docs/87548: LIST_*, TAILQ_* man pages include memory leak in sample code

[David Leppik]

>Number:         87548
>Category:       docs
>Synopsis:       LIST_*, TAILQ_* man pages include memory leak in sample code
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Oct 16 22:00:27 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     David Leppik
>Release:        None (old BSD code--see below)
>Organization:
Vocal Laboratories
>Environment:
>Description:
I've seen this on Mac OS X and Linux, so this probably affects FreeBSD as well.

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

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

I was so shocked that I checked queue.h and sure enough, TAILQ_REMOVE does not deallocate the queue entry (nor should it.)  The same is true for the other structures mentioned in this man page.
>How-To-Repeat:

>Fix:
I'm just a lowly Java programmer, but I think the fix is:

while (head.tqh_first != NULL) {
             np = head.tqh_first;
             TAILQ_REMOVE(&head, np, entries);
             free(np);
}
>Release-Note:
>Audit-Trail:
>Unformatted: