Move tasks from Makefile to Meson

Author: hongquan

Makefile

@@ -99,6 +99,16 @@ python.install_sources(
         subdir: 'systemd/test',
 )
 
+run_target(
+        'update-constants',
+        command: [
+                python,
+                files('update-constants.py'),
+                '-i', libsystemd_dep.get_variable('includedir'),
+                '-s', meson.project_source_root() / 'systemd',
+        ],
+)
+
 # Run target to generate TAGS file for Emacs
 run_target(
         'etags',

meson.build

@@ -1,9 +1,81 @@
+"""
+Read definitions from /usr/include/systemd/sd-messages.h and systemd/id128-defines.h files, convert to ones in systemd/id128-constants.h
+"""
+
+import os
+import re
 import sys
+import itertools
+import argparse
+from pathlib import Path
+from collections.abc import Iterable
+from typing import cast
+
+
+REGEX_DEFINE = re.compile(r'^#define\s+(?P<name>SD_MESSAGE_[A-Z0-9_]+)\s+\w+')
+
+
+parser = argparse.ArgumentParser(description="Convert systemd header definitions to id128 constants.")
+parser.add_argument('-i', '--include-dir', type=Path, required=True, help='Path to libsystemd include directory')
+parser.add_argument('-s', '--source-dir', type=Path, required=True, help='Path to C source directory')
+args = parser.parse_args()
 
-for file in sys.argv[1:]:
-    lines = iter(open(file).read().splitlines())
+
+def extract_define_lines(file_path: Path) -> list[str]:
+    lines = iter(file_path.open().readlines())
+    out: list[str] = []
     for line in lines:
         if line.startswith('#define SD_MESSAGE') and '_STR ' not in line:
             if line.endswith('\\'):
                 line = line[:-1] + next(lines)
-            print(' '.join(line.split()))
+            out.append(' '.join(line.split()))
+    return out
+
+
+def extract_symbol(line: str) -> str:
+    """
+    Extract the symbol name from a line defining a constant.
+
+    For example, given the line:
+    #define SD_MESSAGE_USER_STARTUP_FINISHED SD_ID128_MAKE(ee,d0,0a,68,ff,d8,4e,31,88,21,05,fd,97,3a,bd,d1)
+    this function will return:
+    SD_MESSAGE_USER_STARTUP_FINISHED
+    or empty string if the line does not match the expected format.
+    """
+    if match := REGEX_DEFINE.match(line):
+        return match.group('name')
+    return ''
+
+
+def build_line_for_constant(name: str) -> str:
+    return f'add_id(m, "{name}", {name}) JOINER'
+
+
+def update_docs(source_dir: Path, symbols: Iterable[str]):
+    doc_file = source_dir.joinpath('../docs/id128.rst')
+    headers = doc_file.read_text().splitlines()[:9]
+    lines = [f'   .. autoattribute:: systemd.id128.{s}' for s in symbols]
+    new_content = '\n'.join(headers + lines) + '\n'
+    doc_file.write_text(new_content)
+    rel_doc_path = doc_file.resolve().relative_to(Path('.').resolve(), walk_up=True)
+    print(f'Updated {rel_doc_path}.', file=sys.stderr)
+
+
+def main():
+    source_files = [cast(Path, args.include_dir).joinpath('systemd/sd-messages.h'), cast(Path, args.source_dir).joinpath('id128-defines.h')]
+    print(f'To extract symbols from {source_files}...', file=sys.stderr)
+    source_lines = tuple(itertools.chain.from_iterable(extract_define_lines(file) for file in source_files))
+    print(f'Read {len(source_lines)} lines.', file=sys.stderr)
+    symbols = tuple(sorted(frozenset(s for line in source_lines if (s := extract_symbol(line)))))
+    print(f'Found {len(symbols)} unique symbols.', file=sys.stderr)
+    converted_lines = tuple(build_line_for_constant(s) for s in symbols)
+    print(f'Converted to {len(converted_lines)} lines.', file=sys.stderr)
+    dest_file = cast(Path, args.source_dir).joinpath('id128-constants.h')
+    dest_file.write_text('\n'.join(converted_lines) + '\n')
+    print(f'Wrote {len(converted_lines)} constants to {dest_file}.', file=sys.stderr)
+    update_docs(cast(Path, args.source_dir), symbols)
+    print('🎉 Done.', file=sys.stderr)
+
+
+if __name__ == '__main__':
+    main()