Unix: Add sigqueue

[yshui]

Description

Add prototype for sigqueue

Sources

https://github.com/bminor/glibc/blob/8543577b04ded6d979ffcc5a818930e4d74d0645/include/signal.h#L50-L51
https://github.com/bminor/musl/blob/8fd5d031876345e42ae3d11cc07b962f8625bc3b/include/signal.h#L228

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI

[tgross35]

Please also update the PR description with permalinks to the relevant headers.

[tgross35]

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[yshui]

@rustbot ready

[tgross35]

One more thing, from the PR template:

>     * [ ]  Relevant tests in `libc-test/semver` have been updated

[tgross35]

Looking into this more, I'm not seeing this for OpenBSD or for Android. I don't think it's a safe assumption that this is available on all Unix platforms except Apple and emscripten.

So, please add one definition in src/unix/bsd that excludes target_vendor = "apple", and add one in src/unix/linux_like/linux. Then the semver files freebsd.txt, linux.txt, and netbsd.txt should be updated.

[yshui]

kinda in a weird situation:

android has it.
illumos seems to have it. (can't find the header, though)
cygwin has it.
redox has it, IIUC
qnx neutrino has it
aix has it
haiku has it

i think openbsd and hurd are the ones that don't have it.

[yshui]

and sigqueue is POSIX.1-2001, not an os-specific extension

[tgross35]

Thanks for the sources. Could you update to exclude OpenBSD and Hurd then?

Since there are exclusions, the semver files can't be in unix.txt unfortunately. Instead, it should go in the .txt files for all the platforms you mentioned (or at least the major ones).

illumos seems to have it. (can't find the header, though)

At least they seem to have a manpage https://smartos.org/man/3C/sigqueue

and sigqueue is POSIX.1-2001, not an os-specific extension

I figure you know already but just confirming, we try to match what the platform actually has available since they don't all always have the complete POSIX-defined API.