stdio on SYSV vrs BSD

[Doug Gwyn]

In article <558 at venice.SEDD.TRW.COM> waldorf at venice.sedd.trw.com (Jerry Waldorf) writes:
>	In the file /usr/include/stdio.h on a BSD box, there is a defined:
>#define _IOSTRG	0100
>	What exactly is this used for?  What is the equivalent on SYSV machines?

It's a flag bit used internally by sprintf() and sscanf(), in a FILE structure
that they own, to indicate that I/O is from/to a memory buffer, instead of the
usual file descriptor in a user-supplied FILE structure.  UNIX System V often
uses a totally different kludge for this; in Release 2 it was to reserve the
last _iob[] member for this purpose.  Better approaches are possible.