1 files changed, 114 insertions, 0 deletions
diff --git a/third_party/rust/lucet-wasi-wasmsbx/build.rs b/third_party/rust/lucet-wasi-wasmsbx/build.rs
new file mode 100644
index 0000000000..068e214fae
--- /dev/null
+++ b/third_party/rust/lucet-wasi-wasmsbx/build.rs
@@ -0,0 +1,114 @@
+#![allow(unused)]
+
+use std::env;
+use std::fs::File;
+use std::path::{Path, PathBuf};
+use std::process::{Command, Stdio};
+
+fn wasi_sdk() -> PathBuf {
+    Path::new(&env::var("WASI_SDK").unwrap_or("/opt/wasi-sdk".to_owned())).to_path_buf()
+}
+
+fn wasi_sysroot() -> PathBuf {
+    match env::var("WASI_SYSROOT") {
+        Ok(wasi_sysroot) => Path::new(&wasi_sysroot).to_path_buf(),
+        Err(_) => {
+            let mut path = wasi_sdk();
+            path.push("share");
+            path.push("wasi-sysroot");
+            path
+        }
+    }
+}
+
+fn wasm_clang_root() -> PathBuf {
+    match env::var("CLANG_ROOT") {
+        Ok(clang) => Path::new(&clang).to_path_buf(),
+        Err(_) => {
+            let mut path = wasi_sdk();
+            path.push("lib");
+            path.push("clang");
+            path.push("8.0.1");
+            path
+        }
+    }
+}
+
+// `src/wasi_host.rs` is automatically generated using clang and
+// wasi-libc headers. This requires these to be present, and installed
+// at specific paths, which is not something we can rely on outside
+// of our environment.
+// So, we follow what most other tools using `bindgen` do, and provide
+// a pre-generated version of the file, along with a way to update it.
+// This is what the `update-bindings` feature do. It requires the WASI SDK
+// to be either installed in `/opt/wasi-sdk`, or at a location defined by
+// a `WASI_SDK` environment variable, as well as `clang` headers either
+// being part of `WASI_SDK`, or found in a path defined by a
+// `CLANG_ROOT` environment variable.
+#[cfg(not(feature = "update-bindings"))]
+fn main() {}
+
+#[cfg(feature = "update-bindings")]
+fn main() {
+    let wasi_sysroot = wasi_sysroot();
+    let wasm_clang_root = wasm_clang_root();
+    assert!(
+        wasi_sysroot.exists(),
+        "wasi-sysroot not present at {:?}",
+        wasi_sysroot
+    );
+    assert!(
+        wasm_clang_root.exists(),
+        "clang-root not present at {:?}",
+        wasm_clang_root
+    );
+
+    let wasi_sysroot_core_h = wasi_sysroot.join("include/wasi/core.h");
+
+    assert!(
+        wasi_sysroot_core_h.exists(),
+        "wasi-sysroot core.h not present at {:?}",
+        wasi_sysroot_core_h
+    );
+
+    println!("cargo:rerun-if-changed={}", wasi_sysroot_core_h.display());
+
+    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+
+    let core_h_path = out_path.join("core.h");
+    let core_h = File::create(&core_h_path).unwrap();
+
+    // `bindgen` doesn't understand typed constant macros like `UINT8_C(123)`, so this fun regex
+    // strips them off to yield a copy of `wasi/core.h` with bare constants.
+    let sed_result = Command::new("sed")
+        .arg("-E")
+        .arg(r#"s/U?INT[0-9]+_C\(((0x)?[0-9]+)\)/\1/g"#)
+        .arg(wasi_sysroot_core_h)
+        .stdout(Stdio::from(core_h))
+        .status()
+        .expect("can execute sed");
+
+    if !sed_result.success() {
+        // something failed, but how?
+        match sed_result.code() {
+            Some(code) => panic!("sed failed with code {}", code),
+            None => panic!("sed exited abnormally"),
+        }
+    }
+
+    let host_builder = bindgen::Builder::default()
+        .clang_arg("-nostdinc")
+        .clang_arg("-D__wasi__")
+        .clang_arg(format!("-isystem={}/include/", wasi_sysroot.display()))
+        .clang_arg(format!("-I{}/include/", wasm_clang_root.display()))
+        .header(core_h_path.to_str().unwrap())
+        .whitelist_type("__wasi_.*")
+        .whitelist_var("__WASI_.*");
+
+    let src_path = Path::new("src");
+    host_builder
+        .generate()
+        .expect("can generate host bindings")
+        .write_to_file(src_path.join("wasi_host.rs"))
+        .expect("can write host bindings");
+}