From: Tanaka Akira <akr@...>
Date: 2010-01-06T02:24:54+09:00
Subject: [ruby-core:27427] Re: closing of the stderr pipe not detected - 	issue in 1.9.1?

2010/1/6 Robert Klemme <shortcutter@googlemail.com>:
>
> Thank you for the hint!  Why should I do this?  Does Ruby somehow
> prevent the stream to be closed in order to be able to deliver error
> messages?

The standard input/output/error may be used by external library.
So error messages may be produced for stderr (fd 2) even if
Ruby closes stderr.

If we close stderr (fd 2), fd 2 is reused for next fd allocation: open(),
socket(), etc.
If fd 2 is used for a socket, the error message is sent to the server.
If fd 2 is used for a database (dbm), the error message break it.
Another example is CVE-2002-0572.  (It doesn't use close, though)

So I think the standard input/output/error should not be closed.

reopen doesn't have the problems because stderr is not reused because
it is still open (to /dev/null).
-- 
Tanaka Akira