Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Shared/File.php
public static function sysGetTempDir()
    {
        if (self::$useUploadTempDirectory) {
            //  use upload-directory when defined to allow running on environments having very restricted
            //      open_basedir configs
            if (ini_get('upload_tmp_dir') !== false) {
                if ($temp = ini_get('upload_tmp_dir')) {
                    if (file_exists($temp)) {
                        return realpath($temp);
                    }
                }
            }
        }

        return realpath(sys_get_temp_dir());
    }
public static function sysGetTempDir()
    {
        if (self::$useUploadTempDirectory) {
            //  use upload-directory when defined to allow running on environments having very restricted
            //      open_basedir configs
            if (ini_get('upload_tmp_dir') !== false) {
                if ($temp = ini_get('upload_tmp_dir')) {
                    if (file_exists($temp)) {
                        return realpath($temp);
                    }
                }
            }
        }

        return realpath(sys_get_temp_dir());
    }
Get the systems temporary directory.

@return string