rustix/
timespec.rs

1//! `Timespec` and related types, which are used by multiple public API
2//! modules.
3
4#[cfg(not(fix_y2038))]
5use crate::backend::c;
6
7/// `struct timespec`
8#[cfg(not(fix_y2038))]
9pub type Timespec = c::timespec;
10
11/// `struct timespec`
12#[cfg(fix_y2038)]
13#[derive(Debug, Clone, Copy)]
14#[repr(C)]
15pub struct Timespec {
16    /// Seconds.
17    pub tv_sec: Secs,
18
19    /// Nanoseconds. Must be less than 1_000_000_000.
20    pub tv_nsec: Nsecs,
21}
22
23/// A type for the `tv_sec` field of [`Timespec`].
24#[cfg(not(fix_y2038))]
25#[allow(deprecated)]
26pub type Secs = c::time_t;
27
28/// A type for the `tv_sec` field of [`Timespec`].
29#[cfg(fix_y2038)]
30pub type Secs = i64;
31
32/// A type for the `tv_sec` field of [`Timespec`].
33#[cfg(any(
34    fix_y2038,
35    linux_raw,
36    all(libc, target_arch = "x86_64", target_pointer_width = "32")
37))]
38pub type Nsecs = i64;
39
40/// A type for the `tv_nsec` field of [`Timespec`].
41#[cfg(all(
42    not(fix_y2038),
43    libc,
44    not(all(target_arch = "x86_64", target_pointer_width = "32"))
45))]
46pub type Nsecs = c::c_long;
47
48/// On 32-bit glibc platforms, `timespec` has anonymous padding fields, which
49/// Rust doesn't support yet (see `unnamed_fields`), so we define our own
50/// struct with explicit padding, with bidirectional `From` impls.
51#[cfg(fix_y2038)]
52#[repr(C)]
53#[derive(Debug, Clone)]
54pub(crate) struct LibcTimespec {
55    pub(crate) tv_sec: Secs,
56
57    #[cfg(target_endian = "big")]
58    padding: core::mem::MaybeUninit<u32>,
59
60    pub(crate) tv_nsec: i32,
61
62    #[cfg(target_endian = "little")]
63    padding: core::mem::MaybeUninit<u32>,
64}
65
66#[cfg(fix_y2038)]
67impl From<LibcTimespec> for Timespec {
68    #[inline]
69    fn from(t: LibcTimespec) -> Self {
70        Self {
71            tv_sec: t.tv_sec,
72            tv_nsec: t.tv_nsec as _,
73        }
74    }
75}
76
77#[cfg(fix_y2038)]
78impl From<Timespec> for LibcTimespec {
79    #[inline]
80    fn from(t: Timespec) -> Self {
81        Self {
82            tv_sec: t.tv_sec,
83            tv_nsec: t.tv_nsec as _,
84            padding: core::mem::MaybeUninit::uninit(),
85        }
86    }
87}
88
89#[test]
90fn test_sizes() {
91    assert_eq_size!(Secs, u64);
92    const_assert!(core::mem::size_of::<Timespec>() >= core::mem::size_of::<(u64, u32)>());
93    const_assert!(core::mem::size_of::<Nsecs>() >= 4);
94
95    let mut t = Timespec {
96        tv_sec: 0,
97        tv_nsec: 0,
98    };
99
100    // `tv_nsec` needs to be able to hold nanoseconds up to a second.
101    t.tv_nsec = 999_999_999_u32 as _;
102    assert_eq!(t.tv_nsec as u64, 999_999_999_u64);
103
104    // `tv_sec` needs to be able to hold more than 32-bits of seconds.
105    t.tv_sec = 0x1_0000_0000_u64 as _;
106    assert_eq!(t.tv_sec as u64, 0x1_0000_0000_u64);
107}
108
109// Test that our workarounds are needed.
110#[cfg(fix_y2038)]
111#[test]
112#[allow(deprecated)]
113fn test_fix_y2038() {
114    assert_eq_size!(libc::time_t, u32);
115}
rustix/timespec.rs

rustix/
timespec.rs
