MC no longer working with cygwin 3.1.x

MC no longer working with cygwin 3.1.x

[Laurent R]

Dear all,

After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc works perfectly.

I tested with cygwin-3.1.0, same problem.

The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.

Regards.

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Re: MC no longer working with cygwin 3.1.x

[Takashi Yano]

On Wed, 18 Dec 2019 14:42:53 +0000
Laurent R wrote:
> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc works perfectly.
> 
> I tested with cygwin-3.1.0, same problem.
> 
> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.

Thanks for the report. I looked into this problem and the cause
is the bug in pty code.

I will submit the patch for this issue soon.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

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Re: MC no longer working with cygwin 3.1.x

[Marco Atzeri]

Am 18.12.2019 um 15:42 schrieb Laurent R:
> Dear all,
> 
> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc works perfectly.
> 
> I tested with cygwin-3.1.0, same problem.
> 
> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
> 
> Regards.
> 

confirmed

there must be a race somewhere as running /usr/bin/mc.exe from strace
works fine.

Regards
Marco


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Re: MC no longer working with cygwin 3.1.x

[Corinna Vinschen]

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On Dec 18 17:23, Marco Atzeri wrote:
> Am 18.12.2019 um 15:42 schrieb Laurent R:
> > Dear all,
> > 
> > After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc works perfectly.
> > 
> > I tested with cygwin-3.1.0, same problem.
> > 
> > The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
> > 
> > Regards.
> > 
> 
> confirmed
> 
> there must be a race somewhere as running /usr/bin/mc.exe from strace
> works fine.

But that's not the only problem running mc AFAICS.  I'm seeing an
error message in the background:

Cannot open named pipe /tmp/mc-corinna/mc.pipe.384
  /cygdrive/d/cyg_pub/devel/mc/mc-4.8.23-1.x86_64/src/mc-4.8.23/src/subshell/common.c: open: Permission denied

It looks like there's another problem, this time with the new FIFO
code.

Ken, care to take a look?


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer

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Re: MC no longer working with cygwin 3.1.x

[Ken Brown]

On 12/18/2019 2:32 PM, Corinna Vinschen wrote:
> On Dec 18 17:23, Marco Atzeri wrote:
>> Am 18.12.2019 um 15:42 schrieb Laurent R:
>>> Dear all,
>>>
>>> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc works perfectly.
>>>
>>> I tested with cygwin-3.1.0, same problem.
>>>
>>> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
>>>
>>> Regards.
>>>
>>
>> confirmed
>>
>> there must be a race somewhere as running /usr/bin/mc.exe from strace
>> works fine.
> 
> But that's not the only problem running mc AFAICS.  I'm seeing an
> error message in the background:
> 
> Cannot open named pipe /tmp/mc-corinna/mc.pipe.384
>    /cygdrive/d/cyg_pub/devel/mc/mc-4.8.23-1.x86_64/src/mc-4.8.23/src/subshell/common.c: open: Permission denied
> 
> It looks like there's another problem, this time with the new FIFO
> code.
> 
> Ken, care to take a look?

I've just looked at the mc source code, and it seems that (under tcsh only), mc 
creates a fifo and tries to open it twice as O_RDWR.  This is not supported on 
Cygwin, so the second attempt fails.

Here's the relevant code from src/subshell/common.c:

         if (mc_global.shell->type == SHELL_TCSH)
         {
             g_snprintf (tcsh_fifo, sizeof (tcsh_fifo), "%s/mc.pipe.%d",
                         mc_tmpdir (), (int) getpid ());
             if (mkfifo (tcsh_fifo, 0600) == -1)
             [...]
             /* Opening the FIFO as O_RDONLY or O_WRONLY causes deadlock */

             if ((subshell_pipe[READ] = open (tcsh_fifo, O_RDWR)) == -1
                 || (subshell_pipe[WRITE] = open (tcsh_fifo, O_RDWR)) == -1)
             {
                 fprintf (stderr, _("Cannot open named pipe %s\n"), tcsh_fifo);
                 perror (__FILE__ ": open");
                 mc_global.tty.use_subshell = FALSE;
                 [...]

