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//! Based on [heim's](https://github.com/heim-rs/heim/blob/master/heim-disk/src/sys/unix/bindings/mod.rs)
//! implementation.
use std::io::Error;
const MNT_NOWAIT: libc::c_int = 2;
extern "C" {
fn getfsstat64(buf: *mut libc::statfs, bufsize: libc::c_int, flags: libc::c_int)
-> libc::c_int;
}
/// Returns all the mounts on the system at the moment.
pub(crate) fn mounts() -> anyhow::Result<Vec<libc::statfs>> {
// SAFETY: System API FFI call, arguments should be correct.
let expected_len = unsafe { getfsstat64(std::ptr::null_mut(), 0, MNT_NOWAIT) };
let mut mounts: Vec<libc::statfs> = Vec::with_capacity(expected_len as usize);
// SAFETY: System API FFI call, arguments should be correct.
let result = unsafe {
getfsstat64(
mounts.as_mut_ptr(),
std::mem::size_of::<libc::statfs>() as libc::c_int * expected_len,
MNT_NOWAIT,
)
};
if result == -1 {
Err(anyhow::Error::from(Error::last_os_error()).context("getfsstat64"))
} else {
debug_assert_eq!(
expected_len, result,
"Expected {expected_len} statfs entries, but instead got {result} entries",
);
// SAFETY: We have a debug assert check, and if `result` is not correct (-1), we check against it.
// Otherwise, getfsstat64 should return the number of statfs structures if it succeeded.
//
// Source: https://man.freebsd.org/cgi/man.cgi?query=getfsstat&sektion=2&format=html
unsafe {
mounts.set_len(result as usize);
}
Ok(mounts)
}
}
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