Date: Tue, 24 Nov 2009 17:20:25 -0500 (EST) From: Daniel Eischen <deischen@freebsd.org> To: Mark Andrews <marka@isc.org> Cc: Kostik Belousov <kostikbel@gmail.com>, FreeBSD Stable <freebsd-stable@freebsd.org>, Mikolaj Golub <to.my.trociny@gmail.com> Subject: Re: pthread.h: typo in #define pthread_cleanup_push/pthread_cleanup_pop Message-ID: <Pine.GSO.4.64.0911241718490.5810@sea.ntplx.net> In-Reply-To: <200911242141.nAOLfAQa050429@drugs.dv.isc.org> References: <86aayc7z4g.fsf@zhuzha.ua1> <8663907xyy.fsf@zhuzha.ua1> <20091124153422.GT2331@deviant.kiev.zoral.com.ua> <200911242141.nAOLfAQa050429@drugs.dv.isc.org>
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On Wed, 25 Nov 2009, Mark Andrews wrote:
>
> In message <20091124153422.GT2331@deviant.kiev.zoral.com.ua>, Kostik Belousov write
> s:
>>
>> --i616tqyc3hrkKsk2
>> Content-Type: text/plain; charset=us-ascii
>> Content-Disposition: inline
>> Content-Transfer-Encoding: quoted-printable
>>
>> On Tue, Nov 24, 2009 at 05:18:29PM +0200, Mikolaj Golub wrote:
>>
>> pthread_cleanup_push/pop are supposed to be used from the common
>> lexical scope. Citation from SUSv4:
>>
>> These functions may be implemented as macros. The application shall
>> ensure that they appear as statements, and in pairs within the same
>> lexical scope (that is, the pthread_cleanup_push() macro may be
>> thought to expand to a token list whose first token is '{' with
>> pthread_cleanup_pop() expanding to a token list whose last token is the
>> corresponding '}' ).
>>
>> Your change is wrong.
>>
>> Basically, the code should do
>> pthread_cleanup_push(some_func, arh);
>> something ...
>> pthread_cleanup_pop(1);
>> (1 denotes that some_func should be called).
>
> The problem is that that expands to C code that can only be used
> with newer C compilers. This expansion should be usable with all
> C compilers.
>
> #define pthread_cleanup_push(cleanup_routine, cleanup_arg) \
> { \
> struct _pthread_cleanup_info __cleanup_info__; \
> __pthread_cleanup_push_imp(cleanup_routine, cleanup _arg,\
> &__cleanup_info__)
>
> #define pthread_cleanup_pop(execute) \
> __pthread_cleanup_pop_imp(execute); \
> } ((void)0)
Hmm, agreed. But note that Solaris 10 does it this way:
#define pthread_cleanup_push(routine, args) { \
_cleanup_t _cleanup_info; \
__pthread_cleanup_push((_Voidfp)(routine), (void *)(args), \
(caddr_t)_getfp(), &_cleanup_info);
#define pthread_cleanup_pop(ex) \
__pthread_cleanup_pop(ex, &_cleanup_info); \
}
--
DE
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