nydus-error

The Nydus error contract: the project-wide Error/Result and the Context extension trait.

Nydus splits errors along two planes:

• The data plane (storage, fs, and the FUSE/fanotify/NBD/UFFD read paths) keeps std::io::Result: those errors must carry an OS errno so the service edges can answer the kernel with a meaningful POSIX code.
• Everything else (image building, config parsing, CLI, service setup) returns Result with the project-wide Error defined here.

Error wraps io::Error transparently, so data-plane failures cross into the control plane with a plain ?. Use Context to attach human-readable context while keeping the source chain intact.

Following the std guidance that an error exposes its cause either through source() or through Display but not both, Display prints only the outermost layer. Print edges (logs, eprintln!) must format errors with Error::report to keep the whole cause chain on one line.

License

Apache-2.0. This crate is part of the Nydus project.