Merge branch '6472-fix-tempdir' into 'develop'

Resolve "Create a shell user - PHP Fatal error:  Uncaught TypeError: realpath()"

Closes #6472

See merge request ispconfig/ispconfig3!1713

Author: Till Brehm

server/lib/classes/functions.inc.php

@@ -470,14 +470,14 @@ public function generate_ssh_key($client_id, $username = ''){
 		// generate the SSH key pair for the client
 		$app->system->exec_safe('mktemp -dt id_rsa.XXXXXXXX');
 		$tmpdir = $app->system->last_exec_out();
-		$id_rsa_file = $tmpdir . uniqid('',true);
+		$id_rsa_file = $tmpdir[0] . '/' . uniqid('',true);
 		$id_rsa_pub_file = $id_rsa_file.'.pub';
 		if(file_exists($id_rsa_file)) unset($id_rsa_file);
 		if(file_exists($id_rsa_pub_file)) unset($id_rsa_pub_file);
 		if(!file_exists($id_rsa_file) && !file_exists($id_rsa_pub_file)) {
 			$app->system->exec_safe('ssh-keygen -t rsa -C ? -f ? -N ""', $username.'-rsa-key-'.time(), $id_rsa_file);
 			$app->db->query("UPDATE client SET created_at = UNIX_TIMESTAMP(), id_rsa = ?, ssh_rsa = ? WHERE client_id = ?", $app->system->file_get_contents($id_rsa_file), $app->system->file_get_contents($id_rsa_pub_file), $client_id);
-			$app->system->rmdir($tmpdir, true);
+			$app->system->rmdir($tmpdir[0], true);
 		} else {
 			$app->log("Failed to create SSH keypair for ".$username, LOGLEVEL_WARN);
 		}