Re: [Libevent-users]

[Nick Mathewson <nickm@xxxxxxxxxxxxx>]

On Wed, Nov 17, 2010 at 9:26 PM, Ken Feng <kfmfe04@xxxxxxxxx> wrote:
> Hi,
>
> I am a new user of libevent - I ran into the following valgrind error
> on my machine:
>
> Version: libevent-2.0.8-rc
> OS: Ubuntu 10.04 LTS amd64
>
> Of interest is (bufferevent_sock.c:321) inside:
> struct bufferevent *bufferevent_socket_new()
>
> struct bufferevent_private *bufev_p;
> // ...
> if ((bufev_p = mm_calloc(1, sizeof(struct bufferevent_private)))== NULL)
> // ...
> // ----------------------------------------
>
> bufev_p doesn't seem to get freed with mm_free() unless there is an error.

Right, because bufev_p is the thing that is actually returned by the
bufferevent_socket_new() function.  The function allocates a struct
bufferevent_private, with an internal struct bufferevent, and on
success returns to the user a pointer to the struct bufferevent.
Later, when you call bufferevent_free, it upcasts the bufferevent to
get the pointer to the actual allocated thing, and frees that:

	/* Free the actual allocated memory. */
	mm_free(((char*)bufev) - bufev->be_ops->mem_offset);

Probably, you aren't actually calling bufferevent_free on the bufferevent here.
-- 
Nick
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