BP_GOPP_Image_Editor_GS::escapeshellarg( string $arg )

	protected static function escapeshellarg( $arg ) {
		// Note that the only things we're really going to escape, given the strict base file name check,
		// is the "WP_CONTENT_DIR/uploads" directory and the path to the Ghostscript executable.
		if ( self::is_win() ) {
			// Note bang was not zapped in versions of PHP older than about Jul 2015.
			$arg = '"' . str_replace( array( '%', '!', '"' ), ' ', $arg ) . '"'; // So will get "not found" error if any of these chars in directory path.
		} else {
			$arg = "'" . str_replace( "'", "'\\''", $arg ) . "'";
		}
		return $arg;
	}