a GInputStream.
a set of GOutputStreamSpliceFlags.
optional GCancellable object, NULL to ignore. [allow-none]
a gssize containing the size of the data spliced, or -1 if an error occurred. Note that if the number of bytes spliced is greater than G_MAXSSIZE, then that will be returned, and there is no way to determine the actual number of bytes spliced.
GException on failure.
Splices an input stream into an output stream.