From: Omar Polo <op@omarpolo.com>
Subject: Re: ksh: use strtonum()
To: "Todd C. Miller" <millert@openbsd.org>
Cc: tech@openbsd.org
Date: Tue, 27 Aug 2024 20:50:54 +0200

On 2024/08/26 18:49:53 -0600, Todd C. Miller <millert@openbsd.org> wrote:
> On Mon, 26 Aug 2024 23:43:54 +0200, Omar Polo wrote:
> 
> > I don't think, because it is expected to handle also !-N which is
> > different from !N.
> >
> > It's the `start + rec + 1' part at the end of the function that handles
> > the negative numbers turning them into the offset of the _last_ nth
> > command, instead of the nth command.
> 
> Ah, I see.  So that:
>     return start + rec + 1;
> 
> is equivalent to:
>     return rec + maxhist;

yep.  actually, i think it would be easier if written like this


Index: history.c
===================================================================
RCS file: /cvs/src/bin/ksh/history.c,v
diff -u -p -r1.85 history.c
--- history.c	27 Aug 2024 18:45:58 -0000	1.85
+++ history.c	27 Aug 2024 18:48:12 -0000
@@ -509,7 +509,6 @@ findhistrel(const char *str)
 {
 	const char *errstr;
 	int	maxhist = histptr - history;
-	int	start = maxhist - 1;
 	int	rec;
 
 	rec = strtonum(str, -maxhist, maxhist, &errstr);
@@ -520,7 +519,7 @@ findhistrel(const char *str)
 		return -1;
 	if (rec > 0)
 		return rec - 1;
-	return start + rec + 1;
+	return maxhist + rec;
 }
 
 void