Get a temporary filename with a specific extension

temporary_filename.php

/**
 * Get a temporary filename with a specific extension
 * @method temporary_filename
 * @param  string             $dir       The directory where it tries to create the temporary file
 * @param  string             $extension The extension of the file (default: '')
 * @param  string             $prefix    The prefix of the file (default: '')
 * @param  integer            $retry     The number of times it tries to create a random filename (default: 100)
 * @return string|FALSE
 */
function temporary_filename($dir, $extension = '', $prefix = '', $retry = 100) {

    $extension = $extension == '' ? '' : '.' . $extension;
    $dir = str_finish($dir, '/');

    while ($retry > 0) {
        $filename = $dir . $prefix . str_random(20) . $extension;
        if (!file_exists($filename)) {
            touch($filename);
            return $filename;
        }
        $retry--;
    }

    return FALSE;

}