Incorrect dst buffer size for MultiByteToWideChar in _Py_fopen_obj

[izbyshev]

BPO	32869
Nosy	@pfmoore, @vstinner, @tjguk, @zware, @serhiy-storchaka, @zooba, @izbyshev, @miss-islington
PRs	bpo-32869: Fix incorrect dst buffer size for MultiByteToWideChar #5739 [3.7] bpo-32869: Fix incorrect dst buffer size for MultiByteToWideChar (GH-5739) #5741 [3.6] bpo-32869: Fix incorrect dst buffer size for MultiByteToWideChar (GH-5739) #5742

^{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 = None
closed_at = <Date 2018-02-18.22:10:32.002>
created_at = <Date 2018-02-18.16:58:54.000>
labels = ['type-feature', '3.7', 'expert-IO', 'OS-windows']
title = 'Incorrect dst buffer size for MultiByteToWideChar in _Py_fopen_obj'
updated_at = <Date 2018-02-18.22:27:06.307>
user = 'https://github.com/izbyshev'

bugs.python.org fields:

activity = <Date 2018-02-18.22:27:06.307>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2018-02-18.22:10:32.002>
closer = 'izbyshev'
components = ['Windows', 'IO']
creation = <Date 2018-02-18.16:58:54.000>
creator = 'izbyshev'
dependencies = []
files = []
hgrepos = []
issue_num = 32869
keywords = ['patch']
message_count = 5.0
messages = ['312314', '312318', '312322', '312324', '312330']
nosy_count = 8.0
nosy_names = ['paul.moore', 'vstinner', 'tim.golden', 'zach.ware', 'serhiy.storchaka', 'steve.dower', 'izbyshev', 'miss-islington']
pr_nums = ['5739', '5741', '5742']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue32869'
versions = ['Python 3.6', 'Python 3.7']

[izbyshev]

MultiByteToWideChar expects the destination buffer size to be given in wide characters, not bytes.

This is currently not a real issue since _Py_fopen_obj is only used internally with mode being a short constant string in all call sites I've found.

[serhiy-storchaka]

New changeset b3b4a9d by Serhiy Storchaka (Alexey Izbyshev) in branch 'master':
bpo-32869: Fix incorrect dst buffer size for MultiByteToWideChar (bpo-5739)
b3b4a9d

[miss-islington]

New changeset ca82e3c by Miss Islington (bot) in branch '3.7':
bpo-32869: Fix incorrect dst buffer size for MultiByteToWideChar (GH-5739)
ca82e3c

[miss-islington]

New changeset 65a13c1 by Miss Islington (bot) in branch '3.6':
bpo-32869: Fix incorrect dst buffer size for MultiByteToWideChar (GH-5739)
65a13c1

[serhiy-storchaka]

Thank you for your PR Alexey.