/*
* 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.
*
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* 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
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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package org.eclipse.jgit.internal.storage.reftree;
import static org.eclipse.jgit.lib.Constants.HEAD;
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.GITLINK;
import static org.eclipse.jgit.lib.FileMode.SYMLINK;
import static org.eclipse.jgit.lib.FileMode.TYPE_GITLINK;
import static org.eclipse.jgit.lib.FileMode.TYPE_SYMLINK;
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 static org.eclipse.jgit.transport.ReceiveCommand.Result.LOCK_FAILURE;
import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_REASON;
import java.io.IOException;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.jgit.annotations.Nullable;
import org.eclipse.jgit.dircache.DirCache;
import org.eclipse.jgit.dircache.DirCacheBuilder;
import org.eclipse.jgit.dircache.DirCacheEditor;
import org.eclipse.jgit.dircache.DirCacheEditor.DeletePath;
import org.eclipse.jgit.dircache.DirCacheEditor.PathEdit;
import org.eclipse.jgit.dircache.DirCacheEntry;
import org.eclipse.jgit.errors.CorruptObjectException;
import org.eclipse.jgit.errors.DirCacheNameConflictException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectIdRef;
import org.eclipse.jgit.lib.ObjectInserter;
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.util.RawParseUtils;
/**
* Tree of references in the reference graph.
* <p>
* The root corresponds to the {@code "refs/"} subdirectory, for example the
* default reference {@code "refs/heads/master"} is stored at path
* {@code "heads/master"} in a {@code RefTree}.
* <p>
* Normal references are stored as {@link FileMode#GITLINK} tree entries. The
* ObjectId in the tree entry is the ObjectId the reference refers to.
* <p>
* Symbolic references are stored as {@link FileMode#SYMLINK} entries, with the
* blob storing the name of the target reference.
* <p>
* Annotated tags also store the peeled object using a {@code GITLINK} entry
* with the suffix <code>" ^"</code> (space carrot), for example
* {@code "tags/v1.0"} stores the annotated tag object, while
* <code>"tags/v1.0 ^"</code> stores the commit the tag annotates.
* <p>
* {@code HEAD} is a special case and stored as {@code "..HEAD"}.
*/
public class RefTree {
/** Suffix applied to GITLINK to indicate its the peeled value of a tag. */
public static final String PEELED_SUFFIX = " ^"; //$NON-NLS-1$
static final String ROOT_DOTDOT = ".."; //$NON-NLS-1$
/**
* Create an empty reference tree.
*
* @return a new empty reference tree.
*/
public static RefTree newEmptyTree() {
return new RefTree(DirCache.newInCore());
}
/**
* Load a reference tree.
*
* @param reader
* reader to scan the reference tree with.
* @param tree
* the tree to read.
* @return the ref tree read from the commit.
* @throws IOException
* the repository cannot be accessed through the reader.
* @throws CorruptObjectException
* a tree object is corrupt and cannot be read.
* @throws IncorrectObjectTypeException
* a tree object wasn't actually a tree.
* @throws MissingObjectException
* a reference tree object doesn't exist.
*/
public static RefTree read(ObjectReader reader, RevTree tree)
throws MissingObjectException, IncorrectObjectTypeException,
CorruptObjectException, IOException {
return new RefTree(DirCache.read(reader, tree));
}
private DirCache contents;
private Map<ObjectId, String> pendingBlobs;
private RefTree(DirCache dc) {
this.contents = dc;
}
/**
* Read one reference.
* <p>
* References are always returned peeled ({@link Ref#isPeeled()} is true).
* If the reference points to an annotated tag, the returned reference will
* be peeled and contain {@link Ref#getPeeledObjectId()}.
* <p>
* If the reference is a symbolic reference and the chain depth is less than
* {@link org.eclipse.jgit.lib.RefDatabase#MAX_SYMBOLIC_REF_DEPTH} the
* returned reference is resolved. If the chain depth is longer, the
* symbolic reference is returned without resolving.
*
* @param reader
* to access objects necessary to read the requested reference.
* @param name
* name of the reference to read.
* @return the reference; null if it does not exist.
* @throws IOException
* cannot read a symbolic reference target.
*/
@Nullable
public Ref exactRef(ObjectReader reader, String name) throws IOException {
Ref r = readRef(reader, name);
if (r == null) {
return null;
} else if (r.isSymbolic()) {
return resolve(reader, r, 0);
}
DirCacheEntry p = contents.getEntry(peeledPath(name));
if (p != null && p.getRawMode() == TYPE_GITLINK) {
return new ObjectIdRef.PeeledTag(PACKED, r.getName(),
r.getObjectId(), p.getObjectId());
}
return r;
}
private Ref readRef(ObjectReader reader, String name) throws IOException {
DirCacheEntry e = contents.getEntry(refPath(name));
return e != null ? toRef(reader, e, name) : null;
}
private Ref toRef(ObjectReader reader, DirCacheEntry e, String name)
throws IOException {
int mode = e.getRawMode();
if (mode == TYPE_GITLINK) {
ObjectId id = e.getObjectId();
return new ObjectIdRef.PeeledNonTag(PACKED, name, id);
}
if (mode == TYPE_SYMLINK) {
ObjectId id = e.getObjectId();
String n = pendingBlobs != null ? pendingBlobs.get(id) : null;
if (n == null) {
byte[] bin = reader.open(id, OBJ_BLOB).getCachedBytes();
n = RawParseUtils.decode(bin);
}
Ref dst = new ObjectIdRef.Unpeeled(NEW, n, null);
return new SymbolicRef(name, dst);
}
return null; // garbage file or something; not a reference.
