diff --git a/src/applications/diffusion/herald/HeraldCommitAdapter.php b/src/applications/diffusion/herald/HeraldCommitAdapter.php
index b8ebf9c022..af7c757cd9 100644
--- a/src/applications/diffusion/herald/HeraldCommitAdapter.php
+++ b/src/applications/diffusion/herald/HeraldCommitAdapter.php
@@ -1,396 +1,405 @@
 <?php
 
 final class HeraldCommitAdapter
   extends HeraldAdapter
   implements HarbormasterBuildableAdapterInterface {
 
   protected $diff;
   protected $revision;
 
   protected $commit;
   private $commitDiff;
 
   protected $affectedPaths;
   protected $affectedRevision;
   protected $affectedPackages;
   protected $auditNeededPackages;
 
   private $buildRequests = array();
 
   public function getAdapterApplicationClass() {
     return 'PhabricatorDiffusionApplication';
   }
 
   protected function newObject() {
     return new PhabricatorRepositoryCommit();
   }
 
   public function isTestAdapterForObject($object) {
     return ($object instanceof PhabricatorRepositoryCommit);
   }
 
   public function getAdapterTestDescription() {
     return pht(
       'Test rules which run after a commit is discovered and imported.');
   }
 
   public function newTestAdapter(PhabricatorUser $viewer, $object) {
     return id(clone $this)
       ->setObject($object);
   }
 
   protected function initializeNewAdapter() {
     $this->commit = $this->newObject();
   }
 
   public function setObject($object) {
     $viewer = $this->getViewer();
     $commit_phid = $object->getPHID();
 
     $commit = id(new DiffusionCommitQuery())
       ->setViewer($viewer)
       ->withPHIDs(array($commit_phid))
       ->needCommitData(true)
       ->needIdentities(true)
       ->needAuditRequests(true)
       ->executeOne();
     if (!$commit) {
       throw new Exception(
         pht(
           'Failed to reload commit ("%s") to fetch commit data.',
           $commit_phid));
     }
 
     $this->commit = $commit;
 
     return $this;
   }
 
   public function getObject() {
     return $this->commit;
   }
 
   public function getAdapterContentType() {
     return 'commit';
   }
 
   public function getAdapterContentName() {
     return pht('Commits');
   }
 
   public function getAdapterContentDescription() {
     return pht(
       "React to new commits appearing in tracked repositories.\n".
       "Commit rules can send email, flag commits, trigger audits, ".
       "and run build plans.");
   }
 
   public function supportsRuleType($rule_type) {
     switch ($rule_type) {
       case HeraldRuleTypeConfig::RULE_TYPE_GLOBAL:
       case HeraldRuleTypeConfig::RULE_TYPE_PERSONAL:
       case HeraldRuleTypeConfig::RULE_TYPE_OBJECT:
         return true;
       default:
         return false;
     }
   }
 
   public function canTriggerOnObject($object) {
     if ($object instanceof PhabricatorRepository) {
       return true;
     }
     if ($object instanceof PhabricatorProject) {
       return true;
     }
     return false;
   }
 
   public function getTriggerObjectPHIDs() {
     $project_type = PhabricatorProjectObjectHasProjectEdgeType::EDGECONST;
 
     $repository_phid = $this->getRepository()->getPHID();
     $commit_phid = $this->getObject()->getPHID();
 
     $phids = array();
     $phids[] = $commit_phid;
     $phids[] = $repository_phid;
 
     // NOTE: This is projects for the repository, not for the commit. When
     // Herald evaluates, commits normally can not have any project tags yet.
     $repository_project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
       $repository_phid,
       $project_type);
     foreach ($repository_project_phids as $phid) {
       $phids[] = $phid;
     }
 
     $phids = array_unique($phids);
     $phids = array_values($phids);
 
     return $phids;
   }
 
   public function explainValidTriggerObjects() {
     return pht('This rule can trigger for **repositories** and **projects**.');
   }
 
   public function getHeraldName() {
     return $this->commit->getMonogram();
   }
 
   public function loadAffectedPaths() {
     $viewer = $this->getViewer();
 
     if ($this->affectedPaths === null) {
       $result = PhabricatorOwnerPathQuery::loadAffectedPaths(
         $this->getRepository(),
         $this->commit,
         $viewer);
       $this->affectedPaths = $result;
     }
 
     return $this->affectedPaths;
   }
 
   public function loadAffectedPackages() {
     if ($this->affectedPackages === null) {
       $packages = PhabricatorOwnersPackage::loadAffectedPackages(
         $this->getRepository(),
         $this->loadAffectedPaths());
       $this->affectedPackages = $packages;
     }
     return $this->affectedPackages;
   }
 
   public function loadAuditNeededPackages() {
     if ($this->auditNeededPackages === null) {
       $status_arr = array(
         PhabricatorAuditRequestStatus::AUDIT_REQUIRED,
         PhabricatorAuditRequestStatus::CONCERNED,
       );
       $requests = id(new PhabricatorRepositoryAuditRequest())
           ->loadAllWhere(
         'commitPHID = %s AND auditStatus IN (%Ls)',
         $this->commit->getPHID(),
         $status_arr);
       $this->auditNeededPackages = $requests;
     }
     return $this->auditNeededPackages;
   }
 
   public function loadDifferentialRevision() {
     if ($this->affectedRevision === null) {
       $viewer = $this->getViewer();
 
       // NOTE: The viewer here is omnipotent, which means that Herald discloses
       // some information users do not normally have access to when rules load
       // the revision related to a commit. See D20468.
 
       // A user who wants to learn about "Dxyz" can write a Herald rule which
       // uses all the "Related revision..." fields, then push a commit which
       // contains "Differential Revision: Dxyz" in the message to make Herald
       // evaluate the commit with "Dxyz" as the related revision.
 
       // At time of writing, this commit will link to the revision and the
       // transcript for the commit will disclose some information about the
       // revision (like reviewers, subscribers, and build status) which the
       // commit author could not otherwise see.
 
       // For now, we just accept this. The disclosures are relatively
       // uninteresting and you have to jump through a lot of hoops (and leave
       // a lot of evidence) to get this information.
 
       $revision = DiffusionCommitRevisionQuery::loadRevisionForCommit(
         $viewer,
         $this->getObject());
       if ($revision) {
         $this->affectedRevision = $revision;
       } else {
         $this->affectedRevision = false;
       }
     }
 
     return $this->affectedRevision;
   }
 
   public static function getEnormousByteLimit() {
     return 256 * 1024 * 1024; // 256MB. See T13142 and T13143.
   }
 
   public static function getEnormousTimeLimit() {
     return 60 * 15; // 15 Minutes
   }
 
   private function loadCommitDiff() {
     $viewer = $this->getViewer();
 
     $byte_limit = self::getEnormousByteLimit();
     $time_limit = self::getEnormousTimeLimit();
 
     $diff_info = $this->callConduit(
       'diffusion.rawdiffquery',
       array(
         'commit' => $this->commit->getCommitIdentifier(),
         'timeout' => $time_limit,
         'byteLimit' => $byte_limit,
         'linesOfContext' => 0,
       ));
 
     if ($diff_info['tooHuge']) {
       throw new Exception(
         pht(
           'The raw text of this change is enormous (larger than %s byte(s)). '.
           'Herald can not process it.',
           new PhutilNumber($byte_limit)));
     }
 
     if ($diff_info['tooSlow']) {
       throw new Exception(
         pht(
           'The raw text of this change took too long to process (longer '.
           'than %s second(s)). Herald can not process it.',
           new PhutilNumber($time_limit)));
     }
 
     $file_phid = $diff_info['filePHID'];
     $diff_file = id(new PhabricatorFileQuery())
       ->setViewer($viewer)
       ->withPHIDs(array($file_phid))
       ->executeOne();
     if (!$diff_file) {
       throw new Exception(
         pht(
           'Failed to load diff ("%s") for this change.',
           $file_phid));
     }
 
     $raw = $diff_file->loadFileData();
 
+    // See T13667. This happens when a commit is empty and affects no files.
+    if (!strlen($raw)) {
+      return false;
+    }
+
     $parser = new ArcanistDiffParser();
     $changes = $parser->parseDiff($raw);
 
     $diff = DifferentialDiff::newEphemeralFromRawChanges(
       $changes);
     return $diff;
   }
 
   public function isDiffEnormous() {
     $this->loadDiffContent('*');
     return ($this->commitDiff instanceof Exception);
   }
 
   public function loadDiffContent($type) {
     if ($this->commitDiff === null) {
       try {
         $this->commitDiff = $this->loadCommitDiff();
       } catch (Exception $ex) {
         $this->commitDiff = $ex;
         phlog($ex);
       }
     }
 
+    if ($this->commitDiff === false) {
+      return array();
+    }
+
     if ($this->commitDiff instanceof Exception) {
       $ex = $this->commitDiff;
       $ex_class = get_class($ex);
       $ex_message = pht('Failed to load changes: %s', $ex->getMessage());
 
       return array(
         '<'.$ex_class.'>' => $ex_message,
       );
     }
 
     $changes = $this->commitDiff->getChangesets();
 
     $result = array();
     foreach ($changes as $change) {
       $lines = array();
       foreach ($change->getHunks() as $hunk) {
         switch ($type) {
           case '-':
             $lines[] = $hunk->makeOldFile();
             break;
           case '+':
             $lines[] = $hunk->makeNewFile();
             break;
           case '*':
             $lines[] = $hunk->makeChanges();
             break;
           default:
             throw new Exception(pht("Unknown content selection '%s'!", $type));
         }
       }
       $result[$change->getFilename()] = implode("\n", $lines);
     }
 
     return $result;
   }
 
   public function loadIsMergeCommit() {
     $parents = $this->callConduit(
       'diffusion.commitparentsquery',
       array(
         'commit' => $this->getObject()->getCommitIdentifier(),
       ));
 
     return (count($parents) > 1);
   }
 
   private function callConduit($method, array $params) {
     $viewer = $this->getViewer();
 
     $drequest = DiffusionRequest::newFromDictionary(
       array(
         'user' => $viewer,
         'repository' => $this->getRepository(),
         'commit' => $this->commit->getCommitIdentifier(),
       ));
 
     return DiffusionQuery::callConduitWithDiffusionRequest(
       $viewer,
       $drequest,
       $method,
       $params);
   }
 
   private function getRepository() {
     return $this->getObject()->getRepository();
   }
 
   public function getAuthorPHID() {
     return $this->getObject()->getEffectiveAuthorPHID();
   }
 
   public function getCommitterPHID() {
     $commit = $this->getObject();
 
     if ($commit->hasCommitterIdentity()) {
       $identity = $commit->getCommitterIdentity();
       return $identity->getCurrentEffectiveUserPHID();
     }
 
     return null;
   }
 
 
 /* -(  HarbormasterBuildableAdapterInterface  )------------------------------ */
 
 
   public function getHarbormasterBuildablePHID() {
     return $this->getObject()->getPHID();
   }
 
   public function getHarbormasterContainerPHID() {
     return $this->getObject()->getRepository()->getPHID();
   }
 
   public function getQueuedHarbormasterBuildRequests() {
     return $this->buildRequests;
   }
 
   public function queueHarbormasterBuildRequest(
     HarbormasterBuildRequest $request) {
     $this->buildRequests[] = $request;
   }
 
 }
diff --git a/src/applications/diffusion/query/pathchange/DiffusionPathChangeQuery.php b/src/applications/diffusion/query/pathchange/DiffusionPathChangeQuery.php
index 850c06f105..98798582a7 100644
--- a/src/applications/diffusion/query/pathchange/DiffusionPathChangeQuery.php
+++ b/src/applications/diffusion/query/pathchange/DiffusionPathChangeQuery.php
@@ -1,117 +1,122 @@
 <?php
 
 final class DiffusionPathChangeQuery extends Phobject {
 
   private $request;
   private $limit;
 
   public function setLimit($limit) {
     $this->limit = $limit;
     return $this;
   }
 
   public function getLimit() {
     return $this->limit;
   }
 
   private function __construct() {
     // <private>
   }
 
   public static function newFromDiffusionRequest(
     DiffusionRequest $request) {
     $query = new DiffusionPathChangeQuery();
     $query->request = $request;
 
     return $query;
   }
 
   protected function getRequest() {
     return $this->request;
   }
 
   public function loadChanges() {
     return $this->executeQuery();
   }
 
   protected function executeQuery() {
 
     $drequest = $this->getRequest();
     $repository = $drequest->getRepository();
 
     $commit = $drequest->loadCommit();
 
     $conn_r = $repository->establishConnection('r');
 
     if ($this->limit) {
       $limit = qsprintf(
         $conn_r,
         'LIMIT %d',
         $this->limit + 1);
     } else {
       $limit = qsprintf($conn_r, '');
     }
 
     $raw_changes = queryfx_all(
       $conn_r,
       'SELECT c.*, p.path pathName, t.path targetPathName,
           i.commitIdentifier targetCommitIdentifier
         FROM %T c
           LEFT JOIN %T p ON c.pathID = p.id
           LEFT JOIN %T t ON c.targetPathID = t.id
           LEFT JOIN %T i ON c.targetCommitID = i.id
         WHERE c.commitID = %d AND isDirect = 1 %Q',
       PhabricatorRepository::TABLE_PATHCHANGE,
       PhabricatorRepository::TABLE_PATH,
       PhabricatorRepository::TABLE_PATH,
       $commit->getTableName(),
       $commit->getID(),
       $limit);
 
     $limited = $this->limit && (count($raw_changes) > $this->limit);
     if ($limited) {
       $raw_changes = array_slice($raw_changes, 0, $this->limit);
     }
 
     $changes = array();
 
     $raw_changes = isort($raw_changes, 'pathName');
     foreach ($raw_changes as $raw_change) {
       $type = $raw_change['changeType'];
       if ($type == DifferentialChangeType::TYPE_CHILD) {
         continue;
       }
 
       $change = new DiffusionPathChange();
       $change->setPath(ltrim($raw_change['pathName'], '/'));
       $change->setChangeType($raw_change['changeType']);
       $change->setFileType($raw_change['fileType']);
       $change->setCommitIdentifier($commit->getCommitIdentifier());
 
-      $change->setTargetPath(ltrim($raw_change['targetPathName'], '/'));
+      $target_path = $raw_change['targetPathName'];
+      if ($target_path !== null) {
+        $target_path = ltrim($target_path, '/');
+      }
+      $change->setTargetPath($target_path);
+
       $change->setTargetCommitIdentifier($raw_change['targetCommitIdentifier']);
 
       $id = $raw_change['pathID'];
       $changes[$id] = $change;
     }
 
     // Deduce the away paths by examining all the changes, if we loaded them
     // all.
 
     if (!$limited) {
       $away = array();
       foreach ($changes as $change) {
         if ($change->getTargetPath()) {
           $away[$change->getTargetPath()][] = $change->getPath();
         }
       }
       foreach ($changes as $change) {
         if (isset($away[$change->getPath()])) {
           $change->setAwayPaths($away[$change->getPath()]);
         }
       }
     }
 
     return $changes;
   }
 }
diff --git a/src/applications/diffusion/request/DiffusionRequest.php b/src/applications/diffusion/request/DiffusionRequest.php
index 49ea305908..e6e4c5b16d 100644
--- a/src/applications/diffusion/request/DiffusionRequest.php
+++ b/src/applications/diffusion/request/DiffusionRequest.php
@@ -1,698 +1,700 @@
 <?php
 
 /**
  * Contains logic to parse Diffusion requests, which have a complicated URI
  * structure.
  *
  * @task new Creating Requests
  * @task uri Managing Diffusion URIs
  */
 abstract class DiffusionRequest extends Phobject {
 
   protected $path;
   protected $line;
   protected $branch;
   protected $lint;
 
   protected $symbolicCommit;
   protected $symbolicType;
   protected $stableCommit;
 
   protected $repository;
   protected $repositoryCommit;
   protected $repositoryCommitData;
 
   private $isClusterRequest = false;
   private $initFromConduit = true;
   private $user;
   private $branchObject = false;
   private $refAlternatives;
 
   final public function supportsBranches() {
     return $this->getRepository()->supportsRefs();
   }
 
   abstract protected function isStableCommit($symbol);
 
   protected function didInitialize() {
     return null;
   }
 
 
 /* -(  Creating Requests  )-------------------------------------------------- */
 
 
   /**
    * Create a new synthetic request from a parameter dictionary. If you need
    * a @{class:DiffusionRequest} object in order to issue a DiffusionQuery, you
    * can use this method to build one.
    *
    * Parameters are:
    *
    *   - `repository` Repository object or identifier.
    *   - `user` Viewing user. Required if `repository` is an identifier.
    *   - `branch` Optional, branch name.
    *   - `path` Optional, file path.
    *   - `commit` Optional, commit identifier.
    *   - `line` Optional, line range.
    *
    * @param   map                 See documentation.
    * @return  DiffusionRequest    New request object.
    * @task new
    */
   final public static function newFromDictionary(array $data) {
     $repository_key = 'repository';
     $identifier_key = 'callsign';
     $viewer_key = 'user';
 
     $repository = idx($data, $repository_key);
     $identifier = idx($data, $identifier_key);
 
     $have_repository = ($repository !== null);
     $have_identifier = ($identifier !== null);
 
     if ($have_repository && $have_identifier) {
       throw new Exception(
         pht(
           'Specify "%s" or "%s", but not both.',
           $repository_key,
           $identifier_key));
     }
 
     if (!$have_repository && !$have_identifier) {
       throw new Exception(
         pht(
           'One of "%s" and "%s" is required.',
           $repository_key,
           $identifier_key));
     }
 
     if ($have_repository) {
       if (!($repository instanceof PhabricatorRepository)) {
         if (empty($data[$viewer_key])) {
           throw new Exception(
             pht(
               'Parameter "%s" is required if "%s" is provided.',
               $viewer_key,
               $identifier_key));
         }
 
         $identifier = $repository;
         $repository = null;
       }
     }
 
     if ($identifier !== null) {
       $object = self::newFromIdentifier(
         $identifier,
         $data[$viewer_key],
         idx($data, 'edit'));
     } else {
       $object = self::newFromRepository($repository);
     }
 
     if (!$object) {
       return null;
     }
 
     $object->initializeFromDictionary($data);
 
     return $object;
   }
 
   /**
    * Internal.
    *
    * @task new
    */
   private function __construct() {
     // <private>
   }
 
 
   /**
    * Internal. Use @{method:newFromDictionary}, not this method.
    *
    * @param   string              Repository identifier.
    * @param   PhabricatorUser     Viewing user.
    * @return  DiffusionRequest    New request object.
    * @task new
    */
   private static function newFromIdentifier(
     $identifier,
     PhabricatorUser $viewer,
     $need_edit = false) {
 
     $query = id(new PhabricatorRepositoryQuery())
       ->setViewer($viewer)
       ->withIdentifiers(array($identifier))
       ->needProfileImage(true)
       ->needURIs(true);
 
     if ($need_edit) {
       $query->requireCapabilities(
         array(
           PhabricatorPolicyCapability::CAN_VIEW,
           PhabricatorPolicyCapability::CAN_EDIT,
         ));
     }
 
     $repository = $query->executeOne();
 
     if (!$repository) {
       return null;
     }
 
     return self::newFromRepository($repository);
   }
 
 
   /**
    * Internal. Use @{method:newFromDictionary}, not this method.
    *
    * @param   PhabricatorRepository   Repository object.
    * @return  DiffusionRequest        New request object.
    * @task new
    */
   private static function newFromRepository(
     PhabricatorRepository $repository) {
 
     $map = array(
       PhabricatorRepositoryType::REPOSITORY_TYPE_GIT => 'DiffusionGitRequest',
       PhabricatorRepositoryType::REPOSITORY_TYPE_SVN => 'DiffusionSvnRequest',
       PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL =>
         'DiffusionMercurialRequest',
     );
 
     $class = idx($map, $repository->getVersionControlSystem());
 
     if (!$class) {
       throw new Exception(pht('Unknown version control system!'));
     }
 
     $object = new $class();
 
     $object->repository = $repository;
 
     return $object;
   }
 
 
   /**
    * Internal. Use @{method:newFromDictionary}, not this method.
    *
    * @param map Map of parsed data.
    * @return void
    * @task new
    */
   private function initializeFromDictionary(array $data) {
     $blob = idx($data, 'blob');
-    if (strlen($blob)) {
+    if (phutil_nonempty_string($blob)) {
       $blob = self::parseRequestBlob($blob, $this->supportsBranches());
       $data = $blob + $data;
     }
 
     $this->path = idx($data, 'path');
     $this->line = idx($data, 'line');
     $this->initFromConduit = idx($data, 'initFromConduit', true);
     $this->lint = idx($data, 'lint');
 
     $this->symbolicCommit = idx($data, 'commit');
     if ($this->supportsBranches()) {
       $this->branch = idx($data, 'branch');
     }
 
     if (!$this->getUser()) {
       $user = idx($data, 'user');
       if (!$user) {
         throw new Exception(
           pht(
             'You must provide a %s in the dictionary!',
             'PhabricatorUser'));
       }
       $this->setUser($user);
     }
 
