gix_index/decode/
header.rspub(crate) const SIZE: usize = 4 + 4 + 4 ;
use crate::{util::from_be_u32, Version};
pub(crate) const SIGNATURE: &[u8] = b"DIRC";
mod error {
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("{0}")]
Corrupt(&'static str),
#[error("Index version {0} is not supported")]
UnsupportedVersion(u32),
}
}
pub use error::Error;
pub(crate) fn decode(data: &[u8], object_hash: gix_hash::Kind) -> Result<(Version, u32, &[u8]), Error> {
if data.len() < (3 * 4) + object_hash.len_in_bytes() {
return Err(Error::Corrupt(
"File is too small even for header with zero entries and smallest hash",
));
}
let (signature, data) = data.split_at(4);
if signature != SIGNATURE {
return Err(Error::Corrupt(
"Signature mismatch - this doesn't claim to be a header file",
));
}
let (version, data) = data.split_at(4);
let version = match from_be_u32(version) {
2 => Version::V2,
3 => Version::V3,
4 => Version::V4,
unknown => return Err(Error::UnsupportedVersion(unknown)),
};
let (entries, data) = data.split_at(4);
let entries = from_be_u32(entries);
Ok((version, entries, data))
}