Fails to build with musl due to incorrect arguments to libc::ioctl

[jirutka]

   Compiling below-ethtool v0.8.1 (below-0.8.1/below/ethtool)
error[E0308]: mismatched types
   --> below/ethtool/src/reader.rs:36:58
    |
36  |     let exit_code = unsafe { libc::ioctl(fd.as_raw_fd(), nix::libc::SIOCETHTOOL, &ifr) };
    |                              -----------                 ^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `u64`
    |                              |
    |                              arguments to this function are incorrect
    |
note: function defined here
   --> .cargo/registry/src/index.crates.io-6f17d22bba15001f/libc-0.2.153/src/unix/linux_like/linux/musl/mod.rs:850:12
    |
850 |     pub fn ioctl(fd: ::c_int, request: ::c_int, ...) -> ::c_int;
    |            ^^^^^
help: you can convert a `u64` to an `i32` and panic if the converted value doesn't fit
    |
36  |     let exit_code = unsafe { libc::ioctl(fd.as_raw_fd(), nix::libc::SIOCETHTOOL.try_into().unwrap(), &ifr) };
    |                                                                                ++++++++++++++++++++

• Alpine Linux Edge x86_64
• musl libc 1.2.5
• rust 1.77.0

[brianc118]

Just confirming, are you building on a 32 bit system?

[jirutka]

No, this is from x86_64.

[brianc118]

Ah I see for musl the libc crate uses i32 instead of u64 for ioctl: https://docs.rs/libc/0.2.153/x86_64-unknown-linux-musl/libc/fn.ioctl.html

The constant is u64 in musl libc: https://docs.rs/libc/0.2.153/x86_64-unknown-linux-musl/libc/constant.SIOCETHTOOL.html.

Probably the best option here is to do the cast as suggested by the compiler. Do you mind testing out that change?

[tqfx]

termux/termux-packages#19609