Re: [PATCH v3 2/4] kstrtox: introduce a safer version of memparse()
From: Randy Dunlap
Date: Thu Jan 04 2024 - 01:51:18 EST
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