[pacman-dev] [PATCH v2 2/2] Update the question callback

[Olivier Brunel]

On 06/24/14 08:14, Allan McRae wrote:
> On 26/05/14 01:30, Andrew Gregory wrote:
>> On 05/24/14 at 03:49pm, Olivier Brunel wrote:
>>> Much like with events, instead of using a bunch of void* arguments for
>>> all questions, we now send one pointer to an alpm_question_t struct.
>>> This contains the type of question that was triggered.
>>>
>>> With this information, the pointer can then be typecasted to the
>>> question-specific struct in order to get additional arguments.
>>>
>>> Signed-off-by: Olivier Brunel <jjk at jjacky.com>
>>> ---
>>>  lib/libalpm/alpm.h    |  92 +++++++++++++++++++++++++++++++++++++++--
>>>  lib/libalpm/deps.c    |  38 ++++++++++-------
>>>  lib/libalpm/handle.h  |   4 +-
>>>  lib/libalpm/signing.c |  12 ++++--
>>>  lib/libalpm/sync.c    |  60 +++++++++++++++++----------
>>>  src/pacman/callback.c | 110 +++++++++++++++++++++++++++-----------------------
>>>  src/pacman/callback.h |   3 +-
>>>  7 files changed, 222 insertions(+), 97 deletions(-)
>>
>> The generic to specific struct casts cause Clang to fail when pacman
>> is configured with --enable-warningflags:
>>
>>  callback.c:377:44: error: cast from 'alpm_question_t *' (aka 'struct
>>        _alpm_question_t *') to 'alpm_question_install_ignorepkg_t *'
>>        (aka 'struct _alpm_question_install_ignorepkg_t *') increases
>>        required alignment from 4 to 8 [-Werror,-Wcast-align]
>>    ...*q = (alpm_question_install_ignorepkg_t *) question;
>>            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
> 
> These are silenced.
> 
>> The earlier changes to the event callback have the same issue and also
>> give errors about using non-literal strings with vprintf:
>>
>>  testdb.c:53:11: error: format string is not a string literal
>>        [-Werror,-Wformat-nonliteral]
>>                  vprintf(event->fmt, event->args);
>>                          ^~~~~~~~~~
> 
> 
> BAH!   Why did gcc no see this?
> 
> Anyway, possible ways to fix this:
> 
> 1)
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wformat-nonliteral"
>                 vprintf(event->fmt, event->args);
> +#pragma GCC diagnostic pop
> 
> This is crap because all clients that want to print a log message will
> need to wrap their calls like this.
> 
> 2)
> Revert that change that made the logging an event.
> 
> 
> Unless someone comes up with something else, I'll do the revert soon.

I can't think of another way to silence the warning, but there's a way
to "work around" it: instead of putting fmt & args inside
alpm_event_log_t, we put the resulting string (i.e. call pm_asprintf()
in alpm and send the resulting string in the event).

No more false warnings then (but a malloc/free for each log event). I
can send a patch if you'd like.

-j

> 
> Allan
>