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From: "phi.debian at gmail dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug tui/26036] GDB core dump TUI + rl
Date: Wed, 27 May 2020 07:00:29 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D26036

--- Comment #2 from Phi <phi.debian at gmail dot com> ---
Well in case someone takes ownership, here is my finding.

I am NOT c++ aware, and I don't know GDB software organisation at all, so I=
 may
be completly out of bounds.

To me TUI is the culprit (not RL that got a NULL *FILE).

In the function=20
/ldev/gdb-9.[12]/gdb/tui/tui-io.c
tui_setup_io (int mode)=20=20=20=20=20=20=20=20=20
{
}

When mode=3D=3D1 (curses) there is a killing sequence.

  if (mode)
    {
      /* Redirect readline to TUI.  */
...
      tui_old_rl_outstream =3D rl_outstream;
...
      rl_outstream =3D tui_rl_outstream;
...

    }

When run with -tui  we enter here with RL not initialised, then
rl_outstream=3D=3D0, later on on GDB first prompt, we strike ^X^A, tui rest=
ore the
tui_old_rl_outstream that is still 0x0 (whatever RL got initialised), then
kaboom.

To me a fix 'could be'=20
<    tui_old_rl_outstream =3D rl_outstream;
>    tui_old_rl_outstream =3D rl_outstream ? rl_outstream:tui_rl_outstream;

Because even though RL is not inited at that time, TUI is and then this is =
what
could be backed up.

I tried this on both 9.1 and 9.2 and it solve here.

BUT it may not be the final way to do this.

Good luck!
Phi

--=20
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