}
private Ref resolve(ObjectReader reader, Ref ref, int depth)
throws IOException {
if (ref.isSymbolic() && depth < MAX_SYMBOLIC_REF_DEPTH) {
Ref r = readRef(reader, ref.getTarget().getName());
if (r == null) {
return ref;
}
Ref dst = resolve(reader, r, depth + 1);
return new SymbolicRef(ref.getName(), dst);
}
return ref;
}
/**
* Attempt a batch of commands against this RefTree.
* <p>
* The batch is applied atomically, either all commands apply at once, or
* they all reject and the RefTree is left unmodified.
* <p>
* On success (when this method returns {@code true}) the command results
* are left as-is (probably {@code NOT_ATTEMPTED}). Result fields are set
* only when this method returns {@code false} to indicate failure.
*
* @param cmdList
* to apply. All commands should still have result NOT_ATTEMPTED.
* @return true if the commands applied; false if they were rejected.
*/
public boolean apply(Collection<Command> cmdList) {
try {
DirCacheEditor ed = contents.editor();
for (Command cmd : cmdList) {
if (!isValidRef(cmd)) {
cmd.setResult(REJECTED_OTHER_REASON,
JGitText.get().funnyRefname);
Command.abort(cmdList, null);
return false;
}
apply(ed, cmd);
}
ed.finish();
return true;
} catch (DirCacheNameConflictException e) {
String r1 = refName(e.getPath1());
String r2 = refName(e.getPath2());
for (Command cmd : cmdList) {
if (r1.equals(cmd.getRefName())
|| r2.equals(cmd.getRefName())) {
cmd.setResult(LOCK_FAILURE);
break;
}
}
Command.abort(cmdList, null);
return false;
} catch (LockFailureException e) {
Command.abort(cmdList, null);
return false;
}
}
private static boolean isValidRef(Command cmd) {
String n = cmd.getRefName();
return HEAD.equals(n) || Repository.isValidRefName(n);
}
private void apply(DirCacheEditor ed, final Command cmd) {
String path = refPath(cmd.getRefName());
Ref oldRef = cmd.getOldRef();
final Ref newRef = cmd.getNewRef();
if (newRef == null) {
checkRef(contents.getEntry(path), cmd);
ed.add(new DeletePath(path));
cleanupPeeledRef(ed, oldRef);
return;
}
if (newRef.isSymbolic()) {
final String dst = newRef.getTarget().getName();
ed.add(new PathEdit(path) {
@Override
public void apply(DirCacheEntry ent) {
checkRef(ent, cmd);
ObjectId id = Command.symref(dst);
ent.setFileMode(SYMLINK);
ent.setObjectId(id);
if (pendingBlobs == null) {
pendingBlobs = new HashMap<>(4);
}
pendingBlobs.put(id, dst);
}
}.setReplace(false));
cleanupPeeledRef(ed, oldRef);
return;
}
ed.add(new PathEdit(path) {
@Override
public void apply(DirCacheEntry ent) {
checkRef(ent, cmd);
ent.setFileMode(GITLINK);
ent.setObjectId(newRef.getObjectId());
}
}.setReplace(false));
if (newRef.getPeeledObjectId() != null) {
ed.add(new PathEdit(peeledPath(newRef.getName())) {
@Override
public void apply(DirCacheEntry ent) {
ent.setFileMode(GITLINK);
ent.setObjectId(newRef.getPeeledObjectId());
}
}.setReplace(false));
} else {
cleanupPeeledRef(ed, oldRef);
}
}
private static void checkRef(@Nullable DirCacheEntry ent, Command cmd) {
if (!cmd.checkRef(ent)) {
cmd.setResult(LOCK_FAILURE);
throw new LockFailureException();
}
}
private static void cleanupPeeledRef(DirCacheEditor ed, Ref ref) {
if (ref != null && !ref.isSymbolic()
&& (!ref.isPeeled() || ref.getPeeledObjectId() != null)) {
ed.add(new DeletePath(peeledPath(ref.getName())));
}
}
/**
* Convert a path name in a RefTree to the reference name known by Git.
*
* @param path
* name read from the RefTree structure, for example
* {@code "heads/master"}.
* @return reference name for the path, {@code "refs/heads/master"}.
*/
public static String refName(String path) {
if (path.startsWith(ROOT_DOTDOT)) {
return path.substring(2);
}
return R_REFS + path;
}
static String refPath(String name) {
if (name.startsWith(R_REFS)) {
return name.substring(R_REFS.length());
}
return ROOT_DOTDOT + name;
}
private static String peeledPath(String name) {
return refPath(name) + PEELED_SUFFIX;
}
/**
* Write this reference tree.
*
* @param inserter
* inserter to use when writing trees to the object database.
* Caller is responsible for flushing the inserter before trying
* to read the objects, or exposing them through a reference.
* @return the top level tree.
* @throws IOException
* a tree could not be written.
*/
public ObjectId writeTree(ObjectInserter inserter) throws IOException {
if (pendingBlobs != null) {
for (String s : pendingBlobs.values()) {
inserter.insert(OBJ_BLOB, encode(s));
}
pendingBlobs = null;
}
return contents.writeTree(inserter);
}
/** @return a deep copy of this RefTree. */
public RefTree copy() {
RefTree r = new RefTree(DirCache.newInCore());
DirCacheBuilder b = r.contents.builder();
for (int i = 0; i < contents.getEntryCount(); i++) {
b.add(new DirCacheEntry(contents.getEntry(i)));
}
b.finish();
if (pendingBlobs != null) {
r.pendingBlobs = new HashMap<>(pendingBlobs);
}
return r;
}
private static class LockFailureException extends RuntimeException {
private static final long serialVersionUID = 1L;
}
}