gix_shallow/
lib.rs

1//! [Read](read()) and [write](write()) shallow files, while performing typical operations on them.
2#![deny(missing_docs, rust_2018_idioms)]
3#![forbid(unsafe_code)]
4
5/// An instruction on how to
6#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)]
7#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
8pub enum Update {
9    /// Shallow the given `id`.
10    Shallow(gix_hash::ObjectId),
11    /// Don't shallow the given `id` anymore.
12    Unshallow(gix_hash::ObjectId),
13}
14
15/// Return a list of shallow commits as unconditionally read from `shallow_file`.
16///
17/// The list of shallow commits represents the shallow boundary, beyond which we are lacking all (parent) commits.
18/// Note that the list is never empty, as `Ok(None)` is returned in that case indicating the repository
19/// isn't a shallow clone.
20pub fn read(shallow_file: &std::path::Path) -> Result<Option<nonempty::NonEmpty<gix_hash::ObjectId>>, read::Error> {
21    use bstr::ByteSlice;
22    let buf = match std::fs::read(shallow_file) {
23        Ok(buf) => buf,
24        Err(err) if err.kind() == std::io::ErrorKind::NotFound => return Ok(None),
25        Err(err) => return Err(err.into()),
26    };
27
28    let mut commits = buf
29        .lines()
30        .map(gix_hash::ObjectId::from_hex)
31        .collect::<Result<Vec<_>, _>>()?;
32
33    commits.sort();
34    Ok(nonempty::NonEmpty::from_vec(commits))
35}
36
37///
38pub mod write {
39    pub(crate) mod function {
40        use std::io::Write;
41
42        use super::Error;
43        use crate::Update;
44
45        /// Write the [previously obtained](crate::read()) (possibly non-existing) `shallow_commits` to the shallow `file`
46        /// after applying all `updates`.
47        ///
48        /// If this leaves the list of shallow commits empty, the file is removed.
49        ///
50        /// ### Deviation
51        ///
52        /// Git also prunes the set of shallow commits while writing, we don't until we support some sort of pruning.
53        pub fn write(
54            mut file: gix_lock::File,
55            shallow_commits: Option<nonempty::NonEmpty<gix_hash::ObjectId>>,
56            updates: &[Update],
57        ) -> Result<(), Error> {
58            let mut shallow_commits = shallow_commits.map(Vec::from).unwrap_or_default();
59            for update in updates {
60                match update {
61                    Update::Shallow(id) => {
62                        shallow_commits.push(*id);
63                    }
64                    Update::Unshallow(id) => shallow_commits.retain(|oid| oid != id),
65                }
66            }
67            if shallow_commits.is_empty() {
68                if let Err(err) = std::fs::remove_file(file.resource_path()) {
69                    if err.kind() != std::io::ErrorKind::NotFound {
70                        return Err(err.into());
71                    }
72                }
73                drop(file);
74                return Ok(());
75            }
76            shallow_commits.sort();
77            let mut buf = Vec::<u8>::new();
78            for commit in shallow_commits {
79                commit.write_hex_to(&mut buf).map_err(Error::Io)?;
80                buf.push(b'\n');
81            }
82            file.write_all(&buf).map_err(Error::Io)?;
83            file.flush().map_err(Error::Io)?;
84            file.commit()?;
85            Ok(())
86        }
87    }
88
89    /// The error returned by [`write()`](crate::write()).
90    #[derive(Debug, thiserror::Error)]
91    #[allow(missing_docs)]
92    pub enum Error {
93        #[error(transparent)]
94        Commit(#[from] gix_lock::commit::Error<gix_lock::File>),
95        #[error("Could not remove an empty shallow file")]
96        RemoveEmpty(#[from] std::io::Error),
97        #[error("Failed to write object id to shallow file")]
98        Io(std::io::Error),
99    }
100}
101pub use write::function::write;
102
103///
104pub mod read {
105    /// The error returned by [`read`](crate::read()).
106    #[derive(Debug, thiserror::Error)]
107    #[allow(missing_docs)]
108    pub enum Error {
109        #[error("Could not open shallow file for reading")]
110        Io(#[from] std::io::Error),
111        #[error("Could not decode a line in shallow file as hex-encoded object hash")]
112        DecodeHash(#[from] gix_hash::decode::Error),
113    }
114}
gix_shallow/lib.rs

gix_shallow/
lib.rs
