From: Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>
To: cygwin@cygwin.com
Subject: Re: Problems with native Unix domain sockets on Win 10/2019
Date: Thu, 24 Sep 2020 11:11:01 -0600 [thread overview]
Message-ID: <445fc4db-739c-7569-926b-739ebd1ffbf9@SystematicSw.ab.ca> (raw)
In-Reply-To: <bb34a767-0cb5-1d48-7f9b-ad914762f9f7@oracle.com>
On 2020-09-24 06:01, Michael McMahon via Cygwin wrote:
>
>
> On 24/09/2020 12:26, Ken Brown wrote:
>> On 9/23/2020 7:25 AM, Michael McMahon via Cygwin wrote:
>>> Hi,
>>>
>>> I searched for related issues but haven't found anything.
>>>
>>> I am having some trouble with Windows native Unix domain sockets
>>> (a recent feature in Windows 10 and 2019 server) and Cygwin.
>>> I think I possibly know the cause since I had to investigate a similar
>>> looking issue on another platform built on Windows.
>>>
>>> The problem is that cygwin commands don't seem to recognise native Unix
>>> domain sockets correctly. For example, the socket "foo.sock" should
>>> have the same ownership and similar permissions to other files
>>> in the example below:
>>>
>>> $ ls -lrt
>>> total 2181303
>>>
>>> -rw-r--r-- 1 mimcmah None 1259 Sep 23 10:22 test.c
>>> -rwxr-xr-x 1 mimcmah None 3680 Sep 23 10:22 test.obj
>>> -rwxr-xr-x 1 mimcmah None 121344 Sep 23 10:22 test.exe
>>> -rw-r----- 1 Unknown+User Unknown+Group 0 Sep 23 10:23 foo.sock
>>> -rw-r--r-- 1 mimcmah None 144356 Sep 23 10:27 check.ot
>>>
>>> A bigger problem is that foo.sock can't be deleted with the cygwin "rm"
>>> command.
>>>
>>> $ rm -f foo.sock
>>> rm: cannot remove 'foo.sock': Permission denied
>>>
>>> $ chmod 777 foo.sock
>>> chmod: changing permissions of 'foo.sock': Permission denied
>>>
>>> $ cmd /c del foo.sock
>>>
>>> But, native Windows commands are okay, as the third example shows.
>>>
>>> I think the problem may relate to the way native Unix domain sockets are
>>> implemented in Windows and the resulting special handling required.
>>> They are implemented as NTFS reparse points and when opening them
>>> with CreateFile, you need to specify the FILE_FLAG_OPEN_REPARSE_POINT
>>> flag. Otherwise, you get an ERROR_CANT_ACCESS_FILE. There are other
>>> complications unfortunately, which I'd be happy to discuss further.
>>>
>>> But, to reproduce it, you can compile the attached code snippet
>>> which creates foo.sock in the current directory. Obviously, this
>>> only works on recent versions of Windows 10 and 2019 server.
>>
>> Cygwin doesn't currently support native Windows AF_UNIX sockets, as you've
>> discovered. See
>>
>>
>> https://urldefense.com/v3/__https://cygwin.com/pipermail/cygwin/2020-June/245088.html__;!!GqivPVa7Brio!P7lIFI4rYAtWh8_DtCbRCxT-M_E4vwQ0qwzQ0p656T73BpJ0jbUkLI_bXdA6mmSL9lJcSQ$
>>
>> for the current state of AF_UNIX sockets on Cygwin, including the possibility
>> of using native Windows AF_UNIX sockets on systems that support them.
>>
>> If all you want is for Cygwin to recognize such sockets and allow you to apply
>> rm, chmod, etc., I don't think it would be hard to add that capability. But I
>> doubt if that's all you want.
>>
>> Further discussion of this will have to wait until Corinna is available.
>>
>
> Thanks for the info. It's mainly about recognition of sockets for
> regular commands. Since these objects can exist on Windows filesystems
> now, potentially created by any kind of Windows application,
> it would be great if Cygwin could handle them, irrespective of whether
> the Cygwin development environment does. Though that sounds like a
> good idea too.
See recent discussion:
https://cygwin.com/pipermail/cygwin/2020-June/245077.html
--
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.
[Data in binary units and prefixes, physical quantities in SI.]
next prev parent reply other threads:[~2020-09-24 17:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 11:25 Michael McMahon
2020-09-24 11:26 ` Ken Brown
2020-09-24 12:01 ` Michael McMahon
2020-09-24 17:11 ` Brian Inglis [this message]
2020-09-25 13:19 ` Ken Brown
2020-09-25 14:29 ` Michael McMahon
2020-09-25 14:37 ` Eliot Moss
2020-09-25 16:13 ` Michael McMahon
2020-09-25 16:32 ` Eliot Moss
2020-09-25 18:50 ` Ken Brown
2020-09-25 20:30 ` Ken Brown
2020-09-26 0:31 ` Duncan Roe
2020-09-26 1:22 ` Ken Brown
2020-09-26 7:30 ` Michael McMahon
2020-09-28 11:03 ` Michael McMahon
2021-01-30 16:00 ` Ken Brown
2021-01-31 23:30 ` Michael McMahon
2021-02-01 15:04 ` Ken Brown
2021-02-01 15:10 ` Corinna Vinschen
2021-02-07 19:35 ` Michael McMahon
2021-02-08 15:30 ` Ken Brown
2021-03-16 11:06 ` Sv: " sten.kristian.ivarsson
2021-03-16 13:00 ` Michael McMahon
2021-03-16 15:19 ` Ken Brown
2021-03-17 12:47 ` Sv: " sten.kristian.ivarsson
2021-03-17 15:47 ` Ken Brown
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