Implementation of quicksort in C

quicksort.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#define _int uint8_t

_int *quicksort(_int *arr, int size_of_arr) {

  if (size_of_arr <= 1)
    return arr;

  _int *current_arr = arr + 1;

  _int *smaller = malloc(sizeof(arr) - 1);
  _int *bigger = malloc(sizeof(arr) - 1);

  int smaller_count = 0;
  int bigger_count = 0;

  _int pivot_value = arr[0];

  int i;
  for (i = 0; i < size_of_arr - 1; i++) {
    if (current_arr[i] <= pivot_value)
      smaller[smaller_count++] = current_arr[i];
    else
      bigger[bigger_count++] = current_arr[i];
  }

  smaller = quicksort(smaller, smaller_count);
  bigger = quicksort(bigger, bigger_count);

  for (i = 0; i < smaller_count; i++)
    arr[i] = smaller[i];

  arr[i++] = pivot_value;

  int m;
  for (m = 0; m < bigger_count; m++)
    arr[m+i] = bigger[m];

  free(smaller);
  smaller = NULL;

  free(bigger);
  bigger = NULL;

  return arr;
}

int main() {
  printf("Beginning quicksort thingy\n\n");
  int size_of_arr = 10;

  _int *arr_to_sort = malloc(size_of_arr);
  arr_to_sort[0] = 3;
  arr_to_sort[1] = 4;
  arr_to_sort[2] = 1;
  arr_to_sort[3] = 6;
  arr_to_sort[4] = 2;
  arr_to_sort[5] = 15;
  arr_to_sort[6] = 8;
  arr_to_sort[7] = 1;
  arr_to_sort[8] = 3;
  arr_to_sort[9] = 1;

  printf( "Before sort:\n" );

  int j;
  for (j = 0; j < size_of_arr; j++)
    printf("%i\n", (int)arr_to_sort[j]);

  (void)quicksort(arr_to_sort, size_of_arr);

  printf( "\nAfter sort:\n" );

  for (j = 0; j < size_of_arr; j++)
    printf("%i\n", arr_to_sort[j]);

  free(arr_to_sort);

  return 0;
}