Fix infinite loops when walking project hierarchy

Always walk up the tree using a special iterator that knows how
to track visited project names and breaks any cycle, ensuring
All-Projects is always reached.

Change-Id: Ib6ad9505b3225bfa40ba067c799ce18130eafd29

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/project/ProjectDetailFactory.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.httpd.rpc.project;
 
+import com.google.common.collect.Iterables;
 import com.google.gerrit.common.data.ProjectDetail;
 import com.google.gerrit.httpd.rpc.Handler;
 import com.google.gerrit.reviewdb.client.InheritedBoolean;
@@ -78,7 +79,7 @@ class ProjectDetailFactory extends Handler<ProjectDetail> {
     useSignedOffBy.setValue(projectState.getProject().getUseSignedOffBy());
     useContentMerge.setValue(projectState.getProject().getUseContentMerge());
     requireChangeID.setValue(projectState.getProject().getRequireChangeID());
-    final ProjectState parentState = projectState.getParentState();
+    ProjectState parentState = Iterables.getFirst(projectState.parents(), null);
     if (parentState != null) {
       useContributorAgreements.setInheritedValue(parentState
           .isUseContributorAgreements());

gerrit-server/src/main/java/com/google/gerrit/server/mail/ChangeEmail.java

@@ -375,8 +375,7 @@ public abstract class ChangeEmail extends NotificationEmail {
       }
     }
 
-    ProjectState state = projectState;
-    while (state != null) {
+    for (ProjectState state : projectState.tree()) {
       for (NotifyConfig nc : state.getConfig().getNotifyConfigs()) {
         if (nc.isNotify(type)) {
           try {
@@ -389,7 +388,6 @@ public abstract class ChangeEmail extends NotificationEmail {
           }
         }
       }
-      state = state.getParentState();
     }
 
     return matching;

gerrit-server/src/main/java/com/google/gerrit/server/project/DashboardsCollection.java

@@ -21,7 +21,6 @@ import com.google.common.base.Objects;
 import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Sets;
 import com.google.gerrit.extensions.registration.DynamicMap;
 import com.google.gerrit.extensions.restapi.AcceptsCreate;
 import com.google.gerrit.extensions.restapi.ChildCollection;
@@ -30,6 +29,7 @@ import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.extensions.restapi.RestModifyView;
 import com.google.gerrit.extensions.restapi.RestView;
 import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.UrlEncoded;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.util.Url;
@@ -49,7 +49,6 @@ import org.eclipse.jgit.lib.Repository;
 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.util.List;
-import java.util.Set;
 
 class DashboardsCollection implements
     ChildCollection<ProjectResource, DashboardResource>,
@@ -99,13 +98,12 @@ class DashboardsCollection implements
       throw new ResourceNotFoundException(id);
     }
 
+    CurrentUser user = myCtl.getCurrentUser();
     String ref = Url.decode(parts.get(0));
     String path = Url.decode(parts.get(1));
-    ProjectControl ctl = myCtl;
-    Set<Project.NameKey> seen = Sets.newHashSet(ctl.getProject().getNameKey());
-    for (;;) {
+    for (ProjectState ps : myCtl.getProjectState().tree()) {
       try {
-        return parse(ctl, ref, path, myCtl);
+        return parse(ps.controlFor(user), ref, path, myCtl);
       } catch (AmbiguousObjectException e) {
         throw new ResourceNotFoundException(id);
       } catch (IncorrectObjectTypeException e) {
@@ -113,14 +111,10 @@ class DashboardsCollection implements
       } catch (ConfigInvalidException e) {
         throw new ResourceNotFoundException(id);
       } catch (ResourceNotFoundException e) {
-        ProjectState ps = ctl.getProjectState().getParentState();
-        if (ps != null && seen.add(ps.getProject().getNameKey())) {
-          ctl = ps.controlFor(ctl.getCurrentUser());
-          continue;
-        }
         throw new ResourceNotFoundException(id);
       }
     }
+    throw new ResourceNotFoundException(id);
   }
 
   private DashboardResource parse(ProjectControl ctl, String ref, String path,

gerrit-server/src/main/java/com/google/gerrit/server/project/GetDashboard.java

@@ -17,10 +17,8 @@ package com.google.gerrit.server.project;
 import static com.google.gerrit.server.git.GitRepositoryManager.REFS_DASHBOARDS;
 
 import com.google.common.base.Strings;
-import com.google.common.collect.Sets;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.RestReadView;
-import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.project.DashboardsCollection.DashboardInfo;
 import com.google.inject.Inject;
 
