Re: /dev/random probs in 2.4test(12-pre3)

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <Pine.LNX.4.21.0012021955570.11787-100000@server.serve.me.nl>
By author:    Igmar Palsenberg <maillist@chello.nl>
In newsgroup: linux.dev.kernel
>
> > Indeed, you are correct.  Is vpnd broken then, for assuming
> > that it can gather the required randomness in one read?
> 
> Yep. It assumes that if the required randommness numbers aren't met a read
> to /dev/random will block.
> 
> And it's not the only program that assumes this : I also did. 
> 
> /dev/random is called a blocking random device, which more or less implies
> that it will totally block. I suggest we put this somewhere in the kernel
> docs, since lots of people out there assume that it totally blocks.
> 

That's pretty much ALWAYS wrong -- for pipes, sockets, you name it.  A
blocking read() will only block if there is nothing to read at all.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
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