Add support for OpenBSD

[wezm]

OpenBSD appears to be not currently supported. Attempting to compile nix v0.8.1 on OpenBSD 6.1 amd64 with rust 1.16.0 produces the errors below. I would like to use nix in a project that I'll be deploying on OpenBSD so will take an initial pass at adding support. I'll update the task list here as I get more details on what needs to be implemented:

• Determine what is needed to get nix building on OpenBSD

   Compiling nix v0.8.1
error[E0425]: cannot find value `EV_DISPATCH` in module `libc`
   --> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31
    |
144 |                 const $flag = libc::$flag,
    |                               ^ not found in `libc`
    | 
   ::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs
    |
80  | libc_bitflags!{
    | - in this macro invocation
    |
    = help: possible candidate is found in another module, you can import it into scope:
              `use sys::event::EV_DISPATCH;`
error[E0412]: cannot find type sigevent in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:447:15

|

447 |     sigevent: libc::sigevent

|               ^^^^^^^^^^^^^^ not found in libc
error[E0412]: cannot find type sigevent in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:464:46

|

464 |         let mut sev = unsafe { mem::zeroed::libc::sigevent()};

|                                              ^^^^^^^^^^^^^^ not found in libc
error[E0425]: cannot find value SIGEV_NONE in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:466:39

|

466 |             SigevNotify::SigevNone => libc::SIGEV_NONE,

|                                       ^^^^^^^^^^^^^^^^ not found in libc
error[E0425]: cannot find value SIGEV_SIGNAL in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:467:45

|

467 |             SigevNotify::SigevSignal{..} => libc::SIGEV_SIGNAL,

|                                             ^^^^^^^^^^^^^^^^^^ not found in libc
error[E0412]: cannot find type sigevent in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:506:27

|

506 |     fn set_tid(_sev: &mut libc::sigevent, _sigev_notify: &SigevNotify) {

|                           ^^^^^^^^^^^^^^ not found in libc
error[E0412]: cannot find type sigevent in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:509:31

|

509 |     pub fn sigevent(&self) -> libc::sigevent {

|                               ^^^^^^^^^^^^^^ not found in libc
error[E0412]: cannot find type sigevent in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:536:19

|

536 | impl<'a> From<&'a libc::sigevent> for SigEvent {

|                   ^^^^^^^^^^^^^^ not found in libc
error[E0412]: cannot find type sigevent in module libc

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/signal.rs:537:24

|

537 |     fn from(sigevent: &libc::sigevent) -> Self {

|                        ^^^^^^^^^^^^^^ not found in libc
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error[E0308]: mismatched types

--> /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/macros.rs:144:31

|

144 |                 const $flag = libc::$flag,

|                               ^ expected u32, found u16

|

::: /home/vagrant/.cargo/registry/src/github.com-1ecc6299db9ec823/nix-0.8.1/src/sys/event.rs

|

80  | libc_bitflags!{

| - in this macro invocation

|

= help: here are some functions which might fulfill your needs:

- .count_ones()

- .count_zeros()

- .leading_zeros()

- .trailing_zeros()
error: aborting due to 10 previous errors
error: Could not compile nix.

[Susurrus]

The first priority here is to get OpenBSD supported as a Tier 3 platform, where we automatically test it. We use cross for our testing, and right now it doesn't support OpenBSD. It looks like it'll take a bit of work to make that happen.

We'd also welcome patches to nix (likely in the form of #cfging out certain parts of it on OpenBSD) and libc (where missing constants and functions are added) to improve this support and get compilation working. But without also adding CI support for OpenBSD, this will be a losing battle over the long term. Might be worth pinging japaric on #rust on IRC to see if he'd be willing to help you get OpenBSD into cross (and adding it to trust would be good to do as well for the entire ecosystem).

[Susurrus]

(Also, if you could condense that list into action items, that'd be great. Seems like there are some improper datatypes and missing constants/functions in libc, so it should be pretty easy).

[wezm]

Hmm cross support seems blocked on, "having official releases of the rust-std component for OpenBSD". cross-rs/cross#97 I'll proceed with attempting to get nix building for my own purposes and go from there.

[Susurrus]

Looking at the code for rustup, I would think this would be supported. Have you tried using rustup to install Rust on an OpenBSD machine? If it works doing that, then cross-rs/cross#97 is fixed and support can be added. That's an awfully old issue, so I wonder if things have changed.

[wezm]

Yep I tried it to try to get a version newer than 1.16.0:

$ ftp -o - https://sh.rustup.rs | sh
Trying 54.215.0.2...
Requesting https://sh.rustup.rs
9325 bytes received in 0.02 seconds (541.44 KB/s)
rustup: unrecognized OS type: OpenBSD

It's missing from https://github.com/rust-lang-nursery/rustup.rs/blob/master/rustup-init.sh#L189-L223

Hacking the script to include OpenBSD results in:

$ sh rustup.sh                                                                                                                                                
info: downloading installer
curl: (22) The requested URL returned error: 404 
rustup: command failed: curl -sSfL https://static.rust-lang.org/rustup/dist/x86_64-unknown-openbsd/rustup-init -o /tmp/tmp.rwjaPyJ1gg/rustup-init

[Susurrus]

Alright, well looks like rustup is going to need someone who loves OpenBSD to get to work on it! Is that you?! :-)

Anyways, yes, let's confine ourselves to fixing OpenBSD compilation currently and we'll defer on CI for now.