     $this->didInitialize();
   }
 
   final public function setUser(PhabricatorUser $user) {
     $this->user = $user;
     return $this;
   }
   final public function getUser() {
     return $this->user;
   }
 
   public function getRepository() {
     return $this->repository;
   }
 
   public function setPath($path) {
     $this->path = $path;
     return $this;
   }
 
   public function getPath() {
     return $this->path;
   }
 
   public function getLine() {
     return $this->line;
   }
 
   public function getCommit() {
 
     // TODO: Probably remove all of this.
 
     if ($this->getSymbolicCommit() !== null) {
       return $this->getSymbolicCommit();
     }
 
     return $this->getStableCommit();
   }
 
   /**
    * Get the symbolic commit associated with this request.
    *
    * A symbolic commit may be a commit hash, an abbreviated commit hash, a
    * branch name, a tag name, or an expression like "HEAD^^^". The symbolic
    * commit may also be absent.
    *
    * This method always returns the symbol present in the original request,
    * in unmodified form.
    *
    * See also @{method:getStableCommit}.
    *
    * @return string|null  Symbolic commit, if one was present in the request.
    */
   public function getSymbolicCommit() {
     return $this->symbolicCommit;
   }
 
 
   /**
    * Modify the request to move the symbolic commit elsewhere.
    *
    * @param string New symbolic commit.
    * @return this
    */
   public function updateSymbolicCommit($symbol) {
     $this->symbolicCommit = $symbol;
     $this->symbolicType = null;
     $this->stableCommit = null;
     return $this;
   }
 
 
   /**
    * Get the ref type (`commit` or `tag`) of the location associated with this
    * request.
    *
    * If a symbolic commit is present in the request, this method identifies
    * the type of the symbol. Otherwise, it identifies the type of symbol of
    * the location the request is implicitly associated with. This will probably
    * always be `commit`.
    *
    * @return string   Symbolic commit type (`commit` or `tag`).
    */
   public function getSymbolicType() {
     if ($this->symbolicType === null) {
       // As a side effect, this resolves the symbolic type.
       $this->getStableCommit();
     }
     return $this->symbolicType;
   }
 
 
   /**
    * Retrieve the stable, permanent commit name identifying the repository
    * location associated with this request.
    *
    * This returns a non-symbolic identifier for the current commit: in Git and
    * Mercurial, a 40-character SHA1; in SVN, a revision number.
    *
    * See also @{method:getSymbolicCommit}.
    *
    * @return string Stable commit name, like a git hash or SVN revision. Not
    *                a symbolic commit reference.
    */
   public function getStableCommit() {
     if (!$this->stableCommit) {
       if ($this->isStableCommit($this->symbolicCommit)) {
         $this->stableCommit = $this->symbolicCommit;
         $this->symbolicType = 'commit';
       } else {
         $this->queryStableCommit();
       }
     }
     return $this->stableCommit;
   }
 
 
   public function getBranch() {
     return $this->branch;
   }
 
   public function getLint() {
     return $this->lint;
   }
 
   protected function getArcanistBranch() {
     return $this->getBranch();
   }
 
   public function loadBranch() {
     // TODO: Get rid of this and do real Queries on real objects.
 
     if ($this->branchObject === false) {
       $this->branchObject = PhabricatorRepositoryBranch::loadBranch(
         $this->getRepository()->getID(),
         $this->getArcanistBranch());
     }
 
     return $this->branchObject;
   }
 
   public function loadCoverage() {
     // TODO: This should also die.
     $branch = $this->loadBranch();
     if (!$branch) {
       return;
     }
 
     $path = $this->getPath();
     $path_map = id(new DiffusionPathIDQuery(array($path)))->loadPathIDs();
 
     $coverage_row = queryfx_one(
       id(new PhabricatorRepository())->establishConnection('r'),
       'SELECT * FROM %T WHERE branchID = %d AND pathID = %d
         ORDER BY commitID DESC LIMIT 1',
       'repository_coverage',
       $branch->getID(),
       $path_map[$path]);
 
     if (!$coverage_row) {
       return null;
     }
 
     return idx($coverage_row, 'coverage');
   }
 
 
   public function loadCommit() {
     if (empty($this->repositoryCommit)) {
       $repository = $this->getRepository();
 
       $commit = id(new DiffusionCommitQuery())
         ->setViewer($this->getUser())
         ->withRepository($repository)
         ->withIdentifiers(array($this->getStableCommit()))
         ->executeOne();
       if ($commit) {
         $commit->attachRepository($repository);
       }
       $this->repositoryCommit = $commit;
     }
     return $this->repositoryCommit;
   }
 
   public function loadCommitData() {
     if (empty($this->repositoryCommitData)) {
       $commit = $this->loadCommit();
       $data = id(new PhabricatorRepositoryCommitData())->loadOneWhere(
         'commitID = %d',
         $commit->getID());
       if (!$data) {
         $data = new PhabricatorRepositoryCommitData();
         $data->setCommitMessage(
           pht('(This commit has not been fully parsed yet.)'));
       }
       $this->repositoryCommitData = $data;
     }
     return $this->repositoryCommitData;
   }
 
 /* -(  Managing Diffusion URIs  )-------------------------------------------- */
 
 
   public function generateURI(array $params) {
     if (empty($params['stable'])) {
       $default_commit = $this->getSymbolicCommit();
     } else {
       $default_commit = $this->getStableCommit();
     }
 
     $defaults = array(
       'path'      => $this->getPath(),
       'branch'    => $this->getBranch(),
       'commit'    => $default_commit,
       'lint'      => idx($params, 'lint', $this->getLint()),
     );
 
     foreach ($defaults as $key => $val) {
       if (!isset($params[$key])) { // Overwrite NULL.
         $params[$key] = $val;
       }
     }
 
     return $this->getRepository()->generateURI($params);
   }
 
   /**
    * Internal. Public only for unit tests.
    *
    * Parse the request URI into components.
    *
    * @param   string  URI blob.
    * @param   bool    True if this VCS supports branches.
    * @return  map     Parsed URI.
    *
    * @task uri
    */
   public static function parseRequestBlob($blob, $supports_branches) {
     $result = array(
       'branch'  => null,
       'path'    => null,
       'commit'  => null,
       'line'    => null,
     );
 
     $matches = null;
 
     if ($supports_branches) {
       // Consume the front part of the URI, up to the first "/". This is the
       // path-component encoded branch name.
       if (preg_match('@^([^/]+)/@', $blob, $matches)) {
         $result['branch'] = phutil_unescape_uri_path_component($matches[1]);
         $blob = substr($blob, strlen($matches[1]) + 1);
       }
     }
 
     // Consume the back part of the URI, up to the first "$". Use a negative
     // lookbehind to prevent matching '$$'. We double the '$' symbol when
     // encoding so that files with names like "money/$100" will survive.
     $pattern = '@(?:(?:^|[^$])(?:[$][$])*)[$]([\d,-]+)$@';
     if (preg_match($pattern, $blob, $matches)) {
       $result['line'] = $matches[1];
       $blob = substr($blob, 0, -(strlen($matches[1]) + 1));
     }
 
     // We've consumed the line number if it exists, so unescape "$" in the
     // rest of the string.
     $blob = str_replace('$$', '$', $blob);
 
     // Consume the commit name, stopping on ';;'. We allow any character to
     // appear in commits names, as they can sometimes be symbolic names (like
     // tag names or refs).
     if (preg_match('@(?:(?:^|[^;])(?:;;)*);([^;].*)$@', $blob, $matches)) {
       $result['commit'] = $matches[1];
       $blob = substr($blob, 0, -(strlen($matches[1]) + 1));
     }
 
     // We've consumed the commit if it exists, so unescape ";" in the rest
     // of the string.
     $blob = str_replace(';;', ';', $blob);
 
     if (strlen($blob)) {
       $result['path'] = $blob;
     }
 
-    $parts = explode('/', $result['path']);
-    foreach ($parts as $part) {
-      // Prevent any hyjinx since we're ultimately shipping this to the
-      // filesystem under a lot of workflows.
-      if ($part == '..') {
-        throw new Exception(pht('Invalid path URI.'));
+    if ($result['path'] !== null) {
+      $parts = explode('/', $result['path']);
+      foreach ($parts as $part) {
+        // Prevent any hyjinx since we're ultimately shipping this to the
+        // filesystem under a lot of workflows.
+        if ($part == '..') {
+          throw new Exception(pht('Invalid path URI.'));
+        }
       }
     }
 
     return $result;
   }
 
   /**
    * Check that the working copy of the repository is present and readable.
    *
    * @param   string  Path to the working copy.
    */
   protected function validateWorkingCopy($path) {
     if (!is_readable(dirname($path))) {
       $this->raisePermissionException();
     }
 
     if (!Filesystem::pathExists($path)) {
       $this->raiseCloneException();
     }
   }
 
   protected function raisePermissionException() {
     $host = php_uname('n');
     throw new DiffusionSetupException(
       pht(
         'The clone of this repository ("%s") on the local machine ("%s") '.
         'could not be read. Ensure that the repository is in a '.
         'location where the web server has read permissions.',
         $this->getRepository()->getDisplayName(),
         $host));
   }
 
   protected function raiseCloneException() {
     $host = php_uname('n');
     throw new DiffusionSetupException(
       pht(
         'The working copy for this repository ("%s") has not been cloned yet '.
         'on this machine ("%s"). Make sure you havestarted the Phabricator '.
         'daemons. If this problem persists for longer than a clone should '.
         'take, check the daemon logs (in the Daemon Console) to see if there '.
         'were errors cloning the repository. Consult the "Diffusion User '.
         'Guide" in the documentation for help setting up repositories.',
         $this->getRepository()->getDisplayName(),
         $host));
   }
 
   private function queryStableCommit() {
     $types = array();
     if ($this->symbolicCommit) {
       $ref = $this->symbolicCommit;
     } else {
       if ($this->supportsBranches()) {
         $ref = $this->getBranch();
         $types = array(
           PhabricatorRepositoryRefCursor::TYPE_BRANCH,
         );
       } else {
         $ref = 'HEAD';
       }
     }
 
     $results = $this->resolveRefs(array($ref), $types);
 
     $matches = idx($results, $ref, array());
     if (!$matches) {
       $message = pht(
         'Ref "%s" does not exist in this repository.',
         $ref);
       throw id(new DiffusionRefNotFoundException($message))
         ->setRef($ref);
     }
 
     if (count($matches) > 1) {
       $match = $this->chooseBestRefMatch($ref, $matches);
     } else {
       $match = head($matches);
     }
 
     $this->stableCommit = $match['identifier'];
     $this->symbolicType = $match['type'];
   }
 
   public function getRefAlternatives() {
     // Make sure we've resolved the reference into a stable commit first.
     try {
       $this->getStableCommit();
     } catch (DiffusionRefNotFoundException $ex) {
       // If we have a bad reference, just return the empty set of
       // alternatives.
     }
     return $this->refAlternatives;
   }
 
   private function chooseBestRefMatch($ref, array $results) {
     // First, filter out less-desirable matches.
     $candidates = array();
     foreach ($results as $result) {
       // Exclude closed heads.
       if ($result['type'] == 'branch') {
         if (idx($result, 'closed')) {
           continue;
         }
       }
 
       $candidates[] = $result;
     }
 
     // If we filtered everything, undo the filtering.
     if (!$candidates) {
       $candidates = $results;
     }
 
     // TODO: Do a better job of selecting the best match?
     $match = head($candidates);
 
     // After choosing the best alternative, save all the alternatives so the
     // UI can show them to the user.
     if (count($candidates) > 1) {
       $this->refAlternatives = $candidates;
     }
 
     return $match;
   }
 
   public function resolveRefs(array $refs, array $types = array()) {
     // First, try to resolve refs from fast cache sources.
     $cached_query = id(new DiffusionCachedResolveRefsQuery())
       ->setRepository($this->getRepository())
       ->withRefs($refs);
 
     if ($types) {
       $cached_query->withTypes($types);
     }
 
     $cached_results = $cached_query->execute();
 
     // Throw away all the refs we resolved. Hopefully, we'll throw away
     // everything here.
     foreach ($refs as $key => $ref) {
       if (isset($cached_results[$ref])) {
         unset($refs[$key]);
       }
     }
 
     // If we couldn't pull everything out of the cache, execute the underlying
     // VCS operation.
     if ($refs) {
       $vcs_results = DiffusionQuery::callConduitWithDiffusionRequest(
         $this->getUser(),
         $this,
         'diffusion.resolverefs',
         array(
           'types' => $types,
           'refs' => $refs,
         ));
     } else {
       $vcs_results = array();
     }
 
     return $vcs_results + $cached_results;
   }
 
   public function setIsClusterRequest($is_cluster_request) {
     $this->isClusterRequest = $is_cluster_request;
     return $this;
   }
 
   public function getIsClusterRequest() {
     return $this->isClusterRequest;
   }
 
 }
diff --git a/src/applications/macro/query/PhabricatorMacroQuery.php b/src/applications/macro/query/PhabricatorMacroQuery.php
index 7635b68b73..7261803888 100644
--- a/src/applications/macro/query/PhabricatorMacroQuery.php
+++ b/src/applications/macro/query/PhabricatorMacroQuery.php
@@ -1,268 +1,268 @@
 <?php
 
 final class PhabricatorMacroQuery
   extends PhabricatorCursorPagedPolicyAwareQuery {
 
   private $ids;
   private $phids;
   private $authorPHIDs;
   private $names;
   private $nameLike;
   private $namePrefix;
   private $dateCreatedAfter;
   private $dateCreatedBefore;
   private $flagColor;
 
   private $needFiles;
 
   private $status = 'status-any';
   const STATUS_ANY = 'status-any';
   const STATUS_ACTIVE = 'status-active';
   const STATUS_DISABLED = 'status-disabled';
 
   public static function getStatusOptions() {
     return array(
       self::STATUS_ACTIVE   => pht('Active Macros'),
       self::STATUS_DISABLED => pht('Disabled Macros'),
       self::STATUS_ANY      => pht('Active and Disabled Macros'),
     );
   }
 
   public static function getFlagColorsOptions() {
     $options = array(
       '-1' => pht('(No Filtering)'),
       '-2' => pht('(Marked With Any Flag)'),
     );
 
     foreach (PhabricatorFlagColor::getColorNameMap() as $color => $name) {
       $options[$color] = $name;
     }
 
     return $options;
   }
 
   public function withIDs(array $ids) {
     $this->ids = $ids;
     return $this;
   }
 
   public function withPHIDs(array $phids) {
     $this->phids = $phids;
     return $this;
   }
 
   public function withAuthorPHIDs(array $author_phids) {
     $this->authorPHIDs = $author_phids;
     return $this;
   }
 
   public function withNameLike($name) {
     $this->nameLike = $name;
     return $this;
   }
 
   public function withNames(array $names) {
     $this->names = $names;
     return $this;
   }
 
   public function withNamePrefix($prefix) {
     $this->namePrefix = $prefix;
     return $this;
   }
 
   public function withStatus($status) {
     $this->status = $status;
     return $this;
   }
 
   public function withDateCreatedBefore($date_created_before) {
     $this->dateCreatedBefore = $date_created_before;
     return $this;
   }
 
   public function withDateCreatedAfter($date_created_after) {
     $this->dateCreatedAfter = $date_created_after;
     return $this;
   }
 
   public function withFlagColor($flag_color) {
     $this->flagColor = $flag_color;
     return $this;
   }
 
   public function needFiles($need_files) {
     $this->needFiles = $need_files;
     return $this;
   }
 
   public function newResultObject() {
     return new PhabricatorFileImageMacro();
   }
 
   protected function loadPage() {
     return $this->loadStandardPage(new PhabricatorFileImageMacro());
   }
 
   protected function buildWhereClauseParts(AphrontDatabaseConnection $conn) {
     $where = parent::buildWhereClauseParts($conn);
 
     if ($this->ids !== null) {
       $where[] = qsprintf(
         $conn,
         'm.id IN (%Ld)',
         $this->ids);
     }
 
     if ($this->phids !== null) {
       $where[] = qsprintf(
         $conn,
         'm.phid IN (%Ls)',
         $this->phids);
     }
 
     if ($this->authorPHIDs !== null) {
       $where[] = qsprintf(
         $conn,
         'm.authorPHID IN (%Ls)',
         $this->authorPHIDs);
     }
 
-    if (strlen($this->nameLike)) {
+    if (($this->nameLike !== null) && strlen($this->nameLike)) {
       $where[] = qsprintf(
         $conn,
         'm.name LIKE %~',
         $this->nameLike);
     }
 
     if ($this->names !== null) {
       $where[] = qsprintf(
         $conn,
         'm.name IN (%Ls)',
         $this->names);
     }
 
-    if (strlen($this->namePrefix)) {
+    if (($this->namePrefix !== null) && strlen($this->namePrefix)) {
       $where[] = qsprintf(
         $conn,
         'm.name LIKE %>',
         $this->namePrefix);
     }
 
     switch ($this->status) {
       case self::STATUS_ACTIVE:
         $where[] = qsprintf(
           $conn,
           'm.isDisabled = 0');
         break;
       case self::STATUS_DISABLED:
         $where[] = qsprintf(
           $conn,
           'm.isDisabled = 1');
         break;
       case self::STATUS_ANY:
         break;
       default:
         throw new Exception(pht("Unknown status '%s'!", $this->status));
     }
 
     if ($this->dateCreatedAfter) {
       $where[] = qsprintf(
         $conn,
         'm.dateCreated >= %d',
         $this->dateCreatedAfter);
     }
 
     if ($this->dateCreatedBefore) {
       $where[] = qsprintf(
         $conn,
         'm.dateCreated <= %d',
         $this->dateCreatedBefore);
     }
 
     if ($this->flagColor != '-1' && $this->flagColor !== null) {
       if ($this->flagColor == '-2') {
         $flag_colors = array_keys(PhabricatorFlagColor::getColorNameMap());
       } else {
         $flag_colors = array($this->flagColor);
       }
       $flags = id(new PhabricatorFlagQuery())
         ->withOwnerPHIDs(array($this->getViewer()->getPHID()))
         ->withTypes(array(PhabricatorMacroMacroPHIDType::TYPECONST))
         ->withColors($flag_colors)
         ->setViewer($this->getViewer())
         ->execute();
 
       if (empty($flags)) {
         throw new PhabricatorEmptyQueryException(pht('No matching flags.'));
       } else {
         $where[] = qsprintf(
           $conn,
           'm.phid IN (%Ls)',
           mpull($flags, 'getObjectPHID'));
       }
     }
 
     return $where;
   }
 
   protected function didFilterPage(array $macros) {
     if ($this->needFiles) {
       $file_phids = mpull($macros, 'getFilePHID');
       $files = id(new PhabricatorFileQuery())
         ->setViewer($this->getViewer())
         ->setParentQuery($this)
         ->withPHIDs($file_phids)
         ->execute();
       $files = mpull($files, null, 'getPHID');
 
       foreach ($macros as $key => $macro) {
         $file = idx($files, $macro->getFilePHID());
         if (!$file) {
           unset($macros[$key]);
           continue;
         }
         $macro->attachFile($file);
       }
     }
 
     return $macros;
   }
 
   protected function getPrimaryTableAlias() {
     return 'm';
   }
 
   public function getQueryApplicationClass() {
     return 'PhabricatorMacroApplication';
   }
 
   public function getOrderableColumns() {
     return parent::getOrderableColumns() + array(
       'name' => array(
         'table' => 'm',
         'column' => 'name',
         'type' => 'string',
         'reverse' => true,
         'unique' => true,
       ),
     );
   }
 
   protected function newPagingMapFromPartialObject($object) {
     return array(
       'id' => (int)$object->getID(),
       'name' => $object->getName(),
     );
   }
 
   public function getBuiltinOrders() {
     return array(
       'name' => array(
         'vector' => array('name'),
         'name' => pht('Name'),
       ),
     ) + parent::getBuiltinOrders();
   }
 
 }
diff --git a/src/applications/passphrase/query/PassphraseCredentialQuery.php b/src/applications/passphrase/query/PassphraseCredentialQuery.php
index 2518ad44e5..24f5f7440c 100644
--- a/src/applications/passphrase/query/PassphraseCredentialQuery.php
+++ b/src/applications/passphrase/query/PassphraseCredentialQuery.php
@@ -1,169 +1,169 @@
 <?php
 
 final class PassphraseCredentialQuery
   extends PhabricatorCursorPagedPolicyAwareQuery {
 
   private $ids;
   private $phids;
   private $credentialTypes;
   private $providesTypes;
   private $isDestroyed;
   private $allowConduit;
   private $nameContains;
 
   private $needSecrets;
 
   public function withIDs(array $ids) {
     $this->ids = $ids;
     return $this;
   }
 
   public function withPHIDs(array $phids) {
     $this->phids = $phids;
     return $this;
   }
 
   public function withCredentialTypes(array $credential_types) {
     $this->credentialTypes = $credential_types;
     return $this;
   }
 
   public function withProvidesTypes(array $provides_types) {
     $this->providesTypes = $provides_types;
     return $this;
   }
 
   public function withIsDestroyed($destroyed) {
     $this->isDestroyed = $destroyed;
     return $this;
   }
 
   public function withAllowConduit($allow_conduit) {
     $this->allowConduit = $allow_conduit;
     return $this;
   }
 
   public function withNameContains($name_contains) {
     $this->nameContains = $name_contains;
     return $this;
   }
 
   public function needSecrets($need_secrets) {
     $this->needSecrets = $need_secrets;
     return $this;
   }
 
   public function newResultObject() {
     return new PassphraseCredential();
   }
 
   protected function loadPage() {
     return $this->loadStandardPage($this->newResultObject());
   }
 
   protected function willFilterPage(array $page) {
     if ($this->needSecrets) {
       $secret_ids = mpull($page, 'getSecretID');
       $secret_ids = array_filter($secret_ids);
 
