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SubjectRe: Printing to off-line printer in 2.4.0-prerelease
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Tim Waugh <twaugh@redhat.com> writes:

> On Thu, Jan 04, 2001 at 08:07:19PM +0100, Peter Osterlund wrote:
>
> > If you do this, you should probably also return -EAGAIN if the printer
> > is out of paper, otherwise I would still lose data when the printer
> > goes out of paper. Currently it returns -ENOSPC in this situation. I
> > suppose the different return codes were meant as a way for user space
> > to be able to know why printing failed, so that it could take
> > appropriate actions, but maybe this is not used by any programs.
>
> They were intended for that, yes, but it's probably better to stick
> with the 2.2 return codes. Here's a patch to do that. Look okay?

I assume you meant to return -EAGAIN, not -EIO. However, it doesn't
work if the printer is powered off and LP_ABORT is false. In that case
lp_write calls lp_check_status, which detects the error, waits 10
seconds, but then returns 0. lp_write then calls parport_write which
will happily send the data to the powered off printer, then return
success to user space and the data is lost.

>
> Tim.
> */
>
> 2001-01-04 Tim Waugh <twaugh@redhat.com>
>
> * drivers/char/lp.c: Follow 2.2 behaviour more closely.
>
> --- linux-2.4.0-prerelease/drivers/char/lp.c.offline Thu Jan 4 21:13:02 2001
> +++ linux-2.4.0-prerelease/drivers/char/lp.c Thu Jan 4 21:42:19 2001
> @@ -207,7 +207,7 @@
> last = LP_POUTPA;
> printk(KERN_INFO "lp%d out of paper\n", minor);
> }
> - error = -ENOSPC;
> + error = -EIO;
> } else if (!(status & LP_PSELECD)) {
> if (last != LP_PSELECD) {
> last = LP_PSELECD;
> @@ -230,7 +230,10 @@
> if (last != 0)
> lp_error(minor);
>
> - return error;
> + if (LP_F (minor) & LP_ABORT)
> + return error;
> +
> + return 0;
> }
>
> static ssize_t lp_write(struct file * file, const char * buf,
> @@ -292,7 +295,7 @@
> /* incomplete write -> check error ! */
> int error = lp_check_status (minor);
>
> - if (LP_F(minor) & LP_ABORT) {
> + if (error) {
> if (retv == 0)
> retv = error;
> break;

--
Peter Österlund peter.osterlund@mailbox.swipnet.se
Sköndalsvägen 35 http://home1.swipnet.se/~w-15919
S-128 66 Sköndal +46 8 942647
Sweden

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