Header files with enums instead of defines?

[Matthew D. Fuller]

On Wed, Dec 22, 2004 at 06:45:16PM +0100 I heard the voice of
Poul-Henning Kamp, and lo! it spake thus:
> 
> One of my pet peeves is that comples system calls have no way to
> convey additional information about why the return a given return
> value like EPERM.
> 
> I would almost advocate adding a char[X] to each thread and a system
> call which could retrieve it.  Complex system calls like
> mount/nmount, ioctl and similar could then stick an explanation into
> that string which strerror(3) or err(3) and similar functions could
> pull out and give the user.

I do roughly this in the errno-ish facility in my sadly-dormant
libpostal project.  My error structure looks like

struct postal_errfoo_t
{
    unsigned int    postal_errno;
    char            postal_errstr[POSTAL_ERRSTR_LEN];
};

Of course, I get to mandate that you use postal_errno() and
postal_errstr() to retrieve the data.  I use (1<<15) as a flag in the
errno int (at least, until I get a WHOLE lot more error conditions
that I have now) for when there's an extra message to be returned.  I
don't think I actually USE the capability anywhere right now, but it's
designed in.


-- 
Matthew Fuller     (MF4839)   |  fullermd at over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/

"The only reason I'm burning my candle at both ends, is because I
      haven't figured out how to light the middle yet"