
- }
-
- /**
- * Scan a {@link RefTree} and parse entries into {@link Ref} instances.
- *
- * @param repo
- * source repository containing the commit and tree objects that
- * make up the RefTree.
- * @param src
- * bootstrap reference such as {@code refs/txn/committed} to read
- * the reference tree tip from. The current ObjectId will be
- * included in {@link Result#refTreeId}.
- * @param prefix
- * if non-empty a reference prefix to scan only a subdirectory.
- * For example {@code prefix = "refs/heads/"} will limit the scan
- * to only the {@code "heads"} directory of the RefTree, avoiding
- * other directories like {@code "tags"}. Empty string reads all
- * entries in the RefTree.
- * @param recursive
- * if true recurse into subdirectories of the reference tree;
- * false to read only one level. Callers may use false during an
- * implementation of {@code exactRef(String)} where only one
- * reference is needed out of a specific subtree.
- * @return sorted list of references after parsing.
- * @throws IOException
- * tree cannot be accessed from the repository.
- */
- static Result scanRefTree(Repository repo, @Nullable Ref src, String prefix,
- boolean recursive) throws IOException {
- RefList.Builder<Ref> all = new RefList.Builder<>();
- RefList.Builder<Ref> sym = new RefList.Builder<>();
-
- ObjectId srcId;
- if (src != null && src.getObjectId() != null) {
- try (ObjectReader reader = repo.newObjectReader()) {
- srcId = src.getObjectId();
- scan(reader, srcId, prefix, recursive, all, sym);
- }
- } else {
- srcId = ObjectId.zeroId();
- }
-
- RefList<Ref> aList = all.toRefList();
- for (int idx = 0; idx < sym.size();) {
- Ref s = sym.get(idx);
- Ref r = resolve(s, 0, aList);
- if (r != null) {
- sym.set(idx++, r);
- } else {
- // Remove broken symbolic reference, they don't exist.
- sym.remove(idx);
- int rm = aList.find(s.getName());
- if (0 <= rm) {
- aList = aList.remove(rm);
- }
- }
- }
- return new Result(srcId, aList, sym.toRefList());
- }
-
- private static void scan(ObjectReader reader, AnyObjectId srcId,
- String prefix, boolean recursive,
- RefList.Builder<Ref> all, RefList.Builder<Ref> sym)
- throws IncorrectObjectTypeException, IOException {
- CanonicalTreeParser p = createParserAtPath(reader, srcId, prefix);
- if (p == null) {
- return;
- }
-
- while (!p.eof()) {
- int mode = p.getEntryRawMode();
- if (mode == TYPE_TREE) {
- if (recursive) {
- p = p.createSubtreeIterator(reader);
- } else {
- p = p.next();
- }
- continue;
- }
-
- if (!curElementHasPeelSuffix(p)) {
- Ref r = toRef(reader, mode, p);
- if (r != null) {
- all.add(r);
- if (r.isSymbolic()) {
- sym.add(r);
- }
- }
- } else if (mode == TYPE_GITLINK) {
- peel(all, p);
- }
- p = p.next();
- }
- }
-
- private static CanonicalTreeParser createParserAtPath(ObjectReader reader,
- AnyObjectId srcId, String prefix) throws IOException {
- ObjectId root = toTree(reader, srcId);
- if (prefix.isEmpty()) {
- return new CanonicalTreeParser(BINARY_R_REFS, reader, root);
- }
-
- String dir = RefTree.refPath(Paths.stripTrailingSeparator(prefix));
- TreeWalk tw = TreeWalk.forPath(reader, dir, root);
- if (tw == null || !tw.isSubtree()) {
- return null;
- }
-
- ObjectId id = tw.getObjectId(0);
- return new CanonicalTreeParser(encode(prefix), reader, id);
- }
-
- private static Ref resolve(Ref ref, int depth, RefList<Ref> refs)
- throws IOException {
- if (!ref.isSymbolic()) {
- return ref;
- } else if (MAX_SYMBOLIC_REF_DEPTH <= depth) {
- return null;
- }
-
- Ref r = refs.get(ref.getTarget().getName());
- if (r == null) {
- return ref;
- }
-
- Ref dst = resolve(r, depth + 1, refs);
- if (dst == null) {
- return null;
- }
- return new SymbolicRef(ref.getName(), dst);
- }
-
- @SuppressWarnings("resource")
- private static RevTree toTree(ObjectReader reader, AnyObjectId id)
- throws IOException {
- return new RevWalk(reader).parseTree(id);
- }
-
- private static boolean curElementHasPeelSuffix(AbstractTreeIterator itr) {
- int n = itr.getEntryPathLength();
- byte[] c = itr.getEntryPathBuffer();
- return n > 2 && c[n - 2] == ' ' && c[n - 1] == '^';
- }
-
- private static void peel(RefList.Builder<Ref> all, CanonicalTreeParser p) {
- String name = refName(p, true);
- for (int idx = all.size() - 1; 0 <= idx; idx--) {
- Ref r = all.get(idx);
- int cmp = r.getName().compareTo(name);
- if (cmp == 0) {
- all.set(idx, new ObjectIdRef.PeeledTag(PACKED, r.getName(),
- r.getObjectId(), p.getEntryObjectId()));
- break;
- } else if (cmp < 0) {
- // Stray peeled name without matching base name; skip entry.
- break;
- }
- }
- }
-
- private static Ref toRef(ObjectReader reader, int mode,
- CanonicalTreeParser p) throws IOException {
- if (mode == TYPE_GITLINK) {
- String name = refName(p, false);
- ObjectId id = p.getEntryObjectId();
- return new ObjectIdRef.PeeledNonTag(PACKED, name, id);
-
- } else if (mode == TYPE_SYMLINK) {
- ObjectId id = p.getEntryObjectId();
- byte[] bin = reader.open(id, OBJ_BLOB)
- .getCachedBytes(MAX_SYMLINK_BYTES);
- String dst = RawParseUtils.decode(bin);
- Ref trg = new ObjectIdRef.Unpeeled(NEW, dst, null);
- String name = refName(p, false);
- return new SymbolicRef(name, trg);
- }
- return null;
- }
-
- private static String refName(CanonicalTreeParser p, boolean peel) {
- byte[] buf = p.getEntryPathBuffer();
- int len = p.getEntryPathLength();
- if (peel) {
- len -= 2;
- }
- int ptr = 0;
- if (RawParseUtils.match(buf, ptr, REFS_DOT_DOT) > 0) {
- ptr = 7;
- }
- return RawParseUtils.decode(buf, ptr, len);
- }
-
- private Scanner() {
- }
- }
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