Static code analysis _032 (Coercion Alters Value - offsetScaledLogVariance)

[PawelModrzejewski]

Short summary (details in attached file):

buildPTPMessage()
.../common/ptp_message.cpp

PTPMessageCommon *buildPTPMessage
( char *buf, int size, LinkLayerAddress *remote,
  CommonPort *port )
{
...
                    annc->
                      grandmasterClockQuality->offsetScaledLogVariance =
                      	
Coercion Alters Value help
PLAT_ntohs(...) is coerced from unsigned short to short.

                      PLAT_ntohs 
                      ( annc->grandmasterClockQuality->
                        offsetScaledLogVariance );

PLAT_ntohs()
.../linux/src/platform.cpp
uint16_t PLAT_ntohs( uint16_t s ) {
        return ntohs( s );
}        	

SCA complains here about ntohs() but I believe the real issue is the type of offsetScaledLogVariance in struct ClockQuality, which currently in the code is int16_t. There seems to be inconsistency in IEEE 802.1AS-2011:

• in 6.3.3.8 ClockQuality offsetScaledLogVariance is defined as UInteger16;
• later in the document it's used as Integer16 (Table 14-1, code examples etc.);

This inconsistency has been corrected in IEEE 802.1AS-2011/Cor 1-2013 where UInteger16 was specified in the Table 14-1 and later in the code examples.

gptp_032.txt