fix perm to octal

[sukumo28]

Hi. I found out that you pass a perm for WriteFile method as decimal. But you want to pass octal arn't you?

For example, 0777 is 111111111 in binary and it means rwxrwxrwx. 777 is 1100001001 in binary and it means r----x--x.

If you want to set perm r----x--x, you should use 0411 instead of decimal 777.