cupsBackChannelRead() fails on Ubuntu 11.10

[Phil Ineichen]

The following code runs fine on Ubuntu 11.04 (CUPS 1.4.6)

byte buf[16];
ssize_t bytesRead = cupsBackChannelRead((char*)buf, sizeof(buf), 2.5);
if(bytesRead == -1)
{
   fprintf(stderr, "DEBUG: cupsBackChannelRead failed, errno=%d\n", errno);
}
else if(bytesRead == 0)
{
   fprintf(stderr, "DEBUG: cupsBackChannelRead no data\n");
}
else
{
   fprintf(stderr, "DEBUG: cupsBackChannelRead has read %i bytes\n", bytesRead);
}

But cupsBackChannelRead() returns -1 and errno 11 on Ubuntu 11.10 (CUPS 1.5.0)!

I am not sure what is causing this behavior (CUPS, driver or Ubuntu).

Thank you!

[Phil Ineichen (pineichen)]

It is not a CUPS 1.5.0 issue since it is working with other Linux distributions with CUPS 1.5.0.

It looks like an Ubuntu 11.10 bug.

[Till Kamppeter (till-kamppeter)]

Is your printer connected via USB? If so, the problem is that the "usb" backend of CUPS in Oneiric has no backchannel support. This problem is fixed in Precise (12.04).

[Phil Ineichen (pineichen)]

Yes, the printer is connected via USB. Then I'll be looking for 12.04.
Thank you

[Till Kamppeter (till-kamppeter)]

Please tell us whether it works on 12.04. Boot a 12.04 live CD and do all updates in the live session, then try again. Does it work now?

[Phil Ineichen (pineichen)]

Ubuntu 12.04 beta does not run in my VMware. I guess I'll try as soon as 12.04 has been released.

[Till Kamppeter (till-kamppeter)]

I am grateful if you could do the live CD test. It should work with any computer with USB port or optical drive and does not modify any thin on the computer.

[Phil Ineichen (pineichen)]

It is working with Ubuntu 12.04 beta.

[Till Kamppeter (till-kamppeter)]

OK, thank you. So I will close this bug as fixed ...