[RFC 01/47] eal: add BSD version of queue.h

[Bruce Richardson]

On Tue, Aug 19, 2025 at 05:29:28PM +0200, Thomas Monjalon wrote:
> 19/08/2025 17:24, Stephen Hemminger:
> > On Tue, 19 Aug 2025 10:37:27 +0200
> > Thomas Monjalon <thomas at monjalon.net> wrote:
> > 
> > > 19/08/2025 01:27, Stephen Hemminger:
> > > > +++ b/lib/eal/include/bsd_queue.h
> > > > @@ -0,0 +1,1075 @@
> > > > +/*-
> > > > + * SPDX-License-Identifier: BSD-3-Clause
> > > > + *
> > > > + * Copyright (c) 1991, 1993
> > > > + *     The Regents of the University of California.  All rights reserved.
> > > > + *
> > > > + * This is a copy of sys/queue.h which is used to overcome
> > > > + * missing parts in the glibc version (and Windows).
> > > > + */
> > > > +
> > > > +#ifndef _SYS_QUEUE_H_
> > > > +#define _SYS_QUEUE_H_  
> > > 
> > > Shouldn't we rename this include flag? with RTE_ prefix?
> > 
> > 
> > No, by keeping the same prefix if the user includes both sys/queue.h and bsd_queue.h
> > there will be no confilcts.
> 
> You mean by checking _SYS_QUEUE_H_ which is the same as sys/queue.h?
> So if I include sys/queue.h first, I will have a limited version.
> It means we should not include it before any DPDK include.
> It looks like a limitation for DPDK users.
> 
I think we should define two defines for our header, and warn if
sys/queue.h is included first.

#ifndef _RTE_BSD_QUEUE_H_
#ifdef _SYS_QUEUE_H_
#warning ...
#endif

#define _RTE_BSD_QUEUE_H_
#define _SYS_QUEUE_H_

...

#endif

This way, sys/queue.h contents will be skipped after our header, but if
it's included first, the user gets a warning about incomplete
implementation.

/Bruce