Date: Thu, 13 Jan 2000 08:01:49 -0500 From: "Mikhail Evstiounin" <evstiounin@adelphia.net> To: <freebsd-questions@FreeBSD.ORG> Subject: Re: Giving a sighandler more information Message-ID: <00eb01bf5dc6$5adffe00$fc353018@evstiouninadelphia.net.pit.adelphia.net>
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-----Original Message-----
From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de>
To: freebsd-questions@FreeBSD.ORG <freebsd-questions@FreeBSD.ORG>
Date: Wednesday, January 12, 2000 11:42 PM
Subject: Re: Giving a sighandler more information
>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:
Oliver, IT'S A REQUIRIMENTS OF THE STANDARD!!! - NOT MY WISH!!!
And Alpha compiler just plain violates this standard (BTW, didn't check
recent
C standard - C99 or C98). This requirement was in there for the purpose -
portability.
>
> #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.)
>
Agreed. This is a real life. But take a look at the standard:
sizeof(short)<=sizeof(int)<=sizeof(long) and sizeof(void*)==sizeof(int).
GCC team is very accurate - if they know that they have something
incompatible
with ANSI standard they always tell it - there is a whole document in
distributuive
that states what is different and why GCC team thinks it should be
different.
> > 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.
Thanx.
>And this is perfectly within ANSI spec.
My reading of ANSI is slightly different. As someone who participate in
writing of 5
compilers I worked with standards a lot. But I didn't do it anymore since
1995.
And since then C commmitte added a lot of stuff to new standard. Could you
point me to the ANSI standard you are refence to? I was talking about, I
believe,
C89.
>
>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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