<pthread.h> includes

[Stefan Farfeleder]

On Sat, Aug 20, 2005 at 03:48:31PM +1000, Bruce Evans wrote:
> On Fri, 19 Aug 2005, Stefan Farfeleder wrote:
> 
> >On Sat, Aug 20, 2005 at 12:04:56AM +1000, Bruce Evans wrote:
> >>On Fri, 19 Aug 2005, Stefan Farfeleder wrote:
> >>
> >>>I think some of the headers included by <pthread.h> violate the POSIX
> >>>specification (I'm looking at SUSv3/POSIX 1003.1 2004) by making more
> >>>symbols visible than allowed.
> >>>
> >>><sys/cdefs.h>		Ok
> >>><sys/types.h>		Ok
> >>><sys/_pthreadtypes.h>	Ok
> >>><sys/time.h>		No? (POSIX allows <time.h> which is a subset)
> >				   ^^^^^^
> >Actually POSIX kind of requires the inclusion of <time.h> (and
> ><sched.h>).  At least all symbols must be visible.
> 
> Urk.  This seems to be the place in POSIX where namespace pollution is
> explictly required.  According to an old draft:
> 
> %%%
> 10351           Inclusion of the <pthread.h> header shall make symbols 
> defined in the headers <sched.h> and
> 10352           <time.h> visible.
> %%%

That's what I have here too.

[...]

> >>...
> >><sys/time.h>		only used to declare sigset_t and struct timespec.
> >>			We have a whole header, <sys/_sigset.h>, to help
> >>			declare sigset_t better (it only declares
> >>			__sigset_t),
> >...
> >I've include <machine/_types.h> (for __uint32_t) and <sys/_sigset.h>
> >instead.  timespec is declared through <time.h>.
> 
> Too bad.

Do you have a better suggestion?

> >><sys/signal.h>		Just namespace pollution.
> >
> >We need MINSIGSTKSZ from <machine/signal.h> though.  The patch includes
> >that header instead and protects its usage with __XSI_VISIBLE.  I'm not
> >happy with this, maybe MINSIGSTKSZ should be moved somewhere else?
> 
> MINSIGSTKSZ is used to define PTHREAD_STACK_MIN.  I didn't notice this
> partly because the old version that I looked at correctly defiens
> PTHREAD_STACK_MIN as a constant.  Everything is wrong here:
> - POSIX requires PTHREAD_STACK_MIN to be defined (if at all) in
>   <limits.h> but not in <pthread.h>.
> - PTHREAD_STACK_MIN must be defined as a number (if at all even if
>   XSI is no visible.

I agree that <limits.h> is missing the
PTHREAD_{DESTRUCTOR_ITERATIONS,KEYS_MAX,STACK_MIN,THREADS_MAX} macros.
It's not an error for <pthread.h> to define them because POSIX
reserves pthread_* and PTHREAD_* for this header.

I'm not sure why MINSIGSTKSZ (which expands to const * 4 on all
architectures) is not a constant.

What do you think about putting __MINSIGSTKSZ in <machine/_limits.h>?

> >><limits.h>		Just namespace pollution.
> >
> ><machine/_limits.h> is included instead and __ULONG_MAX is used.
> 
> __ULONG_MAX is used to define PTHREAD_THREADS_MAX.  POSIX actually requires
> the latter to be defined (if at all) in <limits.h> only too.  I doubt
> that the limit is actually 2^64-1.  Maybe it should be a runtime limit
> _SC_THREAD* are missing, so apparently no one ever asks for the runtime
> limits.

Which _SC_THREAD* is missing?  Calling sysconf() with
_SC_THREAD_THREADS_MAX is buggy because sysconf converts ULONG_MAX to a
long.

Stefan