Hmbown/CodeWhale · error · io::Error

external credential path must name a file

Error message

external credential path must name a file

What it means

After walking every component with `openat`, `open_secure_regular_file` checks that the final component actually opened a leaf file (and subsequently that the metadata is a regular file). A path that ends in a directory or vanishes into a non-leaf (e.g. trailing slash semantics) is rejected with this `InvalidInput` error — the credential API only reads files, not directories.

Solutions

  1. Point the path at the credential file itself, not its directory: e.g. `/home/me/.config/codewhale/credentials.json`.
  2. Remove any trailing `/` from the configured path.
  3. Verify the credential file exists: `ls -la <path>` — if only the directory is present, complete the credential setup/login step that creates the file.
  4. Check whether the tool that should have written the credential file ran and had permission to create it.

Example fix

// before
let creds = read_to_string("/home/me/.config/codewhale/credentials/")?; // directory
// after
let creds = read_to_string("/home/me/.config/codewhale/credentials.json")?;
Defensive patterns

Strategy: validation

Validate before calling

let md = std::fs::metadata(&path)?; // pre-check
if !md.is_file() {
    return Err(anyhow::anyhow!("credential path must be a file, not a directory: {path:?}"));
}

Type guard

fn names_regular_file(p: &Path) -> bool {
    std::fs::metadata(p).map(|m| m.is_file()).unwrap_or(false)
}

Try / catch

match read_to_string(&cred_path) {
    Err(e) if e.to_string().contains("must name a file") => {
        eprintln!("{cred_path:?} points at a directory; set the full path to the credential file.");
    }
    other => other?,
}

Prevention

When it happens

Trigger: `read_to_string`/`read_codewhale_owned_to_string` called with a path that names a directory (e.g. `/home/me/.config/codewhale/` or a credentials directory rather than a file).

Common situations: Config value points at a directory (`~/.ssh`, `~/.config/codewhale/credentials/`) instead of the file inside it; trailing slash in a copied path; the expected credential file was never created so only the parent directory exists.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/6c9f8eed2a923a78. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/external_credentials.rs:217

        let flags = if leaf {
            libc::O_RDONLY | libc::O_CLOEXEC | libc::O_NOFOLLOW | libc::O_NONBLOCK
        } else {
            libc::O_RDONLY | libc::O_CLOEXEC | libc::O_NOFOLLOW | libc::O_DIRECTORY
        };
        use std::os::fd::AsRawFd;
        // SAFETY: the directory fd and component C string are valid for this
        // call and flags require no variadic mode.
        let fd = unsafe { libc::openat(current.as_raw_fd(), component.as_ptr(), flags) };
        if fd < 0 {
            return Err(io::Error::last_os_error());
        }
        // SAFETY: `fd` is newly owned after the successful `openat`.
        current = unsafe { File::from_raw_fd(fd) };
        opened_leaf = leaf;
    }

    if !opened_leaf {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            "external credential path must name a file",
        ));
    }
    let metadata = current.metadata()?;
    if !metadata.file_type().is_file() {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            "external credential path must name a regular file",
        ));
    }
    if require_owner_only {
        use std::os::unix::fs::MetadataExt as _;
        // SAFETY: geteuid(2) dereferences no pointers.
        if metadata.uid() != unsafe { libc::geteuid() }
            || metadata.mode() & 0o077 != 0
            || metadata.nlink() != 1
        {

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