cargo_metadata/
errors.rs

1use std::fmt;
2use std::io;
3use std::str::Utf8Error;
4use std::string::FromUtf8Error;
5
6/// Custom result type for `cargo_metadata::Error`
7pub type Result<T> = ::std::result::Result<T, Error>;
8
9/// Error returned when executing/parsing `cargo metadata` fails.
10///
11/// # Note about Backtraces
12///
13/// This error type does not contain backtraces, but each error variant
14/// comes from _one_ specific place, so it's not really needed for the
15/// inside of this crate. If you need a backtrace down to, but not inside
16/// of, a failed call of `cargo_metadata` you can do one of multiple thinks:
17///
18/// 1. Convert it to a `failure::Error` (possible using the `?` operator),
19///    which is similar to a `Box<::std::error::Error + 'static + Send  + Sync>`.
20/// 2. Have appropriate variants in your own error type. E.g. you could wrap
21///    a `failure::Context<Error>` or add a `failure::Backtrace` field (which
22///    is empty if `RUST_BACKTRACE` is not set, so it's simple to use).
23/// 3. You still can place a failure based error into a `error_chain` if you
24///    really want to. (Either through foreign_links or by making it a field
25///    value of a `ErrorKind` variant).
26///
27#[derive(Debug)]
28pub enum Error {
29    /// Error during execution of `cargo metadata`
30    CargoMetadata {
31        /// stderr returned by the `cargo metadata` command
32        stderr: String,
33    },
34
35    /// IO Error during execution of `cargo metadata`
36    Io(io::Error),
37
38    /// Output of `cargo metadata` was not valid utf8
39    Utf8(Utf8Error),
40
41    /// Error output of `cargo metadata` was not valid utf8
42    ErrUtf8(FromUtf8Error),
43
44    /// Deserialization error (structure of json did not match expected structure)
45    Json(::serde_json::Error),
46
47    /// The output did not contain any json
48    NoJson,
49}
50
51impl From<io::Error> for Error {
52    fn from(v: io::Error) -> Self {
53        Error::Io(v)
54    }
55}
56
57impl From<Utf8Error> for Error {
58    fn from(v: Utf8Error) -> Self {
59        Error::Utf8(v)
60    }
61}
62
63impl From<FromUtf8Error> for Error {
64    fn from(v: FromUtf8Error) -> Self {
65        Error::ErrUtf8(v)
66    }
67}
68
69impl From<::serde_json::Error> for Error {
70    fn from(v: ::serde_json::Error) -> Self {
71        Error::Json(v)
72    }
73}
74
75impl fmt::Display for Error {
76    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
77        match self {
78            Error::CargoMetadata { stderr } => {
79                write!(
80                    f,
81                    "`cargo metadata` exited with an error: {}",
82                    stderr.trim_end()
83                )
84            }
85            Error::Io(err) => write!(f, "failed to start `cargo metadata`: {}", err),
86            Error::Utf8(err) => write!(f, "cannot convert the stdout of `cargo metadata`: {}", err),
87            Error::ErrUtf8(err) => {
88                write!(f, "cannot convert the stderr of `cargo metadata`: {}", err)
89            }
90            Error::Json(err) => write!(f, "failed to interpret `cargo metadata`'s json: {}", err),
91            Error::NoJson => write!(
92                f,
93                "could not find any json in the output of `cargo metadata`"
94            ),
95        }
96    }
97}
98
99impl ::std::error::Error for Error {
100    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
101        match self {
102            Error::CargoMetadata { .. } => None,
103            Error::Io(err) => Some(err),
104            Error::Utf8(err) => Some(err),
105            Error::ErrUtf8(err) => Some(err),
106            Error::Json(err) => Some(err),
107            Error::NoJson => None,
108        }
109    }
110}
cargo_metadata/errors.rs

cargo_metadata/
errors.rs
