Date: Wed, 3 Jun 92 17:12:03 CDT
From: daniel AT asd470 DOT dseg DOT ti DOT com (Daniel Lemon)
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: malloc() doesn't return a null pointer when out of memory
Status: O

I tried compiling the following program with djgcc:
==========================
/* memory.c - allocate memory until out */

struct item
{
  int number;
  char string[100000];
  struct item *next;
} *list;

main ()
{
  struct item *ptr;
  int i=0;
  list = ptr = (struct item *) malloc (sizeof (struct item));
  while (ptr)
    {
      ptr->number = i++;
      printf ("Current pointer: %p  Number of objects: %d  Memory used: %d\n", 
              ptr, i, i * sizeof (struct item));
      ptr = ptr->next = (struct item *) malloc (sizeof (struct item));
    }
  printf ("Current pointer: %p  Number of objects: %d  Memory used: %d\n", 
	  ptr, i, i * sizeof (struct item));
}
=========================
It is supposed to keep allocating memory until there is no more memory
left, at which point I expected to get a NULL pointer returned from
malloc().  Instead, I got this error:

	Fatal! disk full writing to swap file

When I increased the size of the array item.string to 1 000 000 or 
10 000 000, my PC froze and I had to reboot.  When I increased it to
100 000 000, I got the error

	Segmentation violation in pointer 0xe8421000 at 40:1318
	Exception 14 at eip=1318

Shouldn't malloc just return a NULL pointer?  I have some
memory-hogging programs that depend on that for error checking.