getpagesize() was removed from OSX (and posix)

[partouf]

PAGE_SIZE is a macro that can be used (which I'm guessing is defined to be sysconf(_SC_PAGESIZE) probably)

https://stackoverflow.com/questions/37897645/page-size-undeclared-c

[jeremy-rifkin]

Thanks for the PR! The SO post suggests that PAGE_SIZE is only available through kernel headers, do you know if that's still correct? I do see it in /usr/include/x86_64-linux-gnu/sys/user.h but that file also has a note about it being solely for gdb. I'm also not sure about #ifdef getpagesize, at least on my system this doesn't work. Would it be best to just replace the getpagesize call with sysconf(_SC_PAGESIZE)? I'm not seeing any mention of _SC_PAGESIZE in documentation for macos. Worst-case, using sysctl as outlined here https://opensource.apple.com/source/Libc/Libc-262/gen/getpagesize.c.auto.html seems reasonable.

[partouf]

PAGE_SIZE didn't give warnings for me that it would be undefined, but OSX is literally all over the place per minor OS update, I wouldn't be surprised
maybe using sysconf(_SC_PAGESIZE) would be best
you could check for __APPLE__ and _SC_PAGESIZE to be defined

(btw _SC_PAGESIZE is a POSIX thing, not Mac specific https://stackoverflow.com/questions/37193749/getpagesize-vs-sysconf-sc-pagesize)

[partouf]

I will try that later tonight

[partouf]

Ok I think this makes a little bit more sense, but I also don't like it.
The issue I have with the macro PAGE_SIZE is that it's too easily defined by literally anyone and set to something else but the actual page_size, it would be better to check for the existence of getpagesize(), but not sure how

[partouf]

ok this makes more sense I think, use the new way if possible, otherwise fallback to the old ways

ofcourse the reason why getpagesize works on linux is because glibc tries to be backwards compatible with the middleages, and posix is embedded into that, Apple doesn't give a crap about backwards compatibility

[jeremy-rifkin]

Thank you so much, lgtm! I think this is probably the best way to go about it.