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// Copyright (C) 2017 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.project;
import com.google.common.collect.ImmutableList;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.entities.Project;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.logging.Metadata;
import com.google.gerrit.server.logging.TraceContext;
import com.google.gerrit.server.logging.TraceContext.TraceTimer;
import com.google.gerrit.server.permissions.PermissionBackend;
import com.google.gerrit.server.permissions.PermissionBackend.RefFilterOptions;
import com.google.gerrit.server.permissions.PermissionBackendException;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Optional;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.ReachabilityChecker;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
/**
* Report whether a commit is reachable from a set of commits. This is used for checking if a user
* has read permissions on a commit.
*/
@Singleton
public class Reachable {
private static final FluentLogger logger = FluentLogger.forEnclosingClass();
private final PermissionBackend permissionBackend;
@Inject
Reachable(PermissionBackend permissionBackend) {
this.permissionBackend = permissionBackend;
}
/**
* Returns true if a commit is reachable from a given set of refs. This method enforces
* permissions on the given set of refs and performs a reachability check. Tags are not filtered
* separately and will only be returned if reachable by a provided ref.
*/
public boolean fromRefs(
Project.NameKey project, Repository repo, RevCommit commit, List<Ref> refs) {
return fromRefs(project, repo, commit, refs, Optional.empty());
}
boolean fromRefs(
Project.NameKey project,
Repository repo,
RevCommit commit,
List<Ref> refs,
Optional<CurrentUser> optionalUserProvider) {
try (RevWalk rw = new RevWalk(repo)) {
Collection<Ref> filtered =
optionalUserProvider
.map(permissionBackend::user)
.orElseGet(() -> permissionBackend.currentUser())
.project(project)
.filter(refs, repo, RefFilterOptions.defaults());
Collection<RevCommit> visible = new ArrayList<>();
for (Ref r : filtered) {
try {
visible.add(rw.parseCommit(r.getObjectId()));
} catch (IncorrectObjectTypeException notCommit) {
// Its OK for a tag reference to point to a blob or a tree, this
// is common in the Linux kernel or git.git repository.
continue;
} catch (MissingObjectException notHere) {
// Log the problem with this branch, but keep processing.
logger.atWarning().log(
"Reference %s in %s points to dangling object %s",
r.getName(), repo.getDirectory(), r.getObjectId());
continue;
}
}
// The filtering above already produces a voluminous trace. To separate the permission check
// from the reachability check, do the trace here:
try (TraceTimer timer =
TraceContext.newTimer(
"ReachabilityChecker.areAllReachable",
Metadata.builder().projectName(project.get()).resourceCount(refs.size()).build())) {
ReachabilityChecker checker = rw.getObjectReader().createReachabilityChecker(rw);
Optional<RevCommit> unreachable =
checker.areAllReachable(ImmutableList.of(rw.parseCommit(commit)), visible.stream());
return !unreachable.isPresent();
}
} catch (IOException | PermissionBackendException e) {
logger.atSevere().withCause(e).log(
"Cannot verify permissions to commit object %s in repository %s", commit.name(), project);
return false;
}
}
}
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