Re: [PATCH v2 1/3] Posix asynchronous I/O support: aio files

[Mark Geisert <mark at maxrnd dot com>]

On Wed, 2 May 2018, Brian Inglis wrote:
> On 2018-05-02 02:21, Mark Geisert wrote:
> > I found a discrepancy in the Cygwin source tree and would like input on how to
> > resolve it...
> > On Thu, 19 Apr 2018, Corinna Vinschen wrote:
> > > > +static void
> > > > +aionotify (struct aiocb *aio)
> > > > +{
> > > > +  /* if signal notification wanted, send AIO-complete signal */
> > > > +  //XXX Is sigqueue() the best way to send signo+value within same process?
> > > > +  if (aio->aio_sigevent.sigev_notify == SIGEV_SIGNAL)
> > > > +    sigqueue (mypid,
> > > > +              aio->aio_sigevent.sigev_signo,
> > > > +              aio->aio_sigevent.sigev_value);
> > > Given you have direct access to pinfo, you can just as well call
> > > sig_send (myself, ...). This also drop the requirement to know your pid.
> > While making the change from sigqueue() to sig_send() I was researching
> > siginfo_t, and I found that the values for element si_code in Cygwin's
> > /usr/include/sys/signal.h...
> > /* Signal Actions, P1003.1b-1993, p. 64 */
> > /* si_code values, p. 66 */
> > #define SI_USER    1  /* Sent by a user. kill(), abort(), etc */
> > #define SI_QUEUE   2  /* Sent by sigqueue() */
> > #define SI_TIMER   3  /* Sent by expiration of a timer_settime() timer */
> > #define SI_ASYNCIO 4  /* Indicates completion of asycnhronous IO */
> > #define SI_MESGQ   5  /* Indicates arrival of a message at an empty queue */
> > ...are inconsistent with the enum values in internal file
> > winsup/cygwin/include/cygwin/signal.h...
> > enum
> > {
> >   SI_USER = 0,         /* sent by kill, raise, pthread_kill */
> >   SI_ASYNCIO = 2,      /* sent by AIO completion (currently unimplemented) */
> >   SI_MESGQ,            /* sent by real time mesq state change
> >                                            (currently unimplemented) */
> >   SI_TIMER,            /* sent by timer expiration */
> >   SI_QUEUE,            /* sent by sigqueue */
> >   SI_KERNEL,           /* sent by system */
> >
> >   ILL_ILLOPC,          /* illegal opcode */
> >   ILL_ILLOPN,          /* illegal operand */
> >   [...]
> > };
> > I figure it's the /usr/include/sys/signal.h defines that should be changed,
> > given that Posix doesn't specify values but only the names of the values.  And
> > the winsup* enum values are the ones used internally so should likely not be
> > changed.
> > Does this sound like the right way to go?
>
> The other values appear to be used by non-Cygwin newlib implementations
> bracketed by:
>
> 	#if defined(__CYGWIN__)
> 	#include <cygwin/signal.h>
> 	#else
> ... 100+ lines
> 	#endif /* defined(__CYGWIN__) */
>
> and, if that was required, should be changed via the newlib list.

Finally got this question popped to the top of my stack.  Thanks Brian.

It's all good as-is.  I had previously not thought to consider the myriad 
nestings and cross-definitions accomplished by macros.  Props to those on 
the team who keep all this stuff straight.  No mere mortals they.

..mark