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5a738aea | 333 | --></style> |
ef416fc2 | 334 | </head> |
335 | <body> | |
5a738aea | 336 | <div class='body'> |
ef416fc2 | 337 | <!-- |
8b450588 | 338 | "$Id: api-filter.header 8087 2008-10-27 21:37:05Z mike $" |
ef416fc2 | 339 | |
5a738aea MS |
340 | Filter and backend programming header for the Common UNIX Printing System |
341 | (CUPS). | |
ef416fc2 | 342 | |
5a738aea | 343 | Copyright 2008 by Apple Inc. |
ef416fc2 | 344 | |
345 | These coded instructions, statements, and computer programs are the | |
bc44d920 | 346 | property of Apple Inc. and are protected by Federal copyright |
347 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
348 | which should have been included with this file. If this file is | |
349 | file is missing or damaged, see the license at "http://www.cups.org/". | |
ef416fc2 | 350 | --> |
351 | ||
5a738aea MS |
352 | <div class='summary'><table summary='General Information'> |
353 | <thead> | |
354 | <tr> | |
ac884b6a | 355 | <th>Headers</th> |
5a738aea | 356 | <th>cups/backend.h<br> |
79e1d494 | 357 | cups/sidechannel.h</th> |
5a738aea MS |
358 | </tr> |
359 | </thead> | |
360 | <tbody> | |
361 | <tr> | |
362 | <th>Library</th> | |
363 | <td>-lcups</td> | |
364 | </tr> | |
365 | <tr> | |
366 | <th>See Also</th> | |
367 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
368 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
369 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
79e1d494 MS |
370 | Programming: <a href='api-raster.html' target='_top'>Raster API</a><br> |
371 | Specifications: <a href='spec-design' target='_top'>CUPS Design Description</a></td> | |
5a738aea MS |
372 | </tr> |
373 | </tbody> | |
374 | </table></div> | |
375 | <h2 class="title">Contents</h2> | |
376 | <ul class="contents"> | |
426c6a59 | 377 | <ul class="subcontents"> |
5a738aea | 378 | <li><a href="#OVERVIEW">Overview</a><ul class="subcontents"> |
ac884b6a MS |
379 | <li><a href="#SECURITY">Security Considerations</a></li> |
380 | <li><a href="#TEMPFILES">Temporary Files</a></li> | |
381 | <li><a href="#COPIES">Copy Generation</a></li> | |
5a738aea MS |
382 | <li><a href="#EXITCODES">Exit Codes</a></li> |
383 | <li><a href="#ENVIRONMENT">Environment Variables</a></li> | |
384 | <li><a href="#MESSAGES">Communicating with the Scheduler</a></li> | |
20fbc903 MS |
385 | <li><a href="#COMMUNICATING_BACKEND">Communicating with the Backend</a></li> |
386 | <li><a href="#COMMUNICATING_FILTER">Communicating with Filters</a></li> | |
ac884b6a | 387 | <li><a href="#SNMP">Doing SNMP Queries with Network Printers</a></li> |
5a738aea MS |
388 | </ul></li> |
389 | <li><a href="#FUNCTIONS">Functions</a><ul class="code"> | |
390 | <li><a href="#cupsBackChannelRead" title="Read data from the backchannel.">cupsBackChannelRead</a></li> | |
391 | <li><a href="#cupsBackChannelWrite" title="Write data to the backchannel.">cupsBackChannelWrite</a></li> | |
ac884b6a | 392 | <li><a href="#cupsBackendDeviceURI" title="Get the device URI for a backend.">cupsBackendDeviceURI</a></li> |
06d4e77b | 393 | <li><a href="#cupsBackendReport" title="Write a device line from a backend.">cupsBackendReport</a></li> |
5a738aea MS |
394 | <li><a href="#cupsSideChannelDoRequest" title="Send a side-channel command to a backend and wait for a response.">cupsSideChannelDoRequest</a></li> |
395 | <li><a href="#cupsSideChannelRead" title="Read a side-channel message.">cupsSideChannelRead</a></li> | |
20fbc903 MS |
396 | <li><a href="#cupsSideChannelSNMPGet" title="Query a SNMP OID's value.">cupsSideChannelSNMPGet</a></li> |
397 | <li><a href="#cupsSideChannelSNMPWalk" title="Query multiple SNMP OID values.">cupsSideChannelSNMPWalk</a></li> | |
5a738aea | 398 | <li><a href="#cupsSideChannelWrite" title="Write a side-channel message.">cupsSideChannelWrite</a></li> |
8b450588 | 399 | </ul></li> |
5a738aea MS |
400 | <li><a href="#TYPES">Data Types</a><ul class="code"> |
401 | <li><a href="#cups_backend_t" title="Backend exit codes">cups_backend_t</a></li> | |
