Add Subversion ref and content logs to pre-commit hooks

Summary: Ref T4195. SVN has no such thing as refs (I was thinking about writing a quasi-ref anyway like `HEAD: r23 -> r24`, but I'm not sure it would actually be useful). And content is very easy to build.

Test Plan: Pushed some stuff to SVN, got logs from it.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4195

Differential Revision: https://secure.phabricator.com/D7766

src/applications/diffusion/engine/DiffusionCommitHookEngine.php

@@ -733,13 +733,26 @@ final class DiffusionCommitHookEngine extends Phobject {
 
 
   private function findSubversionRefUpdates() {
-    // TODO: Implement.
+    // Subversion doesn't have any kind of mutable ref metadata.
     return array();
   }
 
   private function findSubversionContentUpdates(array $ref_updates) {
-    // TODO: Implement.
-    return array();
+    list($youngest) = execx(
+      'svnlook youngest %s',
+      $this->subversionRepository);
+    $ref_new = (int)$youngest + 1;
+
+    $ref_flags = 0;
+    $ref_flags |= PhabricatorRepositoryPushLog::CHANGEFLAG_ADD;
+    $ref_flags |= PhabricatorRepositoryPushLog::CHANGEFLAG_APPEND;
+
+    $ref_content = $this->newPushLog()
+      ->setRefType(PhabricatorRepositoryPushLog::REFTYPE_COMMIT)
+      ->setRefNew($ref_new)
+      ->setChangeFlags($ref_flags);
+
+    return array($ref_content);
   }