2011/11/9 Eric Wong <normalperson / yhbt.net>:
> I'm not sure if this is a bug or intended as spec.
>
> I noticed when a file name argument is passed to the IO.copy_stream, the
> newly-created destination file has 0600 perms and is not respecting my
> normal umask (0022).

Sometimes the convention, 0666 by default, causes security problem:
It causes world writable files if users forget to set correct umask.

There are various umask related security problem:
CVE-1999-1572, CVE-2001-1322, CVE-2005-1841, CVE-2006-1587,
CVE-2006-3589, CVE-2007-6249

So I didn't use 0666.

0600 may be too restrictive but you can use File.chmod to relax it.
-- 
Tanaka Akira