402 | <li><a href="#cups_sc_bidi_t" title="Bidirectional capabilities">cups_sc_bidi_t</a></li> | |
403 | <li><a href="#cups_sc_command_t" title="Request command codes">cups_sc_command_t</a></li> | |
404 | <li><a href="#cups_sc_state_t" title="Printer state bits">cups_sc_state_t</a></li> | |
405 | <li><a href="#cups_sc_status_t" title="Response status codes">cups_sc_status_t</a></li> | |
20fbc903 | 406 | <li><a href="#cups_sc_walk_func_t" title="SNMP walk callback">cups_sc_walk_func_t</a></li> |
5a738aea MS |
407 | </ul></li> |
408 | <li><a href="#ENUMERATIONS">Constants</a><ul class="code"> | |
409 | <li><a href="#cups_backend_e" title="Backend exit codes">cups_backend_e</a></li> | |
79e1d494 | 410 | <li><a href="#cups_sc_bidi_e" title="Bidirectional capability values">cups_sc_bidi_e</a></li> |
5a738aea MS |
411 | <li><a href="#cups_sc_command_e" title="Request command codes">cups_sc_command_e</a></li> |
412 | <li><a href="#cups_sc_state_e" title="Printer state bits">cups_sc_state_e</a></li> | |
413 | <li><a href="#cups_sc_status_e" title="Response status codes">cups_sc_status_e</a></li> | |
414 | </ul></li> | |
5a738aea | 415 | <!-- |
758a062f | 416 | "$Id: api-filter.shtml 7962 2008-09-18 17:31:33Z mike $" |
ef416fc2 | 417 | |
5a738aea MS |
418 | Filter and backend programming introduction for the Common UNIX Printing |
419 | System (CUPS). | |
ef416fc2 | 420 | |
5a738aea MS |
421 | Copyright 2007-2008 by Apple Inc. |
422 | Copyright 1997-2006 by Easy Software Products, all rights reserved. | |
ef416fc2 | 423 | |
5a738aea MS |
424 | These coded instructions, statements, and computer programs are the |
425 | property of Apple Inc. and are protected by Federal copyright | |
426 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
427 | which should have been included with this file. If this file is | |
428 | file is missing or damaged, see the license at "http://www.cups.org/". | |
429 | --> | |
f7deaa1a | 430 | |
5a738aea | 431 | <h2 class='title'><a name="OVERVIEW">Overview</a></h2> |
ef416fc2 | 432 | |
79e1d494 MS |
433 | <p>Filters (which include printer drivers and port monitors) and backends |
434 | are used to convert job files to a printable format and send that data to the | |
435 | printer itself. All of these programs use a common interface for processing | |
436 | print jobs and communicating status information to the scheduler. Each is run | |
437 | with a standard set of command-line arguments:<p> | |
ef416fc2 | 438 | |
5a738aea | 439 | <dl class="code"> |
f7deaa1a | 440 | |
5a738aea MS |
441 | <dt>argv[1]</dt> |
442 | <dd>The job ID</dd> | |
ef416fc2 | 443 | |
5a738aea MS |
444 | <dt>argv[2]</dt> |
445 | <dd>The user printing the job</dd> | |
f7deaa1a | 446 | |
5a738aea MS |
447 | <dt>argv[3]</dt> |
448 | <dd>The job name/title</dd> | |
f7deaa1a | 449 | |
5a738aea MS |
450 | <dt>argv[4]</dt> |
451 | <dd>The number of copies to print</dd> | |
f7deaa1a | 452 | |
5a738aea MS |
453 | <dt>argv[5]</dt> |
454 | <dd>The options that were provided when the job was submitted</dd> | |
f7deaa1a | 455 | |
5a738aea | 456 | <dt>argv[6]</dt> |
79e1d494 | 457 | <dd>The file to print (first program only)</dd> |
5a738aea | 458 | </dl> |
f7deaa1a | 459 | |
5a738aea MS |
460 | <p>The scheduler runs one or more of these programs to print any given job. The |
461 | first filter reads from the print file and writes to the standard output, while | |
462 | the remaining filters read from the standard input and write to the standard | |
463 | output. The backend is the last filter in the chain and writes to the | |
464 | device.</p> | |
f7deaa1a | 465 | |
ac884b6a MS |
466 | <h3><a name="SECURITY">Security Considerations</a></h3> |
467 | ||
468 | <p>It is always important to use security programming practices. Filters and | |
469 | most backends are run as a non-priviledged user, so the major security | |
470 | consideration is resource utilization - filters should not depend on unlimited | |
471 | amounts of CPU, memory, or disk space, and should protect against conditions | |
