base/sys/unix/
system_info.rs

1// Copyright 2023 The ChromiumOS Authors
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use libc::sysconf;
6use libc::_SC_IOV_MAX;
7use libc::_SC_NPROCESSORS_CONF;
8use libc::_SC_NPROCESSORS_ONLN;
9use libc::_SC_PAGESIZE;
10
11use crate::errno_result;
12use crate::Result;
13
14// Comes from UIO_MAXIOV in "uio.h"
15const IOV_MAX_DEFAULT: usize = 1024;
16
17/// Safe wrapper for `sysconf(_SC_IOV_MAX)`.
18#[inline(always)]
19pub fn iov_max() -> usize {
20    // SAFETY:
21    // Trivially safe
22    let iov_max = unsafe { sysconf(_SC_IOV_MAX) };
23    if iov_max < 0 {
24        IOV_MAX_DEFAULT
25    } else {
26        iov_max as usize
27    }
28}
29
30/// Safe wrapper for `sysconf(_SC_PAGESIZE)`.
31#[inline(always)]
32pub fn pagesize() -> usize {
33    // SAFETY:
34    // Trivially safe
35    // man sysconf says return value "Must not be less than 1."
36    let pagesize = unsafe { sysconf(_SC_PAGESIZE) };
37    if pagesize <= 0 {
38        panic!("Error reading system page size, got invalid value.");
39    }
40    pagesize as usize
41}
42
43/// Returns the number of logical cores on the system.
44#[inline(always)]
45pub fn number_of_logical_cores() -> Result<usize> {
46    // SAFETY:
47    // Safe because we pass a flag for this call and the host supports this system call
48    let nprocs_conf = unsafe { sysconf(_SC_NPROCESSORS_CONF) };
49    if nprocs_conf < 0 {
50        errno_result()
51    } else {
52        Ok(nprocs_conf as usize)
53    }
54}
55
56/// Returns the number of online cores on the system.
57#[inline(always)]
58pub fn number_of_online_cores() -> Result<usize> {
59    // SAFETY:
60    // Safe because we pass a flag for this call and the host supports this system call
61    let nprocs_onln = unsafe { sysconf(_SC_NPROCESSORS_ONLN) };
62    if nprocs_onln < 0 {
63        errno_result()
64    } else {
65        Ok(nprocs_onln as usize)
66    }
67}
base/sys/unix/system_info.rs

base/sys/unix/
system_info.rs
