Support random file of AIX

[ecnelises]

No description provided.

[josephlr]

Could we add some IBM docs to justify the implementation choice? I think this is correct, but I've never worked with AIX

[ecnelises]

The official doc can be found at https://www.ibm.com/docs/en/aix/7.2?topic=files-random-urandom-devices , this discussion in GnuPG mailing list is also good reference.

In short, the mechanism of /dev/urandom (and /dev/random) on AIX is the same as Linux: the former is more reliable (it never blocks).

[josephlr]

@ecnelises I'm just wondering if we will have to poll /dev/random like we do on Linux. I don't think we have to, but I'd like to see what OpenSSL does.

[ecnelises]

@ecnelises I'm just wondering if we will have to poll /dev/random like we do on Linux. I don't think we have to, but I'd like to see what OpenSSL does.

According to rand_unix.c in OpenSSL, only Linux defines DEVRANDOM_WAIT, and /dev/urandom is in the highest priority by default.

[josephlr]

Can you add a row to the documentation in lib.rs about AIX (and link to the official IBM docs).

I think we should also add AIX to the Tier 3 section of our CI. That may require waiting on Rust Nightly to actually understand the target.

[josephlr]

Note: we are blocked on rust-lang/rust#102293 being merged.

[ecnelises]

That PR has been merged :)