Date: Wed, 1 Jun 2016 19:31:51 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Ed Schouten <ed@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r301071 - head/sys/sys Message-ID: <20160601183101.X1028@besplex.bde.org> In-Reply-To: <201605311905.u4VJ5geL053766@repo.freebsd.org> References: <201605311905.u4VJ5geL053766@repo.freebsd.org>
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On Tue, 31 May 2016, Ed Schouten wrote:
> Log:
> Improve POSIX conformance of <signal.h>.
>
> - This header file has always depended on pthread_t, pthread_attr_t,
> struct timespec, size_t and uid_t. Only as of POSIX 2008, these
> dependencies have been states explicitly. They should now be defined.
Not always. POSIX didn't have pthreads or timespecs before about 1993.
> - In our implementation, struct sigevent::sigev_notify_attributes has
> type "void *" instead of "pthread_attr_t *". My guess is that this was
> done to prevent pulling in the pthread types, but this can easily be
> avoided by using the underlying structure types.
Not easily, since the tags of the underlying struct types are in the
application namespace, at least up to POSIX 2001.
> Modified:
> head/sys/sys/signal.h
>
> Modified: head/sys/sys/signal.h
> ==============================================================================
> --- head/sys/sys/signal.h Tue May 31 18:45:52 2016 (r301070)
> +++ head/sys/sys/signal.h Tue May 31 19:05:41 2016 (r301071)
> @@ -45,6 +45,23 @@
> #include <machine/_limits.h> /* __MINSIGSTKSZ */
> #include <machine/signal.h> /* sig_atomic_t; trap codes; sigcontext */
>
> +#if __POSIX_VISIBLE >= 200809
> +
> +#include <sys/_pthreadtypes.h>
This gives the following pollution (which breaks almost everything since
<sys/types.h> includes this header:
- struct tag names pthread*
- struct member names state and mutex
POSIX could reasonably be unimproved by reserving pthread* but not ordinary
identifiers like state and mutex.
> ...
> @@ -160,6 +177,9 @@ union sigval {
> #endif
>
> #if __POSIX_VISIBLE >= 199309
> +
> +struct pthread_attr;
> +
The 1993 version certainly doesn't reserve pthread*.
The 1996 version has a nice table of reserved symbols for every header.
For signal.h, they are just ones with a prefix of sa_, si_, sigev_
and sival_ (these shall not be declared or #defined by the application),
and SIG_, SA_, SI_ and SIGEV_ (these may be used by the application iff
they are #undef'ed before use). This doesn't proprtly separate optional
things.
A draft 2001 version as a not so nice table. The rules are now too
tangled to present in a single table, so there are several tables that
are hard to parse. The first table has sa_, uc_ (new), SIG[A-Z]
(stronger), SIG_[A-Z] (weaker). Then it has ss_ (new) and sv_ (new)
for XSI only. Then it has si_, SI_, sigev_, SIGEV_ and sival_ for
RTS only. The second table has SA_, SIG_[0-9a-z_] (different/weaker),
then massive pollution: BUS_, CLD_, FPE_, ILL_, POLL_, SEGV_, SI_
(now in both tables), SS_, SV_ and TRAP_.
A draft 2007 version is like the 2001 version. It fixes the sorting
of uc_ and makes RTS non-optional. In the second table, it moves SS_,
SV_ and TRAP_ under XSI, and moves POLL_ under OBS XSR.
I think pthread is not reserved since it is not in these tables. Later
versions of POSIX were broken to allow <signal.h> to be pollutied
with all the symbols in <time.h>, but I don't want to check what
is in that now. <time.h> is slightly simpler in POSIX but much
more polluted than <signal.h> in FreeBSD.
> struct sigevent {
> int sigev_notify; /* Notification type */
> int sigev_signo; /* Signal number */
> @@ -168,7 +188,7 @@ struct sigevent {
> __lwpid_t _threadid;
Names like _threadid are bogus. sigev is reserved for uses like this.
Noy using a prefix makes the namespace random.
> struct {
> void (*_function)(union sigval);
> - void *_attribute; /* pthread_attr_t * */
> + struct pthread_attr **_attribute;
pthread is not reserved. pthread*_t is only reserved by the general
rule that everything ending in _t is reserved.
This also has indentation errors.
> } _sigev_thread;
> unsigned short _kevent_flags;
Further bogus names. At least they use a prefix.
> long __spare__[8];
A more bogus name.
> @@ -190,6 +210,7 @@ struct sigevent {
> #define SIGEV_KEVENT 3 /* Generate a kevent. */
> #define SIGEV_THREAD_ID 4 /* Send signal to a kernel thread. */
It is correct to used the reserved prefix for our extensions, but this style
is inconsistent with old parts of the file. In the old parts, we ifdef
out extensions to a fault. This makes the code hard to read but provides
good documentation of what is portable.
> #endif
> +
> #endif /* __POSIX_VISIBLE >= 199309 */
>
> #if __POSIX_VISIBLE >= 199309 || __XSI_VISIBLE
>
Bruce
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