feat: install pnpm

Author: keeakita

devenv/lib/pnpm.py

@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+import os
+import shutil
+import stat
+import tempfile
+
+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:
+        bin_file = archive.download(url, sha256, dest=f"{tmpd}/pnpm")
+
+        target = f"{into}/pnpm"
+        os.replace(bin_file, target)
+        mode = os.stat(target).st_mode
+        os.chmod(target, mode | stat.S_IEXEC)
+
+
+def uninstall(binroot: str) -> None:
+    try:
+        os.remove(f"{binroot}/pnpm")
+    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:
+    stdout = proc.run((binpath, "--version"), stdout=True)
+    # 10.16.1
+    return stdout.strip()
+
+
+def install(version: str, url: str, sha256: str, reporoot: str) -> None:
+    binroot = fs.ensure_binroot(reporoot)
+    binpath = f"{binroot}/pnpm"
+
+    if shutil.which("pnpm", path=binroot) == binpath:
+        installed_version = _version(binpath)
+        if version == installed_version:
+            return
+        print(f"installed pnpm {installed_version} is unexpected!")
+
+    print(f"installing pnpm {version}...")
+    uninstall(binroot)
+    _install(url, sha256, binroot)
+
+    installed_version = _version(binpath)
+    if version != installed_version:
+        raise SystemExit("Failed to install pnpm {version}!")