GitoxideLabs/gitoxide · error · anyhow::Error

Cannot determine data type on path without extension

Error message

Cannot determine data type on path without extension '{}', expecting default extensions 'idx' and 'pack'

What it means

Thrown by `pack_or_pack_index` in the pack verify path when the given path has no file extension at all, so the tool cannot infer whether the input is a pack index (`.idx`) or a pack file (`.pack`). Verification dispatches different logic depending on the extension, so an extensionless path is ambiguous and rejected.

Solutions

Pass the file with its real `.idx` or `.pack` extension
Rename the file to include the proper extension, e.g. `mv packfile packfile.pack`
If the path is a directory, ensure it is one the tool supports (dir traversal arm) rather than an extensionless file

Example fix

// before
gix pack verify ./tmp/packdownload
// after
gix pack verify ./tmp/packdownload.pack

Defensive patterns

Strategy: validation

Validate before calling

if path.extension().is_none() {
    return Err("pass a file with an explicit .idx or .pack extension".into());
}

Type guard

fn has_pack_extension(p: &std::path::Path) -> bool {
    p.extension().map_or(false, |e| e == "idx" || e == "pack")
}

Prevention

Never strip or rename pack files after downloading; keep original names
In scripts, use `find .git/objects/pack -name '*.pack'` to select inputs

When it happens

Trigger: Running `gix pack verify <path>` where `<path>` has no extension, e.g. `gix pack verify ./packfile` or passing a directory-adjacent temp file without a suffix.

Common situations: Piped/temp files downloaded without names, copied pack data with the extension stripped, or scripts that pass a directory where the extension match arm falls through to `_`.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of GitoxideLabs/gitoxide@e73179060b (2026-09-08). Data as JSON: /api/errors/67b7591baa4ee851. Report an issue: GitHub.

Appendix: source

Thrown at gitoxide-core/src/pack/verify.rs:193

                            writeln!(out, "{}", index_name.display()).ok();
                            drop(print_statistics(&mut out, &stats));
                        }
                    }
                    #[cfg(feature = "serde")]
                    Some(OutputFormat::Json) => serde_json::to_writer_pretty(
                        out,
                        &multi_index
                            .index_names()
                            .iter()
                            .zip(res.pack_traverse_statistics)
                            .collect::<Vec<_>>(),
                    )?,
                    _ => {}
                }
                return Ok(());
            }
            _ => {
                return Err(anyhow!(
                    "Cannot determine data type on path without extension '{}', expecting default extensions 'idx' and 'pack'",
                    path.display()
                ));
            }
        },
        ext => return Err(anyhow!("Unknown extension {ext:?}, expecting 'idx' or 'pack'")),
    };
    if let Some(stats) = res.1.as_ref() {
        #[cfg_attr(not(feature = "serde"), allow(clippy::single_match))]
        match output_statistics {
            Some(OutputFormat::Human) => drop(print_statistics(&mut out, stats)),
            #[cfg(feature = "serde")]
            Some(OutputFormat::Json) => serde_json::to_writer_pretty(out, stats)?,
            _ => {}
        }
    }
    Ok(())
}

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