Opening CON for write access fails

[eryksun]

BPO	28161
Nosy	@pfmoore, @tjguk, @zware, @eryksun, @zooba
PRs	[Do Not Merge] Convert Misc/NEWS so that it is managed by towncrier #552

^{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 2016-09-17.20:52:19.218>
created_at = <Date 2016-09-15.03:24:24.824>
labels = ['3.7', 'type-bug', 'library', 'expert-IO', 'OS-windows']
title = 'Opening CON for write access fails'
updated_at = <Date 2017-03-31.16:36:19.951>
user = 'https://github.com/eryksun'

bugs.python.org fields:

activity = <Date 2017-03-31.16:36:19.951>
actor = 'dstufft'
assignee = 'none'
closed = True
closed_date = <Date 2016-09-17.20:52:19.218>
closer = 'steve.dower'
components = ['Library (Lib)', 'Windows', 'IO']
creation = <Date 2016-09-15.03:24:24.824>
creator = 'eryksun'
dependencies = []
files = []
hgrepos = []
issue_num = 28161
keywords = []
message_count = 2.0
messages = ['276507', '276847']
nosy_count = 6.0
nosy_names = ['paul.moore', 'tim.golden', 'python-dev', 'zach.ware', 'eryksun', 'steve.dower']
pr_nums = ['552']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue28161'
versions = ['Python 3.6', 'Python 3.7']

[eryksun]

When opening the CON device the underlying CreateFile call needs to use either GENERIC_READ or GENERIC_WRITE access, but not both. Currently opening for writing fails as follows:

   >>> open('CON', 'wb', buffering=0)
   Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
   OSError: [WinError 87] The parameter is incorrect: 'CON'

If self->writable is true, it should set access = GENERIC_WRITE, not access |= GENERIC_WRITE.

This only applies to CON. It's normal to open CONIN$ and CONOUT$ with both read and write access, and WindowsConsoleIO handles that correctly.

[python-dev]

New changeset d0bab9fda568 by Steve Dower in branch '3.6':
Issue bpo-28161: Opening CON for write access fails
https://hg.python.org/cpython/rev/d0bab9fda568

New changeset 187a114b9ef4 by Steve Dower in branch 'default':
Issue bpo-28161: Opening CON for write access fails
https://hg.python.org/cpython/rev/187a114b9ef4