Under bash, zsh, and some other shells, mc uses ordinary pipes rather than 
FIFOs.  I have no idea why tcsh is treated differently.

Until someone[*] gets around to making it possible to open a FIFO twice for 
reading, I don't think there's anything we can do about it.  I also don't know 
how important this is for mc.  I don't use tcsh or mc, so I can't judge.

Ken

[*] I will probably look into this at some point if there's enough demand for 
it, but I'd like the new FIFO code to get lots of testing first.

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Re: MC no longer working with cygwin 3.1.x

[Thomas Wolff]

Am 18.12.2019 um 22:14 schrieb Ken Brown:
> On 12/18/2019 2:32 PM, Corinna Vinschen wrote:
>> On Dec 18 17:23, Marco Atzeri wrote:
>>> Am 18.12.2019 um 15:42 schrieb Laurent R:
>>>> Dear all,
>>>>
>>>> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc works perfectly.
>>>>
>>>> I tested with cygwin-3.1.0, same problem.
>>>>
>>>> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
>>>>
>>>> Regards.
>>>>
>>> confirmed
>>>
>>> there must be a race somewhere as running /usr/bin/mc.exe from strace
>>> works fine.
>> But that's not the only problem running mc AFAICS.  I'm seeing an
>> error message in the background:
>>
>> Cannot open named pipe /tmp/mc-corinna/mc.pipe.384
>>     /cygdrive/d/cyg_pub/devel/mc/mc-4.8.23-1.x86_64/src/mc-4.8.23/src/subshell/common.c: open: Permission denied
>>
>> It looks like there's another problem, this time with the new FIFO
>> code.
>>
>> Ken, care to take a look?
> I've just looked at the mc source code, and it seems that (under tcsh only), mc
> creates a fifo and tries to open it twice as O_RDWR.  This is not supported on
> Cygwin, so the second attempt fails.
>
> Here's the relevant code from src/subshell/common.c:
>
>           if (mc_global.shell->type == SHELL_TCSH)
>           {
>               g_snprintf (tcsh_fifo, sizeof (tcsh_fifo), "%s/mc.pipe.%d",
>                           mc_tmpdir (), (int) getpid ());
>               if (mkfifo (tcsh_fifo, 0600) == -1)
>               [...]
>               /* Opening the FIFO as O_RDONLY or O_WRONLY causes deadlock */
>
>               if ((subshell_pipe[READ] = open (tcsh_fifo, O_RDWR)) == -1
>                   || (subshell_pipe[WRITE] = open (tcsh_fifo, O_RDWR)) == -1)
>               {
>                   fprintf (stderr, _("Cannot open named pipe %s\n"), tcsh_fifo);
>                   perror (__FILE__ ": open");
>                   mc_global.tty.use_subshell = FALSE;
>                   [...]
>
> Under bash, zsh, and some other shells, mc uses ordinary pipes rather than
> FIFOs.  I have no idea why tcsh is treated differently.
>
> Until someone[*] gets around to making it possible to open a FIFO twice for
> reading, I don't think there's anything we can do about it.  I also don't know
> how important this is for mc.  I don't use tcsh or mc, so I can't judge.
I've reproduced mc to fail, from bash, in cygwin 3.1.0 and 3.1.1, 
Windows 1809 and 1903.

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Re: MC no longer working with cygwin 3.1.x

[Ken Brown]