       $secrets = array();
       if ($secret_ids) {
         $secret_objects = id(new PassphraseSecret())->loadAllWhere(
           'id IN (%Ld)',
           $secret_ids);
         foreach ($secret_objects as $secret) {
           $secret_data = $secret->getSecretData();
           $secrets[$secret->getID()] = new PhutilOpaqueEnvelope($secret_data);
         }
       }
 
       foreach ($page as $key => $credential) {
         $secret_id = $credential->getSecretID();
         if (!$secret_id) {
           $credential->attachSecret(null);
         } else if (isset($secrets[$secret_id])) {
           $credential->attachSecret($secrets[$secret_id]);
         } else {
           unset($page[$key]);
         }
       }
     }
 
     foreach ($page as $key => $credential) {
       $type = PassphraseCredentialType::getTypeByConstant(
         $credential->getCredentialType());
       if (!$type) {
         unset($page[$key]);
         continue;
       }
 
       $credential->attachImplementation(clone $type);
     }
 
     return $page;
   }
 
   protected function buildWhereClauseParts(AphrontDatabaseConnection $conn) {
     $where = parent::buildWhereClauseParts($conn);
 
     if ($this->ids !== null) {
       $where[] = qsprintf(
         $conn,
         'c.id IN (%Ld)',
         $this->ids);
     }
 
     if ($this->phids !== null) {
       $where[] = qsprintf(
         $conn,
         'c.phid IN (%Ls)',
         $this->phids);
     }
 
     if ($this->credentialTypes !== null) {
       $where[] = qsprintf(
         $conn,
         'c.credentialType in (%Ls)',
         $this->credentialTypes);
     }
 
     if ($this->providesTypes !== null) {
       $where[] = qsprintf(
         $conn,
         'c.providesType IN (%Ls)',
         $this->providesTypes);
     }
 
     if ($this->isDestroyed !== null) {
       $where[] = qsprintf(
         $conn,
         'c.isDestroyed = %d',
         (int)$this->isDestroyed);
     }
 
     if ($this->allowConduit !== null) {
       $where[] = qsprintf(
         $conn,
         'c.allowConduit = %d',
         (int)$this->allowConduit);
     }
 
-    if (strlen($this->nameContains)) {
+    if (phutil_nonempty_string($this->nameContains)) {
       $where[] = qsprintf(
         $conn,
         'LOWER(c.name) LIKE %~',
         phutil_utf8_strtolower($this->nameContains));
     }
 
     return $where;
   }
 
   public function getQueryApplicationClass() {
     return 'PhabricatorPassphraseApplication';
   }
 
   protected function getPrimaryTableAlias() {
     return 'c';
   }
 
 }
diff --git a/src/applications/repository/query/PhabricatorRepositoryQuery.php b/src/applications/repository/query/PhabricatorRepositoryQuery.php
index 9150c692b6..05b011e85a 100644
--- a/src/applications/repository/query/PhabricatorRepositoryQuery.php
+++ b/src/applications/repository/query/PhabricatorRepositoryQuery.php
@@ -1,706 +1,706 @@
 <?php
 
 final class PhabricatorRepositoryQuery
   extends PhabricatorCursorPagedPolicyAwareQuery {
 
   private $ids;
   private $phids;
   private $callsigns;
   private $types;
   private $uuids;
   private $uris;
   private $datasourceQuery;
   private $slugs;
   private $almanacServicePHIDs;
 
   private $numericIdentifiers;
   private $callsignIdentifiers;
   private $phidIdentifiers;
   private $monogramIdentifiers;
   private $slugIdentifiers;
 
   private $identifierMap;
 
   const STATUS_OPEN = 'status-open';
   const STATUS_CLOSED = 'status-closed';
   const STATUS_ALL = 'status-all';
   private $status = self::STATUS_ALL;
 
   const HOSTED_PHABRICATOR = 'hosted-phab';
   const HOSTED_REMOTE = 'hosted-remote';
   const HOSTED_ALL = 'hosted-all';
   private $hosted = self::HOSTED_ALL;
 
   private $needMostRecentCommits;
   private $needCommitCounts;
   private $needProjectPHIDs;
   private $needURIs;
   private $needProfileImage;
 
   public function withIDs(array $ids) {
     $this->ids = $ids;
     return $this;
   }
 
   public function withPHIDs(array $phids) {
     $this->phids = $phids;
     return $this;
   }
 
   public function withCallsigns(array $callsigns) {
     $this->callsigns = $callsigns;
     return $this;
   }
 
   public function withIdentifiers(array $identifiers) {
     $identifiers = array_fuse($identifiers);
 
     $ids = array();
     $callsigns = array();
     $phids = array();
     $monograms = array();
     $slugs = array();
 
     foreach ($identifiers as $identifier) {
       if (ctype_digit((string)$identifier)) {
         $ids[$identifier] = $identifier;
         continue;
       }
 
       if (preg_match('/^(r[A-Z]+|R[1-9]\d*)\z/', $identifier)) {
         $monograms[$identifier] = $identifier;
         continue;
       }
 
       $repository_type = PhabricatorRepositoryRepositoryPHIDType::TYPECONST;
       if (phid_get_type($identifier) === $repository_type) {
         $phids[$identifier] = $identifier;
         continue;
       }
 
       if (preg_match('/^[A-Z]+\z/', $identifier)) {
         $callsigns[$identifier] = $identifier;
         continue;
       }
 
       $slugs[$identifier] = $identifier;
     }
 
     $this->numericIdentifiers = $ids;
     $this->callsignIdentifiers = $callsigns;
     $this->phidIdentifiers = $phids;
     $this->monogramIdentifiers = $monograms;
     $this->slugIdentifiers = $slugs;
 
     return $this;
   }
 
   public function withStatus($status) {
     $this->status = $status;
     return $this;
   }
 
   public function withHosted($hosted) {
     $this->hosted = $hosted;
     return $this;
   }
 
   public function withTypes(array $types) {
     $this->types = $types;
     return $this;
   }
 
   public function withUUIDs(array $uuids) {
     $this->uuids = $uuids;
     return $this;
   }
 
   public function withURIs(array $uris) {
     $this->uris = $uris;
     return $this;
   }
 
   public function withDatasourceQuery($query) {
     $this->datasourceQuery = $query;
     return $this;
   }
 
   public function withSlugs(array $slugs) {
     $this->slugs = $slugs;
     return $this;
   }
 
   public function withAlmanacServicePHIDs(array $phids) {
     $this->almanacServicePHIDs = $phids;
     return $this;
   }
 
   public function needCommitCounts($need_counts) {
     $this->needCommitCounts = $need_counts;
     return $this;
   }
 
   public function needMostRecentCommits($need_commits) {
     $this->needMostRecentCommits = $need_commits;
     return $this;
   }
 
   public function needProjectPHIDs($need_phids) {
     $this->needProjectPHIDs = $need_phids;
     return $this;
   }
 
   public function needURIs($need_uris) {
     $this->needURIs = $need_uris;
     return $this;
   }
 
   public function needProfileImage($need) {
     $this->needProfileImage = $need;
     return $this;
   }
 
   public function getBuiltinOrders() {
     return array(
       'committed' => array(
         'vector' => array('committed', 'id'),
         'name' => pht('Most Recent Commit'),
       ),
       'name' => array(
         'vector' => array('name', 'id'),
         'name' => pht('Name'),
       ),
       'callsign' => array(
         'vector' => array('callsign'),
         'name' => pht('Callsign'),
       ),
       'size' => array(
         'vector' => array('size', 'id'),
         'name' => pht('Size'),
       ),
     ) + parent::getBuiltinOrders();
   }
 
   public function getIdentifierMap() {
     if ($this->identifierMap === null) {
       throw new PhutilInvalidStateException('execute');
     }
     return $this->identifierMap;
   }
 
   protected function willExecute() {
     $this->identifierMap = array();
   }
 
   public function newResultObject() {
     return new PhabricatorRepository();
   }
 
   protected function loadPage() {
     $table = $this->newResultObject();
     $data = $this->loadStandardPageRows($table);
     $repositories = $table->loadAllFromArray($data);
 
     if ($this->needCommitCounts) {
       $sizes = ipull($data, 'size', 'id');
       foreach ($repositories as $id => $repository) {
         $repository->attachCommitCount(nonempty($sizes[$id], 0));
       }
     }
 
     if ($this->needMostRecentCommits) {
       $commit_ids = ipull($data, 'lastCommitID', 'id');
       $commit_ids = array_filter($commit_ids);
       if ($commit_ids) {
         $commits = id(new DiffusionCommitQuery())
           ->setViewer($this->getViewer())
           ->withIDs($commit_ids)
           ->needCommitData(true)
           ->needIdentities(true)
           ->execute();
       } else {
         $commits = array();
       }
       foreach ($repositories as $id => $repository) {
         $commit = null;
         if (idx($commit_ids, $id)) {
           $commit = idx($commits, $commit_ids[$id]);
         }
         $repository->attachMostRecentCommit($commit);
       }
     }
 
     return $repositories;
   }
 
   protected function willFilterPage(array $repositories) {
     assert_instances_of($repositories, 'PhabricatorRepository');
 
     // TODO: Denormalize repository status into the PhabricatorRepository
     // table so we can do this filtering in the database.
     foreach ($repositories as $key => $repo) {
       $status = $this->status;
       switch ($status) {
         case self::STATUS_OPEN:
           if (!$repo->isTracked()) {
             unset($repositories[$key]);
           }
           break;
         case self::STATUS_CLOSED:
           if ($repo->isTracked()) {
             unset($repositories[$key]);
           }
           break;
         case self::STATUS_ALL:
           break;
         default:
           throw new Exception("Unknown status '{$status}'!");
       }
 
       // TODO: This should also be denormalized.
       $hosted = $this->hosted;
       switch ($hosted) {
         case self::HOSTED_PHABRICATOR:
           if (!$repo->isHosted()) {
             unset($repositories[$key]);
           }
           break;
         case self::HOSTED_REMOTE:
           if ($repo->isHosted()) {
             unset($repositories[$key]);
           }
           break;
         case self::HOSTED_ALL:
           break;
         default:
           throw new Exception(pht("Unknown hosted failed '%s'!", $hosted));
       }
     }
 
     // Build the identifierMap
     if ($this->numericIdentifiers) {
       foreach ($this->numericIdentifiers as $id) {
         if (isset($repositories[$id])) {
           $this->identifierMap[$id] = $repositories[$id];
         }
       }
     }
 
     if ($this->callsignIdentifiers) {
       $repository_callsigns = mpull($repositories, null, 'getCallsign');
 
       foreach ($this->callsignIdentifiers as $callsign) {
         if (isset($repository_callsigns[$callsign])) {
           $this->identifierMap[$callsign] = $repository_callsigns[$callsign];
         }
       }
     }
 
     if ($this->phidIdentifiers) {
       $repository_phids = mpull($repositories, null, 'getPHID');
 
       foreach ($this->phidIdentifiers as $phid) {
         if (isset($repository_phids[$phid])) {
           $this->identifierMap[$phid] = $repository_phids[$phid];
         }
       }
     }
 
     if ($this->monogramIdentifiers) {
       $monogram_map = array();
       foreach ($repositories as $repository) {
         foreach ($repository->getAllMonograms() as $monogram) {
           $monogram_map[$monogram] = $repository;
         }
       }
 
       foreach ($this->monogramIdentifiers as $monogram) {
         if (isset($monogram_map[$monogram])) {
           $this->identifierMap[$monogram] = $monogram_map[$monogram];
         }
       }
     }
 
     if ($this->slugIdentifiers) {
       $slug_map = array();
       foreach ($repositories as $repository) {
         $slug = $repository->getRepositorySlug();
         if ($slug === null) {
           continue;
         }
 
         $normal = phutil_utf8_strtolower($slug);
         $slug_map[$normal] = $repository;
       }
 
       foreach ($this->slugIdentifiers as $slug) {
         $normal = phutil_utf8_strtolower($slug);
         if (isset($slug_map[$normal])) {
           $this->identifierMap[$slug] = $slug_map[$normal];
         }
       }
     }
 
     return $repositories;
   }
 
   protected function didFilterPage(array $repositories) {
     if ($this->needProjectPHIDs) {
       $type_project = PhabricatorProjectObjectHasProjectEdgeType::EDGECONST;
 
       $edge_query = id(new PhabricatorEdgeQuery())
         ->withSourcePHIDs(mpull($repositories, 'getPHID'))
         ->withEdgeTypes(array($type_project));
       $edge_query->execute();
 
       foreach ($repositories as $repository) {
         $project_phids = $edge_query->getDestinationPHIDs(
           array(
             $repository->getPHID(),
           ));
         $repository->attachProjectPHIDs($project_phids);
       }
     }
 
     $viewer = $this->getViewer();
 
     if ($this->needURIs) {
       $uris = id(new PhabricatorRepositoryURIQuery())
         ->setViewer($viewer)
         ->withRepositories($repositories)
         ->execute();
       $uri_groups = mgroup($uris, 'getRepositoryPHID');
       foreach ($repositories as $repository) {
         $repository_uris = idx($uri_groups, $repository->getPHID(), array());
         $repository->attachURIs($repository_uris);
       }
     }
 
     if ($this->needProfileImage) {
       $default = null;
 
       $file_phids = mpull($repositories, 'getProfileImagePHID');
       $file_phids = array_filter($file_phids);
       if ($file_phids) {
         $files = id(new PhabricatorFileQuery())
           ->setParentQuery($this)
           ->setViewer($this->getViewer())
           ->withPHIDs($file_phids)
           ->execute();
         $files = mpull($files, null, 'getPHID');
       } else {
         $files = array();
       }
 
       foreach ($repositories as $repository) {
         $file = idx($files, $repository->getProfileImagePHID());
         if (!$file) {
           if (!$default) {
             $default = PhabricatorFile::loadBuiltin(
               $this->getViewer(),
               'repo/code.png');
           }
           $file = $default;
         }
         $repository->attachProfileImageFile($file);
       }
     }
 
     return $repositories;
   }
 
   protected function getPrimaryTableAlias() {
     return 'r';
   }
 
   public function getOrderableColumns() {
     return parent::getOrderableColumns() + array(
       'committed' => array(
         'table' => 's',
         'column' => 'epoch',
         'type' => 'int',
         'null' => 'tail',
       ),
       'callsign' => array(
         'table' => 'r',
         'column' => 'callsign',
         'type' => 'string',
         'unique' => true,
         'reverse' => true,
         'null' => 'tail',
       ),
       'name' => array(
         'table' => 'r',
         'column' => 'name',
         'type' => 'string',
         'reverse' => true,
       ),
       'size' => array(
         'table' => 's',
         'column' => 'size',
         'type' => 'int',
         'null' => 'tail',
       ),
     );
   }
 
   protected function newPagingMapFromCursorObject(
     PhabricatorQueryCursor $cursor,
     array $keys) {
 
     $repository = $cursor->getObject();
 
     $map = array(
       'id' => (int)$repository->getID(),
       'callsign' => $repository->getCallsign(),
       'name' => $repository->getName(),
     );
 
     if (isset($keys['committed'])) {
       $map['committed'] = $cursor->getRawRowProperty('epoch');
     }
 
     if (isset($keys['size'])) {
       $map['size'] = $cursor->getRawRowProperty('size');
     }
 
     return $map;
   }
 
   protected function buildSelectClauseParts(AphrontDatabaseConnection $conn) {
     $parts = parent::buildSelectClauseParts($conn);
 
     if ($this->shouldJoinSummaryTable()) {
       $parts[] = qsprintf($conn, 's.*');
     }
 
     return $parts;
   }
 
   protected function buildJoinClauseParts(AphrontDatabaseConnection $conn) {
     $joins = parent::buildJoinClauseParts($conn);
 
     if ($this->shouldJoinSummaryTable()) {
       $joins[] = qsprintf(
         $conn,
         'LEFT JOIN %T s ON r.id = s.repositoryID',
         PhabricatorRepository::TABLE_SUMMARY);
     }
 
     if ($this->shouldJoinURITable()) {
       $joins[] = qsprintf(
         $conn,
         'LEFT JOIN %R uri ON r.phid = uri.repositoryPHID',
         new PhabricatorRepositoryURIIndex());
     }
 
     return $joins;
   }
 
   protected function shouldGroupQueryResultRows() {
     if ($this->shouldJoinURITable()) {
       return true;
     }
 
     return parent::shouldGroupQueryResultRows();
   }
 
   private function shouldJoinURITable() {
     return ($this->uris !== null);
   }
 
   private function shouldJoinSummaryTable() {
     if ($this->needCommitCounts) {
       return true;
     }
 
     if ($this->needMostRecentCommits) {
       return true;
     }
 
     $vector = $this->getOrderVector();
     if ($vector->containsKey('committed')) {
       return true;
     }
 
     if ($vector->containsKey('size')) {
       return true;
     }
 
     return false;
   }
 
   protected function buildWhereClauseParts(AphrontDatabaseConnection $conn) {
     $where = parent::buildWhereClauseParts($conn);
 
     if ($this->ids !== null) {
       $where[] = qsprintf(
         $conn,
         'r.id IN (%Ld)',
         $this->ids);
     }
 
     if ($this->phids !== null) {
       $where[] = qsprintf(
         $conn,
         'r.phid IN (%Ls)',
         $this->phids);
     }
 
     if ($this->callsigns !== null) {
       $where[] = qsprintf(
         $conn,
         'r.callsign IN (%Ls)',
         $this->callsigns);
     }
 
     if ($this->numericIdentifiers ||
       $this->callsignIdentifiers ||
       $this->phidIdentifiers ||
       $this->monogramIdentifiers ||
       $this->slugIdentifiers) {
       $identifier_clause = array();
 
       if ($this->numericIdentifiers) {
         $identifier_clause[] = qsprintf(
           $conn,
           'r.id IN (%Ld)',
           $this->numericIdentifiers);
       }
 
       if ($this->callsignIdentifiers) {
         $identifier_clause[] = qsprintf(
           $conn,
           'r.callsign IN (%Ls)',
           $this->callsignIdentifiers);
       }
 
       if ($this->phidIdentifiers) {
         $identifier_clause[] = qsprintf(
           $conn,
           'r.phid IN (%Ls)',
           $this->phidIdentifiers);
       }
 
       if ($this->monogramIdentifiers) {
         $monogram_callsigns = array();
         $monogram_ids = array();
 
         foreach ($this->monogramIdentifiers as $identifier) {
           if ($identifier[0] == 'r') {
             $monogram_callsigns[] = substr($identifier, 1);
           } else {
             $monogram_ids[] = substr($identifier, 1);
           }
         }
 
         if ($monogram_ids) {
           $identifier_clause[] = qsprintf(
             $conn,
             'r.id IN (%Ld)',
             $monogram_ids);
         }
 
         if ($monogram_callsigns) {
           $identifier_clause[] = qsprintf(
             $conn,
             'r.callsign IN (%Ls)',
             $monogram_callsigns);
         }
       }
 
       if ($this->slugIdentifiers) {
         $identifier_clause[] = qsprintf(
           $conn,
           'r.repositorySlug IN (%Ls)',
           $this->slugIdentifiers);
       }
 
       $where[] = qsprintf($conn, '%LO', $identifier_clause);
     }
 
     if ($this->types) {
       $where[] = qsprintf(
         $conn,
         'r.versionControlSystem IN (%Ls)',
         $this->types);
     }
 
     if ($this->uuids) {
       $where[] = qsprintf(
         $conn,
         'r.uuid IN (%Ls)',
         $this->uuids);
     }
 
-    if (strlen($this->datasourceQuery)) {
+    if (phutil_nonempty_string($this->datasourceQuery)) {
       // This handles having "rP" match callsigns starting with "P...".
       $query = trim($this->datasourceQuery);
       if (preg_match('/^r/', $query)) {
         $callsign = substr($query, 1);
       } else {
         $callsign = $query;
       }
       $where[] = qsprintf(
         $conn,
         'r.name LIKE %> OR r.callsign LIKE %> OR r.repositorySlug LIKE %>',
         $query,
         $callsign,
         $query);
     }
 
     if ($this->slugs !== null) {
       $where[] = qsprintf(
         $conn,
         'r.repositorySlug IN (%Ls)',
         $this->slugs);
     }
 
     if ($this->uris !== null) {
       $try_uris = $this->getNormalizedURIs();
       $try_uris = array_fuse($try_uris);
 
       $where[] = qsprintf(
         $conn,
         'uri.repositoryURI IN (%Ls)',
         $try_uris);
     }
 
     if ($this->almanacServicePHIDs !== null) {
       $where[] = qsprintf(
         $conn,
         'r.almanacServicePHID IN (%Ls)',
         $this->almanacServicePHIDs);
     }
 
     return $where;
   }
 
   public function getQueryApplicationClass() {
     return 'PhabricatorDiffusionApplication';
   }
 
   private function getNormalizedURIs() {
     $normalized_uris = array();
 
     // Since we don't know which type of repository this URI is in the general
     // case, just generate all the normalizations. We could refine this in some
     // cases: if the query specifies VCS types, or the URI is a git-style URI
     // or an `svn+ssh` URI, we could deduce how to normalize it. However, this
     // would be more complicated and it's not clear if it matters in practice.
 
