[alsa-devel] [alsa-lib][PATCH] control: correct assertion in snd_ctl_elem_set_bytes()

[Takashi Sakamoto]

On Feb 22 2016 18:51, Takashi Iwai wrote:
> On Mon, 22 Feb 2016 01:34:30 +0100,
> Takashi Sakamoto wrote:
>>
>> Hi,
>>
>> On Feb 22 2016 02:46, Takashi Iwai wrote:
>>> On Sun, 21 Feb 2016 17:54:09 +0100,
>>> Takashi Sakamoto wrote:
>>>>
>>>> The assert(3) aborts running process when expression arguments is
>>>> false (zero). Although, the snd_ctl_elem_set_bytes() has return
>>>> statement after assert(3). It has meaningless.
>>>
>>> Admittedly this isn't an optimal code, but it has its purpose.
>>> The intention of the original code was to perform the check always but
>>> triggers the assert signal unless NDEBUG is set (remember that
>>> assert() is nop when NDEBUG is defined).
>>
>> Although I realized the effect of NDEBUG for calls of asset(3), I didn't
>> realize the intension to the code, because the other parts of
>> 'src/control/control.c' are written without such intention. We can see
>> many assert(3)s are just used without conditional statements.
>>
>> Hm. I think it better to keep consistency of whole codes rather than
>> such partial intensions. On the other hand, this patch changes library
>> behaviour. It's not generally allowed, but here, I think it better
>> because of the consistency and the actual effect.
> 
> Yeah, that's mostly OK to make it a simple assert.
> 
> Or, if I may judge only from my taste, even removing the assert would
> be nicer.  Triggering assert() is one of the worst behavior as a base
> system library.

I completely agree with the idea ;)

Although, it's out of my plan in this developing cycle. In this time, I
hope just to apply this patch and go to my next work for control element
set APIs. I should post revised version?


Regards

>>>> This commit corrects the statements.
>>>>
>>>> Fixes: 7893ea238d5a('Added mode argument to open functions where it was missing. First part of CTL documentation')
>>>> Signed-off-by: Takashi Sakamoto <o-takashi at sakamocchi.jp>
>>>> ---
>>>>  src/control/control.c | 5 +----
>>>>  1 file changed, 1 insertion(+), 4 deletions(-)
>>>>
>>>> diff --git a/src/control/control.c b/src/control/control.c
>>>> index 328920d..70d168d 100644
>>>> --- a/src/control/control.c
>>>> +++ b/src/control/control.c
>>>> @@ -2627,10 +2627,7 @@ void snd_ctl_elem_value_set_byte(snd_ctl_elem_value_t *obj, unsigned int idx, un
>>>>  void snd_ctl_elem_set_bytes(snd_ctl_elem_value_t *obj, void *data, size_t size)
>>>>  {
>>>>  	assert(obj);
>>>> -	if (size >= ARRAY_SIZE(obj->value.bytes.data)) {
>>>> -		assert(0);
>>>> -		return;
>>>> -	}
>>>> +	assert(size < ARRAY_SIZE(obj->value.bytes.data));
>>>>  	memcpy(obj->value.bytes.data, data, size);
>>>>  }
>>>>  
>>>> -- 
>>>> 2.5.0
>>>>
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