GFileIOStream that can be used to read and write the contents of the file.gFileOpenReadwrite(object, cancellable = NULL, .errwarn = TRUE)objectGFile to opencancellableGFileIOStream] GFileIOStream or NULL on error.errorGError, or NULLcancellable is not NULL, then the operation can be cancelled by
triggering the cancellable object from another thread. If the operation
was cancelled, the error G_IO_ERROR_CANCELLED will be returned.
If the file does not exist, the G_IO_ERROR_NOT_FOUND error will be returned.
If the file is a directory, the G_IO_ERROR_IS_DIRECTORY error will be returned.
Other errors are possible too, and depend on what kind of filesystem the file is on.
Note that in many non-local file cases read and write streams are not supported,
so make sure you really need to do read and write streaming, rather than
just opening for reading or writing.
Since 2.22