gix_index/extension/
decode.rs

1use crate::{extension, extension::Signature, util::from_be_u32};
2
3pub(crate) fn header(data: &[u8]) -> (Signature, u32, &[u8]) {
4    let (signature, data) = data.split_at(4);
5    let (size, data) = data.split_at(4);
6    (signature.try_into().unwrap(), from_be_u32(size), data)
7}
8
9mod error {
10    use crate::extension;
11
12    /// The error returned when decoding extensions.
13    #[derive(Debug, thiserror::Error)]
14    #[allow(missing_docs)]
15    pub enum Error {
16        #[error(
17            "Encountered mandatory extension '{}' which isn't implemented yet",
18            String::from_utf8_lossy(signature)
19        )]
20        MandatoryUnimplemented { signature: extension::Signature },
21        #[error("Could not parse mandatory link extension")]
22        Link(#[from] extension::link::decode::Error),
23    }
24}
25pub use error::Error;
26
27pub(crate) fn all(
28    maybe_beginning_of_extensions: &[u8],
29    object_hash: gix_hash::Kind,
30) -> Result<(Outcome, &[u8]), Error> {
31    let mut ext_iter = match extension::Iter::new_without_checksum(maybe_beginning_of_extensions, object_hash) {
32        Some(iter) => iter,
33        None => return Ok((Outcome::default(), maybe_beginning_of_extensions)),
34    };
35
36    let mut ext = Outcome::default();
37    for (signature, ext_data) in ext_iter.by_ref() {
38        match signature {
39            extension::tree::SIGNATURE => {
40                ext.tree = extension::tree::decode(ext_data, object_hash);
41            }
42            extension::resolve_undo::SIGNATURE => {
43                ext.resolve_undo = extension::resolve_undo::decode(ext_data, object_hash);
44            }
45            extension::untracked_cache::SIGNATURE => {
46                ext.untracked = extension::untracked_cache::decode(ext_data, object_hash);
47            }
48            extension::fs_monitor::SIGNATURE => {
49                ext.fs_monitor = extension::fs_monitor::decode(ext_data);
50            }
51            extension::end_of_index_entry::SIGNATURE => {
52                ext.end_of_index = true;
53            } // skip already done
54            extension::index_entry_offset_table::SIGNATURE => {
55                ext.offset_table = true;
56            } // not relevant/obtained already
57            mandatory if mandatory[0].is_ascii_lowercase() => match mandatory {
58                extension::link::SIGNATURE => ext.link = extension::link::decode(ext_data, object_hash)?.into(),
59                extension::sparse::SIGNATURE => {
60                    if !ext_data.is_empty() {
61                        // only used as a marker, if this changes we need this implementation.
62                        return Err(Error::MandatoryUnimplemented { signature: mandatory });
63                    }
64                    ext.is_sparse = true;
65                }
66                unknown => return Err(Error::MandatoryUnimplemented { signature: unknown }),
67            },
68            _unknown => {} // skip unknown extensions, too
69        }
70    }
71    Ok((ext, &maybe_beginning_of_extensions[ext_iter.consumed..]))
72}
73
74#[derive(Default)]
75pub(crate) struct Outcome {
76    pub tree: Option<extension::Tree>,
77    pub link: Option<extension::Link>,
78    pub resolve_undo: Option<extension::resolve_undo::Paths>,
79    pub untracked: Option<extension::UntrackedCache>,
80    pub fs_monitor: Option<extension::FsMonitor>,
81    pub is_sparse: bool,
82    pub offset_table: bool,
83    pub end_of_index: bool,
84}
gix_index/extension/decode.rs

gix_index/extension/
decode.rs
