Adjust size variable to be signed size_t
Adjust size variable to be signed size_t

'size' was being compared to a negative value for error checking.  This
would never trigger being used as a 'size_t' as it's unsigned.  Changing
to ssize_t accordingly.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp