1 //! Linux `statx`.
2
3 use crate::fd::{AsFd, BorrowedFd};
4 use crate::ffi::CStr;
5 use crate::fs::AtFlags;
6 use crate::{backend, io, path};
7 use core::sync::atomic::{AtomicU8, Ordering};
8
9 pub use backend::fs::types::{Statx, StatxFlags, StatxTimestamp};
10
11 /// `statx(dirfd, path, flags, mask, statxbuf)`
12 ///
13 /// This function returns [`io::Errno::NOSYS`] if `statx` is not available on
14 /// the platform, such as Linux before 4.11. This also includes older Docker
15 /// versions where the actual syscall fails with different error codes; Rustix
16 /// handles this and translates them into `NOSYS`.
17 ///
18 /// # References
19 /// - [Linux]
20 ///
21 /// [Linux]: https://man7.org/linux/man-pages/man2/statx.2.html
22 #[inline]
statx<P: path::Arg, Fd: AsFd>( dirfd: Fd, path: P, flags: AtFlags, mask: StatxFlags, ) -> io::Result<Statx>23 pub fn statx<P: path::Arg, Fd: AsFd>(
24 dirfd: Fd,
25 path: P,
26 flags: AtFlags,
27 mask: StatxFlags,
28 ) -> io::Result<Statx> {
29 path.into_with_c_str(|path| _statx(dirfd.as_fd(), path, flags, mask))
30 }
31
32 // Linux kernel prior to 4.11 old versions of Docker don't support `statx`. We
33 // store the availability in a global to avoid unnecessary syscalls.
34 //
35 // 0: Unknown
36 // 1: Not available
37 // 2: Available
38 static STATX_STATE: AtomicU8 = AtomicU8::new(0);
39
40 #[inline]
_statx( dirfd: BorrowedFd<'_>, path: &CStr, flags: AtFlags, mask: StatxFlags, ) -> io::Result<Statx>41 fn _statx(
42 dirfd: BorrowedFd<'_>,
43 path: &CStr,
44 flags: AtFlags,
45 mask: StatxFlags,
46 ) -> io::Result<Statx> {
47 match STATX_STATE.load(Ordering::Relaxed) {
48 0 => statx_init(dirfd, path, flags, mask),
49 1 => Err(io::Errno::NOSYS),
50 _ => backend::fs::syscalls::statx(dirfd, path, flags, mask),
51 }
52 }
53
54 /// The first `statx` call. We don't know if `statx` is available yet.
statx_init( dirfd: BorrowedFd<'_>, path: &CStr, flags: AtFlags, mask: StatxFlags, ) -> io::Result<Statx>55 fn statx_init(
56 dirfd: BorrowedFd<'_>,
57 path: &CStr,
58 flags: AtFlags,
59 mask: StatxFlags,
60 ) -> io::Result<Statx> {
61 match backend::fs::syscalls::statx(dirfd, path, flags, mask) {
62 Err(io::Errno::NOSYS) => statx_error_nosys(),
63 Err(io::Errno::PERM) => statx_error_perm(),
64 result => {
65 STATX_STATE.store(2, Ordering::Relaxed);
66 result
67 }
68 }
69 }
70
71 /// The first `statx` call failed with `NOSYS` (or something we're treating
72 /// like `NOSYS`).
73 #[cold]
statx_error_nosys() -> io::Result<Statx>74 fn statx_error_nosys() -> io::Result<Statx> {
75 STATX_STATE.store(1, Ordering::Relaxed);
76 Err(io::Errno::NOSYS)
77 }
78
79 /// The first `statx` call failed with `PERM`.
80 #[cold]
statx_error_perm() -> io::Result<Statx>81 fn statx_error_perm() -> io::Result<Statx> {
82 // Some old versions of Docker have `statx` fail with `PERM` when it isn't
83 // recognized. Check whether `statx` really is available, and if so, fail
84 // with `PERM`, and if not, treat it like `NOSYS`.
85 if backend::fs::syscalls::is_statx_available() {
86 STATX_STATE.store(2, Ordering::Relaxed);
87 Err(io::Errno::PERM)
88 } else {
89 statx_error_nosys()
90 }
91 }
92