setresuid doesn't support no-change for any of its arguments

[sevagh]

Hello. The nix docs link to the Linux manpage for setresuid: http://man7.org/linux/man-pages/man2/setresuid.2.html

In Linux you can pass -1 as a parameter of setresuid. How can I do this in nix since the parameters are of type u32?

error[E0600]: cannot apply unary operator `-` to type `u32`
 --> src/main.rs:9:72
  |
9 |     match setresuid(Uid::from_raw(-1), Uid::from_raw(1), Uid::from_raw(-1)) {
  |                                                                        ^^ cannot apply unary operator `-`

[asomers]

Uh, you can't. Best would be if Nix's setresuid took an Option<Uid> instead. Would you submit a PR that makes that change?

[sevagh]

Sounds good, I'll work on that.

[sevagh]

Is there a reason getresuid isn't implemented? I would like to take a shot at that as well if not.

[asomers]

The only reason is because nobody's submitted it yet.

[Susurrus]

Reopening this because it is still a bug with our implementation.

[Susurrus]

Probably the solution here is to make it take Option for each argument and continue to not allow -1.