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From
SubjectRe: /dev/random probs in 2.4test(12-pre3)
Date
Followup to:  <Pine.LNX.4.10.10012011720050.23462-100000@sphinx.mythic-beasts.com>
By author: Matthew Kirkwood <matthew@hairy.beasts.org>
In newsgroup: linux.dev.kernel
>
> Hi,
>
> It looks like the random driver in 2.4test will return a
> short read, rather than blocking. This is breaking vpnd
> (http://sunsite.dk/vpnd/) which breaks with "failed to
> gather random data" or similar.
>
> Here's a sample strace:
>
> open("/dev/random", O_RDONLY) = 3
> read(3, "q\321Nu\204\251^\234i\254\350\370\363\"\305\366R\2708V"..., 72) = 29
> close(3) = 0
>
> Have the semantics of the device changed, or is vpnd doing
> something wrong?
>

vpnd is doing something wrong: it's assuming short reads won't
happen. /dev/random will block if there is NOTHING to be read;
however, if there are bytes to be read, it will return them even if it
is less than the user asked for.

-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt
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