statfs: fixes for s390x+musl

[selfisekai]

I believe this should fix problems in the log, except the one related to the libc crate. however, I'm not sure how to test these changes.

log from an s390x build

   Compiling nix v0.24.2
error[E0428]: the name `fs_type_t` is defined multiple times
  --> /home/buildozer/.cargo/registry/src/github.com-eae4ba8cbf2ce1c7/nix-0.24.2/src/sys/statfs.rs:33:1
   |
31 | type fs_type_t = libc::c_uint;
   | ------------------------------ previous definition of the type `fs_type_t` here
32 | #[cfg(all(target_os = "linux", target_env = "musl"))]
33 | type fs_type_t = libc::c_ulong;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `fs_type_t` redefined here
   |
   = note: `fs_type_t` must be defined only once in the type namespace of this module
   Compiling regex v1.6.0
error[E0425]: cannot find value `O_LARGEFILE` in crate `libc`
   --> /home/buildozer/.cargo/registry/src/github.com-eae4ba8cbf2ce1c7/nix-0.24.2/src/fcntl.rs:121:9
    |
121 |         O_LARGEFILE;
    |         ^^^^^^^^^^^ not found in `libc`
error[E0201]: duplicate definitions with name `optimal_transfer_size`:
   --> /home/buildozer/.cargo/registry/src/github.com-eae4ba8cbf2ce1c7/nix-0.24.2/src/sys/statfs.rs:258:5
    |
248 |     pub fn optimal_transfer_size(&self) -> u32 {
    |     ------------------------------------------ previous definition of `optimal_transfer_size` here
...
258 |     pub fn optimal_transfer_size(&self) -> libc::c_ulong {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ duplicate definition
error[E0201]: duplicate definitions with name `block_size`:
   --> /home/buildozer/.cargo/registry/src/github.com-eae4ba8cbf2ce1c7/nix-0.24.2/src/sys/statfs.rs:309:5
    |
301 |     pub fn block_size(&self) -> u32 {
    |     ------------------------------- previous definition of `block_size` here
...
309 |     pub fn block_size(&self) -> libc::c_ulong {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ duplicate definition
error[E0201]: duplicate definitions with name `maximum_name_length`:
   --> /home/buildozer/.cargo/registry/src/github.com-eae4ba8cbf2ce1c7/nix-0.24.2/src/sys/statfs.rs:367:5
    |
360 |     pub fn maximum_name_length(&self) -> u32 {
    |     ---------------------------------------- previous definition of `maximum_name_length` here
...
367 |     pub fn maximum_name_length(&self) -> libc::c_ulong {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ duplicate definition
Some errors have detailed explanations: E0201, E0425, E0428.
For more information about an error, try `rustc --explain E0201`.
error: could not compile `nix` due to 5 previous errors

[rtzoeller]

@selfisekai thanks for the contribution! Unfortunately it doesn't look like things are quite right, yet. You can test compiling for the s390x-unknown-linux-musl target with

cargo build --target s390x-unknown-linux-musl -Zbuild-std

I am getting more errors with these changes than without, unfortunately.

---

Do you have a use case for the s390x-unknown-linux-musl target? If there's a need for the nix crate to support it, I'd rather see us add it to the list of platforms we automatically build against, to ensure support does not regress. While one-off fixes are welcome, we can't guarantee that compilation won't regress if we aren't automatically testing it.

[selfisekai]

unfortunately I'm unable to run it with -Zbuild-std on my machine as I'm running Rust stable from aports (rustup doesn't have the x86_64-alpine-linux-musl target, while x86_64-unknown-linux-musl produces broken binaries by default). I might try building in a Docker container.

the use case is Alpine Linux supported architectures, I made an RFC for testing on this and more architectures: nix-rust/rfcs#5

[rtzoeller]

Thanks for the link to the RFC; I hadn't seen it.

As a hack to unblock yourself, you might try temporarily setting RUSTC_BOOTSTRAP=1 and trying to pass -Zbuild-std. This should let you use nightly features on stable (which should absolutely not be used in production).

[nekopsykose]

I am getting more errors with these changes than without, unfortunately.

the errors appear to all be caused by libc now instead. things like f_namelen use u_long even though the actual musl source is unsigned for it (s390x) https://github.com/rust-lang/libc/blob/88de3880fbc3e72358023c68ecced285a830a8ca/src/unix/linux_like/linux/musl/b64/s390x.rs#L61 (the same goes for f_bsize, f_type, etc)

the other issues are also most likely also caused by libc definitions, but i didn't look too deeply. the reason there are "more errors" is because the compilation does not abort early on these first ones fixed here, and then gets to the rest of the issues.

that said, the same issue has to be raised in libc.

[nekopsykose]

libc 0.2.145 now has the necessary changes, you should try testing this again

[nekopsykose]

(unless it also needs the O_LARGEFILE one too)

disregard- that also made it in

[williamdes]

What is the status of this PR ?
Should it be rebased since CI fails ?

[selfisekai]

rebased, seems to compile fine for s390x-unknown-linux-musl

[selfisekai]

ah, no. the other way