Re: [PATCH] utils: Reduce chance of rounding inaccuracy in qemu_strtosz.

[Eric Blake <eblake@redhat.com>]

On 3/15/21 8:18 AM, Richard Henderson wrote:
> On 3/15/21 5:33 AM, Eric Blake wrote:
>> On 3/13/21 3:48 PM, Richard Henderson wrote:
>>> On 3/11/21 2:07 PM, Eric Blake wrote:
>>>> +        /*
>>>> +         * Add in a fudge-factor (2^53 when double is IEEE format) for
>>>> +         * all scales less than P (2^50), so that things like
>>>> +         * 12.345M with unit 1000 produce 12345000 instead of
>>>> +         * 12344999.
>>>> +         */
>>>> +        if (mul > 1e49) {
>>>
>>> The comment says less than, the code says greater than.
>>
>> Shoot. A demonstration that I did not have an environment that actually
>> reproduced the bug
> 
> Any i686 vm will do.  I had a debian 10 vm hanging around in which I
> could reproduce it.

Anyways, I've now got a gitlab CI running, and even with my patch
corrected, it still failed in a different spot:
https://gitlab.com/ebblake/qemu/-/jobs/1099334550

ERROR:../tests/unit/test-cutils.c:2096:test_qemu_strtosz_units:
assertion failed (res == EiB): (1152921504606847232 == 1152921504606846976)

so I'm liking your patch in lieu of mine.
https://lists.gnu.org/archive/html/qemu-devel/2021-03/msg05290.html

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org