[cups.bugs] [MOD] STR #3001: backend runloop spins on backchannel EOF

[Michael R Sweet]

Martin Pitt wrote:
> ...
>> --- backend/runloop.c	(revision 8127)
>> +++ backend/runloop.c	(working copy)
>> @@ -283,6 +283,12 @@
>>  	        CUPS_LLCAST bc_bytes);
>>          cupsBackChannelWrite(bc_buffer, bc_bytes, 1.0);
>>        }
>> +      else if (bc_bytes < 0 && errno != EAGAIN && errno != EINTR)
> 
> So this doesn't check for EOF at all (which would be bc_bytes == 0),
> but for an error condition. Maybe it could do both, just to be on the
> safe side? (log a different error for the EOF case, of course, since
> errno will be 0).

Reading from a socket that has been closed by the printer will return
-1 with ECONNRESET.  Similarly, character devices using this function
will return -1 and EIO when there is an error and never EOF since we
run them in raw mode.

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Michael R Sweet                        Senior Printing System Engineer