Use Differential policy columns to drive policies

Summary:
Ref T603. Read policies out of policy columns.

When a revision is associated with a repository (which is currently never), require view access on the repository to see the revision (or, require the viewer to be the owner). This is a blanket "do the right thing" rule which should make Differential's default policies align with user expectations.

Future diffs will populate the `repositoryPHID` when a revision is created.

Test Plan: Tooled around Differential. None of this stuff does anything yet, so nothing very exciting happened.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7134

src/applications/differential/query/DifferentialRevisionQuery.php

@@ -361,6 +361,59 @@ final class DifferentialRevisionQuery
   }
 
   public function willFilterPage(array $revisions) {
+    $viewer = $this->getViewer();
+
+    $repository_phids = mpull($revisions, 'getRepositoryPHID');
+    $repository_phids = array_filter($repository_phids);
+
+    $repositories = array();
+    if ($repository_phids) {
+      $repositories = id(new PhabricatorRepositoryQuery())
+        ->setViewer($this->getViewer())
+        ->withPHIDs($repository_phids)
+        ->execute();
+      $repositories = mpull($repositories, null, 'getPHID');
+    }
+
+    // If a revision is associated with a repository:
+    //
+    //   - the viewer must be able to see the repository; or
+    //   - the viewer must have an automatic view capability.
+    //
+    // In the latter case, we'll load the revision but not load the repository.
+
+    $can_view = PhabricatorPolicyCapability::CAN_VIEW;
+    foreach ($revisions as $key => $revision) {
+      $repo_phid = $revision->getRepositoryPHID();
+      if (!$repo_phid) {
+        // The revision has no associated repository. Attach `null` and move on.
+        $revision->attachRepository(null);
+        continue;
+      }
+
+      $repository = idx($repositories, $repo_phid);
+      if ($repository) {
+        // The revision has an associated repository, and the viewer can see
+        // it. Attach it and move on.
+        $revision->attachRepository($repository);
+        continue;
+      }
+
+      if ($revision->hasAutomaticCapability($can_view, $viewer)) {
+        // The revision has an associated repository which the viewer can not
+        // see, but the viewer has an automatic capability on this revision.
+        // Load the revision without attaching a repository.
+        $revision->attachRepository(null);
+        continue;
+      }
+
+      // The revision has an associated repository, and the viewer can't see
+      // it, and the viewer has no special capabilities. Filter out this
+      // revision.
+      unset($revisions[$key]);
+    }
+
+
     $table = new DifferentialRevision();
     $conn_r = $table->establishConnection('r');
 

src/applications/differential/storage/DifferentialRevision.php

@@ -34,6 +34,7 @@ final class DifferentialRevision extends DifferentialDAO
   private $activeDiff = self::ATTACHABLE;
   private $diffIDs = self::ATTACHABLE;
   private $hashes = self::ATTACHABLE;
+  private $repository = self::ATTACHABLE;
 
   private $reviewerStatus = self::ATTACHABLE;
 
@@ -306,10 +307,25 @@ final class DifferentialRevision extends DifferentialDAO
   }
 
   public function getPolicy($capability) {
-    return PhabricatorPolicies::POLICY_USER;
+    switch ($capability) {
+      case PhabricatorPolicyCapability::CAN_VIEW:
+        return $this->getViewPolicy();
+      case PhabricatorPolicyCapability::CAN_EDIT:
+        return $this->getEditPolicy();
+    }
   }
 
   public function hasAutomaticCapability($capability, PhabricatorUser $user) {
+
+    // A revision's author (which effectively means "owner" after we added
+    // commandeering) can always view and edit it.
+    $author_phid = $this->getAuthorPHID();
+    if ($author_phid) {
+      if ($user->getPHID() == $author_phid) {
+        return true;
+      }
+    }
+
     return false;
   }
 
@@ -329,4 +345,13 @@ final class DifferentialRevision extends DifferentialDAO
     $this->reviewerStatus = $reviewers;
     return $this;
   }
+
+  public function getRepository() {
+    return $this->assertAttached($this->repository);
+  }
+
+  public function attachRepository(PhabricatorRepository $repository = null) {
+    $this->repository = $repository;
+    return $this;
+  }
 }