Thread.allocate_stack: Pass MAP_STACK to mmap() on OpenBSD 6.3+

[jcs]

This is required as of OpenBSD 6.3.

[bcardiff]

Thanks, is there any reference for this at least to add in the PR?

Is there any program you tried and is failing on openbsd without this patch?

[jcs]

The compiler will crash when compiling:

./bin/crystal build  -o .build/std_spec spec/std_spec.cr
Using compiled compiler at `.build/crystal'
Invalid memory access (signal 11) at address 0x0
[0xbff7b532456] *CallStack::print_backtrace:Int32 +118
[0xbff7b514f5b] __crystal_sigfault_handler +75
[0xbff7c206a30] sigfault_handler +48
gmake: *** [Makefile:112: .build/std_spec] Error 11

And a kernel message logged:

trap [crystal]753/414181 type 262: sp 187f8632fbe0 not inside 7f7fffbf6000-7f7fffff5000

This is due to a change in OpenBSD 6.3 which required similar changes in Go and other language ports.

[ysbaddaden]

Does STACK_MAP exists in previous, still supported, openbsd releases? Such as 6.2?

[jcs]

Oops, it will be required for OpenBSD 6.4 (and 6.3-current now). The flag was added for 6.3 but was ignored under the hood, but using the flag in previous versions will return an error. Is there a proper way to check a system .h header when compiling to toggle a flag?

I am getting other crashes when trying to compile the compiler or when running 'make spec', which I am looking into.

[ysbaddaden]

I believe the target triple is amd64-unknown-openbsd6.X, right? If so, You can try:

{% if flag?(:openbsd) && !flag?(:"openbsd6.2") %}

[jcs]

I've updated the commit to skip openbsd6.2.

[jcs]

I've also run crystal tool format on mman.cr since the CI tests appear to require this to pass.

[ysbaddaden]

Thank you!