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<Vec<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    if commits.is_empty() {
35        Ok(None)
36    } else {
37        Ok(Some(commits))
38    }
39}
40
41///
42pub mod write {
43    pub(crate) mod function {
44        use std::io::Write;
45
46        use super::Error;
47        use crate::Update;
48
49        /// Write the [previously obtained](crate::read()) (possibly non-existing) `shallow_commits` to the shallow `file`
50        /// after applying all `updates`.
51        ///
52        /// If this leaves the list of shallow commits empty, the file is removed.
53        ///
54        /// ### Deviation
55        ///
56        /// Git also prunes the set of shallow commits while writing, we don't until we support some sort of pruning.
57        pub fn write(
58            mut file: gix_lock::File,
59            shallow_commits: Option<Vec<gix_hash::ObjectId>>,
60            updates: &[Update],
61        ) -> Result<(), Error> {
62            let mut shallow_commits = shallow_commits.unwrap_or_default();
63            for update in updates {
64                match update {
65                    Update::Shallow(id) => {
66                        shallow_commits.push(*id);
67                    }
68                    Update::Unshallow(id) => shallow_commits.retain(|oid| oid != id),
69                }
70            }
71            if shallow_commits.is_empty() {
72                std::fs::remove_file(file.resource_path())?;
73                drop(file);
74                return Ok(());
75            }
76
77            if shallow_commits.is_empty() {
78                if let Err(err) = std::fs::remove_file(file.resource_path()) {
79                    if err.kind() != std::io::ErrorKind::NotFound {
80                        return Err(err.into());
81                    }
82                }
83            } else {
84                shallow_commits.sort();
85                let mut buf = Vec::<u8>::new();
86                for commit in shallow_commits {
87                    commit.write_hex_to(&mut buf).map_err(Error::Io)?;
88                    buf.push(b'\n');
89                }
90                file.write_all(&buf).map_err(Error::Io)?;
91                file.flush()?;
92            }
93            file.commit()?;
94            Ok(())
95        }
96    }
97
98    /// The error returned by [`write()`](crate::write()).
99    #[derive(Debug, thiserror::Error)]
100    #[allow(missing_docs)]
101    pub enum Error {
102        #[error(transparent)]
103        Commit(#[from] gix_lock::commit::Error<gix_lock::File>),
104        #[error("Could not remove an empty shallow file")]
105        RemoveEmpty(#[from] std::io::Error),
106        #[error("Failed to write object id to shallow file")]
107        Io(std::io::Error),
108    }
109}
110pub use write::function::write;
111
112///
113pub mod read {
114    /// The error returned by [`read`](crate::read()).
115    #[derive(Debug, thiserror::Error)]
116    #[allow(missing_docs)]
117    pub enum Error {
118        #[error("Could not open shallow file for reading")]
119        Io(#[from] std::io::Error),
120        #[error("Could not decode a line in shallow file as hex-encoded object hash")]
121        DecodeHash(#[from] gix_hash::decode::Error),
122    }
123}
gix_shallow/lib.rs

gix_shallow/
lib.rs
