From 34f4fa1609ac53620f8dd9889b34d7f63c9ed694 Mon Sep 17 00:00:00 2001
From: Divma <26765164+divagant-martian@users.noreply.github.com>
Date: Fri, 31 Mar 2023 10:56:56 -0500
Subject: [PATCH] Delegate blst build to crate in preparation for windows
 bindings (#274)

---
 bindings/rust/Cargo.lock | 46 ++++++++++++++++++++++++++++++++++
 bindings/rust/Cargo.toml |  1 +
 bindings/rust/build.rs   | 53 ++++++++++++++++++----------------------
 3 files changed, 71 insertions(+), 29 deletions(-)

diff --git a/bindings/rust/Cargo.lock b/bindings/rust/Cargo.lock
index b100348..11c88eb 100644
--- a/bindings/rust/Cargo.lock
+++ b/bindings/rust/Cargo.lock
@@ -52,6 +52,16 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "blst"
+version = "0.3.10"
+dependencies = [
+ "cc",
+ "glob",
+ "threadpool",
+ "zeroize",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.12.0"
@@ -63,6 +73,7 @@ name = "c-kzg"
 version = "0.1.0"
 dependencies = [
  "bindgen",
+ "blst",
  "criterion",
  "glob",
  "hex",
@@ -78,6 +89,12 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
 
+[[package]]
+name = "cc"
+version = "1.0.79"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50d30906286121d95be3d479533b458f87493b30a4b5f79a607db8f5d11aa91f"
+
 [[package]]
 name = "cexpr"
 version = "0.6.0"
@@ -659,6 +676,15 @@ version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "222a222a5bfe1bba4a77b45ec488a741b3cb8872e5e499451fd7d0129c9c7c3d"
 
+[[package]]
+name = "threadpool"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d050e60b33d41c19108b32cea32164033a9013fe3b46cbd4457559bfbf77afaa"
+dependencies = [
+ "num_cpus",
+]
+
 [[package]]
 name = "tinytemplate"
 version = "1.2.1"
@@ -802,3 +828,23 @@ name = "winapi-x86_64-pc-windows-gnu"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
+[[package]]
+name = "zeroize"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a0956f1ba7c7909bfb66c2e9e4124ab6f6482560f6628b5aaeba39207c9aad9"
+dependencies = [
+ "zeroize_derive",
+]
+
+[[package]]
+name = "zeroize_derive"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce36e65b0d2999d2aafac989fb249189a141aee1f53c612c1f37d72631959f69"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.8",
+]
diff --git a/bindings/rust/Cargo.toml b/bindings/rust/Cargo.toml
index 11accb6..ed070eb 100644
--- a/bindings/rust/Cargo.toml
+++ b/bindings/rust/Cargo.toml
@@ -14,6 +14,7 @@ minimal-spec = []
 hex = "0.4.2"
 libc = "0.2"
 serde = { version = "1.0", features = ["derive"] }
+blst = { path = "../../blst/bindings/rust" }
 
 [dev-dependencies]
 criterion = "0.4"
diff --git a/bindings/rust/build.rs b/bindings/rust/build.rs
index a39e0b7..bb5544b 100644
--- a/bindings/rust/build.rs
+++ b/bindings/rust/build.rs
@@ -15,22 +15,13 @@ fn move_file(src: &Path, dst: &Path) -> Result<(), String> {
 
 fn main() {
     let cargo_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
-    let root_dir = cargo_dir.join("../../");
+    let root_dir = cargo_dir
+        .parent()
+        .expect("rust dir is nested")
+        .parent()
+        .expect("bindings dir is nested");
     let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
 
-    // Ensure libblst exists in `OUT_DIR`
-    // Assuming blst submodule exists
-    Command::new("make")
-        .current_dir(root_dir.join("src"))
-        .arg("blst")
-        .status()
-        .unwrap();
-    move_file(
-        root_dir.join("lib/libblst.a").as_path(),
-        out_dir.join("libblst.a").as_path(),
-    )
-    .unwrap();
-
     let field_elements_per_blob = if cfg!(feature = "minimal-spec") {
         MINIMAL_FIELD_ELEMENTS_PER_BLOB
     } else {
@@ -41,7 +32,7 @@ fn main() {
 
