tflite: patcher: Initial skeleton for patch management

Adds the skeleton for the patch management script. Currently it parses
the archive url and patches from Bazel.

BUG=b:359512663
TEST=./script/patcher.py --debug eject

Change-Id: I6f104b47132f0334ee983d585c2d4d2cf8be62f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/tflite/+/5782534
Reviewed-by: Ching-Kang Yen <chingkang@chromium.org>
Tested-by: Shik Chen <shik@chromium.org>
Commit-Queue: Ching-Kang Yen <chingkang@chromium.org>
Auto-Submit: Shik Chen <shik@chromium.org>

script/patcher.py

diff --git a/script/patcher.py b/script/patcher.py
new file mode 100755
index 0000000..1acd05e
--- /dev/null
+++ b/script/patcher.py
@@ -0,0 +1,143 @@
+#!/usr/bin/env python3
+# Copyright 2024 The ChromiumOS Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""A script to manage tensorflow patches."""
+
+import argparse
+import functools
+import logging
+from pathlib import Path
+import re
+import shlex
+import subprocess
+import sys
+from typing import List, Optional, Tuple
+import xml.etree.ElementTree
+
+
+# TODO(shik): Extract common utilities into a module.
+
+
+@functools.lru_cache(1)
+def get_workspace_root() -> Path:
+    """Gets the root of tflite workspace."""
+    root = Path(__file__).resolve().parent.parent
+    assert root.name == "tflite" and (root / "WORKSPACE.bazel").exists()
+    logging.debug("root = %s", root)
+    return root
+
+
+def shell_join(cmd: List[str]) -> str:
+    return " ".join(shlex.quote(c) for c in cmd)
+
+
+def check_output(args: List[str]) -> str:
+    logging.debug("$ %s", shell_join(args))
+    return subprocess.check_output(args, text=True, cwd=get_workspace_root())
+
+
+def xml_get_value(el: xml.etree.ElementTree.Element, key="value") -> str:
+    value = el.get(key)
+    assert value is not None
+    return value
+
+
+class XMLTree:
+    """Helper for parsing and querying XML using XPath expressions."""
+
+    def __init__(self, xml_content: str):
+        self.root = xml.etree.ElementTree.fromstring(xml_content)
+
+    def get_all(self, xpath: str) -> List[str]:
+        return [xml_get_value(el) for el in self.root.findall(xpath)]
+
+    def get(self, xpath: str) -> str:
+        el = self.root.find(xpath)
+        assert el is not None
+        return xml_get_value(el)
+
+
+def get_url_and_patches() -> Tuple[str, List[str]]:
+    """Gets the TensorFlow archive URL and patches from Bazel."""
+    cmd = [
+        "bazel",
+        "query",
+        "--output=xml",
+        "deps(//external:org_tensorflow)",
+    ]
+    xml_content = check_output(cmd)
+    tree = XMLTree(xml_content)
+
+    rule = ".//rule[@class='http_archive']"
+    url = tree.get(f"{rule}/string[@name='url']")
+
+    patches = []
+    for label in tree.get_all(f"{rule}/list[@name='patches']/label"):
+        # The label looks like `//patch:${num}-some-descriptive-name.patch`
+        m = re.match(r"^//patch:(.+\.patch)$", label)
+        assert m is not None
+        patches.append(m.group(1))
+
+    return (url, patches)
+
+
+def cmd_eject(args: argparse.Namespace):
+    del args
+
+    url, patches = get_url_and_patches()
+    logging.info("url = %s", url)
+    logging.info("patches = %s", patches)
+    # TODO(shik): Download and extract archive.
+    # TODO(shik): Apply patches.
+
+
+def cmd_seal(args: argparse.Namespace):
+    del args
+    logging.info("Not implemented yet")
+    # TODO(shik): Implement seal.
+
+
+def setup_argument_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter
+    )
+    parser.add_argument(
+        "--debug",
+        action="store_true",
+        help="enable debug logging",
+    )
+    parser.set_defaults(func=lambda _: parser.print_help())
+    subparsers = parser.add_subparsers()
+
+    eject_parser = subparsers.add_parser(
+        "eject",
+        help="Eject tensorflow to a local git repo with patches as commits",
+    )
+    eject_parser.set_defaults(func=cmd_eject)
+
+    seal_parser = subparsers.add_parser(
+        "seal",
+        help="Seal the local git repo and format the commits as patches",
+    )
+    seal_parser.set_defaults(func=cmd_seal)
+
+    return parser
+
+
+def main(argv: Optional[List[str]] = None) -> Optional[int]:
+    parser = setup_argument_parser()
+    args = parser.parse_args(argv)
+
+    log_level = logging.DEBUG if args.debug else logging.INFO
+    log_format = "%(asctime)s - %(levelname)s - %(funcName)s: %(message)s"
+    logging.basicConfig(level=log_level, format=log_format)
+
+    logging.debug("args = %s", args)
+
+    args.func(args)
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv[1:]))