gh-144130: support getrandom syscall on non-linux

[dankm]

At least FreeBSD and NetBSD also implement getrandom using the same semantics as Linux >= 3.17. They don't define any of it it in linux/random.h, however. They do define all the necessary bits in sys/random.h. glibc >= 2.25 also defines it there as well as in linux/random.h. Simply use sys/random.h when checking for its existence.

• Issue: Support getrandom syscall on FreeBSD #144130

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[serhiy-storchaka]

See Python/bootstrap_hash.c. Could you make the code similar?

[vstinner]

According to the FreeBSD manual page:

The getrandom() system call first appeared in FreeBSD 12.0.

[dankm]

According to the FreeBSD manual page:

The getrandom() system call first appeared in FreeBSD 12.0.

Yup, FreeBSD since 12.0 (December 2018), and NetBSD since 10.0 (March 2024) both claim to support the syscall now. I've not tested this on NetBSD, but their documentation is similar to FreeBSD's.

To satisfy my own curiosity I checked DragonFly and OpenBSD's documentation too. DragonFly claims support as of version 5.7. OpenBSD does not claim support, so if it has it it's undocumented, but OpenBSD's man pages are usually complete.

[vstinner]

LGTM.

See Python/bootstrap_hash.c. Could you make the code similar?

@serhiy-storchaka: I didn't understand your comment. Which code should be made similar to Python/bootstrap_hash.c?

[dankm]

@serhiy-storchaka: I didn't understand your comment. Which code should be made similar to Python/bootstrap_hash.c?

I wasn't sure either. The code in bootstrap_hash.c already does the right thing, so I added a note about the BSDs.

[serhiy-storchaka]

I meant that the code in Python/bootstrap_hash.c already supports sys/random.h (and it is presumably tested), so it would be better to just copy it from Python/bootstrap_hash.c to Modules/posixmodule.c.

[dankm]

I meant that the code in Python/bootstrap_hash.c already supports sys/random.h (and it is presumably tested), so it would be better to just copy it from Python/bootstrap_hash.c to Modules/posixmodule.c.

Ah, okay, that makes sense. You're suggesting I make Modules/posixmodule.c look like Python/bootstrap_hash.c, keeping Python/bootstrap_hash.c unmodified? I interpreted your suggestion as making modifications to Python/bootstrap_hash.c to reflect the current changes to Modules/posixmodule.c.