radicle_git_metadata/commit/
headers.rs

1use core::fmt;
2use std::borrow::Cow;
3
4const BEGIN_SSH: &str = "-----BEGIN SSH SIGNATURE-----\n";
5const BEGIN_PGP: &str = "-----BEGIN PGP SIGNATURE-----\n";
6
7/// A collection of headers stored in [`super::CommitData`].
8///
9/// Note: these do not include `tree`, `parent`, `author`, and `committer`.
10#[derive(Clone, Debug, Default)]
11pub struct Headers(pub(super) Vec<(String, String)>);
12
13/// A `gpgsig` signature stored in [`super::CommitData`].
14#[derive(Debug)]
15pub enum Signature<'a> {
16    /// A PGP signature, i.e. starts with `-----BEGIN PGP SIGNATURE-----`.
17    Pgp(Cow<'a, str>),
18    /// A SSH signature, i.e. starts with `-----BEGIN SSH SIGNATURE-----`.
19    Ssh(Cow<'a, str>),
20}
21
22impl<'a> Signature<'a> {
23    fn from_str(s: &'a str) -> Result<Self, UnknownScheme> {
24        if s.starts_with(BEGIN_SSH) {
25            Ok(Signature::Ssh(Cow::Borrowed(s)))
26        } else if s.starts_with(BEGIN_PGP) {
27            Ok(Signature::Pgp(Cow::Borrowed(s)))
28        } else {
29            Err(UnknownScheme)
30        }
31    }
32}
33
34impl fmt::Display for Signature<'_> {
35    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
36        match self {
37            Signature::Pgp(pgp) => f.write_str(pgp.as_ref()),
38            Signature::Ssh(ssh) => f.write_str(ssh.as_ref()),
39        }
40    }
41}
42
43pub struct UnknownScheme;
44
45impl Headers {
46    pub fn new() -> Self {
47        Headers(Vec::new())
48    }
49
50    pub fn iter(&self) -> impl Iterator<Item = (&str, &str)> {
51        self.0.iter().map(|(k, v)| (k.as_str(), v.as_str()))
52    }
53
54    pub fn values<'a>(&'a self, name: &'a str) -> impl Iterator<Item = &'a str> + 'a {
55        self.iter()
56            .filter_map(move |(k, v)| (k == name).then_some(v))
57    }
58
59    pub fn signatures(&self) -> impl Iterator<Item = Signature<'_>> + '_ {
60        self.0.iter().filter_map(|(k, v)| {
61            if k == "gpgsig" {
62                Signature::from_str(v).ok()
63            } else {
64                None
65            }
66        })
67    }
68
69    /// Push a header to the end of the headers section.
70    pub fn push(&mut self, name: &str, value: &str) {
71        self.0.push((name.to_owned(), value.trim().to_owned()));
72    }
73}
74
75#[derive(Debug, thiserror::Error)]
76pub enum ParseError {
77    #[error("missing tree")]
78    MissingTree,
79    #[error("invalid tree")]
80    InvalidTree,
81    #[error("invalid format")]
82    InvalidFormat,
83    #[error("invalid parent")]
84    InvalidParent,
85    #[error("invalid header")]
86    InvalidHeader,
87    #[error("invalid author")]
88    InvalidAuthor,
89    #[error("missing author")]
90    MissingAuthor,
91    #[error("invalid committer")]
92    InvalidCommitter,
93    #[error("missing committer")]
94    MissingCommitter,
95}
96
97pub fn parse_commit_header<
98    Tree: std::str::FromStr,
99    Parent: std::str::FromStr,
100    Signature: std::str::FromStr,
101>(
102    header: &str,
103) -> Result<(Tree, Vec<Parent>, Signature, Signature, Headers), ParseError> {
104    let mut lines = header.lines();
105
106    let tree = match lines.next() {
107        Some(tree) => tree
108            .strip_prefix("tree ")
109            .map(Tree::from_str)
110            .transpose()
111            .map_err(|_| ParseError::InvalidTree)?
112            .ok_or(ParseError::MissingTree)?,
113        None => return Err(ParseError::MissingTree),
114    };
115
116    let mut parents = Vec::new();
117    let mut author: Option<Signature> = None;
118    let mut committer: Option<Signature> = None;
119    let mut headers = Headers::new();
120
121    for line in lines {
122        // Check if a signature is still being parsed
123        if let Some(rest) = line.strip_prefix(' ') {
124            let value: &mut String = headers
125                .0
126                .last_mut()
127                .map(|(_, v)| v)
128                .ok_or(ParseError::InvalidFormat)?;
129            value.push('\n');
130            value.push_str(rest);
131            continue;
132        }
133
134        if let Some((name, value)) = line.split_once(' ') {
135            match name {
136                "parent" => parents.push(
137                    value
138                        .parse::<Parent>()
139                        .map_err(|_| ParseError::InvalidParent)?,
140                ),
141                "author" => {
142                    author = Some(
143                        value
144                            .parse::<Signature>()
145                            .map_err(|_| ParseError::InvalidAuthor)?,
146                    )
147                }
148                "committer" => {
149                    committer = Some(
150                        value
151                            .parse::<Signature>()
152                            .map_err(|_| ParseError::InvalidCommitter)?,
153                    )
154                }
155                _ => headers.push(name, value),
156            }
157            continue;
158        }
159    }
160
161    Ok((
162        tree,
163        parents,
164        author.ok_or(ParseError::MissingAuthor)?,
165        committer.ok_or(ParseError::MissingCommitter)?,
166        headers,
167    ))
168}
radicle_git_metadata/commit/headers.rs

radicle_git_metadata/commit/
headers.rs
