battery 0.7.8

Cross-platform information about the notebook batteries
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132

use std::error;
use std::fs::read_to_string;
use std::io;
use std::path::Path;
use std::str::FromStr;

use super::{Scope, Type};
use crate::units::{ElectricCharge, ElectricPotential, Energy, Power};
use crate::Result;

// From the `errno.h`.
// Easier than building whole `libc` dep.
const ENODEV: i32 = 19;

/// Read µWh value from the `energy_` file and convert into `Energy` type.
pub fn energy<T: AsRef<Path>>(path: T) -> Result<Option<Energy>> {
    let path = path.as_ref();
    debug_assert!(path.file_name().unwrap().to_string_lossy().starts_with("energy_"));

    match get::<f32, _>(path) {
        Ok(Some(value_uwh)) => Ok(Some(microwatt_hour!(value_uwh))),
        Ok(None) => Ok(None),
        Err(e) => Err(e),
    }
}

/// Read µAh value from the `charge_` file and convert into `ElectricCharge` type.
pub fn charge<T: AsRef<Path>>(path: T) -> Result<Option<ElectricCharge>> {
    let path = path.as_ref();
    debug_assert!(path.file_name().unwrap().to_string_lossy().starts_with("charge_"));

    match get::<f32, _>(path) {
        Ok(Some(value_uah)) if value_uah > 1.0 => Ok(Some(microampere_hour!(value_uah))),
        Ok(Some(_)) => Ok(None),
        Ok(None) => Ok(None),
        Err(e) => Err(e),
    }
}

/// Read µV value from the `voltage_` file and convert into `ElectricPotential` type.
pub fn voltage<T: AsRef<Path>>(path: T) -> Result<Option<ElectricPotential>> {
    let path = path.as_ref();
    debug_assert!(path.file_name().unwrap().to_string_lossy().starts_with("voltage_"));

    match get::<f32, _>(path) {
        Ok(Some(value_uv)) if value_uv > 1.0 => Ok(Some(microvolt!(value_uv))),
        Ok(Some(_)) => Ok(None),
        Ok(None) => Ok(None),
        Err(e) => Err(e),
    }
}

/// Read µW value from the `power_` file and convert into `Power` type.
pub fn power<T: AsRef<Path>>(path: T) -> Result<Option<Power>> {
    let path = path.as_ref();
    debug_assert!(path.file_name().unwrap().to_string_lossy().starts_with("power_"));

    match get::<f32, _>(path) {
        Ok(Some(value_uw)) if value_uw > 10_000.0 => Ok(Some(microwatt!(value_uw))),
        Ok(Some(_)) => Ok(None),
        Ok(None) => Ok(None),
        Err(e) => Err(e),
    }
}

/// Read device `type` file and convert into `Type` enum.
pub fn type_<T: AsRef<Path>>(path: T) -> Result<Type> {
    let path = path.as_ref();
    debug_assert!(path.file_name().unwrap().to_string_lossy() == "type");

    match get::<Type, _>(path) {
        Ok(Some(value)) => Ok(value),
        Ok(None) => Ok(Type::Unknown),
        Err(e) => Err(e),
    }
}

/// Read device `scope` file and convert into `Scope` enum.
pub fn scope<T: AsRef<Path>>(path: T) -> Result<Scope> {
    let path = path.as_ref();
    debug_assert!(path.file_name().unwrap().to_string_lossy() == "scope");

    match get::<Scope, _>(path) {
        Ok(Some(value)) => Ok(value),
        Ok(None) => Ok(Scope::System),
        Err(e) => Err(e),
    }
}

/// ## Returns
///
/// Ok(Some(value)) - file was read properly
/// Ok(None) - file is missing
/// Err(_) - unable to access file for some reasons (except `NotFound` and `ENODEV`)
pub fn get_string<T: AsRef<Path>>(path: T) -> Result<Option<String>> {
    match read_to_string(path) {
        Ok(mut content) => {
            if content.starts_with('\0') {
                Err(io::Error::from(io::ErrorKind::InvalidData).into())
            } else {
                // In-place trim
                if content.ends_with('\n') {
                    content.truncate(content.len() - 1);
                }

                Ok(Some(content))
            }
        }
        Err(ref e) if e.kind() == io::ErrorKind::NotFound => Ok(None),
        // Some drivers are creating the files, but attempt to read them
        // fails with a `ENODEV` error.
        // See https://github.com/svartalf/rust-battery/issues/28
        Err(ref e) if e.raw_os_error() == Some(ENODEV) => Ok(None),
        Err(e) => Err(e.into()),
    }
}

pub fn get<V, T>(path: T) -> Result<Option<V>>
where
    T: AsRef<Path>,
    V: FromStr,
    <V as FromStr>::Err: error::Error + Sync + Send,
{
    match get_string(path) {
        Ok(Some(ref value)) => match V::from_str(value) {
            Ok(result) => Ok(Some(result)),
            Err(_) => Ok(None),
        },
        Ok(None) => Ok(None),
        Err(e) => Err(e),
    }
}