[screen-devel] [bug #54378] Querying for window title hangs

[Jacek Tomaka]

URL:
  <http://savannah.gnu.org/bugs/?54378>

                 Summary: Querying for window title hangs
                 Project: GNU Screen
            Submitted by: jcztery
            Submitted on: Thu 26 Jul 2018 09:44:26 AM UTC
                Category: Crash/Freeze/Infloop
                Severity: 3 - Normal
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.6.2
           Fixed Release: None
         Planned Release: None
           Work Required: None

    _______________________________________________________

Details:

Attached is a simple reproducer: zupa. 
To reproduce:
1. Open three shells. 
2. In shell 1 type: while true; do ./zupa status; done
3. In shell 2 type: while true; do ./zupa start; done
4. In shell 3 type: while true; do ./zupa stop; done

Alternatively, add another shell with while true; do ./zupa status; done

After some time (~ 1 minute) one or all sessions will hang: 
root     23232  0.0  0.0 139164  1240 pts/8    S+   17:21   0:00 screen -S
zupa -p main -Q title
root     31799  0.0  0.0 168308 24080 ?        Ss   17:20   0:00 SCREEN -S
zupa -d -m bash

I think it has something to do with
/var/run/screen-4.6.2/S-root/31799.zupa-queryA
unix  2      [ ACC ]     STREAM     LISTENING     433339114 31799/SCREEN      
  /var/run/screen-4.6.2/S-root/31799.zupa
unix  2      [ ACC ]     STREAM     LISTENING     433384640 23232/screen      
  /var/run/screen-4.6.2/S-root/31799.zupa-queryA


strace -p 31799
Process 31799 attached
select(1024, [4 5 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23], [], NULL,
NULL

/proc/31799/fd: 
lrwx------ 1 root root   64 Jul 26 17:23 4 -> socket:[433339114]
lrwx------ 1 root root   64 Jul 26 17:23 7 -> socket:[433339117]



strace -p 23232
Process 23232 attached
accept(4, 

/proc/23232/fd: 
lrwx------ 1 root root 64 Jul 26 17:23 4 -> socket:[433384640]

Reproduced on Centos7. 
Regards.
Jacek Tomaka



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Thu 26 Jul 2018 09:44:26 AM UTC  Name: zupa  Size: 1KiB   By: jcztery

<http://savannah.gnu.org/bugs/download.php?file_id=44625>

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?54378>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/