Setting printer status from STOPPED to IDLE

[Michael Sweet]

Bawenang wrote:
> Hi, I've read in the development forum:
> 
> QUOTE from
> http://www.cups.org/newsgroups.php?s933+gcups.development+v941+T1: 
> "The standard CUPS backends only use this exit code for absolutely
> fatal conditions such as bad URIs and other errors that require the
> administrator/user to manually fix the problem."
> 
> So if my application runs into this error and the admin has fixed the
> problem manually, how do I set the status to IDLE again from STOPPED
> in my application? My plan is I'll just make a button that can be
> clicked by the admin to clear the jobs queue and set the status to
> IDLE. I know that to clear the queue I'll just call cupsCancelJob().
> But how to set the printer status? I believe there's a function
> called SetPrinterState() in printers.h. Do I have to call that
> function? If I do, what are the parameters? I can't find the
> explanation anywhere.

You need to use the CUPS-Add-Modify-Printer IPP operation, passing
the printer-uri and printer-state values in addition to the
attributes-natural-language and attributes-charset values.

The CUPS web interface includes help on the CUPS API:

     http://localhost:631/help

The following code snippet (not tested) will start the named printer:

     #include <cups/cups.h>

     void
     start_printer(const char *name)
     {
       http_t *http = httpConnectEncrypt(cupsServer(), ippPort(),
                                         cupsEncryption());
       ipp_t *request;
       char uri[1024];


       httpAssembleURIf(HTTP_URI_CODING_ALL, uri, sizeof(uri), "ipp",
                        NULL, "localhost", ippPort(), "/printers/%s",
                        name);

       request = ippNewRequest(CUPS_ADD_MODIFY_PRINTER);
       ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI,
                    "printer-uri", NULL, uri);
       ippAddInteger(request, IPP_TAG_OPERATION, IPP_TAG_ENUM,
                     "printer-state", IPP_PRINTER_IDLE);

       ippDelete(cupsDoRequest(http, "/admin/", request));
       httpClose(http);

       if (cupsLastError() != IPP_OK)
       {
         // Display error
         puts(cupsLastErrorString());
       }
     }

If you are developing a GUI application, make sure you register a
password callback function that will ask for a username and
password (the standard callback asks on the current console/terminal
window...)

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Publishing Software        http://www.easysw.com