Socket: Failed to read side-channel request

Thomas Küstermann t.kuestermann at tu-bs.de
Fri Apr 4 09:57:28 PDT 2008


> What driver are you using?

We're using the original PPDs shipped with the printers. As my collegues said, these PPD were manually modified, but nobody can say in which way.

I have tested to replace the old PPD with the latest PPD shipped with CUPS according to the printer. The formerly false printed documents are now printed correctly, thank you for the hint!

Now, I try to write a backend wrapper like 'beh' implemented in Groovy (groovy.codehaus.org) that wraps around CUPS and 'socket', but it leads to the same problem as formerly discussed.

The 'socket'-process is started in this way:

'/usr/lib/cups/backend/socket <ID> <USER> <TITLE> <COPIES> <OPTIONS> <PRINT_FILE>'

The wrapper is executed correctly and each argument is given. I have compared the spooled files resulting with wrapper and without and they are byte per byte the same.

Do I have something forgotten or is there something that has to be done before?

> The warning message would seem to indicate the driver is assuming
> that file descriptor 4 is for some other purpose, leading to the
> error you are seeing.

What does that mean 'for some other purpose'? Can you give an example, please?

Thank you for each advice,

- Thomas





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