     $domain_map = PhabricatorRepositoryURI::getURINormalizerDomainMap();
 
     $types = ArcanistRepositoryURINormalizer::getAllURITypes();
     foreach ($this->uris as $uri) {
       foreach ($types as $type) {
         $normalized_uri = new ArcanistRepositoryURINormalizer($type, $uri);
         $normalized_uri->setDomainMap($domain_map);
         $normalized_uris[] = $normalized_uri->getNormalizedURI();
       }
     }
 
     return array_unique($normalized_uris);
   }
 
 }
diff --git a/src/applications/repository/storage/PhabricatorRepository.php b/src/applications/repository/storage/PhabricatorRepository.php
index e719f2cd73..66242f8d15 100644
--- a/src/applications/repository/storage/PhabricatorRepository.php
+++ b/src/applications/repository/storage/PhabricatorRepository.php
@@ -1,2880 +1,2882 @@
 <?php
 
 /**
  * @task uri        Repository URI Management
  * @task publishing Publishing
  * @task sync       Cluster Synchronization
  */
 final class PhabricatorRepository extends PhabricatorRepositoryDAO
   implements
     PhabricatorApplicationTransactionInterface,
     PhabricatorPolicyInterface,
     PhabricatorFlaggableInterface,
     PhabricatorMarkupInterface,
     PhabricatorDestructibleInterface,
     PhabricatorDestructibleCodexInterface,
     PhabricatorProjectInterface,
     PhabricatorSpacesInterface,
     PhabricatorConduitResultInterface,
     PhabricatorFulltextInterface,
     PhabricatorFerretInterface {
 
   /**
    * Shortest hash we'll recognize in raw "a829f32" form.
    */
   const MINIMUM_UNQUALIFIED_HASH = 7;
 
   /**
    * Shortest hash we'll recognize in qualified "rXab7ef2f8" form.
    */
   const MINIMUM_QUALIFIED_HASH = 5;
 
   /**
    * Minimum number of commits to an empty repository to trigger "import" mode.
    */
   const IMPORT_THRESHOLD = 7;
 
   const LOWPRI_THRESHOLD = 64;
 
   const TABLE_PATH = 'repository_path';
   const TABLE_PATHCHANGE = 'repository_pathchange';
   const TABLE_FILESYSTEM = 'repository_filesystem';
   const TABLE_SUMMARY = 'repository_summary';
   const TABLE_LINTMESSAGE = 'repository_lintmessage';
   const TABLE_PARENTS = 'repository_parents';
   const TABLE_COVERAGE = 'repository_coverage';
 
   const STATUS_ACTIVE = 'active';
   const STATUS_INACTIVE = 'inactive';
 
   protected $name;
   protected $callsign;
   protected $repositorySlug;
   protected $uuid;
   protected $viewPolicy;
   protected $editPolicy;
   protected $pushPolicy;
   protected $profileImagePHID;
 
   protected $versionControlSystem;
   protected $details = array();
   protected $credentialPHID;
   protected $almanacServicePHID;
   protected $spacePHID;
   protected $localPath;
 
   private $commitCount = self::ATTACHABLE;
   private $mostRecentCommit = self::ATTACHABLE;
   private $projectPHIDs = self::ATTACHABLE;
   private $uris = self::ATTACHABLE;
   private $profileImageFile = self::ATTACHABLE;
 
 
   public static function initializeNewRepository(PhabricatorUser $actor) {
     $app = id(new PhabricatorApplicationQuery())
       ->setViewer($actor)
       ->withClasses(array('PhabricatorDiffusionApplication'))
       ->executeOne();
 
     $view_policy = $app->getPolicy(DiffusionDefaultViewCapability::CAPABILITY);
     $edit_policy = $app->getPolicy(DiffusionDefaultEditCapability::CAPABILITY);
     $push_policy = $app->getPolicy(DiffusionDefaultPushCapability::CAPABILITY);
 
     $repository = id(new PhabricatorRepository())
       ->setViewPolicy($view_policy)
       ->setEditPolicy($edit_policy)
       ->setPushPolicy($push_policy)
       ->setSpacePHID($actor->getDefaultSpacePHID());
 
     // Put the repository in "Importing" mode until we finish
     // parsing it.
     $repository->setDetail('importing', true);
 
     return $repository;
   }
 
   protected function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,
       self::CONFIG_SERIALIZATION => array(
         'details' => self::SERIALIZATION_JSON,
       ),
       self::CONFIG_COLUMN_SCHEMA => array(
         'name' => 'sort255',
         'callsign' => 'sort32?',
         'repositorySlug' => 'sort64?',
         'versionControlSystem' => 'text32',
         'uuid' => 'text64?',
         'pushPolicy' => 'policy',
         'credentialPHID' => 'phid?',
         'almanacServicePHID' => 'phid?',
         'localPath' => 'text128?',
         'profileImagePHID' => 'phid?',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'callsign' => array(
           'columns' => array('callsign'),
           'unique' => true,
         ),
         'key_name' => array(
           'columns' => array('name(128)'),
         ),
         'key_vcs' => array(
           'columns' => array('versionControlSystem'),
         ),
         'key_slug' => array(
           'columns' => array('repositorySlug'),
           'unique' => true,
         ),
         'key_local' => array(
           'columns' => array('localPath'),
           'unique' => true,
         ),
       ),
     ) + parent::getConfiguration();
   }
 
   public function generatePHID() {
     return PhabricatorPHID::generateNewPHID(
       PhabricatorRepositoryRepositoryPHIDType::TYPECONST);
   }
 
   public static function getStatusMap() {
     return array(
       self::STATUS_ACTIVE => array(
         'name' => pht('Active'),
         'isTracked' => 1,
       ),
       self::STATUS_INACTIVE => array(
         'name' => pht('Inactive'),
         'isTracked' => 0,
       ),
     );
   }
 
   public static function getStatusNameMap() {
     return ipull(self::getStatusMap(), 'name');
   }
 
   public function getStatus() {
     if ($this->isTracked()) {
       return self::STATUS_ACTIVE;
     } else {
       return self::STATUS_INACTIVE;
     }
   }
 
   public function toDictionary() {
     return array(
       'id'          => $this->getID(),
       'name'        => $this->getName(),
       'phid'        => $this->getPHID(),
       'callsign'    => $this->getCallsign(),
       'monogram'    => $this->getMonogram(),
       'vcs'         => $this->getVersionControlSystem(),
       'uri'         => PhabricatorEnv::getProductionURI($this->getURI()),
       'remoteURI'   => (string)$this->getRemoteURI(),
       'description' => $this->getDetail('description'),
       'isActive'    => $this->isTracked(),
       'isHosted'    => $this->isHosted(),
       'isImporting' => $this->isImporting(),
       'encoding'    => $this->getDefaultTextEncoding(),
       'staging' => array(
         'supported' => $this->supportsStaging(),
         'prefix' => 'phabricator',
         'uri' => $this->getStagingURI(),
       ),
     );
   }
 
   public function getDefaultTextEncoding() {
     return $this->getDetail('encoding', 'UTF-8');
   }
 
   public function getMonogram() {
     $callsign = $this->getCallsign();
     if (strlen($callsign)) {
       return "r{$callsign}";
     }
 
     $id = $this->getID();
     return "R{$id}";
   }
 
   public function getDisplayName() {
     $slug = $this->getRepositorySlug();
     if (strlen($slug)) {
       return $slug;
     }
 
     return $this->getMonogram();
   }
 
   public function getAllMonograms() {
     $monograms = array();
 
     $monograms[] = 'R'.$this->getID();
 
     $callsign = $this->getCallsign();
     if (strlen($callsign)) {
       $monograms[] = 'r'.$callsign;
     }
 
     return $monograms;
   }
 
   public function setLocalPath($path) {
     // Convert any extra slashes ("//") in the path to a single slash ("/").
     $path = preg_replace('(//+)', '/', $path);
 
     return parent::setLocalPath($path);
   }
 
   public function getDetail($key, $default = null) {
     return idx($this->details, $key, $default);
   }
 
   public function setDetail($key, $value) {
     $this->details[$key] = $value;
     return $this;
   }
 
   public function attachCommitCount($count) {
     $this->commitCount = $count;
     return $this;
   }
 
   public function getCommitCount() {
     return $this->assertAttached($this->commitCount);
   }
 
   public function attachMostRecentCommit(
     PhabricatorRepositoryCommit $commit = null) {
     $this->mostRecentCommit = $commit;
     return $this;
   }
 
   public function getMostRecentCommit() {
     return $this->assertAttached($this->mostRecentCommit);
   }
 
   public function getDiffusionBrowseURIForPath(
     PhabricatorUser $user,
     $path,
     $line = null,
     $branch = null) {
 
     $drequest = DiffusionRequest::newFromDictionary(
       array(
         'user' => $user,
         'repository' => $this,
         'path' => $path,
         'branch' => $branch,
       ));
 
     return $drequest->generateURI(
       array(
         'action' => 'browse',
         'line'   => $line,
       ));
   }
 
   public function getSubversionBaseURI($commit = null) {
     $subpath = $this->getDetail('svn-subpath');
-    if (!strlen($subpath)) {
+
+    if (!phutil_nonempty_string($subpath)) {
       $subpath = null;
     }
+
     return $this->getSubversionPathURI($subpath, $commit);
   }
 
   public function getSubversionPathURI($path = null, $commit = null) {
     $vcs = $this->getVersionControlSystem();
     if ($vcs != PhabricatorRepositoryType::REPOSITORY_TYPE_SVN) {
       throw new Exception(pht('Not a subversion repository!'));
     }
 
     if ($this->isHosted()) {
       $uri = 'file://'.$this->getLocalPath();
     } else {
       $uri = $this->getDetail('remote-uri');
     }
 
     $uri = rtrim($uri, '/');
 
-    if (strlen($path)) {
+    if (phutil_nonempty_string($path)) {
       $path = rawurlencode($path);
       $path = str_replace('%2F', '/', $path);
       $uri = $uri.'/'.ltrim($path, '/');
     }
 
     if ($path !== null || $commit !== null) {
       $uri .= '@';
     }
 
     if ($commit !== null) {
       $uri .= $commit;
     }
 
     return $uri;
   }
 
   public function attachProjectPHIDs(array $project_phids) {
     $this->projectPHIDs = $project_phids;
     return $this;
   }
 
   public function getProjectPHIDs() {
     return $this->assertAttached($this->projectPHIDs);
   }
 
 
   /**
    * Get the name of the directory this repository should clone or checkout
    * into. For example, if the repository name is "Example Repository", a
    * reasonable name might be "example-repository". This is used to help users
    * get reasonable results when cloning repositories, since they generally do
    * not want to clone into directories called "X/" or "Example Repository/".
    *
    * @return string
    */
   public function getCloneName() {
     $name = $this->getRepositorySlug();
 
     // Make some reasonable effort to produce reasonable default directory
     // names from repository names.
     if (!strlen($name)) {
       $name = $this->getName();
       $name = phutil_utf8_strtolower($name);
       $name = preg_replace('@[ -/:->]+@', '-', $name);
       $name = trim($name, '-');
       if (!strlen($name)) {
         $name = $this->getCallsign();
       }
     }
 
     return $name;
   }
 
   public static function isValidRepositorySlug($slug) {
     try {
       self::assertValidRepositorySlug($slug);
       return true;
     } catch (Exception $ex) {
       return false;
     }
   }
 
   public static function assertValidRepositorySlug($slug) {
     if (!strlen($slug)) {
       throw new Exception(
         pht(
           'The empty string is not a valid repository short name. '.
           'Repository short names must be at least one character long.'));
     }
 
     if (strlen($slug) > 64) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names must not be longer than 64 characters.',
           $slug));
     }
 
     if (preg_match('/[^a-zA-Z0-9._-]/', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names may only contain letters, numbers, periods, hyphens '.
           'and underscores.',
           $slug));
     }
 
     if (!preg_match('/^[a-zA-Z0-9]/', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names must begin with a letter or number.',
           $slug));
     }
 
     if (!preg_match('/[a-zA-Z0-9]\z/', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names must end with a letter or number.',
           $slug));
     }
 
     if (preg_match('/__|--|\\.\\./', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names must not contain multiple consecutive underscores, '.
           'hyphens, or periods.',
           $slug));
     }
 
     if (preg_match('/^[A-Z]+\z/', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names may not contain only uppercase letters.',
           $slug));
     }
 
     if (preg_match('/^\d+\z/', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names may not contain only numbers.',
           $slug));
     }
 
     if (preg_match('/\\.git/', $slug)) {
       throw new Exception(
         pht(
           'The name "%s" is not a valid repository short name. Repository '.
           'short names must not end in ".git". This suffix will be added '.
           'automatically in appropriate contexts.',
           $slug));
     }
   }
 
   public static function assertValidCallsign($callsign) {
     if (!strlen($callsign)) {
       throw new Exception(
         pht(
           'A repository callsign must be at least one character long.'));
     }
 
     if (strlen($callsign) > 32) {
       throw new Exception(
         pht(
           'The callsign "%s" is not a valid repository callsign. Callsigns '.
           'must be no more than 32 bytes long.',
           $callsign));
     }
 
     if (!preg_match('/^[A-Z]+\z/', $callsign)) {
       throw new Exception(
         pht(
           'The callsign "%s" is not a valid repository callsign. Callsigns '.
           'may only contain UPPERCASE letters.',
           $callsign));
     }
   }
 
   public function getProfileImageURI() {
     return $this->getProfileImageFile()->getBestURI();
   }
 
   public function attachProfileImageFile(PhabricatorFile $file) {
     $this->profileImageFile = $file;
     return $this;
   }
 
   public function getProfileImageFile() {
     return $this->assertAttached($this->profileImageFile);
   }
 
 
 
 /* -(  Remote Command Execution  )------------------------------------------- */
 
 
   public function execRemoteCommand($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newRemoteCommandFuture($args)->resolve();
   }
 
   public function execxRemoteCommand($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newRemoteCommandFuture($args)->resolvex();
   }
 
   public function getRemoteCommandFuture($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newRemoteCommandFuture($args);
   }
 
   public function passthruRemoteCommand($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newRemoteCommandPassthru($args)->resolve();
   }
 
   private function newRemoteCommandFuture(array $argv) {
     return $this->newRemoteCommandEngine($argv)
       ->newFuture();
   }
 
   private function newRemoteCommandPassthru(array $argv) {
     return $this->newRemoteCommandEngine($argv)
       ->setPassthru(true)
       ->newFuture();
   }
 
   private function newRemoteCommandEngine(array $argv) {
     return DiffusionCommandEngine::newCommandEngine($this)
       ->setArgv($argv)
       ->setCredentialPHID($this->getCredentialPHID())
       ->setURI($this->getRemoteURIObject());
   }
 
 /* -(  Local Command Execution  )-------------------------------------------- */
 
 
   public function execLocalCommand($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newLocalCommandFuture($args)->resolve();
   }
 
   public function execxLocalCommand($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newLocalCommandFuture($args)->resolvex();
   }
 
   public function getLocalCommandFuture($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newLocalCommandFuture($args);
   }
 
   public function passthruLocalCommand($pattern /* , $arg, ... */) {
     $args = func_get_args();
     return $this->newLocalCommandPassthru($args)->resolve();
   }
 
   private function newLocalCommandFuture(array $argv) {
     $this->assertLocalExists();
 
     $future = DiffusionCommandEngine::newCommandEngine($this)
       ->setArgv($argv)
       ->newFuture();
 
     if ($this->usesLocalWorkingCopy()) {
       $future->setCWD($this->getLocalPath());
     }
 
     return $future;
   }
 
   private function newLocalCommandPassthru(array $argv) {
     $this->assertLocalExists();
 
     $future = DiffusionCommandEngine::newCommandEngine($this)
       ->setArgv($argv)
       ->setPassthru(true)
       ->newFuture();
 
     if ($this->usesLocalWorkingCopy()) {
       $future->setCWD($this->getLocalPath());
     }
 
     return $future;
   }
 
   public function getURI() {
     $short_name = $this->getRepositorySlug();
-    if (strlen($short_name)) {
+    if (phutil_nonempty_string($short_name)) {
       return "/source/{$short_name}/";
     }
 
     $callsign = $this->getCallsign();
-    if (strlen($callsign)) {
+    if (phutil_nonempty_string($callsign)) {
       return "/diffusion/{$callsign}/";
     }
 
     $id = $this->getID();
     return "/diffusion/{$id}/";
   }
 
   public function getPathURI($path) {
     return $this->getURI().ltrim($path, '/');
   }
 
   public function getCommitURI($identifier) {
     $callsign = $this->getCallsign();
-    if (strlen($callsign)) {
+    if (phutil_nonempty_string($callsign)) {
       return "/r{$callsign}{$identifier}";
     }
 
     $id = $this->getID();
     return "/R{$id}:{$identifier}";
   }
 
   public static function parseRepositoryServicePath($request_path, $vcs) {
     $is_git = ($vcs == PhabricatorRepositoryType::REPOSITORY_TYPE_GIT);
 
     $patterns = array(
       '(^'.
         '(?P<base>/?(?:diffusion|source)/(?P<identifier>[^/]+))'.
         '(?P<path>.*)'.
       '\z)',
     );
 
     $identifier = null;
     foreach ($patterns as $pattern) {
       $matches = null;
       if (!preg_match($pattern, $request_path, $matches)) {
         continue;
       }
 
       $identifier = $matches['identifier'];
       if ($is_git) {
         $identifier = preg_replace('/\\.git\z/', '', $identifier);
       }
 
       $base = $matches['base'];
       $path = $matches['path'];
       break;
     }
 
     if ($identifier === null) {
       return null;
     }
 
     return array(
       'identifier' => $identifier,
       'base' => $base,
       'path' => $path,
     );
   }
 
   public function getCanonicalPath($request_path) {
     $standard_pattern =
       '(^'.
         '(?P<prefix>/(?:diffusion|source)/)'.
         '(?P<identifier>[^/]+)'.
         '(?P<suffix>(?:/.*)?)'.
       '\z)';
 
     $matches = null;
     if (preg_match($standard_pattern, $request_path, $matches)) {
       $suffix = $matches['suffix'];
       return $this->getPathURI($suffix);
     }
 
     $commit_pattern =
       '(^'.
         '(?P<prefix>/)'.
         '(?P<monogram>'.
           '(?:'.
             'r(?P<repositoryCallsign>[A-Z]+)'.
             '|'.
             'R(?P<repositoryID>[1-9]\d*):'.
           ')'.
           '(?P<commit>[a-f0-9]+)'.
         ')'.
       '\z)';
 
     $matches = null;
     if (preg_match($commit_pattern, $request_path, $matches)) {
       $commit = $matches['commit'];
       return $this->getCommitURI($commit);
     }
 
     return null;
   }
 
   public function generateURI(array $params) {
     $req_branch = false;
     $req_commit = false;
 
     $action = idx($params, 'action');
     switch ($action) {
       case 'history':
       case 'clone':
       case 'blame':
       case 'browse':
       case 'document':
       case 'change':
       case 'lastmodified':
       case 'tags':
       case 'branches':
       case 'lint':
       case 'pathtree':
       case 'refs':
       case 'compare':
         break;
       case 'branch':
         // NOTE: This does not actually require a branch, and won't have one
         // in Subversion. Possibly this should be more clear.
         break;
       case 'commit':
       case 'rendering-ref':
         $req_commit = true;
         break;
       default:
         throw new Exception(
           pht(
             'Action "%s" is not a valid repository URI action.',
             $action));
     }
 
     $path     = idx($params, 'path');
     $branch   = idx($params, 'branch');
     $commit   = idx($params, 'commit');
     $line     = idx($params, 'line');
 
     $head = idx($params, 'head');
     $against = idx($params, 'against');
 
     if ($req_commit && !strlen($commit)) {
       throw new Exception(
         pht(
           'Diffusion URI action "%s" requires commit!',
           $action));
     }
 
     if ($req_branch && !strlen($branch)) {
       throw new Exception(
         pht(
           'Diffusion URI action "%s" requires branch!',
           $action));
     }
 
     if ($action === 'commit') {
       return $this->getCommitURI($commit);
     }
 
-    if (strlen($path)) {
+    if (phutil_nonempty_string($path)) {
       $path = ltrim($path, '/');
       $path = str_replace(array(';', '$'), array(';;', '$$'), $path);
       $path = phutil_escape_uri($path);
     }
 
     $raw_branch = $branch;
-    if (strlen($branch)) {
+    if (phutil_nonempty_string($branch)) {
       $branch = phutil_escape_uri_path_component($branch);
       $path = "{$branch}/{$path}";
     }
 
