linux/scripts/gen_compile_commands.py
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   1#!/usr/bin/env python
   2# SPDX-License-Identifier: GPL-2.0
   3#
   4# Copyright (C) Google LLC, 2018
   5#
   6# Author: Tom Roeder <tmroeder@google.com>
   7#
   8"""A tool for generating compile_commands.json in the Linux kernel."""
   9
  10import argparse
  11import json
  12import logging
  13import os
  14import re
  15
  16_DEFAULT_OUTPUT = 'compile_commands.json'
  17_DEFAULT_LOG_LEVEL = 'WARNING'
  18
  19_FILENAME_PATTERN = r'^\..*\.cmd$'
  20_LINE_PATTERN = r'^cmd_[^ ]*\.o := (.* )([^ ]*\.c)$'
  21_VALID_LOG_LEVELS = ['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL']
  22
  23# A kernel build generally has over 2000 entries in its compile_commands.json
  24# database. If this code finds 300 or fewer, then warn the user that they might
  25# not have all the .cmd files, and they might need to compile the kernel.
  26_LOW_COUNT_THRESHOLD = 300
  27
  28
  29def parse_arguments():
  30    """Sets up and parses command-line arguments.
  31
  32    Returns:
  33        log_level: A logging level to filter log output.
  34        directory: The directory to search for .cmd files.
  35        output: Where to write the compile-commands JSON file.
  36    """
  37    usage = 'Creates a compile_commands.json database from kernel .cmd files'
  38    parser = argparse.ArgumentParser(description=usage)
  39
  40    directory_help = ('Path to the kernel source directory to search '
  41                      '(defaults to the working directory)')
  42    parser.add_argument('-d', '--directory', type=str, help=directory_help)
  43
  44    output_help = ('The location to write compile_commands.json (defaults to '
  45                   'compile_commands.json in the search directory)')
  46    parser.add_argument('-o', '--output', type=str, help=output_help)
  47
  48    log_level_help = ('The level of log messages to produce (one of ' +
  49                      ', '.join(_VALID_LOG_LEVELS) + '; defaults to ' +
  50                      _DEFAULT_LOG_LEVEL + ')')
  51    parser.add_argument(
  52        '--log_level', type=str, default=_DEFAULT_LOG_LEVEL,
  53        help=log_level_help)
  54
  55    args = parser.parse_args()
  56
  57    log_level = args.log_level
  58    if log_level not in _VALID_LOG_LEVELS:
  59        raise ValueError('%s is not a valid log level' % log_level)
  60
  61    directory = args.directory or os.getcwd()
  62    output = args.output or os.path.join(directory, _DEFAULT_OUTPUT)
  63    directory = os.path.abspath(directory)
  64
  65    return log_level, directory, output
  66
  67
  68def process_line(root_directory, file_directory, command_prefix, relative_path):
  69    """Extracts information from a .cmd line and creates an entry from it.
  70
  71    Args:
  72        root_directory: The directory that was searched for .cmd files. Usually
  73            used directly in the "directory" entry in compile_commands.json.
  74        file_directory: The path to the directory the .cmd file was found in.
  75        command_prefix: The extracted command line, up to the last element.
  76        relative_path: The .c file from the end of the extracted command.
  77            Usually relative to root_directory, but sometimes relative to
  78            file_directory and sometimes neither.
  79
  80    Returns:
  81        An entry to append to compile_commands.
  82
  83    Raises:
  84        ValueError: Could not find the extracted file based on relative_path and
  85            root_directory or file_directory.
  86    """
  87    # The .cmd files are intended to be included directly by Make, so they
  88    # escape the pound sign '#', either as '\#' or '$(pound)' (depending on the
  89    # kernel version). The compile_commands.json file is not interepreted
  90    # by Make, so this code replaces the escaped version with '#'.
  91    prefix = command_prefix.replace('\#', '#').replace('$(pound)', '#')
  92
  93    cur_dir = root_directory
  94    expected_path = os.path.join(cur_dir, relative_path)
  95    if not os.path.exists(expected_path):
  96        # Try using file_directory instead. Some of the tools have a different
  97        # style of .cmd file than the kernel.
  98        cur_dir = file_directory
  99        expected_path = os.path.join(cur_dir, relative_path)
 100        if not os.path.exists(expected_path):
 101            raise ValueError('File %s not in %s or %s' %
 102                             (relative_path, root_directory, file_directory))
 103    return {
 104        'directory': cur_dir,
 105        'file': relative_path,
 106        'command': prefix + relative_path,
 107    }
 108
 109
 110def main():
 111    """Walks through the directory and finds and parses .cmd files."""
 112    log_level, directory, output = parse_arguments()
 113
 114    level = getattr(logging, log_level)
 115    logging.basicConfig(format='%(levelname)s: %(message)s', level=level)
 116
 117    filename_matcher = re.compile(_FILENAME_PATTERN)
 118    line_matcher = re.compile(_LINE_PATTERN)
 119
 120    compile_commands = []
 121    for dirpath, _, filenames in os.walk(directory):
 122        for filename in filenames:
 123            if not filename_matcher.match(filename):
 124                continue
 125            filepath = os.path.join(dirpath, filename)
 126
 127            with open(filepath, 'rt') as f:
 128                for line in f:
 129                    result = line_matcher.match(line)
 130                    if not result:
 131                        continue
 132
 133                    try:
 134                        entry = process_line(directory, dirpath,
 135                                             result.group(1), result.group(2))
 136                        compile_commands.append(entry)
 137                    except ValueError as err:
 138                        logging.info('Could not add line from %s: %s',
 139                                     filepath, err)
 140
 141    with open(output, 'wt') as f:
 142        json.dump(compile_commands, f, indent=2, sort_keys=True)
 143
 144    count = len(compile_commands)
 145    if count < _LOW_COUNT_THRESHOLD:
 146        logging.warning(
 147            'Found %s entries. Have you compiled the kernel?', count)
 148
 149
 150if __name__ == '__main__':
 151    main()
 152