Introduce ref operation validation

Create extension point that is responsible for ref operations validation.

Change-Id: Ia6386ce6480ae63b75ec3b2836267c2f8d68d426
Signed-off-by: Jacek Centkowski <geminica.programs@gmail.com>

Documentation/config-validation.txt

@@ -21,6 +21,17 @@ and cherry-pick buttons.
 Out of the box, Gerrit includes a plugin that checks the length of the
 subject and body lines of commit messages on uploaded commits.
 
+[[ref-operation-validation]]
+== Ref operation validation
+
+
+Plugins implementing the `RefOperationValidationListener` interface can
+perform additional validation checks against ref creation/deletion operation
+before it is applied to the git repository.
+
+If the ref operation fails the validation, the plugin can throw an exception
+which will cause the operation to fail.
+
 [[pre-merge-validation]]
 == Pre-merge validation
 

gerrit-server/src/main/java/com/google/gerrit/server/config/GerritGlobalModule.java

@@ -91,6 +91,8 @@ import com.google.gerrit.server.git.validators.CommitValidators;
 import com.google.gerrit.server.git.validators.MergeValidationListener;
 import com.google.gerrit.server.git.validators.MergeValidators;
 import com.google.gerrit.server.git.validators.MergeValidators.ProjectConfigValidator;
+import com.google.gerrit.server.git.validators.RefOperationValidationListener;
+import com.google.gerrit.server.git.validators.RefOperationValidators;
 import com.google.gerrit.server.git.validators.UploadValidationListener;
 import com.google.gerrit.server.git.validators.UploadValidators;
 import com.google.gerrit.server.group.GroupModule;
@@ -272,6 +274,7 @@ public class GerritGlobalModule extends FactoryModule {
         .to(ProjectConfigEntry.UpdateChecker.class);
     DynamicSet.setOf(binder(), ChangeListener.class);
     DynamicSet.setOf(binder(), CommitValidationListener.class);
+    DynamicSet.setOf(binder(), RefOperationValidationListener.class);
     DynamicSet.setOf(binder(), MergeValidationListener.class);
     DynamicSet.setOf(binder(), ProjectCreationValidationListener.class);
     DynamicSet.setOf(binder(), GroupCreationValidationListener.class);
@@ -294,6 +297,7 @@ public class GerritGlobalModule extends FactoryModule {
     bind(AnonymousUser.class);
 
     factory(CommitValidators.Factory.class);
+    factory(RefOperationValidators.Factory.class);
     factory(MergeValidators.Factory.class);
     factory(ProjectConfigValidator.Factory.class);
     factory(NotesBranchUtil.Factory.class);

gerrit-server/src/main/java/com/google/gerrit/server/events/RefOperationReceivedEvent.java

@@ -0,0 +1,26 @@
+// Copyright (C) 2014 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.events;
+
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.IdentifiedUser;
+
+import org.eclipse.jgit.transport.ReceiveCommand;
+
+public class RefOperationReceivedEvent extends ChangeEvent {
+  public final String type = "ref-received";
+  public ReceiveCommand command;
+  public Project project;
+  public IdentifiedUser user;
+}

gerrit-server/src/main/java/com/google/gerrit/server/git/validators/RefOperationValidationException.java

@@ -0,0 +1,41 @@
+// Copyright (C) 2014 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.git.validators;
+
+import com.google.gerrit.server.validators.ValidationException;
+
+public class RefOperationValidationException extends ValidationException {
+  private static final long serialVersionUID = 1L;
+  private final Iterable<ValidationMessage> messages;
+
+  public RefOperationValidationException(String reason,
+      Iterable<ValidationMessage> messages) {
+    super(reason);
+    this.messages = messages;
+  }
+
+  public Iterable<ValidationMessage> getMessages() {
+    return messages;
+  }
+
+  @Override
+  public String getMessage() {
+    StringBuilder msg = new StringBuilder(super.getMessage());
+    for (ValidationMessage error : messages) {
+      msg.append("\n").append(error.getMessage());
+    }
+    return msg.toString();
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/git/validators/RefOperationValidationListener.java

