Date: Thu, 13 Jan 2000 05:41:43 +0100 (CET) From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de> To: freebsd-questions@FreeBSD.ORG Subject: Re: Giving a sighandler more information Message-ID: <200001130441.FAA69981@dorifer.heim3.tu-clausthal.de> In-Reply-To: <85jef2$1q71$1@atlantis.rz.tu-clausthal.de>
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Mikhail Evstiounin <evstiounin@adelphia.net> wrote in list.freebsd-questions:
> From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de>
>>Laurence Berland <stuyman@confusion.net> wrote in list.freebsd-questions:
>> > Followup question: is a sig_atomic_t appropriate to hold the value of a
>> > FILE * ?
>>
>>No. It is only guaranteed to be large enough to hold an int.
>>Of course, on intel PCs, a pointer has the same size as an int,
>>but not on other platforms (e.g. the Alpha). Therefore,
>>portable programs cannot store a pointer in a sig_atomic_t.
>
> Sorry, guys, but it requirenments of ANSI that sizeof(void*)==sizeof(int).
No! A program which assumes that an int is large enough to
store a pointer is BROKEN. See this simple test program:
#include <stdio.h>
int main (int argc, char *argv[]) {
printf("sizeof(int) == %d\n", sizeof(int));
printf("sizeof(void*) == %d\n", sizeof(void*));
return 0;
}
On an Alpha (64bit), the result is:
sizeof(int) == 4
sizeof(void*) == 8
That was compiled with DEC's C compiler in -std1 mode. This
is one of the most ANSI/ISO-compliant compilers that I'm aware
of. (Note that gcc is not that ANSI-compliant.)
> and question does it mean that alpha integer is 32 bit, or pointer has more
> than 64?
See above. ints are 32 bits, pointers are 64 bits.
And this is perfectly within ANSI spec.
Regards
Oliver
--
Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany
(Info: finger userinfo:olli@dorifer.heim3.tu-clausthal.de)
"In jedem Stück Kohle wartet ein Diamant auf seine Geburt"
(Terry Pratchett)
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