Re: [PATCH v3 2/4] kstrtox: introduce a safer version of memparse()

Qu Wenruo
2024-01-04T06:56:37Z

On 2024/1/4 17:20, Randy Dunlap wrote:
>
>
> On 1/3/24 22:42, Qu Wenruo wrote:
>>
>>
>> On 2024/1/4 17:00, Randy Dunlap wrote:
>>> Hi,
>>>
>> [...]
>>>> + *        parameter.
>>>> + *
>>>> + * @suffixes:    The suffixes which should be parsed. Use logical ORed
>>>> + *        memparse_suffix enum to indicate the supported suffixes.
>>>> + *        The suffixes are case-insensive, all 2 ^ 10 based.
>>>
>>>                          case-insensitive
>>>
>>>> + *        Supported ones are "KMGPTE".
>>>> + *        NOTE: If one suffix out of the supported one is hit, it would
>>>
>>>                                                  ones
>>>
>>>> + *        end the parse normally, with @retptr pointed to the unsupported
>>>> + *        suffix.
>>>
>>> Could you explain (or give an example) of "to the unsupported suffix"?
>>> This isn't clear IMO.
>>
>> Oh, my bad, that sentence itself is not correct.
>>
>> What I really want to say is:
>>
>>  If one suffix (one of "KMGPTE") is hit but that suffix is not
>>  specified in the @suffxies parameter, it would end the parse normally,
>>  with @retptr pointed to the (unsupported) suffix.
>
> (corrected ^^^)
>
>> The example would be the "68k " case in the ok cases in the next patch.
>> We have two different cases for the same "68k" string, with different
>> @suffixes and different results:
>>
>>     "68k ", KMGPTE -> 68 * 1024, @retptr at " ".
>>     "68k ", M -> 68, @retptr at 'k'.
>>
>> I don't have a better expression here unfortunately, maybe the special
>> case is not even worthy explaining?
>>
>
> No, the corrected paragraph above is good. (s/would end/ends/)
>
> Except for one thing: the examples here terminate on a space character,
> but the function kernel-doc says "null-terminated":

Oh, all the strings used here and in the test cases are all "\0" ended.
Just to make it a little more readable (and easier to type), the tailing
"\0" is not explicitly showed.

That extra ' ' in the "68k \0" case is just to make sure the @retptr is
properly updated.

For all the other existing ok cases for memparse_safe() (those without
extra tailing chars), the @retptr points to the tailing NUL '\0'.

Thanks,
Qu

>
> +/**
> + * memparse_safe - convert a string to an unsigned long long, safer version of
> + * memparse()
> + *
> + * @s: The start of the string. Must be null-terminated.
>
>
>
>
>>>
>>>> + *
>>>> + * @res:    Where to write the result.
>>>> + *
>>>> + * @retptr:    (output) Optional pointer to the next char after parse completes.
>>>> + *
>>>> + * Return 0 if any valid numberic string can be parsed, and @retptr updated.
>>>> + * Return -INVALID if no valid number string can be found.
>>>> + * Return -ERANGE if the number overflows.
>>>> + * For minus return values, @retptr would not be updated.
>>>
>>>   * Returns:
>>>   * * %0 if any valid numeric string can be parsed, and @retptr is updated.
>>>   * * %-EINVAL if no valid number string can be found.
>>>   * * %-ERANGE if the number overflows.
>>>   * * For negative return values, @retptr is not updated.
>>>
>>>
>>> For *ALL* of the comments, I request/suggest that you change the "would be" or
>>> "would not be" to "is" or "is not" or whatever present tense words make the
>>> most sense.
>>
>> No problem.
>
>