# C API for fluxio
This provides auxiliary pieces for a C API to use the fluxio library.
## Unstable
The C API of fluxio is currently **unstable**, which means it's not part of the semver contract as the rest of the Rust API is.
Because of that, it's only accessible if `--cfg fluxio_unstable_ffi` is passed to `rustc` when compiling. The easiest way to do that is setting the `RUSTFLAGS` environment variable.
## Building
The C API is part of the Rust library, but isn't compiled by default. Using a nightly release of `cargo`, starting with `nightly-2022-03-02`, it can be compiled with the following command:
```
RUSTFLAGS="--cfg fluxio_unstable_ffi" cargo +nightly rustc --features client,http1,http2,ffi -Z unstable-options --crate-type cdylib
```