PROBLEM: memory leak in LIST_*, TAILQ_* man page

PROBLEM: memory leak in LIST_*, TAILQ_* man page

[David Leppik]

My apologies if this is the wrong mailing list;  I didn't find a better one.

The man page for TAILQ_REMOVE, etc. contains the following sample code:

while (head.tqh_first != NULL)
     TAILQ_REMOVE(&head, head.tqh_first, entries);

I checked /usr/include/sys/queue.h and, sure enough, TAILQ_REMOVE 
doesn't free
head.tqh_first.  Nor should it-- this isn't Objective-C, after all. :-)

It should be something like:

while (head.tqh_first != NULL) {
              np = head.tqh_first;
              TAILQ_REMOVE(&head, np, entries);
              free(np);
}


The same bug is repeated for all the data structures in this man page.


In this day and age of Java, C#, and Objective-C programmers, kids these 
days
are less likely to remember to clean up after themselves.  Therefore it was
particularly jarring to find this bug.  Ten years ago I might have 
laughed it
off.  That's probably why it's been around for so long.

David

[OT] Re: PROBLEM: memory leak in LIST_*, TAILQ_* man page

[YOSHIFUJI Hideaki / 吉藤英明]

In article <43530379.6040504@vocalabs.com> (at Sun, 16 Oct 2005 20:50:49 -0500), David Leppik <dleppik@vocalabs.com> says:

> The man page for TAILQ_REMOVE, etc. contains the following sample code:
> 
> while (head.tqh_first != NULL)
>      TAILQ_REMOVE(&head, head.tqh_first, entries);
> 
> I checked /usr/include/sys/queue.h and, sure enough, TAILQ_REMOVE 
> doesn't free
> head.tqh_first.  Nor should it-- this isn't Objective-C, after all. :-)
> 
> It should be something like:
> 
> while (head.tqh_first != NULL) {
>               np = head.tqh_first;
>               TAILQ_REMOVE(&head, np, entries);
>               free(np);
> }

Wrong. People do not always destroy the item removed
from the list, I think.

--yoshfuji