On 12/18/2019 5:55 PM, Thomas Wolff wrote:
> 
> 
> Am 18.12.2019 um 22:14 schrieb Ken Brown:
>> On 12/18/2019 2:32 PM, Corinna Vinschen wrote:
>>> On Dec 18 17:23, Marco Atzeri wrote:
>>>> Am 18.12.2019 um 15:42 schrieb Laurent R:
>>>>> Dear all,
>>>>>
>>>>> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer 
>>>>> starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc 
>>>>> works perfectly.
>>>>>
>>>>> I tested with cygwin-3.1.0, same problem.
>>>>>
>>>>> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
>>>>>
>>>>> Regards.
>>>>>
>>>> confirmed
>>>>
>>>> there must be a race somewhere as running /usr/bin/mc.exe from strace
>>>> works fine.
>>> But that's not the only problem running mc AFAICS.  I'm seeing an
>>> error message in the background:
>>>
>>> Cannot open named pipe /tmp/mc-corinna/mc.pipe.384
>>>     
>>> /cygdrive/d/cyg_pub/devel/mc/mc-4.8.23-1.x86_64/src/mc-4.8.23/src/subshell/common.c: 
>>> open: Permission denied
>>>
>>> It looks like there's another problem, this time with the new FIFO
>>> code.
>>>
>>> Ken, care to take a look?
>> I've just looked at the mc source code, and it seems that (under tcsh only), mc
>> creates a fifo and tries to open it twice as O_RDWR.  This is not supported on
>> Cygwin, so the second attempt fails.
>>
>> Here's the relevant code from src/subshell/common.c:
>>
>>           if (mc_global.shell->type == SHELL_TCSH)
>>           {
>>               g_snprintf (tcsh_fifo, sizeof (tcsh_fifo), "%s/mc.pipe.%d",
>>                           mc_tmpdir (), (int) getpid ());
>>               if (mkfifo (tcsh_fifo, 0600) == -1)
>>               [...]
>>               /* Opening the FIFO as O_RDONLY or O_WRONLY causes deadlock */
>>
>>               if ((subshell_pipe[READ] = open (tcsh_fifo, O_RDWR)) == -1
>>                   || (subshell_pipe[WRITE] = open (tcsh_fifo, O_RDWR)) == -1)
>>               {
>>                   fprintf (stderr, _("Cannot open named pipe %s\n"), tcsh_fifo);
>>                   perror (__FILE__ ": open");
>>                   mc_global.tty.use_subshell = FALSE;
>>                   [...]
>>
>> Under bash, zsh, and some other shells, mc uses ordinary pipes rather than
>> FIFOs.  I have no idea why tcsh is treated differently.
>>
>> Until someone[*] gets around to making it possible to open a FIFO twice for
>> reading, I don't think there's anything we can do about it.  I also don't know
>> how important this is for mc.  I don't use tcsh or mc, so I can't judge.
> I've reproduced mc to fail, from bash, in cygwin 3.1.0 and 3.1.1, Windows 1809 
> and 1903.

That's not related to what I've been talking about, which is the error message 
"Cannot open named pipe /tmp/mc-corinna/mc.pipe.384" that Corinna reported.  The 
failure you're talking about occurs in all shells and has already been fixed by 
Takashi.  I imagine Corinna will release 3.1.2 with the fix very soon.

Ken

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Re: MC no longer working with cygwin 3.1.x

[Corinna Vinschen]

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On Dec 18 23:09, Ken Brown wrote:
> On 12/18/2019 5:55 PM, Thomas Wolff wrote:
> > Am 18.12.2019 um 22:14 schrieb Ken Brown:
> >> On 12/18/2019 2:32 PM, Corinna Vinschen wrote:
> >>> On Dec 18 17:23, Marco Atzeri wrote:
> >>>> Am 18.12.2019 um 15:42 schrieb Laurent R:
> >>>>> Dear all,
> >>>>>
> >>>>> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer 
> >>>>> starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc 
> >>>>> works perfectly.
> >>>>>
> >>>>> I tested with cygwin-3.1.0, same problem.
> >>>>>
> >>>>> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
> >>>> confirmed
> >>>>
> >>>> there must be a race somewhere as running /usr/bin/mc.exe from strace
> >>>> works fine.
> >>> But that's not the only problem running mc AFAICS.  I'm seeing an
> >>> error message in the background:
> >>>
> >>> Cannot open named pipe /tmp/mc-corinna/mc.pipe.384
> >>>     
> >>> /cygdrive/d/cyg_pub/devel/mc/mc-4.8.23-1.x86_64/src/mc-4.8.23/src/subshell/common.c: 
> >>> open: Permission denied
> >>> [...]
> >> I've just looked at the mc source code, and it seems that (under tcsh only), mc
> >> creates a fifo and tries to open it twice as O_RDWR.  This is not supported on
> >> Cygwin, so the second attempt fails.
> >>
> >> Here's the relevant code from src/subshell/common.c:
> >> [...]
> >> Under bash, zsh, and some other shells, mc uses ordinary pipes rather than
> >> FIFOs.  I have no idea why tcsh is treated differently.
> >>
> >> Until someone[*] gets around to making it possible to open a FIFO twice for
> >> reading, I don't think there's anything we can do about it.  I also don't know
> >> how important this is for mc.  I don't use tcsh or mc, so I can't judge.

