From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>,
"Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>
Subject: bug in roundup(3) from <sys/param.h>
Date: Tue, 17 Jan 2023 19:16:32 +0000 [thread overview]
Message-ID: <PAWPR08MB898295545D7DDC1F4051E95F83C69@PAWPR08MB8982.eurprd08.prod.outlook.com> (raw)
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.
Cheers,
Wilco
next reply other threads:[~2023-01-17 19:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 19:16 Wilco Dijkstra [this message]
2023-01-17 19:50 ` Alejandro Colomar
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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