Gets any loaded data from the @ostream. Ownership of the data
is transferred to the caller; when no longer needed it must be
freed using the free function set in @ostream's
#GMemoryOutputStream:destroy-function property.
@ostream must be closed before calling this function.
Gets any loaded data from the @ostream. Ownership of the data is transferred to the caller; when no longer needed it must be freed using the free function set in @ostream's #GMemoryOutputStream:destroy-function property.
@ostream must be closed before calling this function.