an optional [entity tag][gfile-etag] for the current #GFile, or #NULL to ignore
%TRUE if a backup should be created
a set of #GFileCreateFlags
optional #GCancellable object, %NULL to ignore
a #GFileIOStream or %NULL on error. Free the returned object with g_object_unref().
GException on failure.
2.22
Returns an output stream for overwriting the file in readwrite mode, possibly creating a backup copy of the file first. If the file doesn't exist, it will be created.
For details about the behaviour, see g_file_replace() which does the same thing but returns an output stream only.
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.