     $raw_commit = $commit;
-    if (strlen($commit)) {
+    if (phutil_nonempty_string($commit)) {
       $commit = str_replace('$', '$$', $commit);
       $commit = ';'.phutil_escape_uri($commit);
     }
 
-    if (strlen($line)) {
+    if (phutil_nonempty_string($line)) {
       $line = '$'.phutil_escape_uri($line);
     }
 
     $query = array();
     switch ($action) {
       case 'change':
       case 'history':
       case 'blame':
       case 'browse':
       case 'document':
       case 'lastmodified':
       case 'tags':
       case 'branches':
       case 'lint':
       case 'pathtree':
       case 'refs':
         $uri = $this->getPathURI("/{$action}/{$path}{$commit}{$line}");
         break;
       case 'compare':
         $uri = $this->getPathURI("/{$action}/");
         if (strlen($head)) {
           $query['head'] = $head;
         } else if (strlen($raw_commit)) {
           $query['commit'] = $raw_commit;
         } else if (strlen($raw_branch)) {
           $query['head'] = $raw_branch;
         }
 
         if (strlen($against)) {
           $query['against'] = $against;
         }
         break;
       case 'branch':
         if (strlen($path)) {
           $uri = $this->getPathURI("/repository/{$path}");
         } else {
           $uri = $this->getPathURI('/');
         }
         break;
       case 'external':
         $commit = ltrim($commit, ';');
         $uri = "/diffusion/external/{$commit}/";
         break;
       case 'rendering-ref':
         // This isn't a real URI per se, it's passed as a query parameter to
         // the ajax changeset stuff but then we parse it back out as though
         // it came from a URI.
         $uri = rawurldecode("{$path}{$commit}");
         break;
       case 'clone':
         $uri = $this->getPathURI("/{$action}/");
       break;
     }
 
     if ($action == 'rendering-ref') {
       return $uri;
     }
 
     if (isset($params['lint'])) {
       $params['params'] = idx($params, 'params', array()) + array(
         'lint' => $params['lint'],
       );
     }
 
     $query = idx($params, 'params', array()) + $query;
 
     return new PhutilURI($uri, $query);
   }
 
   public function updateURIIndex() {
     $indexes = array();
 
     $uris = $this->getURIs();
     foreach ($uris as $uri) {
       if ($uri->getIsDisabled()) {
         continue;
       }
 
       $indexes[] = $uri->getNormalizedURI();
     }
 
     PhabricatorRepositoryURIIndex::updateRepositoryURIs(
       $this->getPHID(),
       $indexes);
 
     return $this;
   }
 
   public function isTracked() {
     $status = $this->getDetail('tracking-enabled');
     $map = self::getStatusMap();
     $spec = idx($map, $status);
 
     if (!$spec) {
       if ($status) {
         $status = self::STATUS_ACTIVE;
       } else {
         $status = self::STATUS_INACTIVE;
       }
       $spec = idx($map, $status);
     }
 
     return (bool)idx($spec, 'isTracked', false);
   }
 
   public function getDefaultBranch() {
     $default = $this->getDetail('default-branch');
-    if (strlen($default)) {
+    if (phutil_nonempty_string($default)) {
       return $default;
     }
 
     $default_branches = array(
       PhabricatorRepositoryType::REPOSITORY_TYPE_GIT        => 'master',
       PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL  => 'default',
     );
 
     return idx($default_branches, $this->getVersionControlSystem());
   }
 
   public function getDefaultArcanistBranch() {
     return coalesce($this->getDefaultBranch(), 'svn');
   }
 
   private function isBranchInFilter($branch, $filter_key) {
     $vcs = $this->getVersionControlSystem();
 
     $is_git = ($vcs == PhabricatorRepositoryType::REPOSITORY_TYPE_GIT);
 
     $use_filter = ($is_git);
     if (!$use_filter) {
       // If this VCS doesn't use filters, pass everything through.
       return true;
     }
 
 
     $filter = $this->getDetail($filter_key, array());
 
     // If there's no filter set, let everything through.
     if (!$filter) {
       return true;
     }
 
     // If this branch isn't literally named `regexp(...)`, and it's in the
     // filter list, let it through.
     if (isset($filter[$branch])) {
       if (self::extractBranchRegexp($branch) === null) {
         return true;
       }
     }
 
     // If the branch matches a regexp, let it through.
     foreach ($filter as $pattern => $ignored) {
       $regexp = self::extractBranchRegexp($pattern);
       if ($regexp !== null) {
         if (preg_match($regexp, $branch)) {
           return true;
         }
       }
     }
 
     // Nothing matched, so filter this branch out.
     return false;
   }
 
   public static function extractBranchRegexp($pattern) {
     $matches = null;
     if (preg_match('/^regexp\\((.*)\\)\z/', $pattern, $matches)) {
       return $matches[1];
     }
     return null;
   }
 
   public function shouldTrackRef(DiffusionRepositoryRef $ref) {
     // At least for now, don't track the staging area tags.
     if ($ref->isTag()) {
       if (preg_match('(^phabricator/)', $ref->getShortName())) {
         return false;
       }
     }
 
     if (!$ref->isBranch()) {
       return true;
     }
 
     return $this->shouldTrackBranch($ref->getShortName());
   }
 
   public function shouldTrackBranch($branch) {
     return $this->isBranchInFilter($branch, 'branch-filter');
   }
 
   public function isBranchPermanentRef($branch) {
     return $this->isBranchInFilter($branch, 'close-commits-filter');
   }
 
   public function formatCommitName($commit_identifier, $local = false) {
     $vcs = $this->getVersionControlSystem();
 
     $type_git = PhabricatorRepositoryType::REPOSITORY_TYPE_GIT;
     $type_hg = PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL;
 
     $is_git = ($vcs == $type_git);
     $is_hg = ($vcs == $type_hg);
     if ($is_git || $is_hg) {
       $name = substr($commit_identifier, 0, 12);
       $need_scope = false;
     } else {
       $name = $commit_identifier;
       $need_scope = true;
     }
 
     if (!$local) {
       $need_scope = true;
     }
 
     if ($need_scope) {
       $callsign = $this->getCallsign();
       if ($callsign) {
         $scope = "r{$callsign}";
       } else {
         $id = $this->getID();
         $scope = "R{$id}:";
       }
       $name = $scope.$name;
     }
 
     return $name;
   }
 
   public function isImporting() {
     return (bool)$this->getDetail('importing', false);
   }
 
   public function isNewlyInitialized() {
     return (bool)$this->getDetail('newly-initialized', false);
   }
 
   public function loadImportProgress() {
     $progress = queryfx_all(
       $this->establishConnection('r'),
       'SELECT importStatus, count(*) N FROM %T WHERE repositoryID = %d
         GROUP BY importStatus',
       id(new PhabricatorRepositoryCommit())->getTableName(),
       $this->getID());
 
     $done = 0;
     $total = 0;
     foreach ($progress as $row) {
       $total += $row['N'] * 3;
       $status = $row['importStatus'];
       if ($status & PhabricatorRepositoryCommit::IMPORTED_MESSAGE) {
         $done += $row['N'];
       }
       if ($status & PhabricatorRepositoryCommit::IMPORTED_CHANGE) {
         $done += $row['N'];
       }
       if ($status & PhabricatorRepositoryCommit::IMPORTED_PUBLISH) {
         $done += $row['N'];
       }
     }
 
     if ($total) {
       $ratio = ($done / $total);
     } else {
       $ratio = 0;
     }
 
     // Cap this at "99.99%", because it's confusing to users when the actual
     // fraction is "99.996%" and it rounds up to "100.00%".
     if ($ratio > 0.9999) {
       $ratio = 0.9999;
     }
 
     return $ratio;
   }
 
 /* -(  Publishing  )--------------------------------------------------------- */
 
   public function newPublisher() {
     return id(new PhabricatorRepositoryPublisher())
       ->setRepository($this);
   }
 
   public function isPublishingDisabled() {
     return $this->getDetail('herald-disabled');
   }
 
   public function getPermanentRefRules() {
     return array_keys($this->getDetail('close-commits-filter', array()));
   }
 
   public function setPermanentRefRules(array $rules) {
     $rules = array_fill_keys($rules, true);
     $this->setDetail('close-commits-filter', $rules);
     return $this;
   }
 
   public function getTrackOnlyRules() {
     return array_keys($this->getDetail('branch-filter', array()));
   }
 
   public function setTrackOnlyRules(array $rules) {
     $rules = array_fill_keys($rules, true);
     $this->setDetail('branch-filter', $rules);
     return $this;
   }
 
   public function supportsFetchRules() {
     if ($this->isGit()) {
       return true;
     }
 
     return false;
   }
 
   public function getFetchRules() {
     return $this->getDetail('fetch-rules', array());
   }
 
   public function setFetchRules(array $rules) {
     return $this->setDetail('fetch-rules', $rules);
   }
 
 
 /* -(  Repository URI Management  )------------------------------------------ */
 
 
   /**
    * Get the remote URI for this repository.
    *
    * @return string
    * @task uri
    */
   public function getRemoteURI() {
     return (string)$this->getRemoteURIObject();
   }
 
 
   /**
    * Get the remote URI for this repository, including credentials if they're
    * used by this repository.
    *
    * @return PhutilOpaqueEnvelope URI, possibly including credentials.
    * @task uri
    */
   public function getRemoteURIEnvelope() {
     $uri = $this->getRemoteURIObject();
 
     $remote_protocol = $this->getRemoteProtocol();
     if ($remote_protocol == 'http' || $remote_protocol == 'https') {
       // For SVN, we use `--username` and `--password` flags separately, so
       // don't add any credentials here.
       if (!$this->isSVN()) {
         $credential_phid = $this->getCredentialPHID();
         if ($credential_phid) {
           $key = PassphrasePasswordKey::loadFromPHID(
             $credential_phid,
             PhabricatorUser::getOmnipotentUser());
 
           $uri->setUser($key->getUsernameEnvelope()->openEnvelope());
           $uri->setPass($key->getPasswordEnvelope()->openEnvelope());
         }
       }
     }
 
     return new PhutilOpaqueEnvelope((string)$uri);
   }
 
 
   /**
    * Get the clone (or checkout) URI for this repository, without authentication
    * information.
    *
    * @return string Repository URI.
    * @task uri
    */
   public function getPublicCloneURI() {
     return (string)$this->getCloneURIObject();
   }
 
 
   /**
    * Get the protocol for the repository's remote.
    *
    * @return string Protocol, like "ssh" or "git".
    * @task uri
    */
   public function getRemoteProtocol() {
     $uri = $this->getRemoteURIObject();
     return $uri->getProtocol();
   }
 
 
   /**
    * Get a parsed object representation of the repository's remote URI..
    *
    * @return wild A @{class@arcanist:PhutilURI}.
    * @task uri
    */
   public function getRemoteURIObject() {
     $raw_uri = $this->getDetail('remote-uri');
     if (!strlen($raw_uri)) {
       return new PhutilURI('');
     }
 
     if (!strncmp($raw_uri, '/', 1)) {
       return new PhutilURI('file://'.$raw_uri);
     }
 
     return new PhutilURI($raw_uri);
   }
 
 
   /**
    * Get the "best" clone/checkout URI for this repository, on any protocol.
    */
   public function getCloneURIObject() {
     if (!$this->isHosted()) {
       if ($this->isSVN()) {
         // Make sure we pick up the "Import Only" path for Subversion, so
         // the user clones the repository starting at the correct path, not
         // from the root.
         $base_uri = $this->getSubversionBaseURI();
         $base_uri = new PhutilURI($base_uri);
         $path = $base_uri->getPath();
         if (!$path) {
           $path = '/';
         }
 
         // If the trailing "@" is not required to escape the URI, strip it for
         // readability.
         if (!preg_match('/@.*@/', $path)) {
           $path = rtrim($path, '@');
         }
 
         $base_uri->setPath($path);
         return $base_uri;
       } else {
         return $this->getRemoteURIObject();
       }
     }
 
     // TODO: This should be cleaned up to deal with all the new URI handling.
     $another_copy = id(new PhabricatorRepositoryQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withPHIDs(array($this->getPHID()))
       ->needURIs(true)
       ->executeOne();
 
     $clone_uris = $another_copy->getCloneURIs();
     if (!$clone_uris) {
       return null;
     }
 
     return head($clone_uris)->getEffectiveURI();
   }
 
   private function getRawHTTPCloneURIObject() {
     $uri = PhabricatorEnv::getProductionURI($this->getURI());
     $uri = new PhutilURI($uri);
 
     if ($this->isGit()) {
       $uri->setPath($uri->getPath().$this->getCloneName().'.git');
     } else if ($this->isHg()) {
       $uri->setPath($uri->getPath().$this->getCloneName().'/');
     }
 
     return $uri;
   }
 
 
   /**
    * Determine if we should connect to the remote using SSH flags and
    * credentials.
    *
    * @return bool True to use the SSH protocol.
    * @task uri
    */
   private function shouldUseSSH() {
     if ($this->isHosted()) {
       return false;
     }
 
     $protocol = $this->getRemoteProtocol();
     if ($this->isSSHProtocol($protocol)) {
       return true;
     }
 
     return false;
   }
 
 
   /**
    * Determine if we should connect to the remote using HTTP flags and
    * credentials.
    *
    * @return bool True to use the HTTP protocol.
    * @task uri
    */
   private function shouldUseHTTP() {
     if ($this->isHosted()) {
       return false;
     }
 
     $protocol = $this->getRemoteProtocol();
     return ($protocol == 'http' || $protocol == 'https');
   }
 
 
   /**
    * Determine if we should connect to the remote using SVN flags and
    * credentials.
    *
    * @return bool True to use the SVN protocol.
    * @task uri
    */
   private function shouldUseSVNProtocol() {
     if ($this->isHosted()) {
       return false;
     }
 
     $protocol = $this->getRemoteProtocol();
     return ($protocol == 'svn');
   }
 
 
   /**
    * Determine if a protocol is SSH or SSH-like.
    *
    * @param string A protocol string, like "http" or "ssh".
    * @return bool True if the protocol is SSH-like.
    * @task uri
    */
   private function isSSHProtocol($protocol) {
     return ($protocol == 'ssh' || $protocol == 'svn+ssh');
   }
 
   public function delete() {
     $this->openTransaction();
 
       $paths = id(new PhabricatorOwnersPath())
         ->loadAllWhere('repositoryPHID = %s', $this->getPHID());
       foreach ($paths as $path) {
         $path->delete();
       }
 
       queryfx(
         $this->establishConnection('w'),
         'DELETE FROM %T WHERE repositoryPHID = %s',
         id(new PhabricatorRepositorySymbol())->getTableName(),
         $this->getPHID());
 
       $commits = id(new PhabricatorRepositoryCommit())
         ->loadAllWhere('repositoryID = %d', $this->getID());
       foreach ($commits as $commit) {
         // note PhabricatorRepositoryAuditRequests and
         // PhabricatorRepositoryCommitData are deleted here too.
         $commit->delete();
       }
 
       $uris = id(new PhabricatorRepositoryURI())
         ->loadAllWhere('repositoryPHID = %s', $this->getPHID());
       foreach ($uris as $uri) {
         $uri->delete();
       }
 
       $ref_cursors = id(new PhabricatorRepositoryRefCursor())
         ->loadAllWhere('repositoryPHID = %s', $this->getPHID());
       foreach ($ref_cursors as $cursor) {
         $cursor->delete();
       }
 
       $conn_w = $this->establishConnection('w');
 
       queryfx(
         $conn_w,
         'DELETE FROM %T WHERE repositoryID = %d',
         self::TABLE_FILESYSTEM,
         $this->getID());
 
       queryfx(
         $conn_w,
         'DELETE FROM %T WHERE repositoryID = %d',
         self::TABLE_PATHCHANGE,
         $this->getID());
 
       queryfx(
         $conn_w,
         'DELETE FROM %T WHERE repositoryID = %d',
         self::TABLE_SUMMARY,
         $this->getID());
 
       $result = parent::delete();
 
     $this->saveTransaction();
     return $result;
   }
 
   public function isGit() {
     $vcs = $this->getVersionControlSystem();
     return ($vcs == PhabricatorRepositoryType::REPOSITORY_TYPE_GIT);
   }
 
   public function isSVN() {
     $vcs = $this->getVersionControlSystem();
     return ($vcs == PhabricatorRepositoryType::REPOSITORY_TYPE_SVN);
   }
 
   public function isHg() {
     $vcs = $this->getVersionControlSystem();
     return ($vcs == PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL);
   }
 
   public function isHosted() {
     return (bool)$this->getDetail('hosting-enabled', false);
   }
 
   public function setHosted($enabled) {
     return $this->setDetail('hosting-enabled', $enabled);
   }
 
   public function canServeProtocol(
     $protocol,
     $write,
     $is_intracluster = false) {
 
     // See T13192. If a repository is inactive, don't serve it to users. We
     // still synchronize it within the cluster and serve it to other repository
     // nodes.
     if (!$is_intracluster) {
       if (!$this->isTracked()) {
         return false;
       }
     }
 
     $clone_uris = $this->getCloneURIs();
     foreach ($clone_uris as $uri) {
       if ($uri->getBuiltinProtocol() !== $protocol) {
         continue;
       }
 
       $io_type = $uri->getEffectiveIoType();
       if ($io_type == PhabricatorRepositoryURI::IO_READWRITE) {
         return true;
       }
 
       if (!$write) {
         if ($io_type == PhabricatorRepositoryURI::IO_READ) {
           return true;
         }
       }
     }
 
     if ($write) {
       if ($this->isReadOnly()) {
         return false;
       }
     }
 
     return false;
   }
 
   public function hasLocalWorkingCopy() {
     try {
       self::assertLocalExists();
       return true;
     } catch (Exception $ex) {
       return false;
     }
   }
 
   /**
    * Raise more useful errors when there are basic filesystem problems.
    */
   private function assertLocalExists() {
     if (!$this->usesLocalWorkingCopy()) {
       return;
     }
 
     $local = $this->getLocalPath();
     Filesystem::assertExists($local);
     Filesystem::assertIsDirectory($local);
     Filesystem::assertReadable($local);
   }
 
   /**
    * Determine if the working copy is bare or not. In Git, this corresponds
    * to `--bare`. In Mercurial, `--noupdate`.
    */
   public function isWorkingCopyBare() {
     switch ($this->getVersionControlSystem()) {
       case PhabricatorRepositoryType::REPOSITORY_TYPE_SVN:
       case PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL:
         return false;
       case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
         $local = $this->getLocalPath();
         if (Filesystem::pathExists($local.'/.git')) {
           return false;
         } else {
           return true;
         }
     }
   }
 
   public function usesLocalWorkingCopy() {
     switch ($this->getVersionControlSystem()) {
       case PhabricatorRepositoryType::REPOSITORY_TYPE_SVN:
         return $this->isHosted();
       case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
       case PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL:
         return true;
     }
   }
 
   public function getHookDirectories() {
     $directories = array();
     if (!$this->isHosted()) {
       return $directories;
     }
 
     $root = $this->getLocalPath();
 
     switch ($this->getVersionControlSystem()) {
       case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
         if ($this->isWorkingCopyBare()) {
           $directories[] = $root.'/hooks/pre-receive-phabricator.d/';
         } else {
           $directories[] = $root.'/.git/hooks/pre-receive-phabricator.d/';
         }
         break;
       case PhabricatorRepositoryType::REPOSITORY_TYPE_SVN:
         $directories[] = $root.'/hooks/pre-commit-phabricator.d/';
         break;
       case PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL:
         // NOTE: We don't support custom Mercurial hooks for now because they're
         // messy and we can't easily just drop a `hooks.d/` directory next to
         // the hooks.
         break;
     }
 
     return $directories;
   }
 
   public function canDestroyWorkingCopy() {
     if ($this->isHosted()) {
       // Never destroy hosted working copies.
       return false;
     }
 
     $default_path = PhabricatorEnv::getEnvConfig(
       'repository.default-local-path');
     return Filesystem::isDescendant($this->getLocalPath(), $default_path);
   }
 
   public function canUsePathTree() {
     return !$this->isSVN();
   }
 
   public function canUseGitLFS() {
     if (!$this->isGit()) {
       return false;
     }
 
     if (!$this->isHosted()) {
       return false;
     }
 
     if (!PhabricatorEnv::getEnvConfig('diffusion.allow-git-lfs')) {
       return false;
     }
 
     return true;
   }
 
   public function getGitLFSURI($path = null) {
     if (!$this->canUseGitLFS()) {
       throw new Exception(
         pht(
           'This repository does not support Git LFS, so Git LFS URIs can '.
           'not be generated for it.'));
     }
 
     $uri = $this->getRawHTTPCloneURIObject();
     $uri = (string)$uri;
     $uri = $uri.'/'.$path;
 
     return $uri;
   }
 
   public function canMirror() {
     if ($this->isGit() || $this->isHg()) {
       return true;
     }
 
     return false;
   }
 
   public function canAllowDangerousChanges() {
     if (!$this->isHosted()) {
       return false;
     }
 
     // In Git and Mercurial, ref deletions and rewrites are dangerous.
     // In Subversion, editing revprops is dangerous.
 
     return true;
   }
 
   public function shouldAllowDangerousChanges() {
     return (bool)$this->getDetail('allow-dangerous-changes');
   }
 
   public function canAllowEnormousChanges() {
     if (!$this->isHosted()) {
       return false;
     }
 
     return true;
   }
 
   public function shouldAllowEnormousChanges() {
     return (bool)$this->getDetail('allow-enormous-changes');
   }
 
   public function writeStatusMessage(
     $status_type,
     $status_code,
     array $parameters = array()) {
 
     $table = new PhabricatorRepositoryStatusMessage();
     $conn_w = $table->establishConnection('w');
     $table_name = $table->getTableName();
 
     if ($status_code === null) {
       queryfx(
         $conn_w,
         'DELETE FROM %T WHERE repositoryID = %d AND statusType = %s',
         $table_name,
         $this->getID(),
         $status_type);
     } else {
       // If the existing message has the same code (e.g., we just hit an
       // error and also previously hit an error) we increment the message
       // count. This allows us to determine how many times in a row we've
       // run into an error.
 
