uuid/
error.rs

1use crate::std::fmt;
2
3/// A general error that can occur when working with UUIDs.
4#[derive(Clone, Debug, Eq, Hash, PartialEq)]
5pub struct Error(pub(crate) ErrorKind);
6
7#[derive(Clone, Debug, Eq, Hash, PartialEq)]
8pub(crate) enum ErrorKind {
9    /// Invalid character in the [`Uuid`] string.
10    ///
11    /// [`Uuid`]: ../struct.Uuid.html
12    Char { character: char, index: usize },
13    /// A simple [`Uuid`] didn't contain 32 characters.
14    ///
15    /// [`Uuid`]: ../struct.Uuid.html
16    SimpleLength { len: usize },
17    /// A byte array didn't contain 16 bytes
18    ByteLength { len: usize },
19    /// A hyphenated [`Uuid`] didn't contain 5 groups
20    ///
21    /// [`Uuid`]: ../struct.Uuid.html
22    GroupCount { count: usize },
23    /// A hyphenated [`Uuid`] had a group that wasn't the right length
24    ///
25    /// [`Uuid`]: ../struct.Uuid.html
26    GroupLength {
27        group: usize,
28        len: usize,
29        index: usize,
30    },
31    /// The input was not a valid UTF8 string
32    InvalidUTF8,
33    /// The UUID is nil.
34    Nil,
35    /// Some other error occurred.
36    Other,
37}
38
39/// A string that is guaranteed to fail to parse to a [`Uuid`].
40///
41/// This type acts as a lightweight error indicator, suggesting
42/// that the string cannot be parsed but offering no error
43/// details. To get details, use `InvalidUuid::into_err`.
44///
45/// [`Uuid`]: ../struct.Uuid.html
46#[derive(Clone, Debug, Eq, Hash, PartialEq)]
47pub struct InvalidUuid<'a>(pub(crate) &'a [u8]);
48
49impl<'a> InvalidUuid<'a> {
50    /// Converts the lightweight error type into detailed diagnostics.
51    pub fn into_err(self) -> Error {
52        // Check whether or not the input was ever actually a valid UTF8 string
53        let input_str = match std::str::from_utf8(self.0) {
54            Ok(s) => s,
55            Err(_) => return Error(ErrorKind::InvalidUTF8),
56        };
57
58        let (uuid_str, offset, simple) = match input_str.as_bytes() {
59            [b'{', s @ .., b'}'] => (s, 1, false),
60            [b'u', b'r', b'n', b':', b'u', b'u', b'i', b'd', b':', s @ ..] => {
61                (s, "urn:uuid:".len(), false)
62            }
63            s => (s, 0, true),
64        };
65
66        let mut hyphen_count = 0;
67        let mut group_bounds = [0; 4];
68
69        // SAFETY: the byte array came from a valid utf8 string,
70        // and is aligned along char boundaries.
71        let uuid_str = unsafe { std::str::from_utf8_unchecked(uuid_str) };
72
73        for (index, character) in uuid_str.char_indices() {
74            let byte = character as u8;
75            if character as u32 - byte as u32 > 0 {
76                // Multibyte char
77                return Error(ErrorKind::Char {
78                    character,
79                    index: index + offset + 1,
80                });
81            } else if byte == b'-' {
82                // While we search, also count group breaks
83                if hyphen_count < 4 {
84                    group_bounds[hyphen_count] = index;
85                }
86                hyphen_count += 1;
87            } else if !byte.is_ascii_hexdigit() {
88                // Non-hex char
89                return Error(ErrorKind::Char {
90                    character: byte as char,
91                    index: index + offset + 1,
92                });
93            }
94        }
95
96        if hyphen_count == 0 && simple {
97            // This means that we tried and failed to parse a simple uuid.
98            // Since we verified that all the characters are valid, this means
99            // that it MUST have an invalid length.
100            Error(ErrorKind::SimpleLength {
101                len: input_str.len(),
102            })
103        } else if hyphen_count != 4 {
104            // We tried to parse a hyphenated variant, but there weren't
105            // 5 groups (4 hyphen splits).
106            Error(ErrorKind::GroupCount {
107                count: hyphen_count + 1,
108            })
109        } else {
110            // There are 5 groups, one of them has an incorrect length
111            const BLOCK_STARTS: [usize; 5] = [0, 9, 14, 19, 24];
112            for i in 0..4 {
113                if group_bounds[i] != BLOCK_STARTS[i + 1] - 1 {
114                    return Error(ErrorKind::GroupLength {
115                        group: i,
116                        len: group_bounds[i] - BLOCK_STARTS[i],
117                        index: offset + BLOCK_STARTS[i] + 1,
118                    });
119                }
120            }
121
122            // The last group must be too long
123            Error(ErrorKind::GroupLength {
124                group: 4,
125                len: input_str.len() - BLOCK_STARTS[4],
126                index: offset + BLOCK_STARTS[4] + 1,
127            })
128        }
129    }
130}
131
132// NOTE: This impl is part of the public API. Breaking changes to it should be carefully considered
133impl fmt::Display for Error {
134    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
135        match self.0 {
136            ErrorKind::Char {
137                character, index, ..
138            } => {
139                write!(f, "invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `{}` at {}", character, index)
140            }
141            ErrorKind::SimpleLength { len } => {
142                write!(
143                    f,
144                    "invalid length: expected length 32 for simple format, found {}",
145                    len
146                )
147            }
148            ErrorKind::ByteLength { len } => {
149                write!(f, "invalid length: expected 16 bytes, found {}", len)
150            }
151            ErrorKind::GroupCount { count } => {
152                write!(f, "invalid group count: expected 5, found {}", count)
153            }
154            ErrorKind::GroupLength { group, len, .. } => {
155                let expected = [8, 4, 4, 4, 12][group];
156                write!(
157                    f,
158                    "invalid group length in group {}: expected {}, found {}",
159                    group, expected, len
160                )
161            }
162            ErrorKind::InvalidUTF8 => write!(f, "non-UTF8 input"),
163            ErrorKind::Nil => write!(f, "the UUID is nil"),
164            ErrorKind::Other => write!(f, "failed to parse a UUID"),
165        }
166    }
167}
168
169#[cfg(feature = "std")]
170mod std_support {
171    use super::*;
172    use crate::std::error;
173
174    impl error::Error for Error {}
175}
uuid/error.rs

uuid/
error.rs
