rustix/fs/
statx.rs

1//! Linux `statx`.
2
3use crate::fd::AsFd;
4use crate::fs::AtFlags;
5use crate::{backend, io, path};
6use backend::c;
7use bitflags::bitflags;
8
9#[cfg(feature = "linux_4_11")]
10use backend::fs::syscalls::statx as _statx;
11#[cfg(not(feature = "linux_4_11"))]
12use compat::statx as _statx;
13
14/// `struct statx` for use with [`statx`].
15#[repr(C)]
16#[derive(Debug, Copy, Clone)]
17#[allow(missing_docs)]
18#[non_exhaustive]
19pub struct Statx {
20    pub stx_mask: u32,
21    pub stx_blksize: u32,
22    pub stx_attributes: StatxAttributes,
23    pub stx_nlink: u32,
24    pub stx_uid: u32,
25    pub stx_gid: u32,
26    pub stx_mode: u16,
27    pub(crate) __spare0: [u16; 1],
28    pub stx_ino: u64,
29    pub stx_size: u64,
30    pub stx_blocks: u64,
31    pub stx_attributes_mask: StatxAttributes,
32    pub stx_atime: StatxTimestamp,
33    pub stx_btime: StatxTimestamp,
34    pub stx_ctime: StatxTimestamp,
35    pub stx_mtime: StatxTimestamp,
36    pub stx_rdev_major: u32,
37    pub stx_rdev_minor: u32,
38    pub stx_dev_major: u32,
39    pub stx_dev_minor: u32,
40    pub stx_mnt_id: u64,
41    pub stx_dio_mem_align: u32,
42    pub stx_dio_offset_align: u32,
43    pub stx_subvol: u64,
44    pub stx_atomic_write_unit_min: u32,
45    pub stx_atomic_write_unit_max: u32,
46    pub stx_atomic_write_segments_max: u32,
47    pub stx_dio_read_offset_align: u32,
48    pub stx_atomic_write_unit_max_opt: u32,
49    pub __spare2: [u32; 1usize],
50    pub __spare3: [u64; 8usize],
51}
52
53/// `struct statx_timestamp` for use with [`Statx`].
54#[repr(C)]
55#[derive(Debug, Copy, Clone)]
56#[non_exhaustive]
57pub struct StatxTimestamp {
58    /// Seconds.
59    pub tv_sec: i64,
60
61    /// Nanoseconds. Must be less than 1_000_000_000.
62    pub tv_nsec: u32,
63
64    pub(crate) __reserved: i32,
65}
66
67bitflags! {
68    /// `STATX_*` constants for use with [`statx`].
69    ///
70    /// [`statx`]: crate::fs::statx
71    #[repr(transparent)]
72    #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
73    pub struct StatxFlags: u32 {
74        /// `STATX_TYPE`
75        const TYPE = c::STATX_TYPE;
76
77        /// `STATX_MODE`
78        const MODE = c::STATX_MODE;
79
80        /// `STATX_NLINK`
81        const NLINK = c::STATX_NLINK;
82
83        /// `STATX_UID`
84        const UID = c::STATX_UID;
85
86        /// `STATX_GID`
87        const GID = c::STATX_GID;
88
89        /// `STATX_ATIME`
90        const ATIME = c::STATX_ATIME;
91
92        /// `STATX_MTIME`
93        const MTIME = c::STATX_MTIME;
94
95        /// `STATX_CTIME`
96        const CTIME = c::STATX_CTIME;
97
98        /// `STATX_INO`
99        const INO = c::STATX_INO;
100
101        /// `STATX_SIZE`
102        const SIZE = c::STATX_SIZE;
103
104        /// `STATX_BLOCKS`
105        const BLOCKS = c::STATX_BLOCKS;
106
107        /// `STATX_BASIC_STATS`
108        const BASIC_STATS = c::STATX_BASIC_STATS;
109
110        /// `STATX_BTIME`
111        const BTIME = c::STATX_BTIME;
112
113        /// `STATX_MNT_ID` (since Linux 5.8)
114        const MNT_ID = c::STATX_MNT_ID;
115
116        /// `STATX_DIOALIGN` (since Linux 6.1)
117        const DIOALIGN = c::STATX_DIOALIGN;
118
119        /// `STATX_ALL`
120        const ALL = c::STATX_ALL;
121
122        /// <https://docs.rs/bitflags/*/bitflags/#externally-defined-flags>
123        const _ = !0;
124    }
125}
126
127bitflags! {
128    /// `STATX_ATTR_*` flags for use with [`Statx`].
129    #[repr(transparent)]
130    #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
131    pub struct StatxAttributes: u64 {
132        /// `STATX_ATTR_COMPRESSED`
133        const COMPRESSED = c::STATX_ATTR_COMPRESSED as u64;
134
135        /// `STATX_ATTR_IMMUTABLE`
136        const IMMUTABLE = c::STATX_ATTR_IMMUTABLE as u64;
137
138        /// `STATX_ATTR_APPEND`
139        const APPEND = c::STATX_ATTR_APPEND as u64;
140
141        /// `STATX_ATTR_NODUMP`
142        const NODUMP = c::STATX_ATTR_NODUMP as u64;
143
144        /// `STATX_ATTR_ENCRYPTED`
145        const ENCRYPTED = c::STATX_ATTR_ENCRYPTED as u64;
146
147        /// `STATX_ATTR_AUTOMOUNT`
148        const AUTOMOUNT = c::STATX_ATTR_AUTOMOUNT as u64;
149
150        /// `STATX_ATTR_MOUNT_ROOT`
151        const MOUNT_ROOT = c::STATX_ATTR_MOUNT_ROOT as u64;
152
153        /// `STATX_ATTR_VERITY`
154        const VERITY = c::STATX_ATTR_VERITY as u64;
155
156        /// `STATX_ATTR_DAX`
157        const DAX = c::STATX_ATTR_DAX as u64;
158
159        /// <https://docs.rs/bitflags/*/bitflags/#externally-defined-flags>
160        const _ = !0;
161    }
162}
163
164/// `statx(dirfd, path, flags, mask, statxbuf)`—Extended `stat`.
