vendor/gix-index/src/extension/index_entry_offset_table.rs

   1 use crate::{extension, extension::Signature, util::read_u32};
   2
   3 #[derive(Debug, Clone, Copy)]
   4 pub struct Offset {
   5     pub from_beginning_of_file: u32,
   6     pub num_entries: u32,
   7 }
   8
   9 pub const SIGNATURE: Signature = *b"IEOT";
  10
  11 pub fn decode(data: &[u8]) -> Option<Vec<Offset>> {
  12     let (version, mut data) = read_u32(data)?;
  13     match version {
  14         1 => {}
  15         _unknown => return None,
  16     }
  17
  18     let entry_size = 4 + 4;
  19     let num_offsets = data.len() / entry_size;
  20     if num_offsets == 0 || data.len() % entry_size != 0 {
  21         return None;
  22     }
  23
  24     let mut out = Vec::with_capacity(entry_size);
  25     for _ in 0..num_offsets {
  26         let (offset, chunk) = read_u32(data)?;
  27         let (num_entries, chunk) = read_u32(chunk)?;
  28         out.push(Offset {
  29             from_beginning_of_file: offset,
  30             num_entries,
  31         });
  32         data = chunk;
  33     }
  34     debug_assert!(data.is_empty());
  35
  36     out.into()
  37 }
  38
  39 pub fn find(extensions: &[u8], object_hash: gix_hash::Kind) -> Option<Vec<Offset>> {
  40     extension::Iter::new_without_checksum(extensions, object_hash)?
  41         .find_map(|(sig, ext_data)| (sig == SIGNATURE).then_some(ext_data))
  42         .and_then(decode)
  43 }