>> void *
>> memmem(const void *b1, const void *b2, size_t len1, size_t len2);

glibc already has memmem(), but the order of its arguments is
different as follows:

:        void *memmem(const void *haystack, size_t haystacklen,
:               const void *needle, size_t needlelen);
: 
: DESCRIPTION
:        The  memmem() function finds the start of the first occur,A-(B
:        rence of the substring needle of length needlelen  in  the
:        memory area haystack of length haystacklen.
: 
: RETURN VALUE
:        The  memmem()  function returns a pointer to the beginning
:        of the substring, or NULL if the substring is not found.

I guess it's better to be compatible with the existing one, at least.
--
soda