nix/sys/
sysinfo.rs

1use libc::SI_LOAD_SHIFT;
2use std::time::Duration;
3use std::{cmp, mem};
4
5use crate::errno::Errno;
6use crate::Result;
7
8/// System info structure returned by `sysinfo`.
9#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
10#[repr(transparent)]
11pub struct SysInfo(libc::sysinfo);
12
13// The fields are c_ulong on 32-bit linux, u64 on 64-bit linux; x32's ulong is u32
14#[cfg(all(target_arch = "x86_64", target_pointer_width = "32"))]
15type mem_blocks_t = u64;
16#[cfg(not(all(target_arch = "x86_64", target_pointer_width = "32")))]
17type mem_blocks_t = libc::c_ulong;
18
19impl SysInfo {
20    /// Returns the load average tuple.
21    ///
22    /// The returned values represent the load average over time intervals of
23    /// 1, 5, and 15 minutes, respectively.
24    pub fn load_average(&self) -> (f64, f64, f64) {
25        (
26            self.0.loads[0] as f64 / (1 << SI_LOAD_SHIFT) as f64,
27            self.0.loads[1] as f64 / (1 << SI_LOAD_SHIFT) as f64,
28            self.0.loads[2] as f64 / (1 << SI_LOAD_SHIFT) as f64,
29        )
30    }
31
32    /// Returns the time since system boot.
33    // The cast is not unnecessary on all platforms.
34    #[allow(clippy::unnecessary_cast)]
35    pub fn uptime(&self) -> Duration {
36        // Truncate negative values to 0
37        Duration::from_secs(cmp::max(self.0.uptime, 0) as u64)
38    }
39
40    /// Current number of processes.
41    pub fn process_count(&self) -> u16 {
42        self.0.procs
43    }
44
45    /// Returns the amount of swap memory in Bytes.
46    pub fn swap_total(&self) -> u64 {
47        self.scale_mem(self.0.totalswap)
48    }
49
50    /// Returns the amount of unused swap memory in Bytes.
51    pub fn swap_free(&self) -> u64 {
52        self.scale_mem(self.0.freeswap)
53    }
54
55    /// Returns the total amount of installed RAM in Bytes.
56    pub fn ram_total(&self) -> u64 {
57        self.scale_mem(self.0.totalram)
58    }
59
60    /// Returns the amount of completely unused RAM in Bytes.
61    ///
62    /// "Unused" in this context means that the RAM in neither actively used by
63    /// programs, nor by the operating system as disk cache or buffer. It is
64    /// "wasted" RAM since it currently serves no purpose.
65    pub fn ram_unused(&self) -> u64 {
66        self.scale_mem(self.0.freeram)
67    }
68
69    // The cast is not unnecessary on all platforms.
70    #[allow(clippy::unnecessary_cast)]
71    fn scale_mem(&self, units: mem_blocks_t) -> u64 {
72        units as u64 * self.0.mem_unit as u64
73    }
74}
75
76/// Returns system information.
77///
78/// [See `sysinfo(2)`](https://man7.org/linux/man-pages/man2/sysinfo.2.html).
79pub fn sysinfo() -> Result<SysInfo> {
80    let mut info = mem::MaybeUninit::uninit();
81    let res = unsafe { libc::sysinfo(info.as_mut_ptr()) };
82    Errno::result(res).map(|_| unsafe { SysInfo(info.assume_init()) })
83}
nix/sys/sysinfo.rs

nix/sys/
sysinfo.rs
