Appending to ZIP archive blows up existing Central Directory entries

[serhiy-storchaka]

BPO	34341
Nosy	@Yhg1s, @serhiy-storchaka, @miss-islington
PRs	bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. #8683 [3.7] bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683) #9356 [3.6] bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683) #9357 [2.7] bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683). #9400

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2018-09-18.20:34:16.711>
created_at = <Date 2018-08-06.07:57:50.199>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = 'Appending to ZIP archive blows up existing Central Directory entries'
updated_at = <Date 2018-09-18.20:34:16.710>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2018-09-18.20:34:16.710>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2018-09-18.20:34:16.711>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2018-08-06.07:57:50.199>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 34341
keywords = ['patch']
message_count = 5.0
messages = ['323181', '325536', '325539', '325542', '325679']
nosy_count = 4.0
nosy_names = ['twouters', 'alanmcintyre', 'serhiy.storchaka', 'miss-islington']
pr_nums = ['8683', '9356', '9357', '9400']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue34341'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7', 'Python 3.8']

[serhiy-storchaka]

When the ZIP archive is opened for appending, it reads the Central Directory at opening and writes existing entries back at closing. The Zip64 Extra Field is appended to existing Extra Fields if necessary. This leads to increasing the size of the Extra Fields data every time when append to the ZIP archive. Since the total size of Extra Fields is limited by 0xffff bytes, this can cause the failure.

The proposed PR removes the Zip64 Extra Field before adding a new Zip64 Extra Field.

[serhiy-storchaka]

New changeset 9bdb7be by Serhiy Storchaka in branch 'master':
bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683)
9bdb7be

[miss-islington]

New changeset efdf316 by Miss Islington (bot) in branch '3.7':
bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683)
efdf316

[miss-islington]

New changeset 83a0985 by Miss Islington (bot) in branch '3.6':
bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683)
83a0985

[serhiy-storchaka]

New changeset 29034ba by Serhiy Storchaka in branch '2.7':
[2.7] bpo-34341: Fix appending to ZIP archives with the ZIP64 extension. (GH-8683). (GH-9400)
29034ba