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List:       cygwin-patches
Subject:    Re: [PATCH v2 1/3] Posix asynchronous I/O support: aio files
From:       Mark Geisert <mark () maxrnd ! com>
Date:       2018-05-15 6:23:52
Message-ID: Pine.BSF.4.63.1805142318390.55746 () m0 ! truegem ! net
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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



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