1# Copyright 2019 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import struct
6import sys
7import zipfile
8
9from util import build_utils
10
11_FIXED_ZIP_HEADER_LEN = 30
12
13
14def _PatchedDecodeExtra(self):
15  # Try to decode the extra field.
16  extra = self.extra
17  unpack = struct.unpack
18  while len(extra) >= 4:
19    tp, ln = unpack('<HH', extra[:4])
20    if tp == 1:
21      if ln >= 24:
22        counts = unpack('<QQQ', extra[4:28])
23      elif ln == 16:
24        counts = unpack('<QQ', extra[4:20])
25      elif ln == 8:
26        counts = unpack('<Q', extra[4:12])
27      elif ln == 0:
28        counts = ()
29      else:
30        raise RuntimeError, "Corrupt extra field %s" % (ln, )
31
32      idx = 0
33
34      # ZIP64 extension (large files and/or large archives)
35      if self.file_size in (0xffffffffffffffffL, 0xffffffffL):
36        self.file_size = counts[idx]
37        idx += 1
38
39      if self.compress_size == 0xFFFFFFFFL:
40        self.compress_size = counts[idx]
41        idx += 1
42
43      if self.header_offset == 0xffffffffL:
44        self.header_offset = counts[idx]
45        idx += 1
46
47    extra = extra[ln + 4:]
48
49
50def ApplyZipFileZipAlignFix():
51  """Fix zipfile.ZipFile() to be able to open zipaligned .zip files.
52
53  Android's zip alignment uses not-quite-valid zip headers to perform alignment.
54  Python < 3.4 crashes when trying to load them.
55  https://bugs.python.org/issue14315
56  """
57  if sys.version_info < (3, 4):
58    zipfile.ZipInfo._decodeExtra = (  # pylint: disable=protected-access
59        _PatchedDecodeExtra)
60
61
62def _SetAlignment(zip_obj, zip_info, alignment):
63  """Sets a ZipInfo's extra field such that the file will be aligned.
64
65  Args:
66    zip_obj: The ZipFile object that is being written.
67    zip_info: The ZipInfo object about to be written.
68    alignment: The amount of alignment (e.g. 4, or 4*1024).
69  """
70  cur_offset = zip_obj.fp.tell()
71  header_size = _FIXED_ZIP_HEADER_LEN + len(zip_info.filename)
72  padding_needed = (alignment - (
73      (cur_offset + header_size) % alignment)) % alignment
74
75
76  # Python writes |extra| to both the local file header and the central
77  # directory's file header. Android's zipalign tool writes only to the
78  # local file header, so there is more overhead in using python to align.
79  zip_info.extra = b'\0' * padding_needed
80
81
82def AddToZipHermetic(zip_file,
83                     zip_path,
84                     src_path=None,
85                     data=None,
86                     compress=None,
87                     alignment=None):
88  """Same as build_utils.AddToZipHermetic(), but with alignment.
89
90  Args:
91    alignment: If set, align the data of the entry to this many bytes.
92  """
93  zipinfo = build_utils.HermeticZipInfo(filename=zip_path)
94  if alignment:
95    _SetAlignment(zip_file, zipinfo, alignment)
96  build_utils.AddToZipHermetic(
97      zip_file, zipinfo, src_path=src_path, data=data, compress=compress)
98