@@ -28,7 +26,6 @@ import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.kohsuke.args4j.Option;
 
 import java.io.IOException;
-import java.util.Set;
 
 class GetDashboard implements RestReadView<DashboardResource> {
   private final DashboardsCollection dashboards;
@@ -78,10 +75,7 @@ class GetDashboard implements RestReadView<DashboardResource> {
       throw new ResourceNotFoundException();
     }
 
-    Set<Project.NameKey> seen = Sets.newHashSet();
-    seen.add(ctl.getProject().getNameKey());
-    ProjectState ps = ctl.getProjectState().getParentState();
-    while (ps != null && seen.add(ps.getProject().getNameKey())) {
+    for (ProjectState ps : ctl.getProjectState().tree()) {
       id = ps.getProject().getDefaultDashboard();
       if ("default".equals(id)) {
         throw new ResourceNotFoundException();
@@ -89,7 +83,6 @@ class GetDashboard implements RestReadView<DashboardResource> {
         ctl = ps.controlFor(ctl.getCurrentUser());
         return dashboards.parse(new ProjectResource(ctl), id);
       }
-      ps = ps.getParentState();
     }
     throw new ResourceNotFoundException();
   }

gerrit-server/src/main/java/com/google/gerrit/server/project/ListDashboards.java

@@ -17,7 +17,6 @@ package com.google.gerrit.server.project;
 import static com.google.gerrit.server.git.GitRepositoryManager.REFS_DASHBOARDS;
 
 import com.google.common.collect.Lists;
-import com.google.common.collect.Sets;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.reviewdb.client.Project;
@@ -39,7 +38,6 @@ import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.util.List;
-import java.util.Set;
 
 class ListDashboards implements RestReadView<ProjectResource> {
   private static final Logger log = LoggerFactory.getLogger(DashboardsCollection.class);
@@ -64,9 +62,9 @@ class ListDashboards implements RestReadView<ProjectResource> {
     }
 
     List<List<DashboardInfo>> all = Lists.newArrayList();
-    Set<Project.NameKey> seen = Sets.newHashSet();
     boolean setDefault = true;
-    for (;;) {
+    for (ProjectState ps : ctl.getProjectState().tree()) {
+      ctl = ps.controlFor(ctl.getCurrentUser());
       if (ctl.isVisible()) {
         List<DashboardInfo> list = scan(ctl, project, setDefault);
         for (DashboardInfo d : list) {
@@ -78,12 +76,6 @@ class ListDashboards implements RestReadView<ProjectResource> {
           all.add(list);
         }
       }
-
-      ProjectState ps = ctl.getProjectState().getParentState();
-      if (ps == null || !seen.add(ps.getProject().getNameKey())) {
-        break;
-      }
-      ctl = ps.controlFor(ctl.getCurrentUser());
     }
     return all;
   }

gerrit-server/src/main/java/com/google/gerrit/server/project/ListProjects.java

@@ -239,7 +239,7 @@ public class ListProjects implements RestReadView<TopLevelResource> {
 
         ProjectInfo info = new ProjectInfo();
         if (type == FilterType.PARENT_CANDIDATES) {
-          ProjectState parentState = e.getParentState();
+          ProjectState parentState = Iterables.getFirst(e.parents(), null);
           if (parentState != null
               && !output.keySet().contains(parentState.getProject().getName())
               && !rejected.contains(parentState.getProject().getName())) {
@@ -272,7 +272,7 @@ public class ListProjects implements RestReadView<TopLevelResource> {
 
           info.setName(projectName.get());
           if (showTree && format.isJson()) {
-            ProjectState parent = e.getParentState();
+            ProjectState parent = Iterables.getFirst(e.parents(), null);
             if (parent != null) {
               ProjectControl parentCtrl = parent.controlFor(currentUser);
               if (parentCtrl.isVisible() || parentCtrl.isOwner()) {

gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectHierarchyIterator.java

@@ -0,0 +1,107 @@
+// 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.project;
+
+import com.google.common.base.Joiner;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.server.config.AllProjectsName;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Set;
+
+/**
+ * Iterates from a project up through its parents to All-Projects.
+ * <p>
+ * If a cycle is detected the cycle is broken and All-Projects is visited.
+ */
+class ProjectHierarchyIterator implements Iterator<ProjectState> {
+  private static final Logger log = LoggerFactory.getLogger(ProjectHierarchyIterator.class);
+
+  private final ProjectCache cache;
+  private final AllProjectsName allProjectsName;
+  private final Set<Project.NameKey> seen;
+  private ProjectState next;
+
+  ProjectHierarchyIterator(ProjectCache c,
+      AllProjectsName all,
+      ProjectState firstResult) {
+    cache = c;
+    allProjectsName = all;
+
+    seen = Sets.newLinkedHashSet();
+    seen.add(firstResult.getProject().getNameKey());
+    next = firstResult;
+  }
+
+  @Override
+  public boolean hasNext() {
+    return next != null;
+  }
+
+  @Override
+  public ProjectState next() {
+    ProjectState n = next;
+    if (n == null) {
+      throw new NoSuchElementException();
+    }
+    next = computeNext(n);
+    return n;
+  }
+
+  private ProjectState computeNext(ProjectState n) {
+    Project.NameKey parentName = n.getProject().getParent();
+    if (parentName != null && visit(parentName)) {
+      ProjectState p = cache.get(parentName);
+      if (p != null) {
+        return p;
+      }
+    }
+
+    // Parent does not exist or was already visited.
+    // Fall back to visit All-Projects exactly once.
+    if (seen.add(allProjectsName)) {
+      return cache.get(allProjectsName);
+    }
+    return null;
+  }
+
+  private boolean visit(Project.NameKey parentName) {
+    if (seen.add(parentName)) {
+      return true;
+    }
+
+    List<String> order = Lists.newArrayListWithCapacity(seen.size() + 1);
+    for (Project.NameKey p : seen) {
+      order.add(p.get());
+    }
+    int idx = order.lastIndexOf(parentName.get());
+    order.add(parentName.get());
+    log.warn("Cycle detected in projects: "
+        + Joiner.on(" -> ").join(order.subList(idx, order.size())));
+    return false;
+  }
+
+  @Override
+  public void remove() {
+    throw new UnsupportedOperationException();
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/project/ProjectState.java

@@ -15,8 +15,9 @@
 package com.google.gerrit.server.project;
 
 import com.google.common.base.Function;
+import com.google.common.base.Predicate;
+import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
-import com.google.common.collect.Sets;
 import com.google.gerrit.common.data.AccessSection;
 import com.google.gerrit.common.data.GroupReference;
 import com.google.gerrit.common.data.Permission;
@@ -47,6 +48,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
 
@@ -230,23 +232,9 @@ public class ProjectState {
       return getLocalAccessSections();
     }
 
-    List<SectionMatcher> all = new ArrayList<SectionMatcher>();
-    Set<Project.NameKey> seen = new HashSet<Project.NameKey>();
-    ProjectState allProjects = projectCache.getAllProjects();
-    seen.add(getProject().getNameKey());
-
-    ProjectState s = this;
-    do {
+    List<SectionMatcher> all = Lists.newArrayList();
+    for (ProjectState s : tree()) {
       all.addAll(s.getLocalAccessSections());
-
-      Project.NameKey parent = s.getProject().getParent();
-      if (parent == null || !seen.add(parent)) {
-        break;
-      }
-      s = projectCache.get(parent);
-    } while (s != null);
-    if (seen.add(allProjects.getProject().getNameKey())) {
-      all.addAll(allProjects.getLocalAccessSections());
     }
     return all;
   }
@@ -258,16 +246,11 @@ public class ProjectState {
    *         that has local owners are returned
    */
   public Set<AccountGroup.UUID> getOwners() {
-    Project.NameKey parentName = getProject().getParent();
-    if (!localOwners.isEmpty() || parentName == null || isAllProjects) {
-      return localOwners;
+    for (ProjectState p : tree()) {
+      if (!p.localOwners.isEmpty()) {
+        return p.localOwners;
       }
-
-    ProjectState parent = projectCache.get(parentName);
-    if (parent != null) {
-      return parent.getOwners();
     }
-
     return Collections.emptySet();
   }
 
@@ -275,23 +258,13 @@ public class ProjectState {
    * @return true if any of the groups listed in {@code groups} was declared to
    *         be an owner of this project, or one of its parent projects..
    */
-  boolean isOwner(GroupMembership groups) {
-    Set<Project.NameKey> seen = new HashSet<Project.NameKey>();
-    seen.add(getProject().getNameKey());
-
-    ProjectState s = this;
-    do {
-      if (groups.containsAnyOf(s.localOwners)) {
-        return true;
+  boolean isOwner(final GroupMembership groups) {
+    return Iterables.any(tree(), new Predicate<ProjectState>() {
+      @Override
+      public boolean apply(ProjectState in) {
+        return groups.containsAnyOf(in.localOwners);
       }
-
-      Project.NameKey parent = s.getProject().getParent();
-      if (parent == null || !seen.add(parent)) {
-        break;
-      }
-      s = projectCache.get(parent);
-    } while (s != null);
-    return false;
+    });
   }
 
   public ProjectControl controlFor(final CurrentUser user) {
@@ -299,15 +272,28 @@ public class ProjectState {
   }
 
