Libvirt Rust bindings could use some work

Wim de With wf at dewith.io
Fri Feb 18 09:28:29 UTC 2022


Hello,

I was reading the Rust bindings for libvirt and I noticed that they are
not very idiomatic. A couple of examples:

1. It is conventional to have a *-sys crate containing only the C
interface and the linking configuration. The virt crate would then
depend on this libvirt-sys crate to implement a safe and ergonomic
wrapper.
2. The API heavily uses integers to indicate flags. Sometimes those
integers are type aliased and sometimes they are not. In Rust, this can
be much nicer, using enums to represent only valid flags. The same
applies to some return values.
3. Since libvirt is thread-safe, the Rust types could be Send and Sync,
so that they can also be used in a multithreaded context. Special care
needs to be taken with translating virGetLastError to Rust Results, but
it shouldn't be a problem.

For a nice example of a Rust wrapper around a C library, see:
https://github.com/rust-lang/git2-rs

I am willing to send some patches to fix some of these problems, but
this will almost certainly lead to breaking API changes, and I am not
sure what your opinion is on that.

Finally, while I am not a legal expert, I believe that licensing a Rust
library as LGPL does not make much sense. Rust does not have a stable
ABI so everything is statically linked. This means that adding virt to a
Cargo.toml file of a non-GPL application is already in violation of the
license.

Thanks,

Wim




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