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Message-ID: <CACeDTm3fyhvY519b2EYHWMD=brm2MD2znp-SiAv2bBC_xYFD7Q@mail.gmail.com>
Date: Fri, 21 Mar 2014 19:10:52 +0100
From: Yves Bastide <ybastide@...il.com>
To: musl <musl@...ts.openwall.com>
Subject: Re: src/string/strstr.c, src/string/wcsstr.c: wrong estimates
for MIN(l,63)?
2014-03-21 18:44 GMT+01:00 Rich Felker <dalias@...ifal.cx>:
> On Fri, Mar 21, 2014 at 06:07:45PM +0100, Szabolcs Nagy wrote:
>> * Rich Felker <dalias@...ifal.cx> [2014-03-21 12:48:17 -0400]:
>> > On Fri, Mar 21, 2014 at 03:07:22PM +0100, Yves Bastide wrote:
>> > > /* Fast estimate for MIN(l,63) */
>> > > size_t grow = l | 63;
>> > >
>> > > "grow" is thus always at least 63...
>> >
>> > If you look at how grow is used on the very next line, this should
>> > make sense.
>>
>> the comment is wrong though
>> z grows by at least max(63,l) unless end-of-string is reached
>
> Yes, (l|63) is >= both l and 63, so it should read MAX, not MIN. The
> idea is that it's useless to grow by less than l, but it's inefficient
> to grow by less than some fixed threshold even if the needle is tiny.
>
> Rich
OK, understood.
Thanks!
yves
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