Return value from open() not checked.

        6. negative_return_fn: Function open("zone.bin", 2) returns a negative number.
   	7. assign: Assigning: fd = open("zone.bin", 2).
334        fd = open("zone.bin", O_RDWR);
   	
CID 1452692 (#1 of 1): Improper use of negative value (NEGATIVE_RETURNS)
8. negative_returns: fd is passed to a parameter that cannot be negative. [show details]

   	52. negative_return_fn: Function open("zone.bin", 2) returns a negative number.
   	53. assign: Assigning: fd = open("zone.bin", 2).
394                fd = open("zone.bin", O_RDWR);
   	
CID 1452709 (#1 of 1): Improper use of negative value (NEGATIVE_RETURNS)
54. negative_returns: fd is passed to a parameter that cannot be negative. [show details]