From: Michael McMahon <michael.x.mcmahon@oracle.com>
To: Ken Brown <kbrown@cornell.edu>, cygwin@cygwin.com
Subject: Re: Problems with native Unix domain sockets on Win 10/2019
Date: Sat, 26 Sep 2020 08:30:02 +0100 [thread overview]
Message-ID: <69ad720c-8ea6-d3bb-b0a5-5556c4550091@oracle.com> (raw)
In-Reply-To: <70b5577f-2cf1-0110-5d3b-cb2bd8ee6df2@cornell.edu>
On 25/09/2020 21:30, Ken Brown wrote:
> On 9/25/2020 2:50 PM, Ken Brown via Cygwin wrote:
>> On 9/25/2020 10:29 AM, Michael McMahon wrote:
>>>
>>>
>>> On 25/09/2020 14:19, Ken Brown wrote:
>>>> On 9/24/2020 8:01 AM, Michael McMahon 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.
>>>>
>>>> I think this has a simple fix (attached), but I can't easily test it
>>>> because your test program doesn't compile for me. First, I got
>>>>
>>>> $ gcc -o native_unix_socket native_unix_socket.c
>>>> native_unix_socket.c:5:10: fatal error: WS2tcpip.h: No such file or
>>>> directory
>>>> 5 | #include <WS2tcpip.h>
>>>> | ^~~~~~~~~~~~
>>>> compilation terminated.
>>>>
>>>> I fixed this by making the include file name lower case. (My system
>>>> is case sensitive, so it matters.)
>>>>
>>>> Next:
>>>>
>>>> $ gcc -o native_unix_socket native_unix_socket.c
>>>> native_unix_socket.c:8:10: fatal error: afunix.h: No such file or
>>>> directory
>>>> 8 | #include <afunix.h>
>>>> | ^~~~~~~~~~
>>>> compilation terminated.
>>>>
>>>> There's no file afunix.h in the Cygwin distribution, but I located
>>>> it online and pasted in the contents. The program now compiles but
>>>> fails to link:
>>>>
>>>> $ gcc -o native_unix_socket native_unix_socket.c
>>>> /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: /tmp/cc74urPr.o:native_unix_socket.c:(.text+0x3b):
>>>> undefined reference to `__imp_WSAStartup'
>>>> /tmp/cc74urPr.o:native_unix_socket.c:(.text+0x3b): relocation
>>>> truncated to fit: R_X86_64_PC32 against undefined symbol
>>>> `__imp_WSAStartup'
>>>> /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: /tmp/cc74urPr.o:native_unix_socket.c:(.text+0xf2):
>>>> undefined reference to `__imp_WSAGetLastError'
>>>> /tmp/cc74urPr.o:native_unix_socket.c:(.text+0xf2): relocation
>>>> truncated to fit: R_X86_64_PC32 against undefined symbol
>>>> `__imp_WSAGetLastError'
>>>> /usr/lib/gcc/x86_64-pc-cygwin/10/../../../../x86_64-pc-cygwin/bin/ld: /tmp/cc74urPr.o:native_unix_socket.c:(.text+0x13d):
>>>> undefined reference to `__imp_WSAGetLastError'
>>>> /tmp/cc74urPr.o:native_unix_socket.c:(.text+0x13d): relocation
>>>> truncated to fit: R_X86_64_PC32 against undefined symbol
>>>> `__imp_WSAGetLastError'
>>>> collect2: error: ld returned 1 exit status
>>>>
>>>> This is probably easy to fix too, but I don't feel like tracking it
>>>> down. Please send compilation instructions (that use Cygwin tools).
>>>>
>>>> Ken
>>>
>>> Hi
>>>
>>> Sorry, I had compiled it in a native Visual C environment.
>>>
>>> Assuming you have afunix.h in the current directory.
>>>
>>> gcc -o native_unix_socket -I. native_unix_socket.c -lws2_32
>>>
>>> should do it.
>>
>> Thanks, that works. But now I can't reproduce your problem. Here's
>> what I see, using Cygwin 3.1.7 without applying my patch:
>>
>> $ ./native_unix_socket.exe
>> getsockname works
>> fam = 1, len = 11
>> offsetof clen = 9
>> strlen = 8
>> name = foo.sock
>>
>> $ ls -l foo.sock
>> -rwxr-xr-x 1 kbrown None 0 2020-09-25 14:39 foo.sock*
>>
>> $ chmod 644 foo.sock
>>
>> $ ls -l foo.sock
>> -rw-r--r-- 1 kbrown None 0 2020-09-25 14:39 foo.sock
>>
>> $ rm foo.sock
>>
>> $ ls -l foo.sock
>> ls: cannot access 'foo.sock': No such file or directory
>>
>> I'm running 64-bit Cygwin on Windows 10 1909.
>
> I just ran the 'rm' command under gdb to see what's going on, and it
> seems that foo.sock is not being recognized as a reparse point. So
> maybe your test program, when compiled and run under Cygwin, doesn't
> actually produce a native Windows AF_UNIX socket. And when I try to run
> it in a Windows Command Prompt, I get
>
> bind failed 10050
> getsockname failed 10022
>
> Can you make your version of the test executable available for me to
> try? Or tell me some other way to create a native Windows AF_UNIX socket?
>
> Ken
That is all very strange. I have checked both the gcc compiled and MS
compiled executables on my system (2019 server) and they are both
definitely producing native AF_UNIX sockets.
I can email you the two exe files. They are both quite small. But, first
I want to check the patch status of my test system.
Thanks,
Michael.
next prev parent reply other threads:[~2020-09-26 7:30 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=69ad720c-8ea6-d3bb-b0a5-5556c4550091@oracle.com \
--to=michael.x.mcmahon@oracle.com \
--cc=cygwin@cygwin.com \
--cc=kbrown@cornell.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).