Tries to write to stream, as with OutputStream.write (if blocking is TRUE) or g_pollable_output_stream_write_nonblocking() (if blocking is FALSE). This can be used to more easily share code between blocking and non-blocking implementations of a method.
If blocking is FALSE, then stream must be a GPollableOutputStream for which g_pollable_output_stream_can_poll() returns TRUE or else the behavior is undefined. If blocking is TRUE, then stream does not need to be a GPollableOutputStream
the buffer containing the data to write.
whether to do blocking I/O
optional gio.Cancellable object, NULL to ignore.
the number of bytes written, or -1 on error.
GException on failure.