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use crate::{extension, extension::Signature, util::read_u32};
#[derive(Debug, Clone, Copy)]
pub struct Offset {
pub from_beginning_of_file: u32,
pub num_entries: u32,
}
pub const SIGNATURE: Signature = *b"IEOT";
pub fn decode(data: &[u8]) -> Option<Vec<Offset>> {
let (version, mut data) = read_u32(data)?;
match version {
1 => {}
_unknown => return None,
}
let entry_size = 4 + 4;
let num_offsets = data.len() / entry_size;
if num_offsets == 0 || data.len() % entry_size != 0 {
return None;
}
let mut out = Vec::with_capacity(entry_size);
for _ in 0..num_offsets {
let (offset, chunk) = read_u32(data)?;
let (num_entries, chunk) = read_u32(chunk)?;
out.push(Offset {
from_beginning_of_file: offset,
num_entries,
});
data = chunk;
}
debug_assert!(data.is_empty());
out.into()
}
pub fn find(extensions: &[u8], object_hash: gix_hash::Kind) -> Option<Vec<Offset>> {
extension::Iter::new_without_checksum(extensions, object_hash)?
.find_map(|(sig, ext_data)| (sig == SIGNATURE).then_some(ext_data))
.and_then(decode)
}
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