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1#!/usr/bin/env python
2# Copyright (c) 2012 The Chromium Authors. All rights reserved.
3# Use of this source code is governed by a BSD-style license that can be
4# found in the LICENSE file.
5
6"""
7Generates shim headers that mirror the directory structure of bundled headers,
8but just forward to the system ones.
9
10This allows seamless compilation against system headers with no changes
11to our source code.
12"""
13
14
15import optparse
16import os.path
17import sys
18
19
20SHIM_TEMPLATE = """
21#if defined(OFFICIAL_BUILD)
22#error shim headers must not be used in official builds!
23#endif
24"""
25
26
27def GeneratorMain(argv):
28  parser = optparse.OptionParser()
29  parser.add_option('--headers-root', action='append')
30  parser.add_option('--define', action='append')
31  parser.add_option('--output-directory')
32  parser.add_option('--prefix', default='')
33  parser.add_option('--use-include-next', action='store_true')
34  parser.add_option('--outputs', action='store_true')
35  parser.add_option('--generate', action='store_true')
36
37  options, args = parser.parse_args(argv)
38
39  if not options.headers_root:
40    parser.error('Missing --headers-root parameter.')
41  if not options.output_directory:
42    parser.error('Missing --output-directory parameter.')
43  if not args:
44    parser.error('Missing arguments - header file names.')
45
46  source_tree_root = os.path.abspath(
47    os.path.join(os.path.dirname(__file__), '..', '..'))
48
49  for root in options.headers_root:
50    target_directory = os.path.join(
51      options.output_directory,
52      os.path.relpath(root, source_tree_root))
53    if options.generate and not os.path.exists(target_directory):
54      os.makedirs(target_directory)
55
56    for header_spec in args:
57      if ';' in header_spec:
58        (header_filename,
59         include_before,
60         include_after) = header_spec.split(';', 2)
61      else:
62        header_filename = header_spec
63        include_before = ''
64        include_after = ''
65      if options.outputs:
66        yield os.path.join(target_directory, header_filename)
67      if options.generate:
68        with open(os.path.join(target_directory, header_filename), 'w') as f:
69          f.write(SHIM_TEMPLATE)
70
71          if options.define:
72            for define in options.define:
73              key, value = define.split('=', 1)
74              # This non-standard push_macro extension is supported
75              # by compilers we support (GCC, clang).
76              f.write('#pragma push_macro("%s")\n' % key)
77              f.write('#undef %s\n' % key)
78              f.write('#define %s %s\n' % (key, value))
79
80          if include_before:
81            for header in include_before.split(':'):
82              f.write('#include %s\n' % header)
83
84          include_target = options.prefix + header_filename
85          if options.use_include_next:
86            f.write('#include_next <%s>\n' % include_target)
87          else:
88            f.write('#include <%s>\n' % include_target)
89
90          if include_after:
91            for header in include_after.split(':'):
92              f.write('#include %s\n' % header)
93
94          if options.define:
95            for define in options.define:
96              key, value = define.split('=', 1)
97              # This non-standard pop_macro extension is supported
98              # by compilers we support (GCC, clang).
99              f.write('#pragma pop_macro("%s")\n' % key)
100
101
102def DoMain(argv):
103  return '\n'.join(GeneratorMain(argv))
104
105
106if __name__ == '__main__':
107  DoMain(sys.argv[1:])
108