Re: errno i xs_wire.h

[Oleg Goldshmidt <pub@goldshmidt.org>]

Mark Williamson <mark.williamson@cl.cam.ac.uk> writes:

> > playing with xenbus support in mini-os, I noticed that xs_wire.h
> > references errno constants such as EINVAL. Is the use of these
> > constants (which could be guest-OS specific)
> 
> Isn't the basic set of errno vals posix standardised?  So even if a guest OS 
> doesn't deal in errnos itself, it can just import the BSD errno.h or 
> similar...?

POSIX does not standardise errno *values*. It only specifies a set of
symbolic error names and their meanings, and says that all the POSIX
symbolic error names must have distinct values.

So if you need to share the values between entities that may have
different error name/value mappings (even if everybody is
POSIX-compliant) you need a conversion protocol.

I suppose "man errno" will give you the set of POSIX error names.

-- 
Oleg Goldshmidt | pub@NOSPAM.goldshmidt.org | http://www.goldshmidt.org