Not using mc either here.  I see the STATUS_ACCESS_DENIED in the strace
output when calling NtCreateNamedPipeFile, but I wonder why that is.

Ken, btw., we should add a PIPE_REJECT_REMOTE_CLIENTS flag, just for
paranoia.

> > I've reproduced mc to fail, from bash, in cygwin 3.1.0 and 3.1.1, Windows 1809 
> > and 1903.
> 
> That's not related to what I've been talking about, which is the error
> message "Cannot open named pipe /tmp/mc-corinna/mc.pipe.384" that
> Corinna reported.  The failure you're talking about occurs in all
> shells and has already been fixed by Takashi.  I imagine Corinna will
> release 3.1.2 with the fix very soon.

Yes, today or tomorrow.  Maybe some other low-hanging fruit roles past...


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer

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Re: MC no longer working with cygwin 3.1.x

[Ken Brown]

On 12/19/2019 4:24 AM, Corinna Vinschen wrote:
> On Dec 18 23:09, Ken Brown wrote:
>> On 12/18/2019 5:55 PM, Thomas Wolff wrote:
>>> Am 18.12.2019 um 22:14 schrieb Ken Brown:
>>>> On 12/18/2019 2:32 PM, Corinna Vinschen wrote:
>>>>> On Dec 18 17:23, Marco Atzeri wrote:
>>>>>> Am 18.12.2019 um 15:42 schrieb Laurent R:
>>>>>>> Dear all,
>>>>>>>
>>>>>>> After the update to cygwin-3.1.1, mc (aka Midnight Commander) no longer
>>>>>>> starts. It goes into an infinite loop, if I go back to cygwin-3.0.7, mc
>>>>>>> works perfectly.
>>>>>>>
>>>>>>> I tested with cygwin-3.1.0, same problem.
>>>>>>>
>>>>>>> The MC version is 4.8.23 and the operating system is Windows 10 Pro x64 1903.
>>>>>> confirmed
>>>>>>
>>>>>> there must be a race somewhere as running /usr/bin/mc.exe from strace
>>>>>> works fine.
>>>>> But that's not the only problem running mc AFAICS.  I'm seeing an
>>>>> error message in the background:
>>>>>
>>>>> Cannot open named pipe /tmp/mc-corinna/mc.pipe.384
>>>>>      
>>>>> /cygdrive/d/cyg_pub/devel/mc/mc-4.8.23-1.x86_64/src/mc-4.8.23/src/subshell/common.c:
>>>>> open: Permission denied
>>>>> [...]
>>>> I've just looked at the mc source code, and it seems that (under tcsh only), mc
>>>> creates a fifo and tries to open it twice as O_RDWR.  This is not supported on
>>>> Cygwin, so the second attempt fails.
>>>>
>>>> Here's the relevant code from src/subshell/common.c:
>>>> [...]
>>>> Under bash, zsh, and some other shells, mc uses ordinary pipes rather than
>>>> FIFOs.  I have no idea why tcsh is treated differently.
>>>>
>>>> Until someone[*] gets around to making it possible to open a FIFO twice for
>>>> reading, I don't think there's anything we can do about it.  I also don't know
>>>> how important this is for mc.  I don't use tcsh or mc, so I can't judge.
> 
> Not using mc either here.  I see the STATUS_ACCESS_DENIED in the strace
> output when calling NtCreateNamedPipeFile, but I wonder why that is.

This happens on the second call to NtCreateNamedPipeFile on the same FIFO, both 
times with FILE_CREATE, as a result of mc trying to open it twice for reading. 
I recall seeing that error before under these circumstances when I was 
developing the new FIFO code.

> Ken, btw., we should add a PIPE_REJECT_REMOTE_CLIENTS flag, just for
> paranoia.

Will do.

Ken

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