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Re: [review] manual: Clarify strnlen, wcsnlen, strndup null termination behavior
* Andreas Schwab:
> On Okt 30 2019, Florian Weimer wrote:
>
>> * Andreas Schwab:
>>
>>> On Okt 30 2019, Florian Weimer (Code Review) wrote:
>>>
>>>> +Note that @var{s} must be an array of at least @var{maxlen} bytes. It
>>>> +is undefined to call @code{strnlen} on a shorter array, even if it is
>>>> +known that the shorter array contains a null terminator.
>>>
>>> This is not true. strnlen _always_ stops before the null byte.
>>
>> This is not how it is specified in POSIX.
>
> Yes, it is.
>
> The strnlen() function shall return the number of bytes preceding
> the first null byte in the array to which s points, if s contains a
> null byte within the first maxlen bytes; otherwise, it shall return
> maxlen.
>
> There is nothing undefined here. Your interpretation would be
> completely useless anyway.
It says “array”, which implies a length. Admittedly, it does not say
that maxlen corresponds to the arrray length. POSIX also says this:
| The strnlen() function shall never examine more than maxlen bytes of
| the array pointed to by s.
But it does NOT say that reading stops after the first null terminator.
Thanks,
Florian