fixup! use setuid and setgid

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

occ

@@ -2,23 +2,53 @@
 <?php
 
 /**
+ * SPDX-FileCopyrightText: 2013 Thomas Müller <thomas.mueller@tmit.eu>
  * SPDX-FileCopyrightText: 2014 ownCloud, Inc.
  * SPDX-FileCopyrightText: 2014 Olivier Paroz
- * SPDX-FileCopyrightText: 2013 Thomas Müller <thomas.mueller@tmit.eu>
+ * SPDX-FileCopyrightText: 2016 Nextcloud GmbH
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+/**
+ * Get the UID and GID of a user name
+ *
+ * @return list{int,int}|false
+ */
+function getIdsByName(string $name): array|false {
+	$info = posix_getpwnam($name);
+	if ($info !== false) {
+		return [$info['uid'], $info['gid']];
+	}
+	return false;
+}
+
+/**
+ * Get the UID and GID of the fileowner of a file.
+ *
+ * @return list{int,int}|false
+ */
+function getIdsByFile(string $path): array|false {
+	$uid = fileowner($path);
+	if ($uid === false) {
+		return false;
+	}
+	$info = posix_getpwuid($uid);
+	if ($info === false) {
+		return false;
+	}
+	return [$uid, $info['gid']];
+}
+
 // Drop privileges when run as root
-if (posix_getuid() === 0){
+if (posix_getuid() === 0) {
 	$configPath = __DIR__ . '/config/config.php';
 	$fallbackUser = 'www-data';
-	$guessedUser = match (file_exists($configPath)) {
-		true => ($ownerUid = fileowner($configPath)) ? posix_getpwuid($ownerUid)['name'] : $fallbackUser,
-		false => $fallbackUser,
-	};
-	$command = implode (' ', $argv);
-	echo(shell_exec("sudo -u $guessedUser php -f " . $command));
-	exit;
-} else {
-	require_once __DIR__ . '/console.php';
+
+	$info = getIdsByFile($configPath) ?: getIdsByName($fallbackUser);
+	if ($info !== false) {
+		posix_setuid($info[0]);
+		posix_setgid($info[1]);
+	}
 }
+
+require_once __DIR__ . '/console.php';