Add Bazel musl V8 build workflow

.github/scripts/rusty_v8_bazel.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import argparse
+import gzip
+import re
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[2]
+MODULE_BAZEL = ROOT / "MODULE.bazel"
+
+
+def parse_v8_crate_version() -> str:
+    text = MODULE_BAZEL.read_text()
+    match = re.search(
+        r"https://static\.crates\.io/crates/v8/v8-([0-9.]+)\.crate",
+        text,
+    )
+    if match is None:
+        raise SystemExit("could not determine v8 crate version from MODULE.bazel")
+    return match.group(1)
+
+
+def bazel_execroot() -> Path:
+    result = subprocess.run(
+        ["bazel", "info", "execution_root"],
+        cwd=ROOT,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    return Path(result.stdout.strip())
+
+
+def bazel_output_files(platform: str, labels: list[str]) -> list[Path]:
+    expression = "set(" + " ".join(labels) + ")"
+    result = subprocess.run(
+        [
+            "bazel",
+            "cquery",
+            f"--platforms=@llvm//platforms:{platform}",
+            "--output=files",
+            expression,
+        ],
+        cwd=ROOT,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    execroot = bazel_execroot()
+    return [execroot / line.strip() for line in result.stdout.splitlines() if line.strip()]
+
+
+def stage_release_assets(platform: str, target: str, output_dir: Path) -> None:
+    target_suffix = target.replace("-", "_")
+    version_suffix = parse_v8_crate_version().replace(".", "_")
+    lib_label = f"//third_party/v8:v8_{version_suffix}_{target_suffix}"
+    binding_label = f"//third_party/v8:src_binding_release_{target_suffix}"
+
+    outputs = bazel_output_files(platform, [lib_label, binding_label])
+    try:
+        lib_path = next(path for path in outputs if path.suffix == ".a")
+    except StopIteration as exc:
+        raise SystemExit(f"missing static archive output for {target}") from exc
+    try:
+        binding_path = next(path for path in outputs if path.suffix == ".rs")
+    except StopIteration as exc:
+        raise SystemExit(f"missing binding output for {target}") from exc
+
+    output_dir.mkdir(parents=True, exist_ok=True)
+    archive_name = f"librusty_v8_release_{target}.a.gz"
+    binding_name = f"src_binding_release_{target}.rs"
+
+    with lib_path.open("rb") as src, (output_dir / archive_name).open("wb") as dst:
+        with gzip.GzipFile(
+            filename="",
+            mode="wb",
+            fileobj=dst,
+            compresslevel=9,
+            mtime=0,
+        ) as gz:
+            shutil.copyfileobj(src, gz)
+
+    shutil.copyfile(binding_path, output_dir / binding_name)
+
+    print(output_dir / archive_name)
+    print(output_dir / binding_name)
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser()
+    subparsers = parser.add_subparsers(dest="command", required=True)
+
+    subparsers.add_parser("print-version")
+
+    stage_parser = subparsers.add_parser("stage")
+    stage_parser.add_argument("--platform", required=True)
+    stage_parser.add_argument("--target", required=True)
+    stage_parser.add_argument("--output-dir", required=True)
+
+    return parser.parse_args()
+
+
+def main() -> int:
+    args = parse_args()
+    if args.command == "print-version":
+        print(parse_v8_crate_version())
+        return 0
+    if args.command == "stage":
+        stage_release_assets(
+            platform=args.platform,
+            target=args.target,
+            output_dir=Path(args.output_dir),
+        )
+        return 0
+    raise SystemExit(f"unsupported command: {args.command}")
+
+
+if __name__ == "__main__":
+    sys.exit(main())