feat: add bun installation support

devenv/lib/archive.py

@@ -48,7 +48,7 @@ def download(
     if os.path.exists(dest):
         return dest
 
-    headers = {}
+    headers: dict[str, str] = {}
     if url.startswith("https://ghcr.io/v2/homebrew"):
         # downloading homebrew blobs requires auth
         # you can get an anonymous token from https://ghcr.io/token?service=ghcr.io&scope=repository%3Ahomebrew/core/go%3Apull
@@ -87,8 +87,8 @@ def download(
         if not secrets.compare_digest(checksum.hexdigest(), sha256):
             raise RuntimeError(
                 f"checksum mismatch for {url}:\n"
-                f"- got: {checksum.hexdigest()}\n"
-                f"- expected: {sha256}\n"
+                + f"- got: {checksum.hexdigest()}\n"
+                + f"- expected: {sha256}\n"
             )
 
         atomic_replace(tmpf.name, dest)

devenv/lib/bun.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+
+import os
+import shutil
+import stat
+import tempfile
+from zipfile import ZipFile
+
+from devenv.lib import archive
+from devenv.lib import fs
+from devenv.lib import proc
+
+
+def _install(url: str, sha256: str, into: str) -> None:
+    with tempfile.TemporaryDirectory(dir=into) as tmpd:
+        archive_file = archive.download(url, sha256, dest=f"{tmpd}/bun.zip")
+        os.makedirs(into, exist_ok=True)
+        with ZipFile(archive_file, mode="r") as zipf:
+            bun_member = next(
+                m for m in zipf.filelist if m.filename.endswith("/bun")
+            )
+            zipf.extract(bun_member, path=f"{tmpd}")
+
+            target = f"{into}/bun"
+            os.replace(f"{tmpd}/{bun_member.filename}", target)
+            mode = os.stat(target).st_mode
+            os.chmod(target, mode | stat.S_IEXEC)
+
+            os.symlink(target, f"{into}/bunx")
+            os.chmod(f"{into}/bunx", mode | stat.S_IEXEC)
+
+
+def uninstall(binroot: str) -> None:
+    for fp in (f"{binroot}/bun", f"{binroot}/bunx"):
+        try:
+            os.remove(fp)
+        except FileNotFoundError:
+            # it's better to do this than to guard with
+            # os.path.exists(fp) because if it's an invalid or circular
+            # symlink the result'll be False!
+            pass
+
+
+def _version(binpath: str) -> str:
+    return proc.run((binpath, "--version"), stdout=True).strip()
+
+
+def install(version: str, url: str, sha256: str, reporoot: str) -> None:
+    binroot = fs.ensure_binroot(reporoot)
+    binpath = f"{binroot}/bun"
+
+    if shutil.which("bun", path=binroot) == binpath:
+        installed_version = _version(binpath)
+        if version == installed_version:
+            return
+        print(f"installed bun {installed_version} is unexpected!")
+
+    print(f"installing bun {version}...")
+    uninstall(binroot)
+    _install(url, sha256, binroot)
+
+    installed_version = _version(binpath)
+    if version != installed_version:
+        raise SystemExit("Failed to install bun {version}!")