GitoxideLabs/gitoxide · error

base graph count to fit in 32-bits

Error message

base graph count to fit in 32-bits

What it means

When initializing a commit-graph File, the BASE_GRAPHS_LIST chunk size divided by the hash length must fit into a u32, since the count of base graphs is a 32-bit quantity in the format. The `try_into()` is expected to succeed because the chunk is already validated. This panic means the chunk file is structurally corrupt or the header/base-graph count disagrees in an unexpected way.

Solutions

1. Delete and regenerate the commit-graph: `rm .git/objects/info/commit-graph* && git commit-graph write`
2. Validate the commit-graph file before use; treat unreadable graphs as optional and fall back to object parsing
3. Report upstream if reproducible with a valid git-generated commit-graph

Example fix

// before
let f = gix_commitgraph::File::at(path, hash)?;
// after (guard at call site)
let f = if path.exists() { gix_commitgraph::File::at(path, hash).ok() } else { None };

// verify chunk sizes before trusting the file
if file_len < expected_min_len { skip_commitgraph(); }

let graph = gix_commitgraph::File::at(path, hash).map_err(|e| e.into_error()).ok();

When it happens

Trigger: Calling `gix_commitgraph::File::at()` (public `new`) on a commit-graph file whose BASE_GRAPHS_LIST chunk is larger than u32::MAX hash entries — i.e. a corrupt or adversarially crafted commit-graph file.

Common situations: Reading a corrupted or hand-crafted commit-graph file; a repository with a malformed .git/objects/info/commit-graph; fuzzing targets; a git version producing non-standard graphs.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• number of commits in CDAT chunk to fit in 32 bits
• an architecture able to hold 32 bits of integer
• ' ' is not a valid configuration key
• Cannot use iter_v1() on index of type
• Cannot use iter_v2() on index of type

AI-assisted analysis of GitoxideLabs/gitoxide@e73179060b (2026-09-08). Data as JSON: /api/errors/c4f7d2671be31a1d. Report an issue: GitHub.

Appendix: source

Thrown at gix-commitgraph/src/file/init.rs:78

        let chunks = gix_chunk::file::Index::from_bytes(&data, ofs, u32::from(chunk_count))
            .or_raise(|| message!("Couldn't read commit-graph file with {chunk_count} chunks at offset {ofs}"))?;

        let base_graphs_list_offset = chunks
            .validated_usize_offset_by_id(BASE_GRAPHS_LIST_CHUNK_ID, |chunk_range| {
                let chunk_size = chunk_range.len();
                if chunk_size % object_hash.len_in_bytes() != 0 {
                    return Err(message!("Commit-graph chunk {BASE_GRAPHS_LIST_CHUNK_ID:?} has invalid size: {msg}",
                        msg = format!(
                            "chunk size {} is not a multiple of {}",
                            chunk_size,
                            object_hash.len_in_bytes()
                        ),
                    ).raise());
                }
                let chunk_base_graph_count: u32 = (chunk_size / object_hash.len_in_bytes())
                    .try_into()
                    .expect("base graph count to fit in 32-bits");
                if chunk_base_graph_count != u32::from(base_graph_count) {
                    return Err(message!("Commit-graph {BASE_GRAPHS_LIST_CHUNK_ID:?} chunk contains {chunk_base_graph_count} base graphs, but commit-graph file header claims {base_graph_count} base graphs").raise())
                }
                Ok(chunk_range.start)
            })
            .ok()
            .transpose()?;

        let (commit_data_offset, commit_data_count): (_, u32) = chunks
            .validated_usize_offset_by_id(COMMIT_DATA_CHUNK_ID, |chunk_range| {
                let chunk_size = chunk_range.len();

                let entry_size = object_hash.len_in_bytes() + COMMIT_DATA_ENTRY_SIZE_SANS_HASH;
                if chunk_size % entry_size != 0 {
                    return Err(message!("Commit-graph chunk {COMMIT_DATA_CHUNK_ID:?} has invalid size: chunk size {chunk_size} is not a multiple of {entry_size}").raise())
                }
                Ok((
                    chunk_range.start,

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