From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <sourceware-bugzilla@sourceware.org>
Received: by sourceware.org (Postfix, from userid 48)
 id B1CDD385AC28; Mon,  7 Mar 2022 21:38:41 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B1CDD385AC28
From: "aburgess at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug gdb/28948] New: Enabling/disabling logging over an interpreter
 switch can crash gdb
Date: Mon, 07 Mar 2022 21:38:41 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gdb
X-Bugzilla-Component: gdb
X-Bugzilla-Version: HEAD
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: aburgess at redhat dot com
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at sourceware dot org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-28948-4717@http.sourceware.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://sourceware.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gdb-prs@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gdb-prs mailing list <gdb-prs.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/gdb-prs>,
 <mailto:gdb-prs-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/gdb-prs/>
List-Help: <mailto:gdb-prs-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/gdb-prs>,
 <mailto:gdb-prs-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Mon, 07 Mar 2022 21:38:41 -0000

https://sourceware.org/bugzilla/show_bug.cgi?id=3D28948

            Bug ID: 28948
           Summary: Enabling/disabling logging over an interpreter switch
                    can crash gdb
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: aburgess at redhat dot com
  Target Milestone: ---

Try this GDB session:

 (gdb) file /path/to/some/executable
 (gdb) set logging file /tmp/gdb.log
 (gdb) set logging debugredirect on=20
 (gdb) set logging enabled on=20
 Copying output to /tmp/gdb.log.
 Redirecting debug output to /tmp/gdb.log.
 (gdb) set debug infrun 1
 (gdb) start
 ... snip ...
 (gdb) tui enable

 # Then at the TUI prompt:

 (gdb) set logging debugredirect off
 (gdb) set logging enabled off
 (gdb) stepi
 (gdb) stepi
 (gdb) stepi

 # By this point GDB has usually crashed for me.

This is very similar to this bug:

  https://sourceware.org/bugzilla/show_bug.cgi?id=3D28620

It might almost be considered a duplicate of that bug, but I'm not 100% sure
the same fix for the previous will also fix this, though the underlying pro=
blem
is identical in nature.

What happens is that when we enable logging, GDB stashes the current output
file descriptors to one side, and replaces them with alternative file
descriptors.  Then, when we switch interpreter (tui enable) we replace the
current output streams with the streams for the new interpreter.

Then, when we disable logging, we replace the current streams (those for the
tui now) with the earlier backed up streams (those from before logging was
enabled), which happen to be the streams for the CLI.

At this point, weird stuff happens.  Usually the TUI will immediately disap=
pear
from the screen, and usually GDB crashes pretty quickly.

--=20
You are receiving this mail because:
You are on the CC list for the bug.=