Problem with Unison

jlacroix · 2010-09-06 22:27:22

Hello everyone, I've always been using Unison to sync between my desktop and laptop. It's been working fine, but lately I've run into a little problem. Whenever I start Unison and load my profile, it sits on "contacting server" indefinitely and never moves passed it. The strange thing is, if I use Unison via the command line and load the same profile, it works perfect. For some reason it appears that the GUI hangs up, but over the command line everything works as it should.

Has anyone else ran into this problem?

ngoonee · 2010-09-06 23:32:25

Try running the unison GUI from the command line, any errors? I use unison-x11 daily, and have not had problems.

jlacroix · 2010-09-07 00:00:30

ngoonee wrote:

Try running the unison GUI from the command line, any errors? I use unison-x11 daily, and have not had problems.

Same problem, unfortunately. It keeps saying "contacting server" and sits there like it's waiting for something.

ngoonee · 2010-09-07 01:38:51

Check if something has changed with your security (ssh daemon or whatnot) on the server.

jlacroix · 2010-09-07 03:17:20

ngoonee wrote:

Check if something has changed with your security (ssh daemon or whatnot) on the server.

On my server, I can connect via SSH no problem, and I can also sync with Unison no problem as long as I'm using the command line (unison nameofprofile.prf). The command line works but the GUI just stops on "contacting server". It's the strangest thing ever, because you'd think it should work if I can do it via command line.

schneida · 2010-09-11 09:03:20

I encounter the same problem. I'm using unison-gtk2 for a few years now without any troubles but since today's update the gui version is broken, however the commandline version works.

The problem is the new openssh version 5.6p1-1 which is causing the troubles. After downgrading to version 5.5p1-1 everything works as expected again. Bugreport??

EDIT: Downgrade is only needed on the client which is running the unison-gui!

Last edited by schneida (2010-09-11 09:05:17)

litemotiv · 2010-09-11 09:26:22

schneida wrote:

Bugreport??

Yes, please post the link here for reference.

schneida · 2010-09-11 10:59:07

I've not done very much bug reporting. Is it then a bug against openssh (which breaks it), or against unison (which is broken)?

jlacroix · 2010-09-11 16:46:30

schneida wrote:

I've not done very much bug reporting. Is it then a bug against openssh (which breaks it), or against unison (which is broken)?

I'm curious too, I'd like to submit a bug report but I don't know which one to target!

daspostloch · 2010-09-20 13:20:46

confirmed, but not smarter on the causalities. sent a mail to unison-users-digest.

jlacroix · 2010-09-20 13:23:38

daspostloch wrote:

confirmed, but not smarter on the causalities. sent a mail to unison-users-digest.

Thanks. I've been using it over commandline, but I actually prefer the GUI for Unison.

schneida · 2010-09-26 19:23:23

I did a bug report now, you can find it here: https://bugs.archlinux.org/task/20956

daspostloch · 2010-10-09 15:37:08

The unison-users mailinglist asks for

"The ssh output has probably changed and is not correctly parsed by Unison. Can you send the ssh ouput when connecting using the console version?"

Currently don't have access to my machine and configuration.

jlacroix · 2010-10-09 16:48:46

daspostloch wrote:

The unison-users mailinglist asks for
"The ssh output has probably changed and is not correctly parsed by Unison. Can you send the ssh ouput when connecting using the console version?"
Currently don't have access to my machine and configuration.

There is no real output, when I use Unison over the command line it just asks for the password, I type it in, and it syncs. Other than that there's nothing else.

schneida · 2010-10-09 17:30:04

A work-around for using unison gui is to connect to your ssh server with public key authentification instead of password.

EDIT: I'm trying to look at the sources of unison and find the problem. By doing so I've found another workaround if you don't mind using the gtk1 version. Just start unison-gtk from the commandline and you will be asked for the password on the commandline.

EDIT2: Ok, spent the whole evening looking for a solution but the only thing that I could find out is that only Arch and Gentoo suffer from this problem (because those are the only distributions already using openssh 5.6p) and that unison breaks in line 232 in file terminal.ml:
Lwt_unix.read fdTerm buf 0 10000 >>= (fun len ->)
I'm not an ocaml developer but from what I've found out it seems that openssh 5.6 is not producing the right output for Lwt_unix.read because it just hangs in this line not recieving anything at all. I've also looked into the changelog of openssh to find changes that could possibly relate to this problem but couldn't find anything suspicious.
Another thing I've found out is that unison won't compile with the ocaml version in the arch repos. You have to downgrade to version 3.11 in order to make builds work again. Again only Arch (possibly Gentoo too) is affected. See: https://bugs.archlinux.org/task/20877?p … ing=unison

It's sad seeing such a good program breaking down because of not being actively maintained anymore...

