@bytecodealliance/jco-node-fs

Native Node.js filesystem helpers used by Jco's WASI shims.

The package intentionally exposes only filesystem operations that the Node.js standard library cannot provide. It is not a general-purpose filesystem API.

import { open } from 'node:fs/promises';
import { fadvise } from '@bytecodealliance/jco-node-fs';

const file = await open('data.bin', 'r');
try {
    fadvise(file.fd, 0n, 0n, 'sequential');
} finally {
    await file.close();
}

rename(oldPath, newPath) synchronously renames a host file or directory. It can atomically replace an existing empty directory on Windows, using Rust's native rename implementation. Symlinks are moved without moving their targets.

import { rename } from '@bytecodealliance/jco-node-fs';

rename('staging', 'destination');

Both paths must be strings. Relative paths use the process's current directory. Errors include code, syscall, path, and dest properties.

This binding supports the directory replacement required by the updated Wasmtime conformance tests. The Preview 2 shim can adopt it after a helper release includes the binding; its current dependency continues to use the existing implementation.