Prevent deleting storage root

Storage mount points are not deletable, so make sure that the unlink
operation and its hooks aren't run in such cases.

Note that some storages might recursively delete their contents when
calling unlink on their root. This fix prevents that as well.

lib/private/files/view.php

@@ -336,6 +336,19 @@ class View {
 	}
 
 	public function unlink($path) {
+		if ($path === '' || $path === '/') {
+			// do not allow deleting the root
+			return false;
+		}
+		$postFix = (substr($path, -1, 1) === '/') ? '/' : '';
+		$absolutePath = Filesystem::normalizePath($this->getAbsolutePath($path));
+		list($storage, $internalPath) = Filesystem::resolvePath($absolutePath . $postFix);
+		if (!$internalPath || $internalPath === '' || $internalPath === '/') {
+			// do not allow deleting the storage's root / the mount point
+			// because for some storages it might delete the whole contents
+			// but isn't supposed to work that way
+			return false;
+		}
 		return $this->basicOperation('unlink', $path, array('delete'));
 	}
 

tests/lib/files/view.php

@@ -306,6 +306,48 @@ class View extends \PHPUnit_Framework_TestCase {
 		$this->assertTrue($rootView->file_exists('anotherfolder/bar.txt'));
 	}
 
+	/**
+	 * @medium
+	 */
+	function testUnlink() {
+		$storage1 = $this->getTestStorage();
+		$storage2 = $this->getTestStorage();
+		\OC\Files\Filesystem::mount($storage1, array(), '/');
+		\OC\Files\Filesystem::mount($storage2, array(), '/substorage');
+
+		$rootView = new \OC\Files\View('');
+		$rootView->file_put_contents('/foo.txt', 'asd');
+		$rootView->file_put_contents('/substorage/bar.txt', 'asd');
+
+		$this->assertTrue($rootView->file_exists('foo.txt'));
+		$this->assertTrue($rootView->file_exists('substorage/bar.txt'));
+
+		$this->assertTrue($rootView->unlink('foo.txt'));
+		$this->assertTrue($rootView->unlink('substorage/bar.txt'));
+
+		$this->assertFalse($rootView->file_exists('foo.txt'));
+		$this->assertFalse($rootView->file_exists('substorage/bar.txt'));
+	}
+
+	/**
+	 * @medium
+	 */
+	function testUnlinkRootMustFail() {
+		$storage1 = $this->getTestStorage();
+		$storage2 = $this->getTestStorage();
+		\OC\Files\Filesystem::mount($storage1, array(), '/');
+		\OC\Files\Filesystem::mount($storage2, array(), '/substorage');
+
+		$rootView = new \OC\Files\View('');
+		$rootView->file_put_contents('/foo.txt', 'asd');
+		$rootView->file_put_contents('/substorage/bar.txt', 'asd');
+
+		$this->assertFalse($rootView->unlink(''));
+		$this->assertFalse($rootView->unlink('/'));
+		$this->assertFalse($rootView->unlink('substorage'));
+		$this->assertFalse($rootView->unlink('/substorage'));
+	}
+
 	/**
 	 * @medium
 	 */