Re: [Qemu-devel] [PATCH] qemu-sockets: Fix assertion failure

[Laszlo Ersek <lersek@redhat.com>]

On 03/06/13 12:11, Kevin Wolf wrote:
> Am 06.03.2013 um 12:04 hat Paolo Bonzini geschrieben:
>> Il 06/03/2013 11:48, Kevin Wolf ha scritto:
>>> inet_connect_opts() tries all possible addrinfos returned by
>>> getaddrinfo(). If one fails with an error, the next one is tried. In
>>> this case, the Error should be discarded because the whole operation is
>>> successful if another addrinfo from the list succeeds; and if it
>>> doesn't, setting an already set Error will trigger an assertion failure.
>>>
>>> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
>>> ---
>>>  util/qemu-sockets.c | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
>>> index 1350ccc..32e609a 100644
>>> --- a/util/qemu-sockets.c
>>> +++ b/util/qemu-sockets.c
>>> @@ -373,6 +373,14 @@ int inet_connect_opts(QemuOpts *opts, Error **errp,
>>>      }
>>>  
>>>      for (e = res; e != NULL; e = e->ai_next) {
>>> +
>>> +        /* Overwriting errors isn't allowed, so clear any error that may have
>>> +         * occured in the previous iteration */
>>> +        if (error_is_set(errp)) {
>>> +            error_free(*errp);
>>> +            *errp = NULL;
>>> +        }
>>> +
>>>          if (connect_state != NULL) {
>>>              connect_state->current_addr = e;
>>>          }
>>>
>>
>> Should we also do nothing if errp is not NULL on entry?
> 
> We could assert(!error_is_set(errp)) if we wanted. As soon as you've got
> an Error, you must return instead of calling more functions with the
> same error pointer.

I think Luiz would suggest (*) to receive any error into a
NULL-initialized local_err pointer; do the logic above on local_err, and
just before returning, error_propagate() it to errp.

(*) I hope you can see what I did there: if you disagree, you get to
take that to Luiz, even though he didn't say anything. I'm getting
better at working this list! :)

Laszlo