Git internals

Git pack-index prefix lookup

Find object prefixes, exact pack offsets and recorded CRCs in one .idx file.

Your inputs

Start with an example

Git pack .idx v2 bytes · hexadecimal

ff744f6300000002000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000010000000100000001000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030000000300000003000000030011111111111111111111111111111111111111abcd000000000000000000000000000000000000abcdffffffffffffffffffffffffffffffffffff11223344aabbccdd000000000000000c800000000000006400000001000000050000000000000000000000000000000000000000ae9e474fcc66b8f1fcc1f1949c7a45c3b16da18b

Repository object format

Object ID hexadecimal prefix

Your inputs stay in your browser.

Your result

Example result

How it works

Check v2 table boundaries, sorted IDs and the fanout histogram. Resolve direct or 64-bit offsets, recompute the index checksum and return all prefix matches within the supplied index.

The prefix abcd matches two SHA-1 IDs. One uses the 64-bit offset table and records byte offset 4294967301.

Limits

One supplied v2 index, up to 8 MiB and 100000 objects; use a longer prefix if more than 20000 rows match. Hash mode is explicit; 4-digit or longer odd/even-nibble prefixes are supported. Pack checksum and CRCs are recorded only: no pack bytes or repository-wide uniqueness check. v1/MIDX/RIDX/pack payloads are excluded.