public inbox for gdb-prs@sourceware.org
help / color / mirror / Atom feed
* [Bug c++/30045] New: GDB crashes when command is used during layout
@ 2023-01-24 20:49 mmoskow1 at stevens dot edu
  2023-01-24 20:49 ` [Bug c++/30045] " mmoskow1 at stevens dot edu
                   ` (17 more replies)
  0 siblings, 18 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-24 20:49 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

            Bug ID: 30045
           Summary: GDB crashes when command is used during layout
           Product: gdb
           Version: 12.1
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: c++
          Assignee: unassigned at sourceware dot org
          Reporter: mmoskow1 at stevens dot edu
  Target Milestone: ---

Created attachment 14619
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14619&action=edit
Crash circumstance recording

See attached video.

Simple cc code. When trying to run during a layout showing, everything crashes.

This repeats itself on any type of terminal on Windows PC with any file.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
@ 2023-01-24 20:49 ` mmoskow1 at stevens dot edu
  2023-01-24 21:53 ` tromey at sourceware dot org
                   ` (16 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-24 20:49 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

Moshe Moskowitz <mmoskow1 at stevens dot edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mmoskow1 at stevens dot edu

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
  2023-01-24 20:49 ` [Bug c++/30045] " mmoskow1 at stevens dot edu
@ 2023-01-24 21:53 ` tromey at sourceware dot org
  2023-01-24 22:36 ` mmoskow1 at stevens dot edu
                   ` (15 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: tromey at sourceware dot org @ 2023-01-24 21:53 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
Can you get a stack trace of gdb at the failure point?
Maybe that would be informative.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
  2023-01-24 20:49 ` [Bug c++/30045] " mmoskow1 at stevens dot edu
  2023-01-24 21:53 ` tromey at sourceware dot org
@ 2023-01-24 22:36 ` mmoskow1 at stevens dot edu
  2023-01-24 23:17 ` tromey at sourceware dot org
                   ` (14 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-24 22:36 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #2 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
I’ve been trying to figure out how to do that, but couldn’t seem to pull it
off. Could you explain to me exactly how?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (2 preceding siblings ...)
  2023-01-24 22:36 ` mmoskow1 at stevens dot edu
@ 2023-01-24 23:17 ` tromey at sourceware dot org
  2023-01-25  0:42 ` mmoskow1 at stevens dot edu
                   ` (13 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: tromey at sourceware dot org @ 2023-01-24 23:17 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #3 from Tom Tromey <tromey at sourceware dot org> ---
In terminal A, run gdb and enter the TUI.
In terminal B, run gdb but do not enter the TUI, just attach to the
gdb in A.  You can do this with 'attach PID', where the PID is
the process ID of the first gdb.
Then in terminal A, reproduce the crash.
In B, type 'bt'.  This should work ok if you have a gdb built with
debug symbols.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (3 preceding siblings ...)
  2023-01-24 23:17 ` tromey at sourceware dot org
@ 2023-01-25  0:42 ` mmoskow1 at stevens dot edu
  2023-01-25  1:52 ` tromey at sourceware dot org
                   ` (12 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-25  0:42 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #4 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
Forgive me if I'm missing something obvious, but I'm not sure where I would
find the process ID to link the terminals.

https://prnt.sc/YwjfZHurb8tR

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (4 preceding siblings ...)
  2023-01-25  0:42 ` mmoskow1 at stevens dot edu
@ 2023-01-25  1:52 ` tromey at sourceware dot org
  2023-01-25  2:15 ` mmoskow1 at stevens dot edu
                   ` (11 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: tromey at sourceware dot org @ 2023-01-25  1:52 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #5 from Tom Tromey <tromey at sourceware dot org> ---
Sorry, I'm not totally sure.  I'm not a windows expert and when
I do debug on windows I use cygwin and just use 'ps'.
Another option is to debug gdb with itself:

gdb gdb
(gdb) set prompt (outer)     # <- make sure you put a space after that paren :)
(outer) run /your/program
(gdb) # in the inner gdb, reproduce the bug...
(outer) bt

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (5 preceding siblings ...)
  2023-01-25  1:52 ` tromey at sourceware dot org
@ 2023-01-25  2:15 ` mmoskow1 at stevens dot edu
  2023-01-25  2:16 ` mmoskow1 at stevens dot edu
                   ` (10 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-25  2:15 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #6 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
Created attachment 14621
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14621&action=edit
Crash 2

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (6 preceding siblings ...)
  2023-01-25  2:15 ` mmoskow1 at stevens dot edu
@ 2023-01-25  2:16 ` mmoskow1 at stevens dot edu
  2023-01-25 18:26 ` mmoskow1 at stevens dot edu
                   ` (9 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-25  2:16 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #7 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
So I tried those steps, but it just crashed on me again (see attached video).
Did I do everything correctly?

