Re: [PATCH 1/3] stkutil: display text attributes as html

[Denis Kenzior <denkenz@gmail.com>]

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Hi Kristen,

On 07/01/2010 06:05 PM, Kristen Carlson Accardi wrote:
> On Thu, 01 Jul 2010 18:08:47 -0500
> Denis Kenzior <denkenz@gmail.com> wrote:
> 
>> Hi Kristen,
>>
>>>>>> Then this code is incorrect, as it handles len 3 attrs only at the end
>>>>>> of the array.  Also please note that SIM Toolkit Text Attributes are
>>>>>> always coded on 4 bytes (see 102.223 Section 8.72 for details).  You
>>>>>> might want to assume 4 byte alignment or invent a data structure for
>>>>>> these attributes.
>>>>>
>>>>> I should have said that attrs_len does not always have to be a multiple
>>>>> of 4 -- it is allowed to only have 3 byte attrs as the last attribute,
>>>>> so the code is correct.  However, since not all attributes are
>>>>> required to be of len 4, we can't just assume attrs_len is a multiple
>>>>> of 4.
>>>>>
>>>>
>>>> How do you figure this?  From 23.040 Section 9.2.3.24.10.1.1	Text Formatting
>>>>
>>>> "Octet 4
>>>>
>>>> This Octet may be omitted by setting the IED length accordingly."
>>>
>>> This isn't the clearest language, so my interpretation of this is
>>> you may omit one byte if you set the length properly.  Clearly
>>> the spec tell you that the byte is optional, so I think it would
>>> be wrong to assume that all are 4 bytes.  Also, since obviously
>>> we can't support mixed 3 and 4 byte fields since we'd have no
>>> way to know if the next byte was the start of the next attribute,
>>> it's got to be at the end of the array.
>>
>> Actually it is not.  Each Text attribute is put into an SMS header, with
>> the header having an IEI (Information Element Identifier), Length and
>> Data.  See SMS_IEI_TEXT_FORMAT in smsutil.h
>>
>> Hence, when an EMS PDU is parsed, you know whether this is a 3 byte or a
>> 4 byte element.
>>
>> Regards,
>> -Denis
> 
> The way this function is - we have no knowledge of the pdu.
> Are you wanting to change the arguments to this function to include
> an sms header?  or a pdu? Or are you saying the caller is responsible 
> for padding out the text attribute into a 4 byte attribute?

Correct, assume the caller will always give you quadruples.  3 byte
values can only happen in EMS, and those are wrapped in user headers.
It is not a single contiguous array.  Some external entity will need to
appropriately format the text attribute array for your consumption in
this case.

Regards,
-Denis