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(crate) __spare1: [u32; 1],
48    pub(crate) __spare3: [u64; 9],
49}
50
51/// `struct statx_timestamp` for use with [`Statx`].
52#[repr(C)]
53#[derive(Debug, Copy, Clone)]
54#[non_exhaustive]
55pub struct StatxTimestamp {
56    /// Seconds.
57    pub tv_sec: i64,
58
59    /// Nanoseconds. Must be less than 1_000_000_000.
60    pub tv_nsec: u32,
61
62    pub(crate) __reserved: i32,
63}
64
65bitflags! {
66    /// `STATX_*` constants for use with [`statx`].
67    ///
68    /// [`statx`]: crate::fs::statx
69    #[repr(transparent)]
70    #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
71    pub struct StatxFlags: u32 {
72        /// `STATX_TYPE`
73        const TYPE = c::STATX_TYPE;
74
75        /// `STATX_MODE`
76        const MODE = c::STATX_MODE;
77
78        /// `STATX_NLINK`
79        const NLINK = c::STATX_NLINK;
80
81        /// `STATX_UID`
82        const UID = c::STATX_UID;
83
84        /// `STATX_GID`
85        const GID = c::STATX_GID;
86
87        /// `STATX_ATIME`
88        const ATIME = c::STATX_ATIME;
89
90        /// `STATX_MTIME`
91        const MTIME = c::STATX_MTIME;
92
93        /// `STATX_CTIME`
94        const CTIME = c::STATX_CTIME;
95
96        /// `STATX_INO`
97        const INO = c::STATX_INO;
98
99        /// `STATX_SIZE`
100        const SIZE = c::STATX_SIZE;
101
102        /// `STATX_BLOCKS`
103        const BLOCKS = c::STATX_BLOCKS;
104
105        /// `STATX_BASIC_STATS`
106        const BASIC_STATS = c::STATX_BASIC_STATS;
107
108        /// `STATX_BTIME`
109        const BTIME = c::STATX_BTIME;
110
111        /// `STATX_MNT_ID` (since Linux 5.8)
112        const MNT_ID = c::STATX_MNT_ID;
113
114        /// `STATX_DIOALIGN` (since Linux 6.1)
115        const DIOALIGN = c::STATX_DIOALIGN;
116
117        /// `STATX_ALL`
118        const ALL = c::STATX_ALL;
119
120        /// <https://docs.rs/bitflags/*/bitflags/#externally-defined-flags>
121        const _ = !0;
122    }
123}
124
125bitflags! {
126    /// `STATX_ATTR_*` flags for use with [`Statx`].
127    #[repr(transparent)]
128    #[derive(Copy, Clone, Eq, PartialEq, Hash, Debug)]
129    pub struct StatxAttributes: u64 {
130        /// `STATX_ATTR_COMPRESSED`
131        const COMPRESSED = c::STATX_ATTR_COMPRESSED as u64;
132
133        /// `STATX_ATTR_IMMUTABLE`
134        const IMMUTABLE = c::STATX_ATTR_IMMUTABLE as u64;
135
136        /// `STATX_ATTR_APPEND`
137        const APPEND = c::STATX_ATTR_APPEND as u64;
138
139        /// `STATX_ATTR_NODUMP`
140        const NODUMP = c::STATX_ATTR_NODUMP as u64;
141
142        /// `STATX_ATTR_ENCRYPTED`
143        const ENCRYPTED = c::STATX_ATTR_ENCRYPTED as u64;
144
145        /// `STATX_ATTR_AUTOMOUNT`
146        const AUTOMOUNT = c::STATX_ATTR_AUTOMOUNT as u64;
147
148        /// `STATX_ATTR_MOUNT_ROOT`
149        const MOUNT_ROOT = c::STATX_ATTR_MOUNT_ROOT as u64;
150
151        /// `STATX_ATTR_VERITY`
152        const VERITY = c::STATX_ATTR_VERITY as u64;
153
154        /// `STATX_ATTR_DAX`
155        const DAX = c::STATX_ATTR_DAX as u64;
156
157        /// <https://docs.rs/bitflags/*/bitflags/#externally-defined-flags>
158        const _ = !0;
159    }
160}
161
162/// `statx(dirfd, path, flags, mask, statxbuf)`—Extended `stat`.
163///
164/// This function returns [`io::Errno::NOSYS`] if `statx` is not available on
165/// the platform, such as Linux before 4.11. This also includes older Docker
166/// versions where the actual syscall fails with different error codes; rustix
167/// handles this and translates them into `NOSYS`.