   /**
-   * @return ProjectState of project's parent. If the project does not have a
-   *         parent, return state of the top level project, All-Projects. If
-   *         this project is All-Projects, return null.
+   * @return an iterable that walks through this project and then the parents of
+   *         this project. Starts from this project and progresses up the
+   *         hierarchy to All-Projects.
    */
-  public ProjectState getParentState() {
-    if (isAllProjects) {
-      return null;
+  public Iterable<ProjectState> tree() {
+    return new Iterable<ProjectState>() {
+      @Override
+      public Iterator<ProjectState> iterator() {
+        return new ProjectHierarchyIterator(
+            projectCache, allProjectsName,
+            ProjectState.this);
       }
-    return projectCache.get(getProject().getParent(allProjectsName));
+    };
+  }
+
+  /**
+   * @return an iterable that walks through the parents of this project. Starts
+   *         from the immediate parent of this project and progresses up the
+   *         hierarchy to All-Projects.
+   */
+  public Iterable<ProjectState> parents() {
+    return Iterables.skip(tree(), 1);
   }
 
   public boolean isAllProjects() {
@@ -351,10 +337,7 @@ public class ProjectState {
   }
 
   private boolean getInheritableBoolean(Function<Project, InheritableBoolean> func) {
-    Set<Project.NameKey> seen = Sets.newHashSet();
-    seen.add(getProject().getNameKey());
-    ProjectState s = this;
-    do {
+    for (ProjectState s : tree()) {
       switch (func.apply(s.getProject())) {
         case TRUE:
           return true;
@@ -362,14 +345,9 @@ public class ProjectState {
           return false;
         case INHERIT:
         default:
-          Project.NameKey parent = s.getProject().getParent(allProjectsName);
-          if (parent != null && seen.add(parent)) {
-            s = projectCache.get(parent);
-          } else {
-            s = null;
+          continue;
       }
     }
-    } while (s != null);
     return false;
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/project/SubmitRuleEvaluator.java

@@ -16,7 +16,6 @@ package com.google.gerrit.server.project;
 
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
-import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.rules.PrologEnvironment;
 import com.google.gerrit.rules.StoredValues;
@@ -31,9 +30,7 @@ import com.googlecode.prolog_cafe.lang.VariableTerm;
 
 import java.io.InputStream;
 import java.util.ArrayList;
-import java.util.HashSet;
 import java.util.List;
-import java.util.Set;
 
 import javax.annotation.Nullable;
 
@@ -184,16 +181,8 @@ public class SubmitRuleEvaluator {
 
   private Term runSubmitFilters(Term results, PrologEnvironment env) throws RuleEvalException {
     ProjectState projectState = projectControl.getProjectState();
-    ProjectState parentState = projectState.getParentState();
     PrologEnvironment childEnv = env;
-    Set<Project.NameKey> projectsSeen = new HashSet<Project.NameKey>();
-    projectsSeen.add(projectState.getProject().getNameKey());
-
-    while (parentState != null) {
-      if (!projectsSeen.add(parentState.getProject().getNameKey())) {
-        // parent has been seen before, stop walk up inheritance tree
-        break;
-      }
+    for (ProjectState parentState : projectState.parents()) {
       PrologEnvironment parentEnv;
       try {
         parentEnv = parentState.newPrologEnvironment();
@@ -223,11 +212,8 @@ public class SubmitRuleEvaluator {
             + " on change " + change.getId() + " of "
             + parentState.getProject().getName(), err);
       }
-
-      parentState = parentState.getParentState();
       childEnv = parentEnv;
     }
-
     return results;
   }
 

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/AdminSetParent.java

@@ -14,6 +14,9 @@
 
 package com.google.gerrit.sshd.commands;
 
+import com.google.common.base.Function;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
 import com.google.gerrit.common.data.GlobalCapability;
 import com.google.gerrit.extensions.annotations.RequiresCapability;
 import com.google.gerrit.reviewdb.client.Project;
@@ -35,6 +38,7 @@ import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -197,17 +201,15 @@ final class AdminSetParent extends SshCommand {
   }
 
   private Set<Project.NameKey> getAllParents(final Project.NameKey projectName) {
-    final Set<Project.NameKey> parents = new HashSet<Project.NameKey>();
-    Project.NameKey p = projectName;
-    while (p != null && parents.add(p)) {
-      final ProjectState e = projectCache.get(p);
-      if (e == null) {
-        // If we can't get it from the cache, pretend it's not present.
-        break;
+    ProjectState ps = projectCache.get(projectName);
+    return ImmutableSet.copyOf(Iterables.transform(
+      ps != null ? ps.parents() : Collections.<ProjectState> emptySet(),
+      new Function<ProjectState, Project.NameKey> () {
+        @Override
+        public Project.NameKey apply(ProjectState in) {
+          return in.getProject().getNameKey();
         }
-      p = e.getProject().getParent(allProjectsName);
-    }
-    return parents;
+      }));
   }
 
   private List<Project> getChildren(final Project.NameKey parentName) {