realloc bug?

There is a bug in dietlibc realloc.  Build and start next file 
with strace and see that it uses 12 pages for 12 bytes at the end.
This is a good exercise for my students to fix the bug!

Another bug exists if one sets WANT_MALLOC_ZERO in dietfeatures.h
This is not very well tested (I'm not 100% sure).


-------------------
#include <stdlib.h>
#include <fime.h>

#define M 12
int main() {
  char *x[M];
  int k;
  for (k=0; k<M; k++)
    x[k] = malloc(6000);

  for (k=0; k<M; k++)
    if (x[k]) 
      realloc(x[k], 3000);

  for (k=0; k<M; k++)
    if (x[k]) 
      realloc(x[k], 1);

  /* sleep(300); */ 
  return 0;
}
-------------------

Nilkola

http://riemann.fmi.uni-sofia.bg/programs/diet/alloc.tar.gz
Seems that this realloc does not have above bug!  May be it have other, 
but I don't know where they are yet ;-)