lfs_core/device_id/
unix.rs

1use {
2    super::{
3        ParseDeviceIdError,
4        ParseDeviceIdSnafu,
5    },
6    crate::Error,
7    snafu::prelude::*,
8    std::{
9        fmt,
10        fs,
11        os::unix::fs::MetadataExt,
12        path::Path,
13        str::FromStr,
14    },
15};
16
17/// Id of a device, as can be found in `MetadataExt.dev()`
18#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
19pub struct DeviceId {
20    pub major: u32,
21    pub minor: u32,
22}
23
24impl fmt::Display for DeviceId {
25    fn fmt(
26        &self,
27        f: &mut fmt::Formatter,
28    ) -> fmt::Result {
29        write!(f, "{}:{}", self.major, self.minor)
30    }
31}
32
33impl FromStr for DeviceId {
34    type Err = ParseDeviceIdError;
35    /// this code is based on `man 5 proc` and my stochastic interpretation
36    fn from_str(string: &str) -> Result<Self, Self::Err> {
37        (|| {
38            let mut parts = string.split(':').fuse();
39            match (parts.next(), parts.next(), parts.next()) {
40                (Some(major), Some(minor), None) => {
41                    let major = major.parse().ok()?;
42                    let minor = minor.parse().ok()?;
43                    Some(Self { major, minor })
44                }
45                (Some(int), None, None) => {
46                    let int: u64 = int.parse().ok()?;
47                    Some(int.into())
48                }
49                _ => None,
50            }
51        })()
52        .with_context(|| ParseDeviceIdSnafu { string })
53    }
54}
55
56impl From<u64> for DeviceId {
57    fn from(num: u64) -> Self {
58        // need to use libc, bit format is platform-dependent
59        let dev = num as libc::dev_t;
60        Self {
61            major: libc::major(dev) as u32,
62            minor: libc::minor(dev) as u32,
63        }
64    }
65}
66
67impl DeviceId {
68    pub fn new(
69        major: u32,
70        minor: u32,
71    ) -> Self {
72        Self { major, minor }
73    }
74    pub fn of_path(path: &Path) -> Result<Self, Error> {
75        let md = fs::metadata(path).map_err(|e| Error::CantReadFileMetadata {
76            source: e,
77            path: path.to_path_buf(),
78        })?;
79        let dev_num = md.dev();
80        Ok(Self::from(dev_num))
81    }
82}
83
84#[test]
85fn test_from_str() {
86    assert_eq!(DeviceId::new(8, 16), DeviceId::from_str("8:16").unwrap());
87}
lfs_core/device_id/unix.rs

lfs_core/device_id/
unix.rs
