164 lines
6.1 KiB
Rust
164 lines
6.1 KiB
Rust
use std::env;
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use std::path::PathBuf;
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fn main() {
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let cargo_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
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let root_dir = cargo_dir
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.parent()
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.expect("rust dir is nested")
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.parent()
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.expect("bindings dir is nested");
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// Obtain the header files of blst
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let blst_base_dir = root_dir.join("blst");
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let blst_headers_dir = blst_base_dir.join("bindings");
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let c_src_dir = root_dir.join("src");
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let mut cc = cc::Build::new();
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#[cfg(all(windows, target_env = "msvc"))]
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{
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cc.flag("-D_CRT_SECURE_NO_WARNINGS");
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// In blst, if __STDC_VERSION__ isn't defined as c99 or greater, it will typedef a bool to
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// an int. There is a bug in bindgen associated with this. It assumes that a bool in C is
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// the same size as a bool in Rust. This is the root cause of the issues on Windows. If/when
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// this is fixed in bindgen, it should be safe to remove this compiler flag.
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cc.flag("/std:c11");
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}
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cc.include(blst_headers_dir.clone());
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cc.warnings(false);
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cc.file(c_src_dir.join("c_kzg_4844.c"));
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cc.try_compile("ckzg").expect("Failed to compile ckzg");
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#[cfg(feature = "generate-bindings")]
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{
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let header_path = c_src_dir.join("c_kzg_4844.h");
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let bindings_out_path = concat!(env!("CARGO_MANIFEST_DIR"), "/src/bindings/generated.rs");
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make_bindings(
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header_path.to_str().expect("valid header path"),
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blst_headers_dir.to_str().expect("valid blst header path"),
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bindings_out_path.as_ref(),
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);
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}
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// Finally, tell cargo this provides ckzg/ckzg_min
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println!("cargo:rustc-link-lib=ckzg");
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}
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#[cfg(feature = "generate-bindings")]
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fn make_bindings(header_path: &str, blst_headers_dir: &str, bindings_out_path: &std::path::Path) {
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use bindgen::Builder;
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#[derive(Debug)]
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struct Callbacks;
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impl bindgen::callbacks::ParseCallbacks for Callbacks {
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fn int_macro(&self, name: &str, _value: i64) -> Option<bindgen::callbacks::IntKind> {
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match name {
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"FIELD_ELEMENTS_PER_BLOB"
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| "BYTES_PER_COMMITMENT"
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| "BYTES_PER_PROOF"
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| "BYTES_PER_FIELD_ELEMENT"
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| "BYTES_PER_BLOB" => Some(bindgen::callbacks::IntKind::Custom {
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name: "usize",
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is_signed: false,
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}),
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_ => None,
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}
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}
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}
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let bindings = Builder::default()
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/*
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* Header definitions.
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*/
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.header(header_path)
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.clang_args([format!("-I{blst_headers_dir}")])
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// Get bindings only for the header file.
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.allowlist_file(".*c_kzg_4844.h")
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/*
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* Cleanup instructions.
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*/
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// Remove stdio definitions related to FILE.
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.opaque_type("FILE")
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// Remove the definition of FILE to use the libc one, which is more convenient.
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.blocklist_type("FILE")
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// Inject rust code using libc's FILE
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.raw_line("use libc::FILE;")
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// Do no generate layout tests.
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.layout_tests(false)
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// Extern functions do not need individual extern blocks.
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.merge_extern_blocks(true)
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// We implement Drop for this type. Copy is not allowed for types with destructors.
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.no_copy("KZGSettings")
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/*
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* API improvements.
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*/
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// Do not create individual constants for enum variants.
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.rustified_enum("C_KZG_RET")
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// Make constants used as sizes `usize`.
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.parse_callbacks(Box::new(Callbacks))
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// Add PartialEq and Eq impls to types.
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.derive_eq(true)
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// All types are hashable.
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.derive_hash(true)
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// Blobs are big, we don't want rust to liberally copy them around.
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.no_copy("Blob")
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// Do not make fields public. If we want to modify them we can create setters/mutable
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// getters when necessary.
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.default_visibility(bindgen::FieldVisibilityKind::Private)
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// Blocklist this type alias to use a custom implementation. If this stops being a type
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// alias this line needs to be removed.
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.blocklist_type("KZGCommitment")
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// Blocklist this type alias to use a custom implementation. If this stops being a type
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// alias this line needs to be removed.
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.blocklist_type("KZGProof")
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/*
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* Re-build instructions
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*/
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.parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
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.generate()
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.unwrap();
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let mut bindings = bindings.to_string();
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bindings = replace_ckzg_ret_repr(bindings);
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std::fs::write(bindings_out_path, bindings).expect("Failed to write bindings");
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}
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// Here we hardcode the C_KZG_RET enum to use C representation. Bindgen
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// will use repr(u32) on Unix and repr(i32) on Windows. We would like to
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// use the same generated bindings for all platforms. This can be removed
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// if/when bindgen fixes this or allows us to choose our own representation
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// for types. Using repr(C) is equivalent to repr(u*) for fieldless enums,
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// so this should be safe to do. The alternative was to modify C_KZG_RET in
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// C, and we decided this was the lesser of two evils. There should be only
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// one instance where repr(C) isn't used: C_KZG_RET.
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// See: https://github.com/rust-lang/rust-bindgen/issues/1907
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#[cfg(feature = "generate-bindings")]
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fn replace_ckzg_ret_repr(mut bindings: String) -> String {
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let target = env::var("TARGET").unwrap_or_default();
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let repr_to_replace = if target.contains("windows") {
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"#[repr(i32)]"
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} else {
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"#[repr(u32)]"
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};
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// Find `repr_to_replace` as an attribute of `enum C_KZG_RET`.
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let ckzg_ret = bindings
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.find("enum C_KZG_RET")
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.expect("Could not find C_KZG_RET in bindings");
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let repr_start = bindings[..ckzg_ret]
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.rfind(repr_to_replace)
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.expect("Could not find repr to replace in bindings");
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// Sanity check that it's an attribute of `C_KZG_RET` and not another type.
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assert!(repr_start > bindings[..ckzg_ret].rfind('}').unwrap());
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bindings.replace_range(repr_start..repr_start + repr_to_replace.len(), "#[repr(C)]");
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bindings
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}
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