build name of a config file in home directory

create_config_name.c

char *create_config_name( const char *name )
{
    char *p1 = getenv( "HOME" );
    char *p2 = "/.";
    int len = strlen( p1 ) + strlen( p2 ) + strlen( name ) + 1;
    char *p3 = malloc( len );
    assert( p3 );
    strcpy( p3, p1 );
    strcat( p3, p2 );
    strcat( p3, name );
    assert( strlen( p3 ) < len );
    return p3;
}