From: Alejandro Colomar <alx.manpages@gmail.com>
To: Wilco Dijkstra <Wilco.Dijkstra@arm.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>
Subject: Re: bug in roundup(3) from <sys/param.h>
Date: Tue, 17 Jan 2023 20:50:49 +0100 [thread overview]
Message-ID: <dc946fc9-ca08-8a58-f942-29ae727eb1c2@gmail.com> (raw)
In-Reply-To: <PAWPR08MB898295545D7DDC1F4051E95F83C69@PAWPR08MB8982.eurprd08.prod.outlook.com>
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Hi Wilco and Adhemerval!
On 1/17/23 20:16, Wilco Dijkstra wrote:
> Hi,
>
>> I really won't bother with this interface, since potentially changing it
>> might generate more potentially breakage than improvements.
>
> The typical use-case is rounding up a pointer to align it or increasing a buffer
> to be allocated. There is no chance of overflow in these cases since you will
> never have pointers that close to SIZE_MAX or get buffers close to the maximum
> memory size. And adding saturation would mean we didn't do what was requested
> either...
>
> 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.
>
Thanks! That clarifies what this macro is for. I'll document that.
Cheers,
Alex
> Cheers,
> Wilco
--
<http://www.alejandro-colomar.es/>
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next prev parent reply other threads:[~2023-01-17 19:51 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 [this message]
2023-01-17 20:11 ` Paul Eggert
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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