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// Copyright (C) 2018 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.server.notedb;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
import static com.google.gerrit.server.notedb.ChangeNoteUtil.parseCommitMessageRange;
import static org.eclipse.jgit.util.RawParseUtils.decode;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.RefNames;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.Optional;
import org.eclipse.jgit.lib.CommitBuilder;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectInserter;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevSort;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.util.RawParseUtils;
/**
* Deletes a change message from NoteDb by rewriting the commit history. After deletion, the whole
* change message will be replaced by a new message indicating the original change message has been
* deleted for the given reason.
*/
public class DeleteChangeMessageRewriter implements NoteDbRewriter {
private final Change.Id changeId;
private final int targetMessageIdx;
private final String newChangeMessage;
DeleteChangeMessageRewriter(Change.Id changeId, int targetMessageIdx, String newChangeMessage) {
this.changeId = changeId;
this.targetMessageIdx = targetMessageIdx;
this.newChangeMessage = newChangeMessage;
}
@Override
public String getRefName() {
return RefNames.changeMetaRef(changeId);
}
@Override
public ObjectId rewriteCommitHistory(RevWalk revWalk, ObjectInserter inserter, ObjectId currTip)
throws IOException {
checkArgument(!currTip.equals(ObjectId.zeroId()));
// Walk from the first commit of the branch.
revWalk.reset();
revWalk.markStart(revWalk.parseCommit(currTip));
revWalk.sort(RevSort.TOPO);
revWalk.sort(RevSort.REVERSE);
ObjectId newTipId = null;
RevCommit originalCommit;
int idx = 0;
while ((originalCommit = revWalk.next()) != null) {
if (idx < targetMessageIdx) {
newTipId = originalCommit;
idx++;
continue;
}
String newCommitMessage =
(idx == targetMessageIdx)
? createNewCommitMessage(originalCommit)
: originalCommit.getFullMessage();
newTipId = rewriteOneCommit(originalCommit, newTipId, newCommitMessage, inserter);
idx++;
}
return newTipId;
}
private String createNewCommitMessage(RevCommit commit) {
byte[] raw = commit.getRawBuffer();
Optional<ChangeNoteUtil.CommitMessageRange> range = parseCommitMessageRange(commit);
checkState(range.isPresent(), "failed to parse commit message");
// Only replace the commit message body, which is the user-provided message. The subject and
// footers are NoteDb metadata.
Charset encoding = RawParseUtils.parseEncoding(raw);
String prefix =
decode(encoding, raw, range.get().subjectStart(), range.get().changeMessageStart());
String postfix = decode(encoding, raw, range.get().changeMessageEnd() + 1, raw.length);
return prefix + newChangeMessage + postfix;
}
/**
* Rewrites one commit.
*
* @param originalCommit the original commit to be rewritten.
* @param parentCommitId the parent of the new commit. For the first rewritten commit, it's the
* parent of 'originalCommit'. For the latter rewritten commits, it's the commit rewritten
* just before it.
* @param commitMessage the full commit message of the new commit.
* @param inserter the {@code ObjectInserter} for the rewrite process.
* @return the {@code objectId} of the new commit.
* @throws IOException
*/
private ObjectId rewriteOneCommit(
RevCommit originalCommit,
ObjectId parentCommitId,
String commitMessage,
ObjectInserter inserter)
throws IOException {
CommitBuilder cb = new CommitBuilder();
if (parentCommitId != null) {
cb.setParentId(parentCommitId);
}
cb.setTreeId(originalCommit.getTree());
cb.setMessage(commitMessage);
cb.setCommitter(originalCommit.getCommitterIdent());
cb.setAuthor(originalCommit.getAuthorIdent());
cb.setEncoding(originalCommit.getEncoding());
return inserter.insert(cb);
}
}
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