astrid-runtime/astrid · error · io::Error

region name too long

Error message

region name too long

What it means

Bounds guard in HostedFileVolume::append: the region name's byte length exceeded u16 range, so it cannot be recorded in the container state's region table and the append is refused with this io error.

Solutions

  1. Shorten region names to <= 65535 bytes (far less in practice)
  2. Hash long identifiers (e.g. SHA-256 hex) and use the digest as the region name
  3. Validate name length before creating the region, failing early with a clearer app-level message
  4. Restructure data to use a short region plus keys inside the payload rather than encoding everything in the name

Example fix

// before
let region = VolumeRegion::new(&format!("{}", giant_user_path))?;
volume.append(&region, payload)?;
// after
let digest = sha256(giant_user_path.as_bytes());
let region = VolumeRegion::new(&hex_encode(digest))?; // 64 bytes
volume.append(&region, payload)?;
Defensive patterns

Strategy: validation

Validate before calling

fn name_fits(name: &str) -> bool { name.as_bytes().len() <= u16::MAX as usize }
assert!(name_fits(&region_name), "region name exceeds 65535 bytes");

Type guard

fn short_region(name: &str) -> Option<VolumeRegion> {
    if name.as_bytes().len() <= u16::MAX as usize { VolumeRegion::new(name).ok() } else { None }
}

Try / catch

match volume.append(&region, payload) {
    Err(e) if e.kind() == std::io::ErrorKind::InvalidInput => {
        let hashed = hash_name(region.as_str());
        volume.append(&VolumeRegion::new(&hashed)?, payload)
    }
    other => other,
}

Prevention

When it happens

Trigger: Calling append() on a HostedFileVolume with a region whose name exceeds 65535 bytes, e.g. programmatically generated names built by concatenating keys/paths.

Common situations: Using file paths, URLs, or user identifiers verbatim as region names; name-collision avoidance schemes that keep appending suffixes until the name is enormous.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

AI-assisted analysis of astrid-runtime/astrid@affd8760f4 (2026-09-09). Data as JSON: /api/errors/7bca64964a29bc62. Report an issue: GitHub.

Appendix: source

Thrown at crates/astrid-storage/src/volume/hosted/mod.rs:112

            .field("path", &self.path)
            .finish_non_exhaustive()
    }
}
impl HostedFileVolume {
    fn append(
        state: &mut ContainerState,
        operation: Operation,
        region: &VolumeRegion,
        offset: u64,
        payload: &[u8],
    ) -> io::Result<(u64, u64)> {
        let next_sequence = state
            .sequence
            .checked_add(1)
            .ok_or_else(|| io::Error::other("Astrid volume sequence exhausted"))?;
        let name = region.as_str().as_bytes();
        let name_len = u16::try_from(name.len())
            .map_err(|_| io::Error::new(io::ErrorKind::InvalidInput, "region name too long"))?;
        let payload_len = u64::try_from(payload.len())
            .map_err(|_| io::Error::other("volume record payload is too large"))?;
        let total_len = u64::try_from(RECORD_FIXED_BYTES)
            .ok()
            .and_then(|fixed| fixed.checked_add(u64::from(name_len)))
            .and_then(|total| total.checked_add(payload_len))
            .ok_or_else(|| io::Error::other("volume record length overflow"))?;
        let mut hasher = blake3::Hasher::new_derive_key("astrid volume record v1");
        hasher.update(&next_sequence.to_le_bytes());
        hasher.update(&[operation as u8]);
        hasher.update(&name_len.to_le_bytes());
        hasher.update(&offset.to_le_bytes());
        hasher.update(&payload_len.to_le_bytes());
        hasher.update(name);
        hasher.update(payload);
        let checksum = *hasher.finalize().as_bytes();

        // A footer occupies the old valid-end until the next append. Truncate

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