release: update-hooks: helper for automatically syncing hooks

These hooks are maintained in other projects.  Add a script to automate
their import so people don't send us changes directly, and we can try to
steer them to the correct place.

Change-Id: Iac0bdb3aae84dda43a1600e73107555b513ce82b
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/422177
Commit-Queue: Mike Frysinger <vapier@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>

release/update-hooks

@@ -0,0 +1,143 @@
+#!/usr/bin/env python3
+# Copyright (C) 2024 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helper tool for updating hooks from their various upstreams."""
+
+import argparse
+import base64
+import json
+from pathlib import Path
+import sys
+from typing import List, Optional
+import urllib.request
+
+
+assert sys.version_info >= (3, 8), "Python 3.8+ required"
+
+
+TOPDIR = Path(__file__).resolve().parent.parent
+HOOKS_DIR = TOPDIR / "hooks"
+
+
+def update_hook_commit_msg() -> None:
+    """Update commit-msg hook from Gerrit."""
+    hook = HOOKS_DIR / "commit-msg"
+    print(
+        f"{hook.name}: Updating from https://gerrit.googlesource.com/gerrit/"
+        "+/HEAD/resources/com/google/gerrit/server/tools/root/hooks/commit-msg"
+    )
+
+    # Get the current commit.
+    url = "https://gerrit.googlesource.com/gerrit/+/HEAD?format=JSON"
+    with urllib.request.urlopen(url) as fp:
+        data = fp.read()
+    # Discard the xss protection.
+    data = data.split(b"\n", 1)[1]
+    data = json.loads(data)
+    commit = data["commit"]
+
+    # Fetch the data for that commit.
+    url = (
+        f"https://gerrit.googlesource.com/gerrit/+/{commit}/"
+        "resources/com/google/gerrit/server/tools/root/hooks/commit-msg"
+    )
+    with urllib.request.urlopen(f"{url}?format=TEXT") as fp:
+        data = fp.read()
+
+    # gitiles base64 encodes text data.
+    data = base64.b64decode(data)
+
+    # Inject header into the hook.
+    lines = data.split(b"\n")
+    lines = (
+        lines[:1]
+        + [
+            b"# DO NOT EDIT THIS FILE",
+            (
+                b"# All updates should be sent upstream: "
+                b"https://gerrit.googlesource.com/gerrit/"
+            ),
+            f"# This is synced from commit: {commit}".encode("utf-8"),
+            b"# DO NOT EDIT THIS FILE",
+        ]
+        + lines[1:]
+    )
+    data = b"\n".join(lines)
+
+    # Update the hook.
+    hook.write_bytes(data)
+    hook.chmod(0o755)
+
+
+def update_hook_pre_auto_gc() -> None:
+    """Update pre-auto-gc hook from git."""
+    hook = HOOKS_DIR / "pre-auto-gc"
+    print(
+        f"{hook.name}: Updating from https://github.com/git/git/"
+        "HEAD/contrib/hooks/pre-auto-gc-battery"
+    )
+
+    # Get the current commit.
+    headers = {
+        "Accept": "application/vnd.github+json",
+        "X-GitHub-Api-Version": "2022-11-28",
+    }
+    url = "https://api.github.com/repos/git/git/git/refs/heads/master"
+    req = urllib.request.Request(url, headers=headers)
+    with urllib.request.urlopen(req) as fp:
+        data = fp.read()
+    data = json.loads(data)
+
+    # Fetch the data for that commit.
+    commit = data["object"]["sha"]
+    url = (
+        f"https://raw.githubusercontent.com/git/git/{commit}/"
+        "contrib/hooks/pre-auto-gc-battery"
+    )
+    with urllib.request.urlopen(url) as fp:
+        data = fp.read()
+
+    # Inject header into the hook.
+    lines = data.split(b"\n")
+    lines = (
+        lines[:1]
+        + [
+            b"# DO NOT EDIT THIS FILE",
+            (
+                b"# All updates should be sent upstream: "
+                b"https://github.com/git/git/"
+            ),
+            f"# This is synced from commit: {commit}".encode("utf-8"),
+            b"# DO NOT EDIT THIS FILE",
+        ]
+        + lines[1:]
+    )
+    data = b"\n".join(lines)
+
+    # Update the hook.
+    hook.write_bytes(data)
+    hook.chmod(0o755)
+
+
+def main(argv: Optional[List[str]] = None) -> Optional[int]:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.parse_args(argv)
+
+    update_hook_commit_msg()
+    update_hook_pre_auto_gc()
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv[1:]))