Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 10 Apr 2018 17:23:12 -0300
From: "dgutson ." <>
Subject: Re: catan errors

On Tue, Apr 10, 2018 at 4:50 PM, Rich Felker <> wrote:

> The OpenBSD catan implementation we're using has a number of
> nonsensical "overflow" (goto ovrf) conditions that aren't errors,
> reported by mepholic on irc. I think the attached patch fixes them
> without introducing new problems, but I'm not sure if any other
> problems remain.
> Note that, of the three cases removed:
> 1. Is not an exceptional case at all, and made no sense to begin with.
> 2. Is only exceptional if x and a are both zero; atan(2x,0) is
>    perfectly well-defined.
> 3. Is only possible if y==1.0 and x==0.0, which is the only real
>    exceptional case for atan: z==I.

Besides the trigonometric case, are you considering de-normalized numbers,
such as 4.94066e-324 as divisor?
For example:
    double x = 1.0;
    double y = 5E-324;
x / y is inf, and y != 0.0.
Shouldn't 'a' be checked against that number or its absolute value >=

> I opted to replace the non-obvious (3) with an explicit check for z==I
> but this isn't necessary.
> As written the patch does not address raising exception flags; that
> should be fixed before it's committed but right now I'm just
> submitting this for comments.
> Prior to the patch, at least the following (utterly dumb -- the first
> is a very real input!) cases are broken:
> - catan(1.0)
> - catan(2*I)
> - catan(I)
> Rich

Who’s got the sweetest disposition?
One guess, that’s who?
Who’d never, ever start an argument?
Who never shows a bit of temperament?
Who's never wrong but always right?
Who'd never dream of starting a fight?
Who get stuck with all the bad luck?

Content of type "text/html" skipped

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.