I also just downloaded and installed cygwin. What would I do on there?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (7 preceding siblings ...)
  2023-01-25  2:16 ` mmoskow1 at stevens dot edu
@ 2023-01-25 18:26 ` mmoskow1 at stevens dot edu
  2023-01-26 19:33 ` mmoskow1 at stevens dot edu
                   ` (8 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-25 18:26 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #8 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
Created attachment 14625
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14625&action=edit
Crash 3

I tried again in cygwin, but unfortunately it crashed in there as well. The
interesting thing though is that in contrast to the windows terminal, the bash
terminal still remains open when gdb crashes.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (8 preceding siblings ...)
  2023-01-25 18:26 ` mmoskow1 at stevens dot edu
@ 2023-01-26 19:33 ` mmoskow1 at stevens dot edu
  2023-01-26 20:11 ` tromey at sourceware dot org
                   ` (7 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-26 19:33 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #9 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
(In reply to Tom Tromey from comment #3)
> In terminal A, run gdb and enter the TUI.
> In terminal B, run gdb but do not enter the TUI, just attach to the
> gdb in A.  You can do this with 'attach PID', where the PID is
> the process ID of the first gdb.
> Then in terminal A, reproduce the crash.
> In B, type 'bt'.  This should work ok if you have a gdb built with
> debug symbols.

So I was able to use PS to find the PID like you mentioned in a different
comment, but once I attach it, terminal A refuses to let me type anything until
I detach and therefore I am unable to recreate the error.

https://prnt.sc/bwerx_E9tkhy

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (9 preceding siblings ...)
  2023-01-26 19:33 ` mmoskow1 at stevens dot edu
@ 2023-01-26 20:11 ` tromey at sourceware dot org
  2023-01-26 22:59 ` mmoskow1 at stevens dot edu
                   ` (6 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: tromey at sourceware dot org @ 2023-01-26 20:11 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #10 from Tom Tromey <tromey at sourceware dot org> ---
After you 'attach', you must 'continue' so that the program you've
attached to keeps running.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (10 preceding siblings ...)
  2023-01-26 20:11 ` tromey at sourceware dot org
@ 2023-01-26 22:59 ` mmoskow1 at stevens dot edu
  2023-01-28 19:28 ` ssbssa at sourceware dot org
                   ` (5 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-26 22:59 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #11 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
Created attachment 14634
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14634&action=edit
PID Linked Test

See attached

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (11 preceding siblings ...)
  2023-01-26 22:59 ` mmoskow1 at stevens dot edu
@ 2023-01-28 19:28 ` ssbssa at sourceware dot org
  2023-01-28 23:49 ` mmoskow1 at stevens dot edu
                   ` (4 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: ssbssa at sourceware dot org @ 2023-01-28 19:28 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

Hannes Domani <ssbssa at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ssbssa at sourceware dot org

--- Comment #12 from Hannes Domani <ssbssa at sourceware dot org> ---
Since the console disappears completely, I'm pretty sure it's a crash of
conhost.exe, not gdb.exe.
You should see with the Windows Event Viewer in the Application logs which
process really crashed.

Note that I have sometimes experienced this on Win10, usually when switching
back and forth between TUI and normal CLI, but I've not been able to make it
crash as consistently as you.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (12 preceding siblings ...)
  2023-01-28 19:28 ` ssbssa at sourceware dot org
@ 2023-01-28 23:49 ` mmoskow1 at stevens dot edu
  2023-01-30 17:04 ` mmoskow1 at stevens dot edu
                   ` (3 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-28 23:49 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #13 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
So the console disappears completely when run in PowerShell, leaving the
message below, however, as can be seen in the Crash 3 video, when running in
MSYS2, the gdb crashes while the overall terminal stays intact. From the
beginning I've been searching Windows Event Logs for possible clues as to what
was happening, but have been so far unsuccessful.

https://prnt.sc/TDpBxrPCg3hd

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (13 preceding siblings ...)
  2023-01-28 23:49 ` mmoskow1 at stevens dot edu
@ 2023-01-30 17:04 ` mmoskow1 at stevens dot edu
  2023-01-30 17:22 ` ssbssa at sourceware dot org
                   ` (2 subsequent siblings)
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-30 17:04 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #14 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
So while I can't speak for myself on this matter, my professor has told me that
this issue had only started around a year or so ago.

