1 files changed, 180 insertions, 0 deletions
diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..7983299
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,180 @@
+//! This build script leverages `bindgen` to generate rust sys files that link to the libnftnl
+//! library. It retrieves the includes needed by `bindgen` using `pkg_config`, and tells cargo
+//! the directives needed by the linker to link against the exported symbols.
+
+use bindgen;
+use lazy_static::lazy_static;
+use pkg_config;
+use regex::{Captures, Regex};
+use std::borrow::Cow;
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+const SYS_HEADER_FILE: &str = "include/wrapper.h";
+const SYS_BINDINGS_FILE: &str = "src/sys.rs";
+const TESTS_HEADER_FILE: &str = "include/tests_wrapper.h";
+const TESTS_BINDINGS_FILE: &str = "tests/sys.rs";
+const MIN_LIBNFTNL_VERSION: &str = "1.0.6";
+const MIN_LIBMNL_VERSION: &str = "1.0.0";
+
+
+fn main() {
+    pkg_config_mnl();
+    let clang_args = pkg_config_nftnl();
+    generate_sys(clang_args.into_iter());
+    generate_tests_sys();
+}
+
+/// Setup rust linking directives for libnftnl, and return the include directory list.
+fn pkg_config_nftnl() -> Vec<String> {
+    let mut res = vec![];
+
+    if let Some(lib_dir) = get_env("LIBNFTNL_LIB_DIR") {
+        if !lib_dir.is_dir() {
+            panic!(
+                "libnftnl library directory does not exist: {}",
+                lib_dir.display()
+            );
+        }
+        println!("cargo:rustc-link-search=native={}", lib_dir.display());
+        println!("cargo:rustc-link-lib=nftnl");
+    } else {
+        // Trying with pkg-config instead
+        println!("Minimum libnftnl version: {}", MIN_LIBNFTNL_VERSION);
+        let pkg_config_res = pkg_config::Config::new()
+            .atleast_version(MIN_LIBNFTNL_VERSION)
+            .probe("libnftnl")
+            .unwrap();
+        for path in pkg_config_res.include_paths {
+            res.push(format!("-I{}", path.to_str().unwrap()));
+        }
+    }
+
+    res
+}
+
+/// Setup rust linking directives for libmnl.
+fn pkg_config_mnl() {
+    if let Some(lib_dir) = get_env("LIBMNL_LIB_DIR") {
+        if !lib_dir.is_dir() {
+            panic!(
+                "libmnl library directory does not exist: {}",
+                lib_dir.display()
+            );
+        }
+        println!("cargo:rustc-link-search=native={}", lib_dir.display());
+        println!("cargo:rustc-link-lib=mnl");
+    } else {
+        // Trying with pkg-config instead
+        pkg_config::Config::new()
+            .atleast_version(MIN_LIBMNL_VERSION)
+            .probe("libmnl")
+            .unwrap();
+    }
+}
+
+fn get_env(var: &'static str) -> Option<PathBuf> {
+    println!("cargo:rerun-if-env-changed={}", var);
+    env::var_os(var).map(PathBuf::from)
+}
+
+/// `bindgen`erate a rust sys file from the C headers of the nftnl library.
+fn generate_sys(clang_args: impl Iterator<Item = String>) {
+    // Tell cargo to invalidate the built crate whenever the headers change.
+    println!("cargo:rerun-if-changed={}", SYS_HEADER_FILE);
+
+    let bindings = bindgen::Builder::default()
+        .header(SYS_HEADER_FILE)
+        .clang_args(clang_args)
+        .generate_comments(false)
+        .prepend_enum_name(false)
+        .use_core()
+        .whitelist_function("^nftnl_.+$")
+        .whitelist_type("^nftnl_.+$")
+        .whitelist_var("^nftnl_.+$")
+        .whitelist_var("^NFTNL_.+$")
+        .blacklist_type("(FILE|iovec)")
+        .blacklist_type("^_IO_.+$")
+        .blacklist_type("^__.+$")
+        .blacklist_type("nlmsghdr")
+        .raw_line("#![allow(non_camel_case_types)]\n\n")
+        .raw_line("pub use libc;")
+        .raw_line("use libc::{c_char, c_int, c_ulong, c_void, iovec, nlmsghdr, FILE};")
+        .raw_line("use core::option::Option;")
+        .ctypes_prefix("libc")
+        // 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("Error: unable to generate bindings");
+
+    let mut s = bindings.to_string()
+                    // Add newlines because in alpine bindgen doesn't add them after
+                    // statements.
+                    .replace(" ; ", ";\n")
+                    .replace("#[derive(Debug, Copy, Clone)]", "");
+    let re = Regex::new(r"libc::(c_[a-z]*)").unwrap();
+    s = re.replace_all(&s, "$1").into();
+    let re = Regex::new(r"::core::option::(Option)").unwrap();
+    s = re.replace_all(&s, "$1").into();
+    let re = Regex::new(r"_bindgen_ty_[0-9]+").unwrap();
+    s = re.replace_all(&s, "u32").into();
+    // Change struct bodies to c_void.
+    let re = Regex::new(r"(pub struct .*) \{\n    *_unused: \[u8; 0\],\n\}\n").unwrap();
+    s = re.replace_all(&s, "$1(c_void);\n").into();
+    let re = Regex::new(r"pub type u32 = u32;\n").unwrap();
+    s = re.replace_all(&s, "").into();
+
+    // Write the bindings to the rust header file.
+    let out_path = PathBuf::from(SYS_BINDINGS_FILE);
+    File::create(out_path)
+        .expect("Error: could not create rust header file.")
+        .write_all(&s.as_bytes())
+        .expect("Error: could not write to the rust header file.");
+}
+
+/// `bindgen`erate a rust sys file from the C kernel headers of the nf_tables capabilities.
+/// Used in the rustables tests.
+fn generate_tests_sys() {
+    // Tell cargo to invalidate the built crate whenever the headers change.
+    println!("cargo:rerun-if-changed={}", TESTS_HEADER_FILE);
+
+    let bindings = bindgen::Builder::default()
+        .header(TESTS_HEADER_FILE)
+        .generate_comments(false)
+        .prepend_enum_name(false)
+        .raw_line("#![allow(non_camel_case_types, dead_code)]\n\n")
+        // 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("Error: unable to generate bindings needed for tests.");
+
+    // Add newlines because in alpine bindgen doesn't add them after statements.
+    let s = bindings.to_string().replace(" ; ", ";\n");
+    let s = reformat_units(&s);
+
+    // Write the bindings to the rust header file.
+    let out_path = PathBuf::from(TESTS_BINDINGS_FILE);
+    File::create(out_path)
+        .expect("Error: could not create rust header file.")
+        .write_all(&s.as_bytes())
+        .expect("Error: could not write to the rust header file.");
+}
+
+/// Recast nft_*_attributes from u32 to u16 in header string `header`.
+fn reformat_units(header: &str) -> Cow<str> {
+    lazy_static! {
+        static ref RE: Regex = Regex::new(r"(pub type nft[a-zA-Z_]*_attributes) = u32;").unwrap();
+    }
+    RE.replace_all(header, |captures: &Captures| {
+        format!("{} = u16;", &captures[1])
+    })
+}
+