       // NOTE: The assignments in "ON DUPLICATE KEY UPDATE" are evaluated
       // in order, so the "messageCount" assignment must occur before the
       // "statusCode" assignment. See T11705.
 
       queryfx(
         $conn_w,
         'INSERT INTO %T
           (repositoryID, statusType, statusCode, parameters, epoch,
             messageCount)
           VALUES (%d, %s, %s, %s, %d, %d)
           ON DUPLICATE KEY UPDATE
             messageCount =
               IF(
                 statusCode = VALUES(statusCode),
                 messageCount + VALUES(messageCount),
                 VALUES(messageCount)),
             statusCode = VALUES(statusCode),
             parameters = VALUES(parameters),
             epoch = VALUES(epoch)',
         $table_name,
         $this->getID(),
         $status_type,
         $status_code,
         json_encode($parameters),
         time(),
         1);
     }
 
     return $this;
   }
 
   public static function assertValidRemoteURI($uri) {
     if (trim($uri) != $uri) {
       throw new Exception(
         pht('The remote URI has leading or trailing whitespace.'));
     }
 
     $uri_object = new PhutilURI($uri);
     $protocol = $uri_object->getProtocol();
 
     // Catch confusion between Git/SCP-style URIs and normal URIs. See T3619
     // for discussion. This is usually a user adding "ssh://" to an implicit
     // SSH Git URI.
     if ($protocol == 'ssh') {
       if (preg_match('(^[^:@]+://[^/:]+:[^\d])', $uri)) {
         throw new Exception(
           pht(
             "The remote URI is not formatted correctly. Remote URIs ".
             "with an explicit protocol should be in the form ".
             "'%s', not '%s'. The '%s' syntax is only valid in SCP-style URIs.",
             'proto://domain/path',
             'proto://domain:/path',
             ':/path'));
       }
     }
 
     switch ($protocol) {
       case 'ssh':
       case 'http':
       case 'https':
       case 'git':
       case 'svn':
       case 'svn+ssh':
         break;
       default:
         // NOTE: We're explicitly rejecting 'file://' because it can be
         // used to clone from the working copy of another repository on disk
         // that you don't normally have permission to access.
 
         throw new Exception(
           pht(
             'The URI protocol is unrecognized. It should begin with '.
             '"%s", "%s", "%s", "%s", "%s", "%s", or be in the form "%s".',
             'ssh://',
             'http://',
             'https://',
             'git://',
             'svn://',
             'svn+ssh://',
             'git@domain.com:path'));
     }
 
     return true;
   }
 
 
   /**
    * Load the pull frequency for this repository, based on the time since the
    * last activity.
    *
    * We pull rarely used repositories less frequently. This finds the most
    * recent commit which is older than the current time (which prevents us from
    * spinning on repositories with a silly commit post-dated to some time in
    * 2037). We adjust the pull frequency based on when the most recent commit
    * occurred.
    *
    * @param   int   The minimum update interval to use, in seconds.
    * @return  int   Repository update interval, in seconds.
    */
   public function loadUpdateInterval($minimum = 15) {
     // First, check if we've hit errors recently. If we have, wait one period
     // for each consecutive error. Normally, this corresponds to a backoff of
     // 15s, 30s, 45s, etc.
 
     $message_table = new PhabricatorRepositoryStatusMessage();
     $conn = $message_table->establishConnection('r');
     $error_count = queryfx_one(
       $conn,
       'SELECT MAX(messageCount) error_count FROM %T
         WHERE repositoryID = %d
         AND statusType IN (%Ls)
         AND statusCode IN (%Ls)',
       $message_table->getTableName(),
       $this->getID(),
       array(
         PhabricatorRepositoryStatusMessage::TYPE_INIT,
         PhabricatorRepositoryStatusMessage::TYPE_FETCH,
       ),
       array(
         PhabricatorRepositoryStatusMessage::CODE_ERROR,
       ));
 
     $error_count = (int)$error_count['error_count'];
     if ($error_count > 0) {
       return (int)($minimum * $error_count);
     }
 
     // If a repository is still importing, always pull it as frequently as
     // possible. This prevents us from hanging for a long time at 99.9% when
     // importing an inactive repository.
     if ($this->isImporting()) {
       return $minimum;
     }
 
     $window_start = (PhabricatorTime::getNow() + $minimum);
 
     $table = id(new PhabricatorRepositoryCommit());
     $last_commit = queryfx_one(
       $table->establishConnection('r'),
       'SELECT epoch FROM %T
         WHERE repositoryID = %d AND epoch <= %d
         ORDER BY epoch DESC LIMIT 1',
       $table->getTableName(),
       $this->getID(),
       $window_start);
     if ($last_commit) {
       $time_since_commit = ($window_start - $last_commit['epoch']);
     } else {
       // If the repository has no commits, treat the creation date as
       // though it were the date of the last commit. This makes empty
       // repositories update quickly at first but slow down over time
       // if they don't see any activity.
       $time_since_commit = ($window_start - $this->getDateCreated());
     }
 
     $last_few_days = phutil_units('3 days in seconds');
 
     if ($time_since_commit <= $last_few_days) {
       // For repositories with activity in the recent past, we wait one
       // extra second for every 10 minutes since the last commit. This
       // shorter backoff is intended to handle weekends and other short
       // breaks from development.
       $smart_wait = ($time_since_commit / 600);
     } else {
       // For repositories without recent activity, we wait one extra second
       // for every 4 minutes since the last commit. This longer backoff
       // handles rarely used repositories, up to the maximum.
       $smart_wait = ($time_since_commit / 240);
     }
 
     // We'll never wait more than 6 hours to pull a repository.
     $longest_wait = phutil_units('6 hours in seconds');
     $smart_wait = min($smart_wait, $longest_wait);
     $smart_wait = max($minimum, $smart_wait);
 
     return (int)$smart_wait;
   }
 
 
   /**
    * Time limit for cloning or copying this repository.
    *
    * This limit is used to timeout operations like `git clone` or `git fetch`
    * when doing intracluster synchronization, building working copies, etc.
    *
    * @return int Maximum number of seconds to spend copying this repository.
    */
   public function getCopyTimeLimit() {
     return $this->getDetail('limit.copy');
   }
 
   public function setCopyTimeLimit($limit) {
     return $this->setDetail('limit.copy', $limit);
   }
 
   public function getDefaultCopyTimeLimit() {
     return phutil_units('15 minutes in seconds');
   }
 
   public function getEffectiveCopyTimeLimit() {
     $limit = $this->getCopyTimeLimit();
     if ($limit) {
       return $limit;
     }
 
     return $this->getDefaultCopyTimeLimit();
   }
 
   public function getFilesizeLimit() {
     return $this->getDetail('limit.filesize');
   }
 
   public function setFilesizeLimit($limit) {
     return $this->setDetail('limit.filesize', $limit);
   }
 
   public function getTouchLimit() {
     return $this->getDetail('limit.touch');
   }
 
   public function setTouchLimit($limit) {
     return $this->setDetail('limit.touch', $limit);
   }
 
   /**
    * Retrieve the service URI for the device hosting this repository.
    *
    * See @{method:newConduitClient} for a general discussion of interacting
    * with repository services. This method provides lower-level resolution of
    * services, returning raw URIs.
    *
    * @param PhabricatorUser Viewing user.
    * @param map<string, wild> Constraints on selectable services.
    * @return string|null URI, or `null` for local repositories.
    */
   public function getAlmanacServiceURI(
     PhabricatorUser $viewer,
     array $options) {
 
     $refs = $this->getAlmanacServiceRefs($viewer, $options);
 
     if (!$refs) {
       return null;
     }
 
     $ref = head($refs);
     return $ref->getURI();
   }
 
   public function getAlmanacServiceRefs(
     PhabricatorUser $viewer,
     array $options) {
 
     PhutilTypeSpec::checkMap(
       $options,
       array(
         'neverProxy' => 'bool',
         'protocols' => 'list<string>',
         'writable' => 'optional bool',
       ));
 
     $never_proxy = $options['neverProxy'];
     $protocols = $options['protocols'];
     $writable = idx($options, 'writable', false);
 
     $cache_key = $this->getAlmanacServiceCacheKey();
     if (!$cache_key) {
       return array();
     }
 
     $cache = PhabricatorCaches::getMutableStructureCache();
     $uris = $cache->getKey($cache_key, false);
 
     // If we haven't built the cache yet, build it now.
     if ($uris === false) {
       $uris = $this->buildAlmanacServiceURIs();
       $cache->setKey($cache_key, $uris);
     }
 
     if ($uris === null) {
       return array();
     }
 
     $local_device = AlmanacKeys::getDeviceID();
     if ($never_proxy && !$local_device) {
       throw new Exception(
         pht(
           'Unable to handle proxied service request. This device is not '.
           'registered, so it can not identify local services. Register '.
           'this device before sending requests here.'));
     }
 
     $protocol_map = array_fuse($protocols);
 
     $results = array();
     foreach ($uris as $uri) {
       // If we're never proxying this and it's locally satisfiable, return
       // `null` to tell the caller to handle it locally. If we're allowed to
       // proxy, we skip this check and may proxy the request to ourselves.
       // (That proxied request will end up here with proxying forbidden,
       // return `null`, and then the request will actually run.)
 
       if ($local_device && $never_proxy) {
         if ($uri['device'] == $local_device) {
           return array();
         }
       }
 
       if (isset($protocol_map[$uri['protocol']])) {
         $results[] = $uri;
       }
     }
 
     if (!$results) {
       throw new Exception(
         pht(
           'The Almanac service for this repository is not bound to any '.
           'interfaces which support the required protocols (%s).',
           implode(', ', $protocols)));
     }
 
     if ($never_proxy) {
       // See PHI1030. This error can arise from various device name/address
       // mismatches which are hard to detect, so try to provide as much
       // information as we can.
 
       if ($writable) {
         $request_type = pht('(This is a write request.)');
       } else {
         $request_type = pht('(This is a read request.)');
       }
 
       throw new Exception(
         pht(
           'This repository request (for repository "%s") has been '.
           'incorrectly routed to a cluster host (with device name "%s", '.
           'and hostname "%s") which can not serve the request.'.
           "\n\n".
           'The Almanac device address for the correct device may improperly '.
           'point at this host, or the "device.id" configuration file on '.
           'this host may be incorrect.'.
           "\n\n".
           'Requests routed within the cluster by Phabricator are always '.
           'expected to be sent to a node which can serve the request. To '.
           'prevent loops, this request will not be proxied again.'.
           "\n\n".
           "%s",
           $this->getDisplayName(),
           $local_device,
           php_uname('n'),
           $request_type));
     }
 
     if (count($results) > 1) {
       if (!$this->supportsSynchronization()) {
         throw new Exception(
           pht(
             'Repository "%s" is bound to multiple active repository hosts, '.
             'but this repository does not support cluster synchronization. '.
             'Declusterize this repository or move it to a service with only '.
             'one host.',
             $this->getDisplayName()));
       }
     }
 
     $refs = array();
     foreach ($results as $result) {
       $refs[] = DiffusionServiceRef::newFromDictionary($result);
     }
 
     // If we require a writable device, remove URIs which aren't writable.
     if ($writable) {
       foreach ($refs as $key => $ref) {
         if (!$ref->isWritable()) {
           unset($refs[$key]);
         }
       }
 
       if (!$refs) {
         throw new Exception(
           pht(
             'This repository ("%s") is not writable with the given '.
             'protocols (%s). The Almanac service for this repository has no '.
             'writable bindings that support these protocols.',
             $this->getDisplayName(),
             implode(', ', $protocols)));
       }
     }
 
     if ($writable) {
       $refs = $this->sortWritableAlmanacServiceRefs($refs);
     } else {
       $refs = $this->sortReadableAlmanacServiceRefs($refs);
     }
 
     return array_values($refs);
   }
 
   private function sortReadableAlmanacServiceRefs(array $refs) {
     assert_instances_of($refs, 'DiffusionServiceRef');
     shuffle($refs);
     return $refs;
   }
 
   private function sortWritableAlmanacServiceRefs(array $refs) {
     assert_instances_of($refs, 'DiffusionServiceRef');
 
     // See T13109 for discussion of how this method routes requests.
 
     // In the absence of other rules, we'll send traffic to devices randomly.
     // We also want to select randomly among nodes which are equally good
     // candidates to receive the write, and accomplish that by shuffling the
     // list up front.
     shuffle($refs);
 
     $order = array();
 
     // If some device is currently holding the write lock, send all requests
     // to that device. We're trying to queue writes on a single device so they
     // do not need to wait for read synchronization after earlier writes
     // complete.
     $writer = PhabricatorRepositoryWorkingCopyVersion::loadWriter(
       $this->getPHID());
     if ($writer) {
       $device_phid = $writer->getWriteProperty('devicePHID');
       foreach ($refs as $key => $ref) {
         if ($ref->getDevicePHID() === $device_phid) {
           $order[] = $key;
         }
       }
     }
 
     // If no device is currently holding the write lock, try to send requests
     // to a device which is already up to date and will not need to synchronize
     // before it can accept the write.
     $versions = PhabricatorRepositoryWorkingCopyVersion::loadVersions(
       $this->getPHID());
     if ($versions) {
       $max_version = (int)max(mpull($versions, 'getRepositoryVersion'));
 
       $max_devices = array();
       foreach ($versions as $version) {
         if ($version->getRepositoryVersion() == $max_version) {
           $max_devices[] = $version->getDevicePHID();
         }
       }
       $max_devices = array_fuse($max_devices);
 
       foreach ($refs as $key => $ref) {
         if (isset($max_devices[$ref->getDevicePHID()])) {
           $order[] = $key;
         }
       }
     }
 
     // Reorder the results, putting any we've selected as preferred targets for
     // the write at the head of the list.
     $refs = array_select_keys($refs, $order) + $refs;
 
     return $refs;
   }
 
   public function supportsSynchronization() {
     // TODO: For now, this is only supported for Git.
     if (!$this->isGit()) {
       return false;
     }
 
     return true;
   }
 
 
   public function supportsRefs() {
     if ($this->isSVN()) {
       return false;
     }
 
     return true;
   }
 
   public function getAlmanacServiceCacheKey() {
     $service_phid = $this->getAlmanacServicePHID();
     if (!$service_phid) {
       return null;
     }
 
     $repository_phid = $this->getPHID();
 
     $parts = array(
       "repo({$repository_phid})",
       "serv({$service_phid})",
       'v4',
     );
 
     return implode('.', $parts);
   }
 
   private function buildAlmanacServiceURIs() {
     $service = $this->loadAlmanacService();
     if (!$service) {
       return null;
     }
 
     $bindings = $service->getActiveBindings();
     if (!$bindings) {
       throw new Exception(
         pht(
           'The Almanac service for this repository is not bound to any '.
           'active interfaces.'));
     }
 
     $uris = array();
     foreach ($bindings as $binding) {
       $iface = $binding->getInterface();
 
       $uri = $this->getClusterRepositoryURIFromBinding($binding);
       $protocol = $uri->getProtocol();
       $device_name = $iface->getDevice()->getName();
       $device_phid = $iface->getDevice()->getPHID();
 
       $uris[] = array(
         'protocol' => $protocol,
         'uri' => (string)$uri,
         'device' => $device_name,
         'writable' => (bool)$binding->getAlmanacPropertyValue('writable'),
         'devicePHID' => $device_phid,
       );
     }
 
     return $uris;
   }
 
   /**
    * Build a new Conduit client in order to make a service call to this
    * repository.
    *
    * If the repository is hosted locally, this method may return `null`. The
    * caller should use `ConduitCall` or other local logic to complete the
    * request.
    *
    * By default, we will return a @{class:ConduitClient} for any repository with
    * a service, even if that service is on the current device.
    *
    * We do this because this configuration does not make very much sense in a
    * production context, but is very common in a test/development context
    * (where the developer's machine is both the web host and the repository
    * service). By proxying in development, we get more consistent behavior
    * between development and production, and don't have a major untested
    * codepath.
    *
    * The `$never_proxy` parameter can be used to prevent this local proxying.
    * If the flag is passed:
    *
    *   - The method will return `null` (implying a local service call)
    *     if the repository service is hosted on the current device.
    *   - The method will throw if it would need to return a client.
    *
    * This is used to prevent loops in Conduit: the first request will proxy,
    * even in development, but the second request will be identified as a
    * cluster request and forced not to proxy.
    *
    * For lower-level service resolution, see @{method:getAlmanacServiceURI}.
    *
    * @param PhabricatorUser Viewing user.
    * @param bool `true` to throw if a client would be returned.
    * @return ConduitClient|null Client, or `null` for local repositories.
    */
   public function newConduitClient(
     PhabricatorUser $viewer,
     $never_proxy = false) {
 
     $uri = $this->getAlmanacServiceURI(
       $viewer,
       array(
         'neverProxy' => $never_proxy,
         'protocols' => array(
           'http',
           'https',
         ),
 
         // At least today, no Conduit call can ever write to a repository,
         // so it's fine to send anything to a read-only node.
         'writable' => false,
       ));
     if ($uri === null) {
       return null;
     }
 
     $domain = id(new PhutilURI(PhabricatorEnv::getURI('/')))->getDomain();
 
     $client = id(new ConduitClient($uri))
       ->setHost($domain);
 
     if ($viewer->isOmnipotent()) {
       // If the caller is the omnipotent user (normally, a daemon), we will
       // sign the request with this host's asymmetric keypair.
 
       $public_path = AlmanacKeys::getKeyPath('device.pub');
       try {
         $public_key = Filesystem::readFile($public_path);
       } catch (Exception $ex) {
         throw new PhutilAggregateException(
           pht(
             'Unable to read device public key while attempting to make '.
             'authenticated method call within the Phabricator cluster. '.
             'Use `%s` to register keys for this device. Exception: %s',
             'bin/almanac register',
             $ex->getMessage()),
           array($ex));
       }
 
       $private_path = AlmanacKeys::getKeyPath('device.key');
       try {
         $private_key = Filesystem::readFile($private_path);
         $private_key = new PhutilOpaqueEnvelope($private_key);
       } catch (Exception $ex) {
         throw new PhutilAggregateException(
           pht(
             'Unable to read device private key while attempting to make '.
             'authenticated method call within the Phabricator cluster. '.
             'Use `%s` to register keys for this device. Exception: %s',
             'bin/almanac register',
             $ex->getMessage()),
           array($ex));
       }
 
       $client->setSigningKeys($public_key, $private_key);
     } else {
       // If the caller is a normal user, we generate or retrieve a cluster
       // API token.
 
       $token = PhabricatorConduitToken::loadClusterTokenForUser($viewer);
       if ($token) {
         $client->setConduitToken($token->getToken());
       }
     }
 
     return $client;
   }
 
   public function newConduitClientForRequest(ConduitAPIRequest $request) {
     // Figure out whether we're going to handle this request on this device,
     // or proxy it to another node in the cluster.
 
     // If this is a cluster request and we need to proxy, we'll explode here
     // to prevent infinite recursion.
 
     $viewer = $request->getViewer();
     $is_cluster_request = $request->getIsClusterRequest();
 
     $client = $this->newConduitClient(
       $viewer,
       $is_cluster_request);
 
     return $client;
   }
 
   public function newConduitFuture(
     PhabricatorUser $viewer,
     $method,
     array $params,
     $never_proxy = false) {
 
     $client = $this->newConduitClient(
       $viewer,
       $never_proxy);
 
     if (!$client) {
       $conduit_call = id(new ConduitCall($method, $params))
         ->setUser($viewer);
       $future = new MethodCallFuture($conduit_call, 'execute');
     } else {
       $future = $client->callMethod($method, $params);
     }
 
     return $future;
   }
 
   public function getPassthroughEnvironmentalVariables() {
     $env = $_ENV;
 
     if ($this->isGit()) {
       // $_ENV does not populate in CLI contexts if "E" is missing from
       // "variables_order" in PHP config. Currently, we do not require this
       // to be configured. Since it may not be, explicitly bring expected Git
       // environmental variables into scope. This list is not exhaustive, but
       // only lists variables with a known impact on commit hook behavior.
 
       // This can be removed if we later require "E" in "variables_order".
 