     // Deleting any existing assembly and object files to ensure that compiling with a different
     // feature flag changes the final linked library file.
-    let obj_file = root_dir.join("src/c_kzg_4844.o");
+    let obj_file = root_dir.join("src").join("c_kzg_4844.o");
     if obj_file.exists() {
         std::fs::remove_file(obj_file).unwrap();
     }
@@ -63,7 +54,7 @@ fn main() {
         .status()
         .unwrap();
     move_file(
-        root_dir.join("src/libckzg.a").as_path(),
+        root_dir.join("src").join("libckzg.a").as_path(),
         out_dir.join("libckzg.a").as_path(),
     )
     .unwrap();
@@ -71,22 +62,31 @@ fn main() {
     println!("cargo:rustc-link-search={}", out_dir.display());
     println!("cargo:rustc-link-search={}", out_dir.display());
     println!("cargo:rustc-link-lib=static=ckzg");
+    // Tell cargo to search for the static blst exposed by the blst-bindings' crate.
     println!("cargo:rustc-link-lib=static=blst");
 
-    let bindings_out_path = cargo_dir.join("src/bindings/generated.rs");
+    let bindings_out_path = cargo_dir.join("src").join("bindings").join("generated.rs");
     let build_target = env::var("TARGET").unwrap();
     let snapshot_path = cargo_dir.join("snapshots").join(format!(
         "bindings_{build_target}_{field_elements_per_blob}.rs"
     ));
+
+    let header_file_path = root_dir.join("src").join("c_kzg_4844.h");
+    let header_file = header_file_path.to_str().expect("valid header file");
+
+    // Obtain the header files exposed by blst-bindings' crate.
+    let blst_headers_dir =
+        std::env::var_os("DEP_BLST_BINDINGS").expect("BLST exposes header files for bindings");
     make_bindings(
         field_elements_per_blob,
-        &root_dir,
+        header_file,
+        &blst_headers_dir.to_string_lossy(),
         bindings_out_path,
         snapshot_path,
     );
 
     // Cleanup
-    let obj_file = root_dir.join("src/c_kzg_4844.o");
+    let obj_file = root_dir.join("src").join("c_kzg_4844.o");
     if obj_file.exists() {
         std::fs::remove_file(obj_file).unwrap();
     }
@@ -94,7 +94,8 @@ fn main() {
 
 fn make_bindings<P>(
     field_elements_per_blob: usize,
-    root_dir: &Path,
+    header_path: &str,
+    blst_headers_dir: &str,
     bindings_out_path: P,
     snapshot_path: P,
 ) where
@@ -120,12 +121,6 @@ fn make_bindings<P>(
         }
     }
 
-    let header_file_path = root_dir.join("src/c_kzg_4844.h");
-    let header_file = header_file_path.to_str().expect("valid header file");
-
-    let inc_dir_path = root_dir.join("inc");
-    let inc_dir = inc_dir_path.to_str().expect("valid inc dir");
-
     let bindings = Builder::default()
         /*
          * Header definitions.
@@ -136,12 +131,12 @@ fn make_bindings<P>(
             "consts",
             &format!("#define FIELD_ELEMENTS_PER_BLOB {field_elements_per_blob}"),
         )
-        .header(header_file)
-        .clang_args([format!("-I{inc_dir}")])
+        .header(header_path)
+        .clang_args([format!("-I{blst_headers_dir}")])
         // Since this is not part of the header file, needs to be allowed explicitly.
         .allowlist_var("FIELD_ELEMENTS_PER_BLOB")
         // Get bindings only for the header file.
-        .allowlist_file(".*/c_kzg_4844.h")
+        .allowlist_file(".*c_kzg_4844.h")
         /*
          * Cleanup instructions.
          */