Re: [PATCH 1/7] mkfs: Save raw user input field to the opts struct

[Jan Tulak <jtulak@redhat.com>]

On 29/07/2017 19:12, Luis R. Rodriguez wrote:
> On Fri, Jul 28, 2017 at 04:45:58PM +0200, Jan Tulak wrote:
>>
>> On 27/07/2017 18:27, Luis R. Rodriguez wrote:
>>> On Thu, Jul 20, 2017 at 11:29:26AM +0200, Jan Tulak wrote:
>>>> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
>>>> index a69190b9..4b030101 100644
>>>> --- a/mkfs/xfs_mkfs.c
>>>> +++ b/mkfs/xfs_mkfs.c
>>>> @@ -107,6 +107,11 @@ unsigned int		sectorsize;
>>>>     *     sets what is used with simple specifying the subopt (-d file).
>>>>     *     A special SUBOPT_NEEDS_VAL can be used to require a user-given
>>>>     *     value in any case.
>>>> + *
>>>> + *   raw_input INTERNAL
>>>> + *     Filled raw string from the user, so we never lose that information e.g.
>>>> + *     to print it back in case of an issue.
>>>> + *
>>>>     */
>>>>    struct opt_params {
>>>>    	const char	name;
>>>> @@ -122,6 +127,7 @@ struct opt_params {
>>>>    		long long	minval;
>>>>    		long long	maxval;
>>>>    		long long	defaultval;
>>>> +		const char	*raw_input;
>>>>    	}		subopt_params[MAX_SUBOPTS];
>>>>    };
>>>> @@ -729,6 +735,18 @@ struct opt_params mopts = {
>>>>     */
>>>>    #define WHACK_SIZE (128 * 1024)
>>>> +static inline void
>>>> +set_conf_raw(struct opt_params *opt, int subopt, const char *value)
>>>> +{
>>>> +	opt->subopt_params[subopt].raw_input = value;
>>>> +}
>>> There are no bounds check on the array here, I think set_conf_raw()
>>> should return int and we would check the return value. It could
>>> return -EINVAL if the subopt is invalid for instance.
>> Good idea. The only issue is with the return code, that causes some issues
>> when we are also returning values - I wanted the values to be turned into
>> uint64. But do we need to return an error? I don't see what usecase there
>> would be for it, other than detecting a bug. So an assert might be a better
>> solution - then it can't happen that a wrong index is used and result not
>> tested.
> The setting of the value can be done by using an extra argument pointer. Then
> if its set it be assigned. Otherwise it would be left alone. The return value
> would return 0 on success, otherwise a standard return value indicating the
> cause of the error.
I strongly prefer to return the value, not an error code. We can do the 
other way around, put the error code into an argument to get roughly the 
same result, while constructions like set_conf_raw(FOO, BAR, baz * 
get_conf_raw(FOO, BAR)) will continue to work without the need for 
intermediate variables.

The *_raw functions are used on few places only, so it would be only a 
small issue there, but for consistency, (get|set)_conf_val should have 
the same behavior and an intermediate variable for every use of those 
would be really annoying. So, how about this?

static inline void
set_conf_raw(struct opt_params *opt, int subopt, const char *value, int 
*err)
{
     if (subopt < 0 || subopt >= MAX_SUBOPTS) {
         if (err != NULL) *err = EINVAL;
         return;
     }
     opt->subopt_params[subopt].raw_input = value;
}

> I don't think we need the too small or too big, a simple range issue should
> suffice and we have -ERANGE.
>
At this moment, we are telling if it is too small or too big, but when 
there is no standard error code for that, ERANGE has to suffice.

Cheers,
Jan