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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
//! Error types

use crate::Config;
use std::error::Error as StdError;
use std::path::PathBuf;
use std::result::Result as StdResult;
use std::{self, fmt, io};

/// Type alias to use this library's `Error` type in a Result
pub type Result<T> = StdResult<T, Error>;

/// Error kinds
#[derive(Debug)]
pub enum ErrorKind {
    /// Generic error
    ///
    /// May be used in cases where a platform specific error is mapped to this type, or for opaque
    /// internal errors.
    Generic(String),

    /// I/O errors.
    Io(io::Error),

    /// A path does not exist.
    PathNotFound,

    /// Attempted to remove a watch that does not exist.
    WatchNotFound,

    /// An invalid value was passed as runtime configuration.
    InvalidConfig(Config),

    /// Can't watch (more) files, limit on the total number of inotify watches reached
    MaxFilesWatch,
}

/// Notify error type.
///
/// Errors are emitted either at creation time of a `Watcher`, or during the event stream. They
/// range from kernel errors to filesystem errors to argument errors.
///
/// Errors can be general, or they can be about specific paths or subtrees. In that later case, the
/// error's `paths` field will be populated.
#[derive(Debug)]
pub struct Error {
    /// Kind of the error.
    pub kind: ErrorKind,

    /// Relevant paths to the error, if any.
    pub paths: Vec<PathBuf>,
}

impl Error {
    /// Adds a path to the error.
    pub fn add_path(mut self, path: PathBuf) -> Self {
        self.paths.push(path);
        self
    }

    /// Replaces the paths for the error.
    pub fn set_paths(mut self, paths: Vec<PathBuf>) -> Self {
        self.paths = paths;
        self
    }

    /// Creates a new Error with empty paths given its kind.
    pub fn new(kind: ErrorKind) -> Self {
        Self {
            kind,
            paths: Vec::new(),
        }
    }

    /// Creates a new generic Error from a message.
    pub fn generic(msg: &str) -> Self {
        Self::new(ErrorKind::Generic(msg.into()))
    }

    /// Creates a new i/o Error from a stdlib `io::Error`.
    pub fn io(err: io::Error) -> Self {
        Self::new(ErrorKind::Io(err))
    }

    /// Creates a new "path not found" error.
    pub fn path_not_found() -> Self {
        Self::new(ErrorKind::PathNotFound)
    }

    /// Creates a new "watch not found" error.
    pub fn watch_not_found() -> Self {
        Self::new(ErrorKind::WatchNotFound)
    }

    /// Creates a new "invalid config" error from the given `Config`.
    pub fn invalid_config(config: &Config) -> Self {
        Self::new(ErrorKind::InvalidConfig(config.clone()))
    }
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let error = match self.kind {
            ErrorKind::PathNotFound => "No path was found.".into(),
            ErrorKind::WatchNotFound => "No watch was found.".into(),
            ErrorKind::InvalidConfig(ref config) => format!("Invalid configuration: {:?}", config),
            ErrorKind::Generic(ref err) => err.clone(),
            ErrorKind::Io(ref err) => err.to_string(),
            ErrorKind::MaxFilesWatch => "OS file watch limit reached.".into(),
        };

        if self.paths.is_empty() {
            write!(f, "{}", error)
        } else {
            write!(f, "{} about {:?}", error, self.paths)
        }
    }
}

impl StdError for Error {
    fn cause(&self) -> Option<&dyn StdError> {
        match self.kind {
            ErrorKind::Io(ref cause) => Some(cause),
            _ => None,
        }
    }
}

impl From<io::Error> for Error {
    fn from(err: io::Error) -> Self {
        Error::io(err)
    }
}

#[cfg(feature = "crossbeam-channel")]
impl<T> From<crossbeam_channel::SendError<T>> for Error {
    fn from(err: crossbeam_channel::SendError<T>) -> Self {
        Error::generic(&format!("internal channel disconnect: {:?}", err))
    }
}
#[cfg(not(feature = "crossbeam-channel"))]
impl<T> From<std::sync::mpsc::SendError<T>> for Error {
    fn from(err: std::sync::mpsc::SendError<T>) -> Self {
        Error::generic(&format!("internal channel disconnect: {:?}", err))
    }
}
#[cfg(feature = "crossbeam-channel")]
impl From<crossbeam_channel::RecvError> for Error {
    fn from(err: crossbeam_channel::RecvError) -> Self {
        Error::generic(&format!("internal channel disconnect: {:?}", err))
    }
}
#[cfg(not(feature = "crossbeam-channel"))]
impl From<std::sync::mpsc::RecvError> for Error {
    fn from(err: std::sync::mpsc::RecvError) -> Self {
        Error::generic(&format!("internal channel disconnect: {:?}", err))
    }
}

impl<T> From<std::sync::PoisonError<T>> for Error {
    fn from(err: std::sync::PoisonError<T>) -> Self {
        Error::generic(&format!("internal mutex poisoned: {:?}", err))
    }
}

#[test]
fn display_formatted_errors() {
    let expected = "Some error";

    assert_eq!(expected, format!("{}", Error::generic(expected)));

    assert_eq!(
        expected,
        format!(
            "{}",
            Error::io(io::Error::new(io::ErrorKind::Other, expected))
        )
    );
}