split out some path manipulation logic

Signed-off-by: Robin Appelman <robin@icewind.nl>

1 files changed, 71 insertions, 0 deletions

diff --git a/lib/private/Files/Utils/PathHelper.php b/lib/private/Files/Utils/PathHelper.php
new file mode 100644
index 00000000000..07985e884ce
--- /dev/null
+++ b/lib/private/Files/Utils/PathHelper.php
@@ -0,0 +1,71 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2022 Robin Appelman <robin@icewind.nl>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Files\Utils;
+
+class PathHelper {
+	/**
+	 * Make a path relative to a root path, or return null if the path is outside the root
+	 *
+	 * @param string $root
+	 * @param string $path
+	 * @return ?string
+	 */
+	public static function getRelativePath(string $root, string $path) {
+		if ($root === '' or $root === '/') {
+			return self::normalizePath($path);
+		}
+		if ($path === $root) {
+			return '/';
+		} elseif (strpos($path, $root . '/') !== 0) {
+			return null;
+		} else {
+			$path = substr($path, strlen($root));
+			return self::normalizePath($path);
+		}
+	}
+
+	/**
+	 * @param string $path
+	 * @return string
+	 */
+	public static function normalizePath(string $path): string {
+		if ($path === '' or $path === '/') {
+			return '/';
+		}
+		//no windows style slashes
+		$path = str_replace('\\', '/', $path);
+		//add leading slash
+		if ($path[0] !== '/') {
+			$path = '/' . $path;
+		}
+		//remove duplicate slashes
+		while (strpos($path, '//') !== false) {
+			$path = str_replace('//', '/', $path);
+		}
+		//remove trailing slash
+		$path = rtrim($path, '/');
+
+		return $path;
+	}
+}