ascmhl

Read and validate ASC Media Hash List (MHL) manifests from Rust.

An ascmhl/ folder travels with footage from the camera card through every copy. Each generation inside it records a content hash for every file. This crate opens the latest generation under a source directory, recomputes the hashes against the files that are there, and tells you whether they match.

What it does

• Finds ascmhl/ directly under the directory you pass, picks the highest-numbered .mhl file, and parses ASC MHL v2 (<path>) and v1 (<file>) entries.
• Recomputes SHA-256, SHA-1 and MD5, the fixed-width hex algorithms, and compares them to the manifest, ignoring case.
• Reports a manifest that carries only xxh64, xxh3 or c4 as detected and unvalidated, with the reason, instead of passing it.
• Returns per-file detail: how many files matched, and a list of mismatches, missing files, and entries without a usable hash.

What it does not do

• It never writes or generates an MHL. Read only.
• It never blocks or deletes anything. A mismatch is a result, not an error; your code decides what happens next.
• It does not implement the xxHash or C4 algorithms.

Example

use std::path::Path;

fn main() -> Result<(), ascmhl::Error> {
    match ascmhl::detect_and_validate(Path::new("/media/card-001"))? {
        None => println!("no ascmhl/ folder here"),
        Some(outcome) if outcome.validated => println!(
            "generation {} validated with {}: {} of {} files matched",
            outcome.generation, outcome.algorithm, outcome.files_matched, outcome.files_in_manifest
        ),
        Some(outcome) => {
            println!("generation {} not validated ({})", outcome.generation, outcome.algorithm);
            for problem in &outcome.mismatches {
                println!("  {problem}");
            }
        }
    }
    Ok(())
}

detect_and_validate returns Ok(None) when there is no ascmhl/ folder, Ok(Some(outcome)) otherwise, and an Err only when the folder, a manifest or a listed file could not be read. AscMhlOutcome::to_sidecar() gives the compact AscMhlValidation record (generation, algorithm, counts, all matched) for storing next to your own records; it derives serde::Serialize and Deserialize.

Where it comes from

This is the ASC MHL check from the Hiberden archive engine, published on its own so other tools can use it. Hiberden runs it on every folder it archives and records the outcome; the engine itself is not part of this crate.

License

MIT. See LICENSE.

Built by AgaveIS for Hiberden.