Re: vanishing history

[Adam Spiers <adam@xxxxxxxxxx>]

[moved to zsh-workers]

Wayne Davison (wayned@xxxxxxxxxxxxxxxxxxxxx) wrote:
> On Wed, 28 Nov 2001, Adam Spiers wrote:
> > Does anyone have any idea why my .zshhistory occasionally looses the
> > vast majority of its contents?  I can't reproduce it, so I can't begin
> > to track down what's going on.
> 
> I've seen this from time to time, but also have been unable to reproduce
> it.  In pouring over the code I did finally see one potential way that
> the loss of contents could happen: if the history file is locked by
> another process while we're trying to rewrite it.  Here's the fix (which
> causes us to just punt on the rewrite if we read nothing):
> 
> Index: Src/hist.c
> --- Src/hist.c	16 Feb 2002 09:15:07 -0000	1.39
> +++ Src/hist.c	16 Feb 2002 09:21:16 -0000
> @@ -2083,7 +2083,8 @@
>  	    hist_ignore_all_dups |= isset(HISTSAVENODUPS);
>  	    readhistfile(fn, err, 0);
>  	    hist_ignore_all_dups = isset(HISTIGNOREALLDUPS);
> -	    savehistfile(fn, err, 0);
> +	    if (histlinect)
> +		savehistfile(fn, err, 0);
>  	    deletehashtable(histtab);
> 
>  	    curhist = remember_curhist;

Thanks for that.  I've found a way to reproduce the bug, and this
patch (or at least, the combination of all cvs commits over the last
few weeks) makes zsh core dump when I try that way, which is to simply
type ^X?, which is bound to _complete_debug.  This somehow manages to
reset the history file to almost empty.  I've tracked it as far as the
inc_append_history option, which disabling stops the core dump.
Beyond that I'm out of my depth.