Re: Bug/Oversight in gatchat/gatresult.c with negative numbers

[Alex J Lennon <ajlennon@dynamicdevices.co.uk>]

[-- Attachment #1: Type: text/plain, Size: 1386 bytes --]

Hi Sebastian,

Please see below:

On 27/07/2021 15:38, Denis Kenzior wrote:
> Hi Alex,
>
> On 7/20/21 11:11 AM, Alex J Lennon wrote:
>> Hi all,
>>
>> I'm doing a bit of work with Ofono again, extending support for a 
>> Quectel EG91 - handling additional cell strength information which 
>> seems necessary for LTE.
>>
>> I'm using Quectel's AT+QCOPS which is returning some negative signal 
>> strengths and after some investigation I've spotted that 
>> gatresult::g_at_result_iter_next_number() doesn't handle negative 
>> numbers.
>
> AT commands do not have a concept of negative numbers.  v.250 Section 
> 5.3.1:
> <number> may be a string of one or more characters from "0" through 
> "9" representing a decimal
> integer value. Commands that expect a <number> are noted in the 
> description of the command (see
> clause 6).
>
> I don't recall any other vendor using negative values in AT commands.
>
> If you want to add a negative number parser to GAtChat, then please 
> make it a separate method, so that it is very clear that a vendor 
> 'extension' is being worked around.
>
> Regards,
> -Denis


The team at Ofono are suggesting that Quectel (EG91) should not be 
returning negative numbers in AT command responses

These are returned to an AT+QCOPS command where signal strength is given.

Can you comment?

Thanks,

Alex