Subject: Re: /etc/login.conf required to exist after user(8) changes
To: None <>
From: Peter Seebach <>
List: current-users
Date: 07/29/2005 06:32:35
In message <>, John Nemeth write
>     I think more to the point, it is irrelevant that the pointer has
>been freed.  It will still contain the same value.  The freeing
>function can not modify the pointer itself; therefore, the second half
>of the patch is completely unnecessary.  Trying to use the data pointed
>to by the pointer would be wrong; however, the original code doesn't do
>this, it merely compares the pointer to NULL.

To be picky, there exist C implementations where at least some, possibly
all, pointers to freed space compare equal to NULL.

However, there also exist platforms on which any reference to them, even
a comparison to NULL, causes undefined behavior.

If the pointer is freed, it should not be referenced, even to compare it
to NULL.