getrandom(2) is missing from the bindings

[marmistrz]

We have getentropy, but not getrandom

[marmistrz]

This can't be implemented until glibc in CI becomes 2.25, adding this binding will break the crate for < 2.25.

[kristate]

Hi @marmistrz ! I am trying to clean-up issues: is this still an issue for you?
(btw, I would recommend lib rand or other cryptographic libraries instead of relying on getrandom(2))

[marmistrz]

@kristate I'm not currently working on the project which needed that, but I still consider this an issue. I should be able use getrandom if my libc is new enough. Otherwise, it defies the purpose of this crate.

IIRC the project did something pretty low-level and thus I wanted to use the syscall directly, but I don't remember the details.

maybe you should do a feature build, just like gtk-rs does - e.g. I can explicitly demand glibc >= 2.25 in my cargo.toml - or just say that I demand that the libc supports getrandom, and then the bindings are generated.

[gnzlbg]

The version of glibc being targeted on CI (and therefore, the minimum version of glibc supported), has been updated. Please feel free to submit a PR implementing these.

[briansmith]

The version of glibc being targeted on CI (and therefore, the minimum version of glibc supported), has been updated. Please feel free to submit a PR implementing these.

My understanding from https://lwn.net/Articles/711013/ is that glibc does NOT implement a fallback in the case that the getrandom() syscall is unavailable. Is that correct, or have things changed? If so, I agree it is a really good idea to expose libc::getrandom() so that no Rust code needs to use the vararg syscall function. (varargs are a bad idea, in general.)