       $git_env = array(
         'GIT_OBJECT_DIRECTORY',
         'GIT_ALTERNATE_OBJECT_DIRECTORIES',
         'GIT_QUARANTINE_PATH',
       );
       foreach ($git_env as $key) {
         $value = getenv($key);
         if (strlen($value)) {
           $env[$key] = $value;
         }
       }
 
       $key = 'GIT_PUSH_OPTION_COUNT';
       $git_count = getenv($key);
       if (strlen($git_count)) {
         $git_count = (int)$git_count;
         $env[$key] = $git_count;
         for ($ii = 0; $ii < $git_count; $ii++) {
           $key = 'GIT_PUSH_OPTION_'.$ii;
           $env[$key] = getenv($key);
         }
       }
     }
 
     $result = array();
     foreach ($env as $key => $value) {
       // In Git, pass anything matching "GIT_*" though. Some of these variables
       // need to be preserved to allow `git` operations to work properly when
       // running from commit hooks.
       if ($this->isGit()) {
         if (preg_match('/^GIT_/', $key)) {
           $result[$key] = $value;
         }
       }
     }
 
     return $result;
   }
 
   public function supportsBranchComparison() {
     return $this->isGit();
   }
 
   public function isReadOnly() {
     return (bool)$this->getDetail('read-only');
   }
 
   public function setReadOnly($read_only) {
     return $this->setDetail('read-only', $read_only);
   }
 
   public function getReadOnlyMessage() {
     return $this->getDetail('read-only-message');
   }
 
   public function setReadOnlyMessage($message) {
     return $this->setDetail('read-only-message', $message);
   }
 
   public function getReadOnlyMessageForDisplay() {
     $parts = array();
     $parts[] = pht(
       'This repository is currently in read-only maintenance mode.');
 
     $message = $this->getReadOnlyMessage();
     if ($message !== null) {
       $parts[] = $message;
     }
 
     return implode("\n\n", $parts);
   }
 
 /* -(  Repository URIs  )---------------------------------------------------- */
 
 
   public function attachURIs(array $uris) {
     $custom_map = array();
     foreach ($uris as $key => $uri) {
       $builtin_key = $uri->getRepositoryURIBuiltinKey();
       if ($builtin_key !== null) {
         $custom_map[$builtin_key] = $key;
       }
     }
 
     $builtin_uris = $this->newBuiltinURIs();
     $seen_builtins = array();
     foreach ($builtin_uris as $builtin_uri) {
       $builtin_key = $builtin_uri->getRepositoryURIBuiltinKey();
       $seen_builtins[$builtin_key] = true;
 
       // If this builtin URI is disabled, don't attach it and remove the
       // persisted version if it exists.
       if ($builtin_uri->getIsDisabled()) {
         if (isset($custom_map[$builtin_key])) {
           unset($uris[$custom_map[$builtin_key]]);
         }
         continue;
       }
 
       // If the URI exists, make sure it's marked as not being disabled.
       if (isset($custom_map[$builtin_key])) {
         $uris[$custom_map[$builtin_key]]->setIsDisabled(false);
       }
     }
 
     // Remove any builtins which no longer exist.
     foreach ($custom_map as $builtin_key => $key) {
       if (empty($seen_builtins[$builtin_key])) {
         unset($uris[$key]);
       }
     }
 
     $this->uris = $uris;
 
     return $this;
   }
 
   public function getURIs() {
     return $this->assertAttached($this->uris);
   }
 
   public function getCloneURIs() {
     $uris = $this->getURIs();
 
     $clone = array();
     foreach ($uris as $uri) {
       if (!$uri->isBuiltin()) {
         continue;
       }
 
       if ($uri->getIsDisabled()) {
         continue;
       }
 
       $io_type = $uri->getEffectiveIoType();
       $is_clone =
         ($io_type == PhabricatorRepositoryURI::IO_READ) ||
         ($io_type == PhabricatorRepositoryURI::IO_READWRITE);
 
       if (!$is_clone) {
         continue;
       }
 
       $clone[] = $uri;
     }
 
     $clone = msort($clone, 'getURIScore');
     $clone = array_reverse($clone);
 
     return $clone;
   }
 
 
   public function newBuiltinURIs() {
     $has_callsign = ($this->getCallsign() !== null);
     $has_shortname = ($this->getRepositorySlug() !== null);
 
     $identifier_map = array(
       PhabricatorRepositoryURI::BUILTIN_IDENTIFIER_CALLSIGN => $has_callsign,
       PhabricatorRepositoryURI::BUILTIN_IDENTIFIER_SHORTNAME => $has_shortname,
       PhabricatorRepositoryURI::BUILTIN_IDENTIFIER_ID => true,
     );
 
     // If the view policy of the repository is public, support anonymous HTTP
     // even if authenticated HTTP is not supported.
     if ($this->getViewPolicy() === PhabricatorPolicies::POLICY_PUBLIC) {
       $allow_http = true;
     } else {
       $allow_http = PhabricatorEnv::getEnvConfig('diffusion.allow-http-auth');
     }
 
     $base_uri = PhabricatorEnv::getURI('/');
     $base_uri = new PhutilURI($base_uri);
     $has_https = ($base_uri->getProtocol() == 'https');
     $has_https = ($has_https && $allow_http);
 
     $has_http = !PhabricatorEnv::getEnvConfig('security.require-https');
     $has_http = ($has_http && $allow_http);
 
     // HTTP is not supported for Subversion.
     if ($this->isSVN()) {
       $has_http = false;
       $has_https = false;
     }
 
     $has_ssh = (bool)strlen(PhabricatorEnv::getEnvConfig('phd.user'));
 
     $protocol_map = array(
       PhabricatorRepositoryURI::BUILTIN_PROTOCOL_SSH => $has_ssh,
       PhabricatorRepositoryURI::BUILTIN_PROTOCOL_HTTPS => $has_https,
       PhabricatorRepositoryURI::BUILTIN_PROTOCOL_HTTP => $has_http,
     );
 
     $uris = array();
     foreach ($protocol_map as $protocol => $proto_supported) {
       foreach ($identifier_map as $identifier => $id_supported) {
         // This is just a dummy value because it can't be empty; we'll force
         // it to a proper value when using it in the UI.
         $builtin_uri = "{$protocol}://{$identifier}";
         $uris[] = PhabricatorRepositoryURI::initializeNewURI()
           ->setRepositoryPHID($this->getPHID())
           ->attachRepository($this)
           ->setBuiltinProtocol($protocol)
           ->setBuiltinIdentifier($identifier)
           ->setURI($builtin_uri)
           ->setIsDisabled((int)(!$proto_supported || !$id_supported));
       }
     }
 
     return $uris;
   }
 
 
   public function getClusterRepositoryURIFromBinding(
     AlmanacBinding $binding) {
     $protocol = $binding->getAlmanacPropertyValue('protocol');
     if ($protocol === null) {
       $protocol = 'https';
     }
 
     $iface = $binding->getInterface();
     $address = $iface->renderDisplayAddress();
 
     $path = $this->getURI();
 
     return id(new PhutilURI("{$protocol}://{$address}"))
       ->setPath($path);
   }
 
   public function loadAlmanacService() {
     $service_phid = $this->getAlmanacServicePHID();
     if (!$service_phid) {
       // No service, so this is a local repository.
       return null;
     }
 
     $service = id(new AlmanacServiceQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withPHIDs(array($service_phid))
       ->needActiveBindings(true)
       ->needProperties(true)
       ->executeOne();
     if (!$service) {
       throw new Exception(
         pht(
           'The Almanac service for this repository is invalid or could not '.
           'be loaded.'));
     }
 
     $service_type = $service->getServiceImplementation();
     if (!($service_type instanceof AlmanacClusterRepositoryServiceType)) {
       throw new Exception(
         pht(
           'The Almanac service for this repository does not have the correct '.
           'service type.'));
     }
 
     return $service;
   }
 
   public function markImporting() {
     $this->openTransaction();
       $this->beginReadLocking();
         $repository = $this->reload();
         $repository->setDetail('importing', true);
         $repository->save();
       $this->endReadLocking();
     $this->saveTransaction();
 
     return $repository;
   }
 
 
 /* -(  Symbols  )-------------------------------------------------------------*/
 
   public function getSymbolSources() {
     return $this->getDetail('symbol-sources', array());
   }
 
   public function getSymbolLanguages() {
     return $this->getDetail('symbol-languages', array());
   }
 
 
 /* -(  Staging  )------------------------------------------------------------ */
 
 
   public function supportsStaging() {
     return $this->isGit();
   }
 
 
   public function getStagingURI() {
     if (!$this->supportsStaging()) {
       return null;
     }
     return $this->getDetail('staging-uri', null);
   }
 
 
 /* -(  Automation  )--------------------------------------------------------- */
 
 
   public function supportsAutomation() {
     return $this->isGit();
   }
 
   public function canPerformAutomation() {
     if (!$this->supportsAutomation()) {
       return false;
     }
 
     if (!$this->getAutomationBlueprintPHIDs()) {
       return false;
     }
 
     return true;
   }
 
   public function getAutomationBlueprintPHIDs() {
     if (!$this->supportsAutomation()) {
       return array();
     }
     return $this->getDetail('automation.blueprintPHIDs', array());
   }
 
 
 /* -(  PhabricatorApplicationTransactionInterface  )------------------------- */
 
 
   public function getApplicationTransactionEditor() {
     return new PhabricatorRepositoryEditor();
   }
 
   public function getApplicationTransactionTemplate() {
     return new PhabricatorRepositoryTransaction();
   }
 
 
 /* -(  PhabricatorPolicyInterface  )----------------------------------------- */
 
 
   public function getCapabilities() {
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,
       PhabricatorPolicyCapability::CAN_EDIT,
       DiffusionPushCapability::CAPABILITY,
     );
   }
 
   public function getPolicy($capability) {
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         return $this->getViewPolicy();
       case PhabricatorPolicyCapability::CAN_EDIT:
         return $this->getEditPolicy();
       case DiffusionPushCapability::CAPABILITY:
         return $this->getPushPolicy();
     }
   }
 
   public function hasAutomaticCapability($capability, PhabricatorUser $user) {
     return false;
   }
 
 
 /* -(  PhabricatorMarkupInterface  )----------------------------------------- */
 
 
   public function getMarkupFieldKey($field) {
     $hash = PhabricatorHash::digestForIndex($this->getMarkupText($field));
     return "repo:{$hash}";
   }
 
   public function newMarkupEngine($field) {
     return PhabricatorMarkupEngine::newMarkupEngine(array());
   }
 
   public function getMarkupText($field) {
     return $this->getDetail('description');
   }
 
   public function didMarkupText(
     $field,
     $output,
     PhutilMarkupEngine $engine) {
     require_celerity_resource('phabricator-remarkup-css');
     return phutil_tag(
       'div',
       array(
         'class' => 'phabricator-remarkup',
       ),
       $output);
   }
 
   public function shouldUseMarkupCache($field) {
     return true;
   }
 
 
 /* -(  PhabricatorDestructibleInterface  )----------------------------------- */
 
 
   public function destroyObjectPermanently(
     PhabricatorDestructionEngine $engine) {
 
     $phid = $this->getPHID();
 
     $this->openTransaction();
 
       $this->delete();
 
       PhabricatorRepositoryURIIndex::updateRepositoryURIs($phid, array());
 
       $books = id(new DivinerBookQuery())
         ->setViewer($engine->getViewer())
         ->withRepositoryPHIDs(array($phid))
         ->execute();
       foreach ($books as $book) {
         $engine->destroyObject($book);
       }
 
       $atoms = id(new DivinerAtomQuery())
         ->setViewer($engine->getViewer())
         ->withRepositoryPHIDs(array($phid))
         ->execute();
       foreach ($atoms as $atom) {
         $engine->destroyObject($atom);
       }
 
       $lfs_refs = id(new PhabricatorRepositoryGitLFSRefQuery())
         ->setViewer($engine->getViewer())
         ->withRepositoryPHIDs(array($phid))
         ->execute();
       foreach ($lfs_refs as $ref) {
         $engine->destroyObject($ref);
       }
 
     $this->saveTransaction();
   }
 
 
 /* -(  PhabricatorDestructibleCodexInterface  )------------------------------ */
 
 
   public function newDestructibleCodex() {
     return new PhabricatorRepositoryDestructibleCodex();
   }
 
 
 /* -(  PhabricatorSpacesInterface  )----------------------------------------- */
 
 
   public function getSpacePHID() {
     return $this->spacePHID;
   }
 
 /* -(  PhabricatorConduitResultInterface  )---------------------------------- */
 
 
   public function getFieldSpecificationsForConduit() {
     return array(
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('name')
         ->setType('string')
         ->setDescription(pht('The repository name.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('vcs')
         ->setType('string')
         ->setDescription(
           pht('The VCS this repository uses ("git", "hg" or "svn").')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('callsign')
         ->setType('string')
         ->setDescription(pht('The repository callsign, if it has one.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('shortName')
         ->setType('string')
         ->setDescription(pht('Unique short name, if the repository has one.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('status')
         ->setType('string')
         ->setDescription(pht('Active or inactive status.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('isImporting')
         ->setType('bool')
         ->setDescription(
           pht(
             'True if the repository is importing initial commits.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('almanacServicePHID')
         ->setType('phid?')
         ->setDescription(
           pht(
             'The Almanac Service that hosts this repository, if the '.
             'repository is clustered.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('refRules')
         ->setType('map<string, list<string>>')
         ->setDescription(
           pht(
             'The "Fetch" and "Permanent Ref" rules for this repository.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('defaultBranch')
         ->setType('string?')
         ->setDescription(pht('Default branch name.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('description')
         ->setType('remarkup')
         ->setDescription(pht('Repository description.')),
     );
   }
 
   public function getFieldValuesForConduit() {
     $fetch_rules = $this->getFetchRules();
     $track_rules = $this->getTrackOnlyRules();
     $permanent_rules = $this->getPermanentRefRules();
 
     $fetch_rules = $this->getStringListForConduit($fetch_rules);
     $track_rules = $this->getStringListForConduit($track_rules);
     $permanent_rules = $this->getStringListForConduit($permanent_rules);
 
     $default_branch = $this->getDefaultBranch();
     if (!strlen($default_branch)) {
       $default_branch = null;
     }
 
     return array(
       'name' => $this->getName(),
       'vcs' => $this->getVersionControlSystem(),
       'callsign' => $this->getCallsign(),
       'shortName' => $this->getRepositorySlug(),
       'status' => $this->getStatus(),
       'isImporting' => (bool)$this->isImporting(),
       'almanacServicePHID' => $this->getAlmanacServicePHID(),
       'refRules' => array(
         'fetchRules' => $fetch_rules,
         'trackRules' => $track_rules,
         'permanentRefRules' => $permanent_rules,
       ),
       'defaultBranch' => $default_branch,
       'description' => array(
         'raw' => (string)$this->getDetail('description'),
       ),
     );
   }
 
   private function getStringListForConduit($list) {
     if (!is_array($list)) {
       $list = array();
     }
 
     foreach ($list as $key => $value) {
       $value = (string)$value;
       if (!strlen($value)) {
         unset($list[$key]);
       }
     }
 
     return array_values($list);
   }
 
   public function getConduitSearchAttachments() {
     return array(
       id(new DiffusionRepositoryURIsSearchEngineAttachment())
         ->setAttachmentKey('uris'),
       id(new DiffusionRepositoryMetricsSearchEngineAttachment())
         ->setAttachmentKey('metrics'),
     );
   }
 
 /* -(  PhabricatorFulltextInterface  )--------------------------------------- */
 
 
   public function newFulltextEngine() {
     return new PhabricatorRepositoryFulltextEngine();
   }
 
 
 /* -(  PhabricatorFerretInterface  )----------------------------------------- */
 
 
   public function newFerretEngine() {
     return new PhabricatorRepositoryFerretEngine();
   }
 
 }
diff --git a/src/infrastructure/markup/PhabricatorMarkupEngine.php b/src/infrastructure/markup/PhabricatorMarkupEngine.php
index 3ad5304945..26851abd5f 100644
--- a/src/infrastructure/markup/PhabricatorMarkupEngine.php
+++ b/src/infrastructure/markup/PhabricatorMarkupEngine.php
@@ -1,715 +1,723 @@
 <?php
 
 /**
  * Manages markup engine selection, configuration, application, caching and
  * pipelining.
  *
  * @{class:PhabricatorMarkupEngine} can be used to render objects which
  * implement @{interface:PhabricatorMarkupInterface} in a batched, cache-aware
  * way. For example, if you have a list of comments written in remarkup (and
  * the objects implement the correct interface) you can render them by first
  * building an engine and adding the fields with @{method:addObject}.
  *
  *   $field  = 'field:body'; // Field you want to render. Each object exposes
  *                           // one or more fields of markup.
  *
  *   $engine = new PhabricatorMarkupEngine();
  *   foreach ($comments as $comment) {
  *     $engine->addObject($comment, $field);
  *   }
  *
  * Now, call @{method:process} to perform the actual cache/rendering
  * step. This is a heavyweight call which does batched data access and
  * transforms the markup into output.
  *
  *   $engine->process();
  *
  * Finally, do something with the results:
  *
  *   $results = array();
  *   foreach ($comments as $comment) {
  *     $results[] = $engine->getOutput($comment, $field);
  *   }
  *
  * If you have a single object to render, you can use the convenience method
  * @{method:renderOneObject}.
  *
  * @task markup Markup Pipeline
  * @task engine Engine Construction
  */
 final class PhabricatorMarkupEngine extends Phobject {
 
   private $objects = array();
   private $viewer;
   private $contextObject;
   private $version = 21;
   private $engineCaches = array();
   private $auxiliaryConfig = array();
 
 
 /* -(  Markup Pipeline  )---------------------------------------------------- */
 
 
   /**
    * Convenience method for pushing a single object through the markup
    * pipeline.
    *
    * @param PhabricatorMarkupInterface  The object to render.
    * @param string                      The field to render.
    * @param PhabricatorUser             User viewing the markup.
    * @param object                      A context object for policy checks
    * @return string                     Marked up output.
    * @task markup
    */
   public static function renderOneObject(
     PhabricatorMarkupInterface $object,
     $field,
     PhabricatorUser $viewer,
     $context_object = null) {
     return id(new PhabricatorMarkupEngine())
       ->setViewer($viewer)
       ->setContextObject($context_object)
       ->addObject($object, $field)
       ->process()
       ->getOutput($object, $field);
   }
 
 
   /**
    * Queue an object for markup generation when @{method:process} is
    * called. You can retrieve the output later with @{method:getOutput}.
    *
    * @param PhabricatorMarkupInterface  The object to render.
    * @param string                      The field to render.
    * @return this
    * @task markup
    */
   public function addObject(PhabricatorMarkupInterface $object, $field) {
     $key = $this->getMarkupFieldKey($object, $field);
     $this->objects[$key] = array(
       'object' => $object,
       'field'  => $field,
     );
 
     return $this;
   }
 
 
   /**
    * Process objects queued with @{method:addObject}. You can then retrieve
    * the output with @{method:getOutput}.
    *
    * @return this
    * @task markup
    */
   public function process() {
     $keys = array();
     foreach ($this->objects as $key => $info) {
       if (!isset($info['markup'])) {
         $keys[] = $key;
       }
     }
 
     if (!$keys) {
       return $this;
     }
 
     $objects = array_select_keys($this->objects, $keys);
 
     // Build all the markup engines. We need an engine for each field whether
     // we have a cache or not, since we still need to postprocess the cache.
     $engines = array();
     foreach ($objects as $key => $info) {
       $engines[$key] = $info['object']->newMarkupEngine($info['field']);
       $engines[$key]->setConfig('viewer', $this->viewer);
       $engines[$key]->setConfig('contextObject', $this->contextObject);
 
       foreach ($this->auxiliaryConfig as $aux_key => $aux_value) {
         $engines[$key]->setConfig($aux_key, $aux_value);
       }
     }
 
     // Load or build the preprocessor caches.
     $blocks = $this->loadPreprocessorCaches($engines, $objects);
     $blocks = mpull($blocks, 'getCacheData');
 
     $this->engineCaches = $blocks;
 
     // Finalize the output.
     foreach ($objects as $key => $info) {
       $engine = $engines[$key];
       $field = $info['field'];
       $object = $info['object'];
 
       $output = $engine->postprocessText($blocks[$key]);
       $output = $object->didMarkupText($field, $output, $engine);
       $this->objects[$key]['output'] = $output;
     }
 
     return $this;
   }
 
 
   /**
    * Get the output of markup processing for a field queued with
    * @{method:addObject}. Before you can call this method, you must call
    * @{method:process}.
    *
    * @param PhabricatorMarkupInterface  The object to retrieve.
    * @param string                      The field to retrieve.
    * @return string                     Processed output.
    * @task markup
    */
   public function getOutput(PhabricatorMarkupInterface $object, $field) {
     $key = $this->getMarkupFieldKey($object, $field);
     $this->requireKeyProcessed($key);
 
     return $this->objects[$key]['output'];
   }
 
 
   /**
    * Retrieve engine metadata for a given field.
    *
    * @param PhabricatorMarkupInterface  The object to retrieve.
    * @param string                      The field to retrieve.
    * @param string                      The engine metadata field to retrieve.
    * @param wild                        Optional default value.
    * @task markup
    */
   public function getEngineMetadata(
     PhabricatorMarkupInterface $object,
     $field,
     $metadata_key,
     $default = null) {
 
     $key = $this->getMarkupFieldKey($object, $field);
     $this->requireKeyProcessed($key);
 
     return idx($this->engineCaches[$key]['metadata'], $metadata_key, $default);
   }
 
 
   /**
    * @task markup
    */
   private function requireKeyProcessed($key) {
     if (empty($this->objects[$key])) {
       throw new Exception(
         pht(
           "Call %s before using results (key = '%s').",
           'addObject()',
           $key));
     }
 
     if (!isset($this->objects[$key]['output'])) {
       throw new PhutilInvalidStateException('process');
     }
   }
 
 
   /**
    * @task markup
    */
   private function getMarkupFieldKey(
     PhabricatorMarkupInterface $object,
     $field) {
 
     static $custom;
     if ($custom === null) {
       $custom = array_merge(
         self::loadCustomInlineRules(),
         self::loadCustomBlockRules());
 
       $custom = mpull($custom, 'getRuleVersion', null);
       ksort($custom);
       $custom = PhabricatorHash::digestForIndex(serialize($custom));
     }
 
     return $object->getMarkupFieldKey($field).'@'.$this->version.'@'.$custom;
   }
 
 
   /**
    * @task markup
    */
   private function loadPreprocessorCaches(array $engines, array $objects) {
     $blocks = array();
 
     $use_cache = array();
     foreach ($objects as $key => $info) {
       if ($info['object']->shouldUseMarkupCache($info['field'])) {
         $use_cache[$key] = true;
       }
     }
 
     if ($use_cache) {
       try {
         $blocks = id(new PhabricatorMarkupCache())->loadAllWhere(
           'cacheKey IN (%Ls)',
           array_keys($use_cache));
         $blocks = mpull($blocks, null, 'getCacheKey');
       } catch (Exception $ex) {
         phlog($ex);
       }
     }
 
     $is_readonly = PhabricatorEnv::isReadOnly();
 
     foreach ($objects as $key => $info) {
       // False check in case MySQL doesn't support unicode characters
       // in the string (T1191), resulting in unserialize returning false.
       if (isset($blocks[$key]) && $blocks[$key]->getCacheData() !== false) {
         // If we already have a preprocessing cache, we don't need to rebuild
         // it.
         continue;
       }
 
       $text = $info['object']->getMarkupText($info['field']);
       $data = $engines[$key]->preprocessText($text);
 
       // NOTE: This is just debugging information to help sort out cache issues.
       // If one machine is misconfigured and poisoning caches you can use this
       // field to hunt it down.
 
