If you call open without the third argument (permissions) it sometimes
creates a file which is read-only. This is because of a bug in
src\libc\posixcntl\open.c at line 38. It doesn't check if you use a third 
argument, instead it uses what happens to be on the stack.

A C-function cannot check how many arguments it was passed.  Therefore,
if a file may be created you must supply the mode parameter.