168///
169/// # References
170///  - [Linux]
171///
172/// # Examples
173///
174/// ```
175/// # use std::path::Path;
176/// # use std::io;
177/// # use rustix::fs::{AtFlags, StatxFlags};
178/// # use rustix::fd::BorrowedFd;
179/// /// Try to determine if the provided path is a mount root. Will return
180/// /// `Ok(None)` if the kernel is not new enough to support `statx` or
181/// /// [`StatxAttributes::MOUNT_ROOT`].
182/// fn is_mountpoint(root: BorrowedFd<'_>, path: &Path) -> io::Result<Option<bool>> {
183///     use rustix::fs::{AtFlags, StatxAttributes, StatxFlags};
184///
185///     match rustix::fs::statx(
186///         root,
187///         path,
188///         AtFlags::NO_AUTOMOUNT | AtFlags::SYMLINK_NOFOLLOW,
189///         StatxFlags::empty(),
190///     ) {
191///         Ok(r) => {
192///             let present = r.stx_attributes_mask.contains(StatxAttributes::MOUNT_ROOT);
193///             Ok(present.then(|| r.stx_attributes.contains(StatxAttributes::MOUNT_ROOT)))
194///         }
195///         Err(rustix::io::Errno::NOSYS) => Ok(None),
196///         Err(e) => Err(e.into()),
197///     }
198/// }
199/// ```
200///
201/// [Linux]: https://man7.org/linux/man-pages/man2/statx.2.html
202#[inline]
203pub fn statx<P: path::Arg, Fd: AsFd>(
204    dirfd: Fd,
205    path: P,
206    flags: AtFlags,
207    mask: StatxFlags,
208) -> io::Result<Statx> {
209    path.into_with_c_str(|path| _statx(dirfd.as_fd(), path, flags, mask))
210}
211
212#[cfg(not(feature = "linux_4_11"))]
213mod compat {
214    use crate::fd::BorrowedFd;
215    use crate::ffi::CStr;
216    use crate::fs::{AtFlags, Statx, StatxFlags};
217    use crate::{backend, io};
218    use core::sync::atomic::{AtomicU8, Ordering};
219
220    // Linux kernel prior to 4.11 and old versions of Docker don't support
221    // `statx`. We store the availability in a global to avoid unnecessary
222    // syscalls.
223    //
224    // 0: Unknown
225    // 1: Not available
226    // 2: Available
227    static STATX_STATE: AtomicU8 = AtomicU8::new(0);
228
229    #[inline]
230    pub fn statx(
231        dirfd: BorrowedFd<'_>,
232        path: &CStr,
233        flags: AtFlags,
234        mask: StatxFlags,
235    ) -> io::Result<Statx> {
236        match STATX_STATE.load(Ordering::Relaxed) {
237            0 => statx_init(dirfd, path, flags, mask),
238            1 => Err(io::Errno::NOSYS),
239            _ => backend::fs::syscalls::statx(dirfd, path, flags, mask),
240        }
241    }
242
243    /// The first `statx` call. We don't know if `statx` is available yet.
244    fn statx_init(
245        dirfd: BorrowedFd<'_>,
246        path: &CStr,
247        flags: AtFlags,
248        mask: StatxFlags,
249    ) -> io::Result<Statx> {
250        match backend::fs::syscalls::statx(dirfd, path, flags, mask) {
251            Err(err) => statx_error(err),
252            result => {
253                STATX_STATE.store(2, Ordering::Relaxed);
254                result
255            }
256        }
257    }
258
259    /// The first `statx` call failed. We can get a variety of error codes
260    /// from seccomp configs or faulty FUSE drivers, so we don't trust
261    /// `ENOSYS` or `EPERM` to tell us whether statx is available.
262    #[cold]
263    fn statx_error(err: io::Errno) -> io::Result<Statx> {
264        if backend::fs::syscalls::is_statx_available() {
265            // Statx is available. Record this, and fail with the error
266            // code of the initial `statx` call.
267            STATX_STATE.store(2, Ordering::Relaxed);
268            Err(err)
269        } else {
270            // Statx is not available. Record this, and fail with `NOSYS`.
271            STATX_STATE.store(1, Ordering::Relaxed);
272            Err(io::Errno::NOSYS)
273        }
274    }
275}
rustix/fs/statx.rs

rustix/fs/
statx.rs
