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