getFd
Gets the file descriptor for a cancellable job. This can be used to implement cancellable operations on Unix systems. The returned fd will turn readable when @cancellable is cancelled.
You are not supposed to read from the fd yourself, just check for readable status. Reading to unset the readable status is done with g_cancellable_reset().
After a successful return from this function, you should use g_cancellable_release_fd() to free up resources allocated for the returned file descriptor.
See also g_cancellable_make_pollfd().
Return
A valid file descriptor. -1
if the file descriptor is not supported, or on errors.