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Message-ID: <20250516125024.GI1827@brightrain.aerifal.cx>
Date: Fri, 16 May 2025 08:50:24 -0400
From: Rich Felker <dalias@...c.org>
To: Nuno Cruces <ncruces@...il.com>
Cc: musl@...ts.openwall.com
Subject: Re: strcasestr("", "") returns NULL
On Fri, May 16, 2025 at 08:32:00AM +0100, Nuno Cruces wrote:
> Hi,
>
> Currently strcasestr("", "") returns NULL which is inconsistent
> with strstr("", "").
>
> For strstr, the C standard specifies "If s2 points to a string with zero
> length, the function returns s1."
>
> strcasestr is a nonstandard extension, but to the best of my knowledge,
> both glibc and the BSDs decide to be consistent with strstr in this case.
Indeed, this should be fixed. Thanks for the report.
As an aside, strcasestr is an awful function we should probably never
have provided and that no one should use, that doesn't admit any
decent optimization. I believe it's vaguely possible to do the twoway
algorithm for the current ascii-only case equivalence strcasecmp does,
but I declined to investigate further or implement because if we ever
want to have strcasecmp do more, the effort would have been wasted (or
worse, would incentivize setting LC_ALL=C for performance purposes if
we left the code conditionally in place).
I'll write a fix and push it along with a big queue of stuff I didn't
realize had piled up.
Rich
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