Add basic bindgen of libvfio-user as -sys crate

Based on https://rust-lang.github.io/rust-bindgen/tutorial-0.html

Still needs bindgen adjustments in order for it to build

.gitignore

@@ -12,3 +12,10 @@ Cargo.lock
 
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
+
+
+# Editor files
+.idea/
+*.iml
+.vs/
+.vscode/

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "libvfio-user-sys/libvfio-user"]
+	path = libvfio-user-sys/libvfio-user
+	url = https://github.com/nutanix/libvfio-user.git

Cargo.toml

@@ -0,0 +1,4 @@
+[workspace]
+members=[
+    "libvfio-user-sys",
+]

libvfio-user-sys/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "libvfio-user-sys"
+version = "0.0.1"
+edition = "2021"
+license = "BSD-3-Clause"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[build-dependencies]
+bindgen = "0.66.1"
+
+[dependencies]

libvfio-user-sys/build.rs

@@ -0,0 +1,35 @@
+use std::env;
+use std::path::PathBuf;
+
+fn main() {
+    // Tell cargo to look for shared libraries in the specified directory
+    println!("cargo:rustc-link-search=libvfio-user/build/lib");
+
+    // Tell cargo to tell rustc to link our `vfio-user` library. Cargo will
+    // automatically know it must look for a `libvfio-user.so` file.
+    println!("cargo:rustc-link-lib=vfio-user");
+
+    // Tell cargo to invalidate the built crate whenever the wrapper changes
+    println!("cargo:rerun-if-changed=libvfio-user/include/libvfio-user.h");
+
+    // The bindgen::Builder is the main entry point
+    // to bindgen, and lets you build up options for
+    // the resulting bindings.
+    let bindings = bindgen::Builder::default()
+        // The input header we would like to generate
+        // bindings for.
+        .header("libvfio-user/include/libvfio-user.h")
+        // Tell cargo to invalidate the built crate whenever any of the
+        // included header files changed.
+        .parse_callbacks(Box::new(bindgen::CargoCallbacks))
+        // Finish the builder and generate the bindings.
+        .generate()
+        // Unwrap the Result and panic on failure.
+        .expect("Unable to generate bindings");
+
+    // Write the bindings to the $OUT_DIR/bindings.rs file.
+    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+    bindings
+        .write_to_file(out_path.join("bindings.rs"))
+        .expect("Couldn't write bindings!");
+}

libvfio-user-sys/src/lib.rs

@@ -0,0 +1,5 @@
+#![allow(non_upper_case_globals)]
+#![allow(non_camel_case_types)]
+#![allow(non_snake_case)]
+
+include!(concat!(env!("OUT_DIR"), "/bindings.rs"));