If your extension is using a third-party library that expects a FILE* or file descriptor, you can use this flag to request the streams API to open the resource but avoid buffering.
If your extension is using a third-party library that expects a FILE* or file descriptor, you can use this flag to request the streams API to open the resource but avoid buffering. You can then use php_stream_cast() to retrieve the FILE* or file descriptor that the library requires.