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fix: make build.rs idempotent #278

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Merged
merged 3 commits into from
Oct 8, 2025
Merged

fix: make build.rs idempotent #278

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2f930a0
fix: make `build.rs` idempotent
alvaro-cuesta Oct 5, 2025
9fbd064
chore: only major version for deps
alvaro-cuesta Oct 5, 2025
a700a90
fix: backup eval files between builds
alvaro-cuesta Oct 7, 2025
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7 changes: 7 additions & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ raw-cpuid = "11"
glob = "0.3"
ar = "0.9"
zstd = { version = "0.13", default-features = false }
fs_extra = "1"

[target.'cfg(windows)'.build-dependencies]
winres = "0.1"
139 changes: 105 additions & 34 deletions build.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,30 @@
#![forbid(unsafe_code)]

use std::{env, fs, fs::File, io::Write, path::Path, process::Command};
use std::{
env,
fs::{self, File},
io::Write,
path::{Path, PathBuf},
process::Command,
sync::LazyLock,
time::SystemTime,
};

use glob::glob;
use zstd::stream::write::Encoder as ZstdEncoder;

const EVAL_FILE: &str = "nn-1c0000000000.nnue";
const EVAL_FILE_SMALL: &str = "nn-37f18f62d772.nnue";
static OUT_PATH: LazyLock<PathBuf> = LazyLock::new(|| PathBuf::from(&env::var("OUT_DIR").unwrap()));
static STOCKFISH_OUT_PATH: LazyLock<PathBuf> = LazyLock::new(|| OUT_PATH.join("Stockfish"));
static FAIRY_STOCKFISH_OUT_PATH: LazyLock<PathBuf> =
LazyLock::new(|| OUT_PATH.join("Fairy-Stockfish"));

const EVAL_FILE_NAME: &str = "nn-1c0000000000.nnue";
static EVAL_FILE_OUT_PATH: LazyLock<PathBuf> =
LazyLock::new(|| STOCKFISH_OUT_PATH.join("src").join(EVAL_FILE_NAME));

const EVAL_FILE_SMALL_NAME: &str = "nn-37f18f62d772.nnue";
static EVAL_FILE_SMALL_OUT_PATH: LazyLock<PathBuf> =
LazyLock::new(|| STOCKFISH_OUT_PATH.join("src").join(EVAL_FILE_SMALL_NAME));

fn main() {
println!(
Expand All @@ -16,16 +34,31 @@ fn main() {

hooks();

// If there are eval files from a previous build, back them up into a temp
// file before overwriting the submodule copies. This avoids re-downloading.
let eval_file_backup = backup_file_if_exists(&EVAL_FILE_OUT_PATH);
let eval_file_small_backup = backup_file_if_exists(&EVAL_FILE_SMALL_OUT_PATH);

// Copy submodule folders to OUT_DIR because their Makefiles create files,
// which would make the build non-idempotent.
copy_overwrite_submodule_folder(Path::new("Stockfish"), &STOCKFISH_OUT_PATH);
copy_overwrite_submodule_folder(Path::new("Fairy-Stockfish"), &FAIRY_STOCKFISH_OUT_PATH);

// Restore backed-up eval files (if we had them)
if let Some(eval_file_backup) = eval_file_backup {
move_file(&eval_file_backup, &EVAL_FILE_OUT_PATH);
};
if let Some(eval_file_small_backup) = eval_file_small_backup {
move_file(&eval_file_small_backup, &EVAL_FILE_SMALL_OUT_PATH);
};

// Build Stockfish and Fairy-Stockfish and archive them (along with eval files)
let mut archive = ar::Builder::new(
ZstdEncoder::new(
File::create(Path::new(&env::var("OUT_DIR").unwrap()).join("assets.ar.zst")).unwrap(),
6,
)
.unwrap(),
ZstdEncoder::new(File::create(OUT_PATH.join("assets.ar.zst")).unwrap(), 6).unwrap(),
);
stockfish_build(&mut archive);
stockfish_eval_file(EVAL_FILE, &mut archive);
stockfish_eval_file(EVAL_FILE_SMALL, &mut archive);
append_file(&mut archive, &*EVAL_FILE_OUT_PATH, 0o644);
append_file(&mut archive, &*EVAL_FILE_SMALL_OUT_PATH, 0o644);
archive.into_inner().unwrap().finish().unwrap();

