[CRIU] Dumping tmux session with a client connected

[Cyrill Gorcunov]

On Sun, Apr 12, 2015 at 11:24:15PM -0700, Allan Cecil wrote:
> Greetings,
> 
> (resend, sorry if this is a duplicate)
> 
> I am continuing my quest to develop a general-purpose "wrapper" where you can run a Python script which starts a shell and you can run a program such as top and hit a key combination such as Ctrl+U to save a checkpoint and then press Ctrl+O later to restore that checkpoint, all while viewing the shell.  Using top is a quick example but the ultimate goal is to get this working with NetHack as part of the nethack-tas-tools project (currently on Gitorious but soon to move to a new repository).
> 
> I'm having issues dumping when a client is connected to the tmux session. Given ps fax:
> 
> 15349 ?        Ss     0:00 criu service -d
> 15323 ?        Ss     0:00 tmux
> 15324 pts/2    Ss     0:00  \_ -bash
> 15619 pts/2    S+     0:00      \_ top
> 
> Using "./criuDump.py 15323" (script attached) fails; the full dump folder is attached - the pertinent bit is:
> 
> (00.019450)     Ext stream not supported: ino 0xbfc1 peer_ino 0xc1fb family    1 type    1 state  1 name (null)
> (00.019453) Error (sk-unix.c:564): Can't dump half of stream unix connection.
> 
> I'm using req.opts.ext_unix_sk = True because without it I get warnings that it's required.  So, my question is, is it possible to use RPC to dump tmux if a client is currently connected?  (I can reliably dump tmux when "no one is watching" which reminds me of Wheatley from Portal 2, but I digress...   I am not tied to using tmux for this, but it seems like the most sensible option that would provide the most flexibility.
> 
> Any suggestions would be appreciated.  Thanks!

An option might be to use plugin (ie write one which would know how to
deal with stream sockets), 'cause criu itself won't be able to restore this
socket.