strncpy doesn't always null-terminate

Question

I am using the code below:

char filename[ 255 ];
strncpy( filename, getenv( \"HOME\" ), 235 );
strncat( filename, \"/.config/stationlist.xml\", 255 );
         


        

Answer 1

1) Your strncpy does not necessarily null-terminate filename. In fact, if getenv("HOME") is longer than 235 characters and getenv("HOME")[234] is not a 0, it won't. 2) Your strncat() may attempt to extend filename beyond 255 characters, because, as it says,

3rd parameter is the maximum number of characters to append. 

(not the total allowed length of dst)