From: Roger Pack <rogerpack2005@...>
Date: 2009-11-17T02:40:50+09:00
Subject: Re: Errno::ENOMEM reading a device in Ruby, not in Java thou


> Interesting.
> with 1.9, it will read all 64K at once (not with 1.8 though--it reads 4K 
> blocks until it reached 64K).
> 
> sysread did work with 1.8, though

As a followup gotcha (in case anybody runs into this).

irb(main):001:0> a = File.open('/dev/nst2', 'rb')
=> #<File:/dev/nst2>
irb(main):002:0> a.eof?
irb(main):005:0> a.sysread 64*1024
IOError: sysread for buffered IO
        from (irb):5:in `sysread'
        from (irb):5

meant "when you call eof? it actually converts the file descriptor 
internally into buffered mode, and read a byte from it to see if it 
reads zero bytes (implying EOF), thus you cannot call sysread after a 
buffered read call like eof?"

-r

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