ptools 0.2.23

Utilities for inspecting Linux processes
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

//
//   Copyright (c) 2017 Steven Fackler
//
//   Licensed under the Apache License, Version 2.0 (the "License");
//   you may not use this file except in compliance with the License.
//   You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the License is distributed on an "AS IS" BASIS,
//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//   See the License for the specific language governing permissions and
//   limitations under the License.
//

use std::borrow::Cow;
use std::error;
use std::ffi::CStr;
use std::fmt;
use std::io;

use libc::c_int;

/// A error returned by DWFL APIs.
pub struct Error {
    code: c_int,
    /// Fallback OS error captured at the point of failure, used when
    /// `dwfl_errmsg` cannot provide a message.
    os_error: Option<io::Error>,
}

impl fmt::Debug for Error {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.debug_struct("Error")
            .field("code", &self.code)
            .field("message", &self.as_str())
            .finish()
    }
}

impl fmt::Display for Error {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&self.as_str(), fmt)
    }
}

impl error::Error for Error {}

impl Error {
    pub(crate) fn new() -> Error {
        // Capture errno before dwfl_errno() which may clear it.
        let saved = io::Error::last_os_error();
        let code = unsafe { crate::dw_sys::dwfl_errno() };
        Error {
            code,
            os_error: saved.raw_os_error().filter(|&e| e != 0).map(|_| saved),
        }
    }

    fn as_str(&self) -> Cow<'_, str> {
        unsafe {
            let s = crate::dw_sys::dwfl_errmsg(self.code);
            if s.is_null() {
                if let Some(ref os_error) = self.os_error {
                    return format!("{os_error}").into();
                }
                "unknown error".into()
            } else {
                CStr::from_ptr(s).to_string_lossy()
            }
        }
    }
}