| # Copyright 2023 The Chromium Authors |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| """Helper functions useful when writing scripts used by action() targets.""" |
| |
| import contextlib |
| import filecmp |
| import os |
| import pathlib |
| import posixpath |
| import shutil |
| import tempfile |
| |
| import gn_helpers |
| |
| from typing import Optional |
| from typing import Sequence |
| |
| |
| @contextlib.contextmanager |
| def atomic_output(path, mode='w+b', only_if_changed=True): |
| """Prevent half-written files and dirty mtimes for unchanged files. |
| |
| Args: |
| path: Path to the final output file, which will be written atomically. |
| mode: The mode to open the file in (str). |
| only_if_changed: Whether to maintain the mtime if the file has not changed. |
| Returns: |
| A Context Manager that yields a NamedTemporaryFile instance. On exit, the |
| manager will check if the file contents is different from the destination |
| and if so, move it into place. |
| |
| Example: |
| with action_helpers.atomic_output(output_path) as tmp_file: |
| subprocess.check_call(['prog', '--output', tmp_file.name]) |
| """ |
| # Create in same directory to ensure same filesystem when moving. |
| dirname = os.path.dirname(path) or '.' |
| os.makedirs(dirname, exist_ok=True) |
| with tempfile.NamedTemporaryFile(mode, |
| suffix=os.path.basename(path), |
| dir=dirname, |
| delete=False) as f: |
| try: |
| yield f |
| |
| # File should be closed before comparison/move. |
| f.close() |
| if not (only_if_changed and os.path.exists(path) |
| and filecmp.cmp(f.name, path)): |
| shutil.move(f.name, path) |
| finally: |
| f.close() |
| if os.path.exists(f.name): |
| os.unlink(f.name) |
| |
| |
| def add_depfile_arg(parser): |
| if hasattr(parser, 'add_option'): |
| func = parser.add_option |
| else: |
| func = parser.add_argument |
| func('--depfile', help='Path to depfile (refer to "gn help depfile")') |
| |
| |
| def write_depfile(depfile_path: str, |
| first_gn_output: str, |
| inputs: Optional[Sequence[str]] = None) -> None: |
| """Writes a ninja depfile. |
| |
| See notes about how to use depfiles in //build/docs/writing_gn_templates.md. |
| |
| Args: |
| depfile_path: Path to file to write. |
| first_gn_output: Path of first entry in action's outputs. |
| inputs: List of inputs to add to depfile. |
| """ |
| assert depfile_path != first_gn_output # http://crbug.com/646165 |
| assert not isinstance(inputs, str) # Easy mistake to make |
| |
| def _process_path(path): |
| assert not os.path.isabs(path), f'Found abs path in depfile: {path}' |
| if os.path.sep != posixpath.sep: |
| path = str(pathlib.Path(path).as_posix()) |
| assert '\\' not in path, f'Found \\ in depfile: {path}' |
| return path.replace(' ', '\\ ') |
| |
| sb = [] |
| sb.append(_process_path(first_gn_output)) |
| if inputs: |
| # Sort and uniquify to ensure file is hermetic. |
| # One path per line to keep it human readable. |
| sb.append(': \\\n ') |
| sb.append(' \\\n '.join(sorted(_process_path(p) for p in set(inputs)))) |
| else: |
| sb.append(': ') |
| sb.append('\n') |
| |
| path = pathlib.Path(depfile_path) |
| path.parent.mkdir(parents=True, exist_ok=True) |
| path.write_text(''.join(sb)) |
| |
| |
| def parse_gn_list(value): |
| """Converts a "GN-list" command-line parameter into a list. |
| |
| Conversions handled: |
| * None -> [] |
| * '' -> [] |
| * 'asdf' -> ['asdf'] |
| * '["a", "b"]' -> ['a', 'b'] |
| * ['["a", "b"]', 'c'] -> ['a', 'b', 'c'] (action='append') |
| |
| This allows passing args like: |
| gn_list = [ "one", "two", "three" ] |
| args = [ "--items=$gn_list" ] |
| """ |
| # Convert None to []. |
| if not value: |
| return [] |
| # Convert a list of GN lists to a flattened list. |
| if isinstance(value, list): |
| ret = [] |
| for arg in value: |
| ret.extend(parse_gn_list(arg)) |
| return ret |
| # Convert normal GN list. |
| if value.startswith('['): |
| return gn_helpers.GNValueParser(value).ParseList() |
| # Convert a single string value to a list. |
| return [value] |