nfsv41-sys

Raw FFI bindings for the NFSv4.1 protocol, vendored from NFS-Ganesha's nfsv41.h. This crate provides the protocol data types (COMPOUND4args, nfs_argop4, nfs_resop4, ...) and the XDR codecs that encode/decode them, as a low-level foundation for the vnfs client.

This is a -sys crate: it exposes unsafe extern types and functions with manual memory management. Higher-level, safe wrappers live in the vnfs crate.

What's in the box

Build

build.rs performs two steps:

1. C codec archive: gcc compiles src/wrapper.c (with libntirpc's include directories, supplied by libntirpc-sys via its links metadata as DEP_NTIRPC_INCLUDE / DEP_NTIRPC_INCLUDE2) into libnfsv41.a.
2. bindgen: generates ~15k lines of Rust declarations from src/wrapper.h into $OUT_DIR/bindings.rs, which src/lib.rs includes.

The archive's object files reference libntirpc.so symbols, so the crate re-emits -lntirpc (and -lntirpcmonitoring) at final link time; binaries also need libntirpc.so on the dynamic linker path at runtime.

Usage

use nfsv41_sys::*;
use std::os::raw::c_char;

unsafe {
    let mut argop: nfs_argop4 = std::mem::zeroed();
    argop.argop = nfs_opnum4_NFS4_OP_PUTFH;
    argop.nfs_argop4_u.opputfh.object.nfs_fh4_len = 4;
    argop.nfs_argop4_u.opputfh.object.nfs_fh4_val = fh.as_ptr() as *mut c_char;

    let mut args: COMPOUND4args = std::mem::zeroed();
    // ... wire up tag / argarray ...

    let mut xdr: XDR = std::mem::zeroed();
    xdrmem_ncreate(&mut xdr, buf.as_mut_ptr() as *mut c_char, BUF, xdr_op_XDR_ENCODE);
    xdr_wrap_COMPOUND4args(&mut xdr, &mut args);
}

Tests

tests/roundtrip.rs encodes a COMPOUND4args/COMPOUND4res (one PUTFH op) with the codecs, decodes it back, and checks the fields match. Run with:

cargo test -p nfsv41-sys

Improvement roadmap

• Pure-Rust codecs via xdrgen. The workspace already carries protocol/nfsv41.x (the RFC 5661 XDR spec) and the xdrgen / xdr-codec dependencies. xdrgen parses the .x spec and emits typed Pack/Unpack implementations, which would remove gcc, wrapper.c, bindgen, and the -Wno-incompatible-pointer-types workaround. See below.
• Safe wrapper layer. Owned buffer types (Vec<u8>, String), RAII for decoded trees (no manual xdr_free_null_stream), and safe accessors for the nfs_argop4_u / nfs_resop4_u unions.
• Narrow the bindings. An allowlist of NFS types (instead of blocklists) would shrink the generated surface and compile time.
• More codec tests. Round-trips cover PUTFH plus the basic ops (READ, WRITE, LOOKUP, READDIR, REMOVE, RENAME, CREATE, GETFH, READLINK, GETATTR, COMMIT, LINK) in tests/ops_roundtrip.rs; property-based round-trips across the remaining ops would catch more XDR bugs.

How xdrgen generates Rust

xdrgen (used together with the xdr-codec runtime) turns an RFC 4506 / RFC 5661 XDR specification into plain Rust source:

1. Parse. The XDR grammar is parsed (xdrgen's parser is built on nom) into an AST of typedefs, structs, unions, enums, constants, and program/version blocks.
2. Emit. The AST is lowered into Rust source text (xdrgen uses quote) written to $OUT_DIR/<name>_xdr.rs. For every type it emits a matching struct (or enum for unions) plus:
   • impl Pack for T — the encoder, following the XDR wire rules (4-byte alignment, variable-length <> prefixes, discriminants for unions),
   • impl Unpack for T — the decoder, allocating owned Vecs/Strings as it goes.
3. Wire up. The generated file is included with include!(concat!(env!("OUT_DIR"), "/nfsv41_xdr.rs")) inside a module, with xdr-codec as a dependency. Types the generator can't express (e.g. the %-passthrough authsys_parms) get hand-written Pack/Unpack impls.

In a build.rs the whole thing is one call:

fn main() {
    xdrgen::compile("protocol/nfsv41.x").unwrap();
}

For NFSv4.1 the practical caveat is that xdrgen 0.4.4 is an old crate (deps from the quote 0.3 / nom 3 era); the complex NFSv4.1 unions and the authsys_parms passthrough may need manual impls, and the generator itself may need a build fix before the raw bindings can be retired.