From 226d7233e17b114ac86d50900f4ee778f6192d7a Mon Sep 17 00:00:00 2001
From: Bernhard Reiter <ockham@raz.or.at>
Date: Fri, 3 Oct 2014 19:32:39 +0200
Subject: [PATCH] In Tags::rename($from, $to), check if there already is a tag
 named $to.

---
 lib/private/tags.php | 7 ++++++-
 tests/lib/tags.php   | 4 ++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/private/tags.php b/lib/private/tags.php
index 82a4aa4d02..5768f19cf2 100644
--- a/lib/private/tags.php
+++ b/lib/private/tags.php
@@ -344,9 +344,14 @@ class Tags implements \OCP\ITags {
 			\OCP\Util::writeLog('core', __METHOD__.', tag: ' . $from. ' does not exist', \OCP\Util::DEBUG);
 			return false;
 		}
+		$tag = $this->tags[$key];
+
+		if($this->userHasTag($to, $tag->getOwner())) {
+			\OCP\Util::writeLog('core', __METHOD__.', A tag named ' . $to. ' already exists for user ' . $tag->getOwner() . '.', \OCP\Util::DEBUG);
+			return false;
+		}
 
 		try {
-			$tag = $this->tags[$key];
 			$tag->setName($to);
 			$this->tags[$key] = $this->mapper->update($tag);
 		} catch(\Exception $e) {
diff --git a/tests/lib/tags.php b/tests/lib/tags.php
index 455b99120a..2f7a1e817f 100644
--- a/tests/lib/tags.php
+++ b/tests/lib/tags.php
@@ -150,8 +150,8 @@ class Test_Tags extends PHPUnit_Framework_TestCase {
 		$this->assertTrue($tagger->rename('Wrok', 'Work'));
 		$this->assertTrue($tagger->hasTag('Work'));
 		$this->assertFalse($tagger->hastag('Wrok'));
-		$this->assertFalse($tagger->rename('Wrok', 'Work'));
-
+		$this->assertFalse($tagger->rename('Wrok', 'Work')); // Rename non-existant tag.
+		$this->assertFalse($tagger->rename('Work', 'Family')); // Collide with existing tag.
 	}
 
 	public function testTagAs() {