(PHP >= 5.3.0, PECL phar >= 2.0.0)
PharData::isWritable — Returns true if the tar/zip archive can be modified
This method returns TRUE if the tar/zip archive on disk is not read-only.
Unlike Phar::isWritable(), data-only tar/zip archives
can be modified even if phar.readonly is set to 1.
No parameters.
Returns TRUE if the tar/zip archive can be modified