On Tue, Sep 19, 2000 at 07:06:26PM -0400, Alexander Stavitsky wrote:
> Is there any newer patch? Was that patch working? tested?
No, I never had a working patch with the hardware I had. It probably
would have worked with non-broken hardware, but since the broken
hardware seems to be quite widespread, I put the patch away and forgot
Basically the way to do it and still remain compatible with this
stupid hardware is to periodically switch to reverse mode and check to
see if there's any data available, and then _switch_ _back_
(i.e. _don't_ rely on an interrupt). This way it should work even
I don't have a network connection as I'm writing this, so I don't know
what's in the message you referred to, but the problem I faced was
with printers that stop _dead_ when in reverse mode, even when they
have a buffer full of data waiting to go on paper and are _not_
advertising themselves as busy. Then they carry on when you go back
to forward mode.
Patrick Powell occasionally sends me mail pleading with me to get
select() working, for the reason you mentioned. It just isn't as easy
as it might sound.
I'd be very interested to know what other vendors have done to make
this work, if there are implementations out there that have working
selectable /dev/lp devices. Does anyone know of any? What does
Solaris do, for example?
(A side-issue that Patrick raised was that according to POSIX select
returning readable means that a read is _guaranteed_ not to block,
which we can't do without reading a byte from the device first. I
don't want to do that stuff, it's just too icky. POSIX has nothing to
say about device special files anyway, AFAIK.)
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