[PATCH] Core: use sysconf(_SC_PAGESIZE) instead of getpagesize()

[Piotr Sikora]

Hey Maxim,

> Any practical reasons for the change?

Kind of... OS X doesn't expose getpagesize() when it's compiled with
_POSIX_C_SOURCE >= 200112L and no other define (not even
_DARWIN_C_SOURCE) can change that.

Side note: I considered adding _DARWIN_C_SOURCE to
ngx_darwin_config.h, like it's done for _GNU_SOURCE, but I decided
against it, because I found the ability to enforce strict POSIX
interface (even if it doesn't really work right now) quite handy...
and it's off by default, so someone needs to force it anyway.

> While getpagesize() isn't required by the current issue of POSIX,
> it is easier to use and used to be more widely available than
> sysconf(_SC_PAGESIZE).

Considering that sysconf(_SC_PAGESIZE) is part of POSIX and
getpagesize() isn't, I don't believe this is true anymore.

> The cast looks unneeded.

It's signed-to-unsigned conversion... it's a little bit on the
pedantic side, but I wouldn't say it's unneeded... and it follows
style from similar cast just few lines below.

Best regards,
Piotr Sikora