ref: a4f55bc2a984f51aa2afef82f7f6257dece7a09d
dir: /src/libc/string/memchr.c/
#include <string.h>
#undef memchr
void *
memchr(const void *s, int c, size_t n)
{
const unsigned char *bp = s;
while (n > 0 && *bp++ != c)
--n;
return (n == 0) ? NULL : bp-1;
}