@@ -0,0 +1,37 @@
+// Copyright (C) 2014 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.git.validators;
+
+import com.google.gerrit.extensions.annotations.ExtensionPoint;
+import com.google.gerrit.server.events.RefOperationReceivedEvent;
+import com.google.gerrit.server.validators.ValidationException;
+
+import java.util.List;
+
+/**
+ * Listener to provide validation on operation that is going to be performed on
+ * given ref
+ */
+@ExtensionPoint
+public interface RefOperationValidationListener {
+  /**
+   * Validate a ref operation before it is performed.
+   *
+   * @param refEvent ref operation specification
+   * @return empty list or informational messages on success
+   * @throws ValidationException if the ref operation fails to validate
+   */
+  List<ValidationMessage> onRefOperation(RefOperationReceivedEvent refEvent)
+      throws ValidationException;
+}

gerrit-server/src/main/java/com/google/gerrit/server/git/validators/RefOperationValidators.java

@@ -0,0 +1,100 @@
+// Copyright (C) 2014 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.git.validators;
+
+import com.google.common.base.Predicate;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
+import com.google.gerrit.extensions.registration.DynamicSet;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.events.RefOperationReceivedEvent;
+import com.google.gerrit.server.validators.ValidationException;
+import com.google.inject.Inject;
+import com.google.inject.assistedinject.Assisted;
+
+import org.eclipse.jgit.lib.RefUpdate;
+import org.eclipse.jgit.transport.ReceiveCommand;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.List;
+
+public class RefOperationValidators {
+  private static final GetErrorMessages GET_ERRORS = new GetErrorMessages();
+  private static final Logger LOG = LoggerFactory
+      .getLogger(RefOperationValidators.class);
+
+  public interface Factory {
+    RefOperationValidators create(Project project, IdentifiedUser user, ReceiveCommand cmd);
+  }
+
+  public static ReceiveCommand getCommand(RefUpdate update, ReceiveCommand.Type type) {
+    return new ReceiveCommand(update.getOldObjectId(), update.getNewObjectId(),
+        update.getName(), type);
+  }
+
+  private final RefOperationReceivedEvent event;
+  private final DynamicSet<RefOperationValidationListener> refOperationValidationListeners;
+
+  @Inject
+  RefOperationValidators(
+      DynamicSet<RefOperationValidationListener> refOperationValidationListeners,
+      @Assisted Project project, @Assisted IdentifiedUser user,
+      @Assisted ReceiveCommand cmd) {
+    this.refOperationValidationListeners = refOperationValidationListeners;
+    event = new RefOperationReceivedEvent();
+    event.command = cmd;
+    event.project = project;
+    event.user = user;
+  }
+
+  public List<ValidationMessage> validateForRefOperation()
+    throws RefOperationValidationException {
+
+    List<ValidationMessage> messages = Lists.newArrayList();
+    boolean withException = false;
+    try {
+      for (RefOperationValidationListener listener : refOperationValidationListeners) {
+        messages.addAll(listener.onRefOperation(event));
+      }
+    } catch (ValidationException e) {
+      messages.add(new ValidationMessage(e.getMessage(), true));
+      withException = true;
+    }
+
+    if (withException) {
+      throwException(messages, event);
+    }
+
+    return messages;
+  }
+
+  private void throwException(Iterable<ValidationMessage> messages,
+      RefOperationReceivedEvent event) throws RefOperationValidationException {
+    Iterable<ValidationMessage> errors = Iterables.filter(messages, GET_ERRORS);
+    String header = String.format(
+        "Ref \"%s\" %S in project %s validation failed", event.command.getRefName(),
+        event.command.getType(), event.project.getName());
+    LOG.error(header);
+    throw new RefOperationValidationException(header, errors);
+  }
+
+  private static class GetErrorMessages implements Predicate<ValidationMessage> {
+    @Override
+    public boolean apply(ValidationMessage input) {
+      return input.isError();
+    }
+  }
+}