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Date: Wed, 9 Apr 2014 15:51:16 +0300
From: Timo Teras <timo.teras@....fi>
To: u-igbb@...ey.se
Cc: musl@...ts.openwall.com
Subject: Re: memmem() - is it correct?

On Wed, 9 Apr 2014 12:49:25 +0200
u-igbb@...ey.se wrote:

> On Wed, Apr 09, 2014 at 01:19:03PM +0300, Timo Teras wrote:
> > >   const char *haystack = "abcde";
> > >   return(!memmem(haystack, 4, "cde", 3));
> 
> > > returns 1 (as I would expect it to) if linked against uclibc
> > > returns 0                           if linked against musl
> > > (on ia32)
> 
> I guess you misinterpreted the test code, there is a '!' which
> transforms a returned pointer (success) to 0 exit status in main()
> and vice versa.

Right. Should have read it more carefully.  Yes, looks like musl bug.

Perhaps something like the following is in place:

diff --git a/src/string/memmem.c b/src/string/memmem.c
index 5211d75..0594fea 100644
--- a/src/string/memmem.c
+++ b/src/string/memmem.c
@@ -138,7 +138,9 @@ void *memmem(const void *h0, size_t k, const void
*n0, size_t l) 
 	/* Use faster algorithms for short needles */
 	h = memchr(h0, *n, k);
-	if (!h || l==1) return (void *)h;
+	if (!h) return 0;
+	if (l==1) return (void *)h;
+	k -= h - h0;
 	if (l==2) return twobyte_memmem(h, k, n);
 	if (l==3) return threebyte_memmem(h, k, n);
 	if (l==4) return fourbyte_memmem(h, k, n);

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