Is there a way I could roll back my GDB for testing purposes in order to see if
the issue remains?

What would you advise?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (14 preceding siblings ...)
  2023-01-30 17:04 ` mmoskow1 at stevens dot edu
@ 2023-01-30 17:22 ` ssbssa at sourceware dot org
  2023-01-30 20:02 ` mmoskow1 at stevens dot edu
  2023-02-05  0:24 ` mmoskow1 at stevens dot edu
  17 siblings, 0 replies; 19+ messages in thread
From: ssbssa at sourceware dot org @ 2023-01-30 17:22 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #15 from Hannes Domani <ssbssa at sourceware dot org> ---
The bug I hit was apparently already fixed in upstream, it just wasn't rolled
out to users yet.
But you can try to download the latest msixbundle from [1], extract it
somewhere, and start gdb.exe from inside its OpenConsole.exe.
So far I haven't had any crashes with this.

[1] https://github.com/microsoft/terminal/releases

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (15 preceding siblings ...)
  2023-01-30 17:22 ` ssbssa at sourceware dot org
@ 2023-01-30 20:02 ` mmoskow1 at stevens dot edu
  2023-02-05  0:24 ` mmoskow1 at stevens dot edu
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-01-30 20:02 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

--- Comment #16 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
It seems to be working perfectly so far in that context which is definitely a
step in the right direction.

Do we know if/when said fix will be implemented into other terminals (MSYS2,
MINGW64, Built-in Windows Terminal)?

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

* [Bug c++/30045] GDB crashes when command is used during layout
  2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
                   ` (16 preceding siblings ...)
  2023-01-30 20:02 ` mmoskow1 at stevens dot edu
@ 2023-02-05  0:24 ` mmoskow1 at stevens dot edu
  17 siblings, 0 replies; 19+ messages in thread
From: mmoskow1 at stevens dot edu @ 2023-02-05  0:24 UTC (permalink / raw)
  To: gdb-prs

https://sourceware.org/bugzilla/show_bug.cgi?id=30045

Moshe Moskowitz <mmoskow1 at stevens dot edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #17 from Moshe Moskowitz <mmoskow1 at stevens dot edu> ---
Hey,
So upon further research, even with the new terminal, while the terminal itself
wasn't crashing, the program running within the TUI would crash, however, a
simple online search found that Setting the gdb to "set new-console on" would
fix the issue.

Source:
https://stackoverflow.com/questions/71432412/gdb-error-in-tui-mode-only-during-startup-program-exited

I built that command into my gdbinit and now it all works without issue.

Thank you so much for your responses and assistance.

-- 
You are receiving this mail because:
You are on the CC list for the bug.

^ permalink raw reply	[flat|nested] 19+ messages in thread

end of thread, other threads:[~2023-02-05  0:24 UTC | newest]

Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-01-24 20:49 [Bug c++/30045] New: GDB crashes when command is used during layout mmoskow1 at stevens dot edu
2023-01-24 20:49 ` [Bug c++/30045] " mmoskow1 at stevens dot edu
2023-01-24 21:53 ` tromey at sourceware dot org
2023-01-24 22:36 ` mmoskow1 at stevens dot edu
2023-01-24 23:17 ` tromey at sourceware dot org
2023-01-25  0:42 ` mmoskow1 at stevens dot edu
2023-01-25  1:52 ` tromey at sourceware dot org
2023-01-25  2:15 ` mmoskow1 at stevens dot edu
2023-01-25  2:16 ` mmoskow1 at stevens dot edu
2023-01-25 18:26 ` mmoskow1 at stevens dot edu
2023-01-26 19:33 ` mmoskow1 at stevens dot edu
2023-01-26 20:11 ` tromey at sourceware dot org
2023-01-26 22:59 ` mmoskow1 at stevens dot edu
2023-01-28 19:28 ` ssbssa at sourceware dot org
2023-01-28 23:49 ` mmoskow1 at stevens dot edu
2023-01-30 17:04 ` mmoskow1 at stevens dot edu
2023-01-30 17:22 ` ssbssa at sourceware dot org
2023-01-30 20:02 ` mmoskow1 at stevens dot edu
2023-02-05  0:24 ` mmoskow1 at stevens dot edu

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).