From: Tanaka Akira <akr@...17n.org>
Date: 2003-11-04T14:26:17+09:00
Subject: Re: CGI uses file size to distinguish between regular values and files

In article <1067898096.626601.19785.nullmailer@picachu.netlab.jp>,
  matz@ruby-lang.org (Yukihiro Matsumoto) writes:

> I understand the problem, but not yet think of the best solution.  Any
> concrete ideas?

I think 

  File.open(upload, 'w') {|f| f.write(file.read) }

is good enough except it reads whole file in memory at once.  It is
a problem for big file.

So I propose IO#copy and StringIO#copy to able to write:

  File.open(upload, 'w') {|f| file.copy(f) }

The implementation is assumed as follows.

class IO
  def copy(destination)
    while buf = self.read(8192)
      destination.write buf
    end
  end
end

class StringIO
  def copy(destination)
    destination.write self.read
  end
end

Note that IO#copy may use sendfile(2) if destination is a socket.
-- 
Tanaka Akira