git_index/extension/
decode.rs

1use std::convert::TryInto;
2
3use crate::{extension, extension::Signature, util::from_be_u32};
4
5pub(crate) fn header(data: &[u8]) -> (Signature, u32, &[u8]) {
6    let (signature, data) = data.split_at(4);
7    let (size, data) = data.split_at(4);
8    (signature.try_into().unwrap(), from_be_u32(size), data)
9}
10
11mod error {
12    use crate::extension;
13
14    /// The error returned when decoding extensions.
15    #[derive(Debug, thiserror::Error)]
16    #[allow(missing_docs)]
17    pub enum Error {
18        #[error(
19            "Encountered mandatory extension '{}' which isn't implemented yet",
20            String::from_utf8_lossy(signature)
21        )]
22        MandatoryUnimplemented { signature: extension::Signature },
23        #[error("Could not parse mandatory link extension")]
24        Link(#[from] extension::link::decode::Error),
25    }
26}
27pub use error::Error;
28
29pub(crate) fn all(
30    maybe_beginning_of_extensions: &[u8],
31    object_hash: git_hash::Kind,
32) -> Result<(Outcome, &[u8]), Error> {
33    let mut ext_iter = match extension::Iter::new_without_checksum(maybe_beginning_of_extensions, object_hash) {
34        Some(iter) => iter,
35        None => return Ok((Outcome::default(), maybe_beginning_of_extensions)),
36    };
37
38    let mut ext = Outcome::default();
39    for (signature, ext_data) in ext_iter.by_ref() {
40        match signature {
41            extension::tree::SIGNATURE => {
42                ext.tree = extension::tree::decode(ext_data, object_hash);
43            }
44            extension::resolve_undo::SIGNATURE => {
45                ext.resolve_undo = extension::resolve_undo::decode(ext_data, object_hash);
46            }
47            extension::untracked_cache::SIGNATURE => {
48                ext.untracked = extension::untracked_cache::decode(ext_data, object_hash);
49            }
50            extension::fs_monitor::SIGNATURE => {
51                ext.fs_monitor = extension::fs_monitor::decode(ext_data);
52            }
53            extension::end_of_index_entry::SIGNATURE => {} // skip already done
54            extension::index_entry_offset_table::SIGNATURE => {} // not relevant/obtained already
55            mandatory if mandatory[0].is_ascii_lowercase() => match mandatory {
56                extension::link::SIGNATURE => ext.link = extension::link::decode(ext_data, object_hash)?.into(),
57                extension::sparse::SIGNATURE => {
58                    if !ext_data.is_empty() {
59                        // only used as a marker, if this changes we need this implementation.
60                        return Err(Error::MandatoryUnimplemented { signature: mandatory });
61                    }
62                    ext.is_sparse = true
63                }
64                unknown => return Err(Error::MandatoryUnimplemented { signature: unknown }),
65            },
66            _unknown => {} // skip unknown extensions, too
67        }
68    }
69    Ok((ext, &maybe_beginning_of_extensions[ext_iter.consumed..]))
70}
71
72#[derive(Default)]
73pub(crate) struct Outcome {
74    pub tree: Option<extension::Tree>,
75    pub link: Option<extension::Link>,
76    pub resolve_undo: Option<extension::resolve_undo::Paths>,
77    pub untracked: Option<extension::UntrackedCache>,
78    pub fs_monitor: Option<extension::FsMonitor>,
79    pub is_sparse: bool,
80}
git_index/extension/decode.rs

git_index/extension/
decode.rs
