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

Randy Dunlap
2024-01-04T06:50:58Z

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":

+/**
+ * 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.

--
#Randy