1  #include <stdio.h>
       2  #include <stdlib.h>
       3  
       4  char *array;
       5  char *array_end;
       6  size_t member_size;
       7  
       8  int
       9  compare (const void *a1, const void *b1)
      10  {
      11    const char *a = a1;
      12    const char *b = b1;
      13  
      14    if (! (array <= a && a < array_end
      15  	 && array <= b && b < array_end))
      16      {
      17        puts ("compare arguments not inside of the array");
      18        exit (EXIT_FAILURE);
      19      }
      20    int ret = b[0] - a[0];
      21    if (ret)
      22      return ret;
      23    if (member_size > 1)
      24      return b[1] - a[1];
      25    return 0;
      26  }
      27  
      28  int
      29  test (size_t nmemb, size_t size)
      30  {
      31    array = malloc (nmemb * size);
      32    if (array == NULL)
      33      {
      34        printf ("%zd x %zd: no memory", nmemb, size);
      35        return 1;
      36      }
      37  
      38    array_end = array + nmemb * size;
      39    member_size = size;
      40  
      41    char *p;
      42    size_t i;
      43    size_t bias = random ();
      44    for (i = 0, p = array; i < nmemb; i++, p += size)
      45      {
      46        p[0] = (char) (i + bias);
      47        if (size > 1)
      48  	p[1] = (char) ((i + bias) >> 8);
      49      }
      50  
      51    qsort (array, nmemb, size, compare);
      52  
      53    for (i = 0, p = array; i < nmemb - 1; i++, p += size)
      54      {
      55        if (p[0] < p[size]
      56  	  || (size > 1 && p[0] == p[size] && p[1] < p[size + 1]))
      57  	{
      58  	  printf ("%zd x %zd: failure at offset %zd\n", nmemb,
      59  		  size, i);
      60  	  free (array);
      61  	  return 1;
      62  	}
      63      }
      64  
      65    free (array);
      66    return 0;
      67  }
      68  
      69  int
      70  main (int argc, char **argv)
      71  {
      72    int ret = 0;
      73    if (argc >= 3)
      74      ret |= test (atoi (argv[1]), atoi (argv[2]));
      75    else
      76      {
      77        ret |= test (10000, 1);
      78        ret |= test (200000, 2);
      79        ret |= test (2000000, 3);
      80        ret |= test (2132310, 4);
      81        ret |= test (1202730, 7);
      82        ret |= test (1184710, 8);
      83        ret |= test (272710, 12);
      84        ret |= test (14170, 32);
      85        ret |= test (4170, 320);
      86      }
      87  
      88    return ret;
      89  }