       $metadata = array(
         'host' => php_uname('n'),
       );
 
       $blocks[$key] = id(new PhabricatorMarkupCache())
         ->setCacheKey($key)
         ->setCacheData($data)
         ->setMetadata($metadata);
 
       if (isset($use_cache[$key]) && !$is_readonly) {
         // This is just filling a cache and always safe, even on a read pathway.
         $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
           $blocks[$key]->replace();
         unset($unguarded);
       }
     }
 
     return $blocks;
   }
 
 
   /**
    * Set the viewing user. Used to implement object permissions.
    *
    * @param PhabricatorUser The viewing user.
    * @return this
    * @task markup
    */
   public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
   /**
    * Set the context object. Used to implement object permissions.
    *
    * @param The object in which context this remarkup is used.
    * @return this
    * @task markup
    */
   public function setContextObject($object) {
     $this->contextObject = $object;
     return $this;
   }
 
   public function setAuxiliaryConfig($key, $value) {
     // TODO: This is gross and should be removed. Avoid use.
     $this->auxiliaryConfig[$key] = $value;
     return $this;
   }
 
 
 /* -(  Engine Construction  )------------------------------------------------ */
 
 
 
   /**
    * @task engine
    */
   public static function newManiphestMarkupEngine() {
     return self::newMarkupEngine(array(
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newPhrictionMarkupEngine() {
     return self::newMarkupEngine(array(
       'header.generate-toc' => true,
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newPhameMarkupEngine() {
     return self::newMarkupEngine(
       array(
         'macros' => false,
         'uri.full' => true,
         'uri.same-window' => true,
         'uri.base' => PhabricatorEnv::getURI('/'),
       ));
   }
 
 
   /**
    * @task engine
    */
   public static function newFeedMarkupEngine() {
     return self::newMarkupEngine(
       array(
         'macros'      => false,
         'youtube'     => false,
       ));
   }
 
   /**
    * @task engine
    */
   public static function newCalendarMarkupEngine() {
     return self::newMarkupEngine(array(
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newDifferentialMarkupEngine(array $options = array()) {
     return self::newMarkupEngine(array(
       'differential.diff' => idx($options, 'differential.diff'),
     ));
   }
 
 
   /**
    * @task engine
    */
   public static function newDiffusionMarkupEngine(array $options = array()) {
     return self::newMarkupEngine(array(
       'header.generate-toc' => true,
     ));
   }
 
   /**
    * @task engine
    */
   public static function getEngine($ruleset = 'default') {
     static $engines = array();
     if (isset($engines[$ruleset])) {
       return $engines[$ruleset];
     }
 
     $engine = null;
     switch ($ruleset) {
       case 'default':
         $engine = self::newMarkupEngine(array());
         break;
       case 'feed':
         $engine = self::newMarkupEngine(array());
         $engine->setConfig('autoplay.disable', true);
         break;
       case 'nolinebreaks':
         $engine = self::newMarkupEngine(array());
         $engine->setConfig('preserve-linebreaks', false);
         break;
       case 'diffusion-readme':
         $engine = self::newMarkupEngine(array());
         $engine->setConfig('preserve-linebreaks', false);
         $engine->setConfig('header.generate-toc', true);
         break;
       case 'diviner':
         $engine = self::newMarkupEngine(array());
         $engine->setConfig('preserve-linebreaks', false);
   //    $engine->setConfig('diviner.renderer', new DivinerDefaultRenderer());
         $engine->setConfig('header.generate-toc', true);
         break;
       case 'extract':
         // Engine used for reference/edge extraction. Turn off anything which
         // is slow and doesn't change reference extraction.
         $engine = self::newMarkupEngine(array());
         $engine->setConfig('pygments.enabled', false);
         break;
       default:
         throw new Exception(pht('Unknown engine ruleset: %s!', $ruleset));
     }
 
     $engines[$ruleset] = $engine;
     return $engine;
   }
 
   /**
    * @task engine
    */
   private static function getMarkupEngineDefaultConfiguration() {
     return array(
       'pygments'      => PhabricatorEnv::getEnvConfig('pygments.enabled'),
       'youtube'       => PhabricatorEnv::getEnvConfig(
         'remarkup.enable-embedded-youtube'),
       'differential.diff' => null,
       'header.generate-toc' => false,
       'macros'        => true,
       'uri.allowed-protocols' => PhabricatorEnv::getEnvConfig(
         'uri.allowed-protocols'),
       'uri.full' => false,
       'syntax-highlighter.engine' => PhabricatorEnv::getEnvConfig(
         'syntax-highlighter.engine'),
       'preserve-linebreaks' => true,
     );
   }
 
 
   /**
    * @task engine
    */
   public static function newMarkupEngine(array $options) {
     $options += self::getMarkupEngineDefaultConfiguration();
 
     $engine = new PhutilRemarkupEngine();
 
     $engine->setConfig('preserve-linebreaks', $options['preserve-linebreaks']);
 
     $engine->setConfig('pygments.enabled', $options['pygments']);
     $engine->setConfig(
       'uri.allowed-protocols',
       $options['uri.allowed-protocols']);
     $engine->setConfig('differential.diff', $options['differential.diff']);
     $engine->setConfig('header.generate-toc', $options['header.generate-toc']);
     $engine->setConfig(
       'syntax-highlighter.engine',
       $options['syntax-highlighter.engine']);
 
     $style_map = id(new PhabricatorDefaultSyntaxStyle())
       ->getRemarkupStyleMap();
     $engine->setConfig('phutil.codeblock.style-map', $style_map);
 
     $engine->setConfig('uri.full', $options['uri.full']);
 
     if (isset($options['uri.base'])) {
       $engine->setConfig('uri.base', $options['uri.base']);
     }
 
     if (isset($options['uri.same-window'])) {
       $engine->setConfig('uri.same-window', $options['uri.same-window']);
     }
 
     $rules = array();
     $rules[] = new PhutilRemarkupEscapeRemarkupRule();
     $rules[] = new PhutilRemarkupEvalRule();
     $rules[] = new PhutilRemarkupMonospaceRule();
 
 
     $rules[] = new PhutilRemarkupDocumentLinkRule();
     $rules[] = new PhabricatorNavigationRemarkupRule();
     $rules[] = new PhabricatorKeyboardRemarkupRule();
     $rules[] = new PhabricatorConfigRemarkupRule();
 
     if ($options['youtube']) {
       $rules[] = new PhabricatorYoutubeRemarkupRule();
     }
 
     $rules[] = new PhabricatorIconRemarkupRule();
     $rules[] = new PhabricatorEmojiRemarkupRule();
     $rules[] = new PhabricatorHandleRemarkupRule();
 
     $applications = PhabricatorApplication::getAllInstalledApplications();
     foreach ($applications as $application) {
       foreach ($application->getRemarkupRules() as $rule) {
         $rules[] = $rule;
       }
     }
 
     $rules[] = new PhutilRemarkupHyperlinkRule();
 
     if ($options['macros']) {
       $rules[] = new PhabricatorImageMacroRemarkupRule();
       $rules[] = new PhabricatorMemeRemarkupRule();
     }
 
     $rules[] = new PhutilRemarkupBoldRule();
     $rules[] = new PhutilRemarkupItalicRule();
     $rules[] = new PhutilRemarkupDelRule();
     $rules[] = new PhutilRemarkupUnderlineRule();
     $rules[] = new PhutilRemarkupHighlightRule();
     $rules[] = new PhutilRemarkupAnchorRule();
 
     foreach (self::loadCustomInlineRules() as $rule) {
       $rules[] = clone $rule;
     }
 
     $blocks = array();
     $blocks[] = new PhutilRemarkupQuotesBlockRule();
     $blocks[] = new PhutilRemarkupReplyBlockRule();
     $blocks[] = new PhutilRemarkupLiteralBlockRule();
     $blocks[] = new PhutilRemarkupHeaderBlockRule();
     $blocks[] = new PhutilRemarkupHorizontalRuleBlockRule();
     $blocks[] = new PhutilRemarkupListBlockRule();
     $blocks[] = new PhutilRemarkupCodeBlockRule();
     $blocks[] = new PhutilRemarkupNoteBlockRule();
     $blocks[] = new PhutilRemarkupTableBlockRule();
     $blocks[] = new PhutilRemarkupSimpleTableBlockRule();
     $blocks[] = new PhutilRemarkupInterpreterBlockRule();
     $blocks[] = new PhutilRemarkupDefaultBlockRule();
 
     foreach (self::loadCustomBlockRules() as $rule) {
       $blocks[] = $rule;
     }
 
     foreach ($blocks as $block) {
       $block->setMarkupRules($rules);
     }
 
     $engine->setBlockRules($blocks);
 
     return $engine;
   }
 
   public static function extractPHIDsFromMentions(
     PhabricatorUser $viewer,
     array $content_blocks) {
 
     $mentions = array();
 
     $engine = self::newDifferentialMarkupEngine();
     $engine->setConfig('viewer', $viewer);
 
     foreach ($content_blocks as $content_block) {
+      if ($content_block === null) {
+        continue;
+      }
+
+      if (!strlen($content_block)) {
+        continue;
+      }
+
       $engine->markupText($content_block);
       $phids = $engine->getTextMetadata(
         PhabricatorMentionRemarkupRule::KEY_MENTIONED,
         array());
       $mentions += $phids;
     }
 
     return $mentions;
   }
 
   public static function extractFilePHIDsFromEmbeddedFiles(
     PhabricatorUser $viewer,
     array $content_blocks) {
     $files = array();
 
     $engine = self::newDifferentialMarkupEngine();
     $engine->setConfig('viewer', $viewer);
 
     foreach ($content_blocks as $content_block) {
       $engine->markupText($content_block);
       $phids = $engine->getTextMetadata(
         PhabricatorEmbedFileRemarkupRule::KEY_EMBED_FILE_PHIDS,
         array());
       foreach ($phids as $phid) {
         $files[$phid] = $phid;
       }
     }
 
     return array_values($files);
   }
 
   public static function summarizeSentence($corpus) {
     $corpus = trim($corpus);
     $blocks = preg_split('/\n+/', $corpus, 2);
     $block = head($blocks);
 
     $sentences = preg_split(
       '/\b([.?!]+)\B/u',
       $block,
       2,
       PREG_SPLIT_DELIM_CAPTURE);
 
     if (count($sentences) > 1) {
       $result = $sentences[0].$sentences[1];
     } else {
       $result = head($sentences);
     }
 
     return id(new PhutilUTF8StringTruncator())
       ->setMaximumGlyphs(128)
       ->truncateString($result);
   }
 
   /**
    * Produce a corpus summary, in a way that shortens the underlying text
    * without truncating it somewhere awkward.
    *
    * TODO: We could do a better job of this.
    *
    * @param string  Remarkup corpus to summarize.
    * @return string Summarized corpus.
    */
   public static function summarize($corpus) {
 
     // Major goals here are:
     //  - Don't split in the middle of a character (utf-8).
     //  - Don't split in the middle of, e.g., **bold** text, since
     //    we end up with hanging '**' in the summary.
     //  - Try not to pick an image macro, header, embedded file, etc.
     //  - Hopefully don't return too much text. We don't explicitly limit
     //    this right now.
 
     $blocks = preg_split("/\n *\n\s*/", $corpus);
 
     $best = null;
     foreach ($blocks as $block) {
       // This is a test for normal spaces in the block, i.e. a heuristic to
       // distinguish standard paragraphs from things like image macros. It may
       // not work well for non-latin text. We prefer to summarize with a
       // paragraph of normal words over an image macro, if possible.
       $has_space = preg_match('/\w\s\w/', $block);
 
       // This is a test to find embedded images and headers. We prefer to
       // summarize with a normal paragraph over a header or an embedded object,
       // if possible.
       $has_embed = preg_match('/^[{=]/', $block);
 
       if ($has_space && !$has_embed) {
         // This seems like a good summary, so return it.
         return $block;
       }
 
       if (!$best) {
         // This is the first block we found; if everything is garbage just
         // use the first block.
         $best = $block;
       }
     }
 
     return $best;
   }
 
   private static function loadCustomInlineRules() {
     return id(new PhutilClassMapQuery())
       ->setAncestorClass('PhabricatorRemarkupCustomInlineRule')
       ->execute();
   }
 
   private static function loadCustomBlockRules() {
     return id(new PhutilClassMapQuery())
       ->setAncestorClass('PhabricatorRemarkupCustomBlockRule')
       ->execute();
   }
 
   public static function digestRemarkupContent($object, $content) {
     $parts = array();
     $parts[] = get_class($object);
 
     if ($object instanceof PhabricatorLiskDAO) {
       $parts[] = $object->getID();
     }
 
     $parts[] = $content;
 
     $message = implode("\n", $parts);
 
     return PhabricatorHash::digestWithNamedKey($message, 'remarkup');
   }
 
 }
diff --git a/src/infrastructure/markup/render.php b/src/infrastructure/markup/render.php
index 7294fc0ecf..84c3616fe8 100644
--- a/src/infrastructure/markup/render.php
+++ b/src/infrastructure/markup/render.php
@@ -1,183 +1,187 @@
 <?php
 
 /**
  * Render an HTML tag in a way that treats user content as unsafe by default.
  *
  * Tag rendering has some special logic which implements security features:
  *
  *   - When rendering `<a>` tags, if the `rel` attribute is not specified, it
  *     is interpreted as `rel="noreferrer"`.
  *   - When rendering `<a>` tags, the `href` attribute may not begin with
  *     `javascript:`.
  *
  * These special cases can not be disabled.
  *
  * IMPORTANT: The `$tag` attribute and the keys of the `$attributes` array are
  * trusted blindly, and not escaped. You should not pass user data in these
  * parameters.
  *
  * @param string The name of the tag, like `a` or `div`.
  * @param map<string, string> A map of tag attributes.
  * @param wild Content to put in the tag.
  * @return PhutilSafeHTML Tag object.
  */
 function phutil_tag($tag, array $attributes = array(), $content = null) {
   // If the `href` attribute is present, make sure it is not a "javascript:"
   // URI. We never permit these.
   if (!empty($attributes['href'])) {
     // This might be a URI object, so cast it to a string.
     $href = (string)$attributes['href'];
 
     if (isset($href[0])) {
       // Block 'javascript:' hrefs at the tag level: no well-designed
       // application should ever use them, and they are a potent attack vector.
 
       // This function is deep in the core and performance sensitive, so we're
       // doing a cheap version of this test first to avoid calling preg_match()
       // on URIs which begin with '/' or `#`. These cover essentially all URIs
       // in Phabricator.
       if (($href[0] !== '/') && ($href[0] !== '#')) {
         // Chrome 33 and IE 11 both interpret "javascript\n:" as a Javascript
         // URI, and all browsers interpret "  javascript:" as a Javascript URI,
         // so be aggressive about looking for "javascript:" in the initial
         // section of the string.
 
         $normalized_href = preg_replace('([^a-z0-9/:]+)i', '', $href);
         if (preg_match('/^javascript:/i', $normalized_href)) {
           throw new Exception(
             pht(
               "Attempting to render a tag with an '%s' attribute that begins ".
               "with '%s'. This is either a serious security concern or a ".
               "serious architecture concern. Seek urgent remedy.",
               'href',
               'javascript:'));
         }
       }
     }
   }
 
   // For tags which can't self-close, treat null as the empty string -- for
   // example, always render `<div></div>`, never `<div />`.
   static $self_closing_tags = array(
     'area'    => true,
     'base'    => true,
     'br'      => true,
     'col'     => true,
     'command' => true,
     'embed'   => true,
     'frame'   => true,
     'hr'      => true,
     'img'     => true,
     'input'   => true,
     'keygen'  => true,
     'link'    => true,
     'meta'    => true,
     'param'   => true,
     'source'  => true,
     'track'   => true,
     'wbr'     => true,
   );
 
   $attr_string = '';
   foreach ($attributes as $k => $v) {
     if ($v === null) {
       continue;
     }
     $v = phutil_escape_html($v);
     $attr_string .= ' '.$k.'="'.$v.'"';
   }
 
   if ($content === null) {
     if (isset($self_closing_tags[$tag])) {
       return new PhutilSafeHTML('<'.$tag.$attr_string.' />');
     } else {
       $content = '';
     }
   } else {
     $content = phutil_escape_html($content);
   }
 
   return new PhutilSafeHTML('<'.$tag.$attr_string.'>'.$content.'</'.$tag.'>');
 }
 
 function phutil_tag_div($class, $content = null) {
   return phutil_tag('div', array('class' => $class), $content);
 }
 
 function phutil_escape_html($string) {
+  if ($string === null) {
+    return '';
+  }
+
   if ($string instanceof PhutilSafeHTML) {
     return $string;
   } else if ($string instanceof PhutilSafeHTMLProducerInterface) {
     $result = $string->producePhutilSafeHTML();
     if ($result instanceof PhutilSafeHTML) {
       return phutil_escape_html($result);
     } else if (is_array($result)) {
       return phutil_escape_html($result);
     } else if ($result instanceof PhutilSafeHTMLProducerInterface) {
       return phutil_escape_html($result);
     } else {
       try {
         assert_stringlike($result);
         return phutil_escape_html((string)$result);
       } catch (Exception $ex) {
         throw new Exception(
           pht(
             "Object (of class '%s') implements %s but did not return anything ".
             "renderable from %s.",
             get_class($string),
             'PhutilSafeHTMLProducerInterface',
             'producePhutilSafeHTML()'));
       }
     }
   } else if (is_array($string)) {
     $result = '';
     foreach ($string as $item) {
       $result .= phutil_escape_html($item);
     }
     return $result;
   }
 
   return htmlspecialchars($string, ENT_QUOTES, 'UTF-8');
 }
 
 function phutil_escape_html_newlines($string) {
   return PhutilSafeHTML::applyFunction('nl2br', $string);
 }
 
 /**
  * Mark string as safe for use in HTML.
  */
 function phutil_safe_html($string) {
   if ($string == '') {
     return $string;
   } else if ($string instanceof PhutilSafeHTML) {
     return $string;
   } else {
     return new PhutilSafeHTML($string);
   }
 }
 
 /**
  * HTML safe version of `implode()`.
  */
 function phutil_implode_html($glue, array $pieces) {
   $glue = phutil_escape_html($glue);
 
   foreach ($pieces as $k => $piece) {
     $pieces[$k] = phutil_escape_html($piece);
   }
 
   return phutil_safe_html(implode($glue, $pieces));
 }
 
 /**
  * Format a HTML code. This function behaves like `sprintf()`, except that all
  * the normal conversions (like %s) will be properly escaped.
  */
 function hsprintf($html /* , ... */) {
   $args = func_get_args();
   array_shift($args);
   return new PhutilSafeHTML(
     vsprintf($html, array_map('phutil_escape_html', $args)));
 }