Re: AC_FUNC_MMAP lacks <unistd.h> include?

[Paul Eggert]

On 2023-05-17 11:14, Florian Weimer wrote:
+#ifndef getpagesize
> > +# ifdef _SC_PAGESIZE
> > +#  define getpagesize() sysconf (_SC_PAGESIZE)
> > +# elif defined _SC_PAGE_SIZE
> > +#  define getpagesize() sysconf (_SC_PAGE_SIZE)
> > +# elif HAVE_GETPAGESIZE
> > +int getpagesize ();
>
> Isn't this a bit weird?  Why can't we rely on the HAVE_GETPAGESIZE
> check?

POSIX has standardized on sysconf; it no longer specifies getpagesize. 
Also, getpagesize doesn't work for page sizes greater than INT_MAX. For 
both reasons, it's better to prefer sysconf to getpagesize nowadays. I 
installed the attached patch to try to make this clearer.


> Shouldn't <unistd.h> come from [AC_INCLUDES_DEFAULT]?

Yes. I didn't see the need for urgent changes there, though. The code 
should work as-is, and although it may be suboptimal right now we're 
limiting ourselves to bug fixes.

0001-Improve-AC_FUNC_MMAP-comments.patch
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