#!/usr/bin/env python3
# Copyright (c) 2012 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
"""Help maintaining DLL import lists."""
import ast
import optparse
import re
import sys

_EXPORT_RE = re.compile(
    r"""
  ^\s*(?P<ordinal>[0-9]+)  # The ordinal field.
  \s+(?P<hint>[0-9A-F]+)   # The hint field.
  \s(?P<rva>........)      # The RVA field.
  \s+(?P<name>[^ ]+)       # And finally the name we're really after.
""", re.VERBOSE)

_USAGE = r"""\
Usage: %prog [options] [master-file]

This script filters a list of exports from a DLL, generated from something
like the following command line:

C:\> dumpbin /exports user32.dll

against a master list of imports built from e.g.

C:\> dumpbin /exports user32.lib

The point of this is to trim non-public exports from the list, and to
normalize the names to their stdcall-mangled form for the generation of
import libraries.
Note that the export names from the latter incanatation are stdcall-mangled,
e.g. they are suffixed with "@" and the number of argument bytes to the
function.
"""


def _ReadMasterFile(master_file):
    # Slurp the master file.
    with open(master_file) as f:
        master_exports = ast.literal_eval(f.read())

    master_mapping = {}
    for export in master_exports:
        name = export.split('@')[0]
        master_mapping[name] = export

    return master_mapping


def main():
    parser = optparse.OptionParser(usage=_USAGE)
    parser.add_option(
        '-r',
        '--reverse',
        action='store_true',
        help='Reverse the matching, e.g. return the functions '
        'in the master list that aren\'t in the input.')

    options, args = parser.parse_args()
    if len(args) != 1:
        parser.error('Must provide a master file.')

    master_mapping = _ReadMasterFile(args[0])

    found_exports = []
    for line in sys.stdin:
        match = _EXPORT_RE.match(line)
        if match:
            export_name = master_mapping.get(match.group('name'), None)
            if export_name:
                found_exports.append(export_name)

    if options.reverse:
        # Invert the found_exports list.
        found_exports = set(master_mapping.values()) - set(found_exports)

    # Sort the found exports for tidy output.
    print('\n'.join(sorted(found_exports)))
    return 0


if __name__ == '__main__':
    sys.exit(main())