Last edited by schneida (2010-10-09 19:34:57)

Jérôme V · 2010-10-11 09:55:23

schneida wrote:

A work-around for using unison gui is to connect to your ssh server with public key authentification instead of password.
EDIT: I'm trying to look at the sources of unison and find the problem. By doing so I've found another workaround if you don't mind using the gtk1 version. Just start unison-gtk from the commandline and you will be asked for the password on the commandline.
EDIT2: Ok, spent the whole evening looking for a solution but the only thing that I could find out is that only Arch and Gentoo suffer from this problem (because those are the only distributions already using openssh 5.6p) and that unison breaks in line 232 in file terminal.ml:
Lwt_unix.read fdTerm buf 0 10000 >>= (fun len ->)
I'm not an ocaml developer but from what I've found out it seems that openssh 5.6 is not producing the right output for Lwt_unix.read because it just hangs in this line not recieving anything at all. I've also looked into the changelog of openssh to find changes that could possibly relate to this problem but couldn't find anything suspicious.
Another thing I've found out is that unison won't compile with the ocaml version in the arch repos. You have to downgrade to version 3.11 in order to make builds work again. Again only Arch (possibly Gentoo too) is affected. See: https://bugs.archlinux.org/task/20877?p … ing=unison
It's sad seeing such a good program breaking down because of not being actively maintained anymore...

The compilation issue is fixed in Unison's subversion repository. I have posted a patch that should work-around the openssh issue to https://bugs.archlinux.org/task/20877.

schneida · 2010-10-12 09:54:27

I can confirm that the patch works. I don't know how the Arch Package "Cycle" works and whether it would be good to inform the package maintainer to recompile the package or just wait.

Basically to recompile the package with the patch you just have to download the PKGBUILD for unison (from ABS or from the web interface), copy arch_patch into that directory and add "patch -p1 -i $srcdir/arch_patch" in the build section of the PKGBUILD (after "cd $startdir/src/$pkgname-$pkgver"). You might get an error complaining about "gdk.cmi is not a compiled interface" which you can avoid by disabling the GTK (1) interface (comment out "UISTYLE=gtk DEBUGGING=false..." and the line after that one) or by recompiling lablgtk from ABS. This is at least the solution that worked for me (guess the problem is that the lablgtk version that is in the repos was not compiled using ocaml 3.12, but again I'm not sure wheter this is just a problem that occured for me).

Thank you very much again for providing the patch, good to have unison back!

Last edited by schneida (2010-10-12 09:55:24)

schneida · 2010-11-01 20:49:01

I just saw that the bugs regarding that problem were closed and marked and fixed and that there is a new unison package in the repos.

Thanks Arch Team!

Arch Linux

#1 2010-09-06 22:27:22

Problem with Unison

#2 2010-09-06 23:32:25

Re: Problem with Unison

#3 2010-09-07 00:00:30

Re: Problem with Unison

#4 2010-09-07 01:38:51

Re: Problem with Unison

#5 2010-09-07 03:17:20

Re: Problem with Unison

#6 2010-09-11 09:03:20

Re: Problem with Unison

#7 2010-09-11 09:26:22

Re: Problem with Unison

#8 2010-09-11 10:59:07

Re: Problem with Unison

#9 2010-09-11 16:46:30

Re: Problem with Unison

#10 2010-09-20 13:20:46

Re: Problem with Unison

#11 2010-09-20 13:23:38

Re: Problem with Unison

#12 2010-09-26 19:23:23

Re: Problem with Unison

#13 2010-10-09 15:37:08

Re: Problem with Unison

#14 2010-10-09 16:48:46

Re: Problem with Unison

#15 2010-10-09 17:30:04

Re: Problem with Unison

#16 2010-10-11 09:55:23

Re: Problem with Unison

#17 2010-10-12 09:54:27

Re: Problem with Unison

#18 2010-11-01 20:49:01

Re: Problem with Unison

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