// Resource compilation may fail when toolchain does not match target,
Expand Down Expand Up @@ -284,7 +317,7 @@ impl Target {
fn build<W: Write>(
&self,
flavor: Flavor,
src_dir: &'static str,
src_path: &Path,
name: &'static str,
archive: &mut ar::Builder<W>,
) {
Expand Down Expand Up @@ -341,14 +374,9 @@ impl Target {
"$(CXX) --version"
);

assert!(
Path::new(src_dir).is_dir(),
"Directory {src_dir:?} does not exist. Try: git submodule update --init",
);

assert!(
Command::new(&make)
.current_dir(src_dir)
.current_dir(src_path)
.env("MAKEFLAGS", env::var("CARGO_MAKEFLAGS").unwrap())
.arg("clean")
.status()
Expand All @@ -359,24 +387,24 @@ impl Target {

if flavor == Flavor::Official
&& !Command::new(&make)
.current_dir(src_dir)
.current_dir(src_path)
.env("MAKEFLAGS", env::var("CARGO_MAKEFLAGS").unwrap())
.arg("-B")
.arg("net")
.status()
.unwrap()
.success()
{
let _ = fs::remove_file(Path::new(src_dir).join(EVAL_FILE));
let _ = fs::remove_file(Path::new(src_dir).join(EVAL_FILE_SMALL));
let _ = fs::remove_file(src_path.join(EVAL_FILE_NAME));
let _ = fs::remove_file(src_path.join(EVAL_FILE_SMALL_NAME));
println!(
"cargo:warning=Deleted corrupted network file {EVAL_FILE} or {EVAL_FILE_SMALL}"
"cargo:warning=Deleted corrupted network file {EVAL_FILE_NAME} or {EVAL_FILE_SMALL_NAME}"
);
}

assert!(
Command::new(&make)
.current_dir(src_dir)
.current_dir(src_path)
.env("MAKEFLAGS", env::var("CARGO_MAKEFLAGS").unwrap())
.env(
"CXXFLAGS",
Expand All @@ -403,7 +431,7 @@ impl Target {

assert!(
Command::new(&make)
.current_dir(src_dir)
.current_dir(src_path)
.env("MAKEFLAGS", env::var("CARGO_MAKEFLAGS").unwrap())
.arg(format!("EXE={exe}"))
.arg("strip")
Expand All @@ -413,19 +441,24 @@ impl Target {
"$(MAKE) strip"
);

let exe_path = Path::new(src_dir).join(exe);
let exe_path = Path::new(src_path).join(exe);
append_file(archive, &exe_path, 0o755);
fs::remove_file(&exe_path).unwrap();
}

fn build_official<W: Write>(&self, archive: &mut ar::Builder<W>) {
self.build(Flavor::Official, "Stockfish/src", "stockfish", archive);
self.build(
Flavor::Official,
&STOCKFISH_OUT_PATH.join("src"),
"stockfish",
archive,
);
}

fn build_multi_variant<W: Write>(&self, archive: &mut ar::Builder<W>) {
self.build(
Flavor::MultiVariant,
"Fairy-Stockfish/src",
&FAIRY_STOCKFISH_OUT_PATH.join("src"),
"fairy-stockfish",
archive,
);
Expand All @@ -437,14 +470,6 @@ impl Target {
}
}

fn stockfish_eval_file<W: Write>(name: &str, archive: &mut ar::Builder<W>) {
append_file(
archive,
Path::new("Stockfish").join("src").join(name),
0o644,
);
}

fn append_file<W: Write, P: AsRef<Path>>(archive: &mut ar::Builder<W>, path: P, mode: u32) {
let file = File::open(&path).unwrap();
let metadata = file.metadata().unwrap();
Expand All @@ -461,3 +486,49 @@ fn append_file<W: Write, P: AsRef<Path>>(archive: &mut ar::Builder<W>, path: P,
header.set_mode(mode);
archive.append(&header, file).unwrap();
}

fn copy_overwrite_submodule_folder(src: &Path, dst: &Path) {
assert!(
src.is_dir(),
"Directory {src:?} does not exist. Try: git submodule update --init",
);
if dst.exists() {
fs::remove_dir_all(dst).unwrap();
}
fs::create_dir_all(dst).unwrap();
fs_extra::dir::copy(
src,
dst,
&fs_extra::dir::CopyOptions::new().content_only(true),
)
.unwrap();
}

/// If `src` exists, copy it to a temporary file.
///
/// Returns the path to the temporary file, or `None` if `src` did not exist.
fn backup_file_if_exists(src: &Path) -> Option<PathBuf> {
if !src.exists() {
return None;
}

// Scope backup files by timestamp to avoid collisions with parallel builds
let timestamp = SystemTime::now()
.duration_since(SystemTime::UNIX_EPOCH)
.unwrap()
.as_secs();
let filename = src.file_name().unwrap().to_str().unwrap();
let tmp_file_path = env::temp_dir().join(format!("{timestamp}-{filename}"));

fs::copy(src, &tmp_file_path).unwrap();

Some(tmp_file_path)
}

/// Move a file from `src` to `dst` by copying and deleting the original.
///
/// Needed because `fs::rename` doesn't work across different filesystems.
fn move_file(src: &Path, dst: &Path) {
fs::copy(src, dst).unwrap();
let _ = fs::remove_file(src);
}
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