165///
166/// This function returns [`io::Errno::NOSYS`] if `statx` is not available on
167/// the platform, such as Linux before 4.11. This also includes older Docker
168/// versions where the actual syscall fails with different error codes; rustix
169/// handles this and translates them into `NOSYS`.
170///
171/// # References
172///  - [Linux]
173///
174/// # Examples
175///
176/// ```
177/// # use std::path::Path;
178/// # use std::io;
179/// # use rustix::fs::{AtFlags, StatxFlags};
180/// # use rustix::fd::BorrowedFd;
181/// /// Try to determine if the provided path is a mount root. Will return
182/// /// `Ok(None)` if the kernel is not new enough to support `statx` or
183/// /// [`StatxAttributes::MOUNT_ROOT`].
184/// fn is_mountpoint(root: BorrowedFd<'_>, path: &Path) -> io::Result<Option<bool>> {
185///     use rustix::fs::{AtFlags, StatxAttributes, StatxFlags};
186///
187///     match rustix::fs::statx(
188///         root,
189///         path,
190///         AtFlags::NO_AUTOMOUNT | AtFlags::SYMLINK_NOFOLLOW,
191///         StatxFlags::empty(),
192///     ) {
193///         Ok(r) => {
194///             let present = r.stx_attributes_mask.contains(StatxAttributes::MOUNT_ROOT);
195///             Ok(present.then(|| r.stx_attributes.contains(StatxAttributes::MOUNT_ROOT)))
196///         }
197///         Err(rustix::io::Errno::NOSYS) => Ok(None),
198///         Err(e) => Err(e.into()),
199///     }
200/// }
201/// ```
202///
203/// [Linux]: https://man7.org/linux/man-pages/man2/statx.2.html
204#[inline]
205pub fn statx<P: path::Arg, Fd: AsFd>(
206    dirfd: Fd,
207    path: P,
208    flags: AtFlags,
209    mask: StatxFlags,
210) -> io::Result<Statx> {
211    path.into_with_c_str(|path| _statx(dirfd.as_fd(), path, flags, mask))
212}
213
214#[cfg(not(feature = "linux_4_11"))]
215mod compat {
216    use crate::fd::BorrowedFd;
217    use crate::ffi::CStr;
218    use crate::fs::{AtFlags, Statx, StatxFlags};
219    use crate::{backend, io};
220    use core::sync::atomic::{AtomicU8, Ordering};
221
222    // Linux kernel prior to 4.11 and old versions of Docker don't support
223    // `statx`. We store the availability in a global to avoid unnecessary
224    // syscalls.
225    //
226    // 0: Unknown
227    // 1: Not available
228    // 2: Available
229    static STATX_STATE: AtomicU8 = AtomicU8::new(0);
230
231    #[inline]
232    pub fn statx(
233        dirfd: BorrowedFd<'_>,
234        path: &CStr,
235        flags: AtFlags,
236        mask: StatxFlags,
237    ) -> io::Result<Statx> {
238        match STATX_STATE.load(Ordering::Relaxed) {
239            0 => statx_init(dirfd, path, flags, mask),
240            1 => Err(io::Errno::NOSYS),
241            _ => backend::fs::syscalls::statx(dirfd, path, flags, mask),
242        }
243    }
244
245    /// The first `statx` call. We don't know if `statx` is available yet.
246    fn statx_init(
247        dirfd: BorrowedFd<'_>,
248        path: &CStr,
249        flags: AtFlags,
250        mask: StatxFlags,
251    ) -> io::Result<Statx> {
252        match backend::fs::syscalls::statx(dirfd, path, flags, mask) {
253            Err(err) => statx_error(err),
254            result => {
255                STATX_STATE.store(2, Ordering::Relaxed);
256                result
257            }
258        }
259    }
260
261    /// The first `statx` call failed. We can get a variety of error codes
262    /// from seccomp configs or faulty FUSE drivers, so we don't trust
263    /// `ENOSYS` or `EPERM` to tell us whether statx is available.
264    #[cold]
265    fn statx_error(err: io::Errno) -> io::Result<Statx> {
266        if backend::fs::syscalls::is_statx_available() {
267            // Statx is available. Record this, and fail with the error
268            // code of the initial `statx` call.
269            STATX_STATE.store(2, Ordering::Relaxed);
270            Err(err)
271        } else {
272            // Statx is not available. Record this, and fail with `NOSYS`.
273            STATX_STATE.store(1, Ordering::Relaxed);
274            Err(io::Errno::NOSYS)
275        }
276    }
277}
rustix/fs/statx.rs

rustix/fs/
statx.rs
