How to distinguish between STREAMS and non-STREAMS

[Dave McCracken]

josef at nixpbe.nixdorf.de (josef Moellers) writes:

>Does anybody now of a bulletproof and FAST method to distinguish between
>a STREAMS fd and a non-STREAMS fd?
>I cannot use calls to getmsg/putmsg, as I am not allowed to change the
>state of the STREAM.

I would say right offhand you should do a streams-specific query ioctl.
A few that might be useful are I_LOOK, I_GRDOPT, I_GRWOPT, and I_LIST.
I_LIST might be particularly fast since if you pass it a NULL pointer
for the list, it just returns the number of modules on the stream,
and this information comes directly out of the stream head.

--
Dave McCracken      dcm at dell.dell.com      (512) 343-3720
Dell Computer       9505 Arboretum Blvd    Austin, TX 78759-7299