From: Otto Moerbeek <otto@drijf.net>
Subject: Re: tog: 'q' exits instead of quitting view (FreeBSD)
To: Christian Weisgerber <naddy@mips.inka.de>
Cc: gameoftrees@openbsd.org
Date: Sun, 15 Nov 2020 08:11:03 +0100

On Sun, Nov 15, 2020 at 12:20:16AM +0100, Christian Weisgerber wrote:

> Stefan Sperling:
> 
> > > I start tog log,
> > > hit 't' to switch to tree view,
> > > hit 'l' to switch to log view for a file,
> > > hit enter for the latest diff,
> > > hit 'q' and ...
> > > 
> > > ... on FreeBSD, tog exits.  No error.  It's as if I had hit 'Q'.
> > 
> > Can you find out which condition causes view_loop() to exit?
> 
> dead_view == main_view && new_view == NULL
> 
> It's a bug hidden by memory randomization, which FreeBSD does not
> have, at least by default.

but but but randomization is supposed to find bugs ... :-)

> The sequence above is:
> 1. open first log view
>    => this view is remembered in main_view
> 2. open tree view
> 3. open second log view, closes first log view and tree view
>    => the memory of the first log view and the tree view is free()ed
> 4. open diff view
>    => malloc() returns the memory previously occupied by the first
>       log view
>    => the new diff view now matches main_view

This scenario can happen on OpenBSD as wel, it is just less likely.

	-Otto