Add Fuchsia support and CI

[tamird]

In general, feature support is identical to Linux.

Updates #78.

[Thomasdezeeuw]

Two small things, but LGTM otherwise.

[Thomasdezeeuw]

@tamird is there manual online for libc/POSIX complicated system call interface for Fuchsia? A link I can add to #154?

[Thomasdezeeuw]

For myself, update #78.

[tamird]

@tamird is there manual online for libc/POSIX complicated system call interface for Fuchsia? A link I can add to #154?

Not that I'm aware of at this time. Fuchsia's libc is derived from musl, so it is largely in line with Linux (or is intended to be, in areas where it is not yet so).

[Thomasdezeeuw]

Thanks @tamird.

[Thomasdezeeuw]

Hey @tamird, apparently Fuchsia doesn't yet work. I tried checking it locally and found the following errors:

error[E0425]: cannot find value `IFNAMSIZ` in crate `libc`
   --> src/sys/unix.rs:934:46
    |
934 |         let mut buf: [MaybeUninit<u8>; libc::IFNAMSIZ] =
    |                                              ^^^^^^^^ not found in `libc`

error[E0425]: cannot find value `IFNAMSIZ` in crate `libc`
   --> src/sys/unix.rs:935:60
    |
935 |             unsafe { MaybeUninit::<[MaybeUninit<u8>; libc::IFNAMSIZ]>::uninit().assume_init() };
    |                                                            ^^^^^^^^ not found in `libc`

error[E0425]: cannot find value `IP_FREEBIND` in crate `libc`
    --> src/sys/unix.rs:1049:69
     |
1049 |             getsockopt::<c_int>(self.inner, libc::SOL_SOCKET, libc::IP_FREEBIND)
     |                                                                     ^^^^^^^^^^^ not found in `libc`

error[E0425]: cannot find value `IP_FREEBIND` in crate `libc`
    --> src/sys/unix.rs:1072:23
     |
1072 |                 libc::IP_FREEBIND,
     |                       ^^^^^^^^^^^ not found in `libc`

So IFNAMSIZ and IP_FREEBIND aren't defined. It's also a problem in the CI, but it passed anyway (now issue #169). Are these two constant available already in Fuchsia?

[tamird]

That's odd! Yeah, those constants are defined in our libc:

IFNAMSIZ: https://cs.opensource.google/fuchsia/fuchsia/+/master:zircon/third_party/ulib/musl/include/net/if.h;l=72;drc=bdf60afa9193c8a9190ee6bb6b5a0a11ad8876b6

IP_FREEBIND: https://cs.opensource.google/fuchsia/fuchsia/+/master:zircon/third_party/ulib/musl/include/netinet/in.h;l=196;drc=bdf60afa9193c8a9190ee6bb6b5a0a11ad8876b6

but apparently not in rust-lang/libc:

IFNAMSIZ should be here: https://github.com/rust-lang/libc/blob/c9fb51bc650427fe22dcf34b503f6aa6fc909c07/src/fuchsia/mod.rs#L1329 -- sent rust-lang/libc#2010.

IP_FREEBIND should be here: https://github.com/rust-lang/libc/blob/c9fb51bc650427fe22dcf34b503f6aa6fc909c07/src/fuchsia/mod.rs#L1765 -- sent rust-lang/libc#2011.