Re: bug found when freeing screen(s)

[Thomas Dickey]

On Fri, 17 Sep 2010, Thomas Dickey wrote:

> On Fri, Sep 17, 2010 at 10:27:19AM +0200, Fr?d?ric Boiteux wrote:
> >     Hello,
> >
> > When porting an own application using ncurses from an old 5.5 version to
> > a current 5.7 (from Debian Lenny system), I found a bug related to free
> > of screens (the application manages multiple terminals) : when the close
> > of terminals was in the same order they was created, the application
> > segfaulted or looped indefinitely. I identified the bug in the
> > delscreen() function, and more precisely in delink_screen() where the
> > global list of screens is incorrectly updated.
> >   I've successfully tested my application with the simple patch attached.
> >
> >   I think the bug is already present in latest version of ncurses.
>
> The current code has this fix, from 2010/4/24:

The previous change to this section in 2008/3/29 introduced the error, but 
fixed a similar error.  My change comment was:

   split-out delink_screen() so I can ensure the screen is found before
   trying to free it.  Noticed this problem when looking to see how to
   use each_screen().

--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net