Allow admins to disable magic ref check on upload

Some sites manage to run their repositories in a way that prevents
users from ever being able to create refs/for, refs/drafts or
refs/publish names in a repository. Allow admins on those servers
to disable this (somewhat) expensive check before every upload.

Change-Id: Ibf51f9fa214aa07ec7bae9c40d6ef8ce6265e816

Documentation/config-gerrit.txt

@@ -1936,6 +1936,20 @@ behavior of Gerrit's 'receive-pack' mechanism.
   maxObjectSizeLimit = 40 m
 ----
 
+[[receive.checkMagicRefs]]receive.checkMagicRefs::
++
+If true, Gerrit will verify the destination repository has
+no references under the magic 'refs/drafts', 'refs/for', or
+'refs/publish' branch namespaces. Names under these locations
+confuse clients when trying to upload code reviews so Gerrit
+requires them to be empty.
++
+If false Gerrit skips the sanity check and assumes administrators
+have ensured the repository does not contain any magic references.
+Setting to false to skip the check can decrease latency during push.
++
+Default is true.
+
 [[receive.checkReferencedObjectsAreReachable]]receive.checkReferencedObjectsAreReachable::
 +
 If set to true, Gerrit will validate that all referenced objects that

gerrit-server/src/main/java/com/google/gerrit/server/git/GitModule.java

@@ -23,5 +23,6 @@ public class GitModule extends FactoryModule {
     factory(RenameGroupOp.Factory.class);
     factory(MetaDataUpdate.InternalFactory.class);
     bind(MetaDataUpdate.Server.class);
+    bind(ReceiveConfig.class);
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java

@@ -59,7 +59,6 @@ import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountResolver;
 import com.google.gerrit.server.config.AllProjectsName;
 import com.google.gerrit.server.config.CanonicalWebUrl;
-import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.TrackingFooters;
 import com.google.gerrit.server.events.CommitReceivedEvent;
 import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
@@ -90,7 +89,6 @@ import com.google.inject.assistedinject.Assisted;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.lib.BatchRefUpdate;
-import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
@@ -251,6 +249,7 @@ public class ReceiveCommits {
   private final RequestScopePropagator requestScopePropagator;
   private final SshInfo sshInfo;
   private final AllProjectsName allProjectsName;
+  private final ReceiveConfig receiveConfig;
 
   private final ProjectControl projectControl;
   private final Project project;
@@ -307,7 +306,7 @@ public class ReceiveCommits {
       final RequestScopePropagator requestScopePropagator,
       final SshInfo sshInfo,
       final AllProjectsName allProjectsName,
-      final @GerritServerConfig Config config,
+      ReceiveConfig config,
       @Assisted final ProjectControl projectControl,
       @Assisted final Repository repo,
       final SubmoduleOp.Factory subOpFactory) throws IOException {
@@ -333,6 +332,7 @@ public class ReceiveCommits {
     this.requestScopePropagator = requestScopePropagator;
     this.sshInfo = sshInfo;
     this.allProjectsName = allProjectsName;
+    this.receiveConfig = config;
 
     this.projectControl = projectControl;
     this.project = projectControl.getProject();
@@ -350,8 +350,7 @@ public class ReceiveCommits {
     rp.setCheckReceivedObjects(true);
 
     if (!projectControl.allRefsAreVisible()) {
-      rp.setCheckReferencedObjectsAreReachable(config.getBoolean("receive",
-          null, "checkReferencedObjectsAreReachable", true));
+      rp.setCheckReferencedObjectsAreReachable(config.checkReferencedObjectsAreReachable);
       rp.setAdvertiseRefsHook(new VisibleRefFilter(tagCache, changeCache, repo, projectControl, db, false));
     }
     List<AdvertiseRefsHook> advHooks = new ArrayList<AdvertiseRefsHook>(3);
@@ -485,8 +484,10 @@ public class ReceiveCommits {
     if (result != Capable.OK) {
       return result;
     }
-
-    return MagicBranch.checkMagicBranchRefs(repo, project);
+    if (receiveConfig.checkMagicRefs) {
+      result = MagicBranch.checkMagicBranchRefs(repo, project);
+    }
+    return result;
   }
 
   private void addMessage(String message) {

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveConfig.java

@@ -0,0 +1,37 @@
+// Copyright (C) 2013 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;
+
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+import org.eclipse.jgit.lib.Config;
+
+@Singleton
+class ReceiveConfig {
+  final boolean checkMagicRefs;
+  final boolean checkReferencedObjectsAreReachable;
+
+  @Inject
+  ReceiveConfig(@GerritServerConfig Config config) {
+    checkMagicRefs = config.getBoolean(
+        "receive", null, "checkMagicRefs",
+        true);
+    checkReferencedObjectsAreReachable = config.getBoolean(
+        "receive", null, "checkReferencedObjectsAreReachable",
+        true);
+  }
+}