text: #include <u.h>
  #include <libc.h>
  
  /*
   * Return pointer to first occurrence of s2 in s1,
   * 0 if none
   */
  Rune*
  runestrstr(Rune *s1, Rune *s2)
  {
  	Rune *p, *pa, *pb;
  	int c0, c;
  
  	c0 = *s2;
  	if(c0 == 0)
  		return s1;
  	s2++;
  	for(p=runestrchr(s1, c0); p; p=runestrchr(p+1, c0)) {
  		pa = p;
  		for(pb=s2;; pb++) {
  			c = *pb;
  			if(c == 0)
  				return p;
  			if(c != *++pa)
  				break;
  		}
  	}
  	return 0;
  }
  