Re: [PATCH] HP-UX does not have select.h

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 20, 2007, 07:52 UTC
Message-ID: <7vlk7preeu.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <20071220081806.0ccdf636@pc09.procura.nl>

"H.Merijn Brand" <h.m.brand@xs4all.nl> writes:

Show 11 quoted lines

>> > Also because these are the *only* _POSIX_VERSION defines in the entire
>> > include tree, and 11.23 does have a select.h, which makes the patch below
>> > to be not OK on 11.23. I'm not stating that HP follows the rules in any
>> > correct way, but if this is to be sure that select.h gets included if the
>> > OS supports it, it will fail.
>> ...
>> But your grep did not catch their definition of _POSIX1_VERSION_$YEAR
>> which are used to define the actual value of _POSIX_VERSION.
>
> If it is used to *define* _POSIX_VERSION, it should have come up too,
> wouldn't it?

Sorry, I should re-read your grep output. It is possible that I am quite confused.

Your grep session begins like this:

>> >> > /usr/include 103 > grep -r POSIX_VERSION *
>> >> > sys/unistd.h:#    define _POSIX_VERSION _POSIX1_VERSION_88
>> >> > sys/unistd.h:#      define _POSIX_VERSION       _POSIX1_VERSION_90
>> >> > sys/unistd.h:#      define _POSIX_VERSION       _POSIX1_VERSION_93

Now, if they had

	#define _POSIX1_VERSION_88	198808L
        #define _POSIX1_VERSION_90	199009L
        #define _POSIX1_VERSION_93	199309L
        #define _POSIX1_VERSION_95	199506L
        #define _POSIX1_VERSION_01	200112L

elsewhere in their include files, then

 (1) "grep -r POSIX_VERSION *" wouldn't have matched them;

 (2) not all of the three output form sys/unistd.h could be in effect at
     the same time.  There may be #ifdef around it to control which
     definition is used, but your "grep" wouldn't have shown them
     either.

Maybe HP-UX include files #ifdef the definition of _POSIX_VERSION depending on what is asked for with feature test macros? We do not define _POSIX_C_SOURCE to 200112L but we do define _XOPEN_SOURCE to 600. According to:

    http://www.opengroup.org/onlinepubs/000095399/functions/xsh_chap02_02.html

this should be sufficient to ask for POSIX.1-2001 features.

But in any case, 88/90/93 are all too old (predates 2001-12) so if these three definitions are only possible values in their include files, then we wouldn't see _POSIX_VERSION set to 200112L. That is unfortunate. It seems we need to go back to that "NO_SYS_SELECT_H=YesPlease" thing.