Rust windows: Set stdin(fd=0) translation mode to binary mode.

_setmode.rs

#[cfg(target_os = "windows")]
extern {
    // https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/setmode?view=msvc-170
    // https://learn.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-6.0/aa298581(v=vs.60)
    fn _setmode(fd: std::os::raw::c_int, mode: std::os::raw::c_int) -> std::os::raw::c_int;
    // https://learn.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2010/wwfcfxas(v=vs.100)
    fn _get_errno(p_value: *mut std::os::raw::c_int) -> std::os::raw::c_int;
}

#[cfg(target_os = "windows")]
pub const _O_TEXT: i32 = 0x4000;

#[cfg(target_os = "windows")]
pub const _O_BINARY: i32 = 0x8000;

#[cfg(target_os = "windows")]
pub const _O_WTEXT: i32 = 0x10000;

#[cfg(target_os = "windows")]
pub const _O_U16TEXT: i32 = 0x20000;

#[cfg(target_os = "windows")]
pub const _O_U8TEXT: i32 = 0x40000;

#[cfg(target_os = "windows")]
// Return the previous translation mode
pub fn fd_setmode(fd: i32, mode: i32) -> anyhow::Result<i32> {
    use std::os::raw::c_int;

    let rc = unsafe { _setmode(c_int::from(fd), c_int::from(mode)) } as i32;
    if rc < 0 {
        let mut errno = c_int::default();
        let rc2 = unsafe { _get_errno(std::ptr::addr_of_mut!(errno)) };
        assert_eq!(rc2, 0, "_get_errno() failed, errno: {}", rc2);
        assert_ne!(errno, 0);
        Err(anyhow::anyhow!("_setmode() failed, errno: {}", errno))
    } else {
        Ok(rc)
    }
}

fn main() -> anyhow::Result<()> {
    #[cfg(target_os = "windows")] {
        let prev_mode = fd_setmode(0, _O_BINARY)?;
        eprintln!("Previous stdin translation mode: {:#x}", prev_mode);
        Ok(())
    }

    #[cfg(not(target_os = "windows"))]
    std::compile_error!("unsupported target os");
}

Cargo.toml dependencies

[dependencies]
anyhow = "1.0"

Output

$ cargo.exe b
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s

$ target/debug/foobar.exe
Previous stdin translation mode: 0x4000

FYI, you could also change stdout/stderr translation mode.