From: Paul Eggert <eggert@cs.ucla.edu>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>,
"Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>
Subject: Re: bug in roundup(3) from <sys/param.h>
Date: Tue, 17 Jan 2023 12:11:27 -0800 [thread overview]
Message-ID: <59e67ba9-a379-16e9-3300-8f7d6114bf5c@cs.ucla.edu> (raw)
In-Reply-To: <PAWPR08MB898295545D7DDC1F4051E95F83C69@PAWPR08MB8982.eurprd08.prod.outlook.com>
On 1/17/23 11:16, Wilco Dijkstra via Libc-alpha wrote:
> So it seems best to state it only works on unsigned values (with y > 0 since division
> by zero is undefined behaviour of course) and it's implementation defined whether
> overflow wraps or saturates.
roundup works just fine on signed integers. Although x should be
nonnegative and y should be positive, there's no requirement that either
x or y must be unsigned.
This sort of thing matters in the C style I prefer nowadays, which is to
use types like ptrdiff_t and idx_t instead of size_t, so that I can
optionally enable runtime overflow checking that works.
next prev parent reply other threads:[~2023-01-17 20:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 19:16 Wilco Dijkstra
2023-01-17 19:50 ` Alejandro Colomar
2023-01-17 20:11 ` Paul Eggert [this message]
2023-01-17 20:13 ` Alejandro Colomar
2023-01-17 20:24 ` [RFC] roundup.3: New page documenting roundup(3) (was: bug in roundup(3) from <sys/param.h>) Alejandro Colomar
2023-01-17 21:53 ` Paul Eggert
2023-01-17 22:29 ` Alejandro Colomar
-- strict thread matches above, loose matches on Subject: below --
2023-01-16 20:46 bug in roundup(3) from <sys/param.h> Alejandro Colomar
2023-01-17 2:22 ` Alejandro Colomar
2023-01-17 14:55 ` Adhemerval Zanella Netto
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