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: Fri, 25 Sep 2020 15:29:35 +0100 [thread overview]
Message-ID: <d9a6467d-e797-8917-3240-e79d55dcfb38@oracle.com> (raw)
In-Reply-To: <97d2b3af-224a-6873-fb4a-55a0ae9cd379@cornell.edu>
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.
Michael.
next prev parent reply other threads:[~2020-09-25 14:31 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 [this message]
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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