472 | that could lead to excess usage of any resource like infinite loops and | |
473 | unbounded recursion. In addition, filters must <em>never</em> allow the user to | |
474 | specify an arbitrary file path to a separator page, template, or other file | |
475 | used by the filter since that can lead to an unauthorized disclosure of | |
476 | information. <em>Always</em> treat input as suspect and validate it!</p> | |
477 | ||
478 | <p>If you are developing a backend that runs as root, make sure to check for | |
479 | potential buffer overflows, integer under/overflow conditions, and file | |
480 | accesses since these can lead to privilege escalations. When writing files, | |
481 | always validate the file path and <em>never</em> allow a user to determine | |
482 | where to store a file.</p> | |
483 | ||
484 | <blockquote><b>Note:</b> | |
485 | ||
486 | <p><em>Never</em> write files to a user's home directory. Aside from the | |
487 | security implications, CUPS is a network print service and as such the network | |
488 | user may not be the same as the local user and/or there may not be a local home | |
489 | directory to write to.</p> | |
490 | ||
491 | <p>In addition, some operating systems provide additional security mechanisms | |
492 | that further limit file system access, even for backends running as root. On | |
493 | Mac OS X, for example, no backend may write to a user's home directory.</p> | |
494 | </blockquote> | |
495 | ||
496 | <h3><a name="TEMPFILES">Temporary Files</a></h3> | |
497 | ||
498 | <p>Temporary files should be created in the directory specified by the | |
499 | "TMPDIR" environment variable. The | |
500 | <a href="#cupsTempFile2"><code>cupsTempFile2</code></a> function can be | |
501 | used to safely create temporary files in this directory.</p> | |
502 | ||
503 | <h3><a name="COPIES">Copy Generation</a></h3> | |
504 | ||
505 | <p>The <code>argv[4]</code> argument specifies the number of copies to produce | |
506 | of the input file. In general, you should only generate copies if the | |
507 | <em>filename</em> argument is supplied. The only exception to this are | |
508 | filters that produce device-independent PostScript output, since the PostScript | |
509 | filter <var>pstops</var> is responsible for generating copies of PostScript | |
510 | files.</p> | |
511 | ||
5a738aea | 512 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 513 | |
5a738aea MS |
514 | <p>Filters must exit with status 0 when they successfully generate print data |
515 | or 1 when they encounter an error. Backends can return any of the | |
516 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 517 | |
5a738aea | 518 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 519 | |
79e1d494 MS |
520 | <p>The following environment variables are defined by the printing system |
521 | when running print filters and backends:</p> | |
f7deaa1a | 522 | |
5a738aea | 523 | <dl class="code"> |
f7deaa1a | 524 | |
5a738aea MS |
525 | <dt>APPLE_LANGUAGES</dt> |
526 | <dd>The Apple language identifier associated with the job | |
527 | (Mac OS X only).</dd> | |
f7deaa1a | 528 | |
5a738aea MS |
529 | <dt>CHARSET</dt> |
530 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 531 | |
5a738aea MS |
532 | <dt>CLASS</dt> |
533 | <dd>When a job is submitted to a printer class, contains the name of | |
534 | the destination printer class. Otherwise this environment | |
535 | variable will not be set.</dd> | |
f7deaa1a | 536 | |
5a738aea MS |
537 | <dt>CONTENT_TYPE</dt> |
538 | <dd>The MIME type associated with the file (e.g. | |
539 | application/postscript).</dd> | |
f7deaa1a | 540 | |
5a738aea | 541 | <dt>CUPS_CACHEDIR</dt> |
79e1d494 MS |
542 | <dd>The directory where cache files can be stored. Cache files can be |
543 | used to retain information between jobs or files in a job.</dd> | |
f7deaa1a | 544 | |
5a738aea | 545 | <dt>CUPS_DATADIR</dt> |
79e1d494 | 546 | <dd>The directory where (read-only) CUPS data files can be found.</dd> |
f7deaa1a | 547 | |
758a062f MS |
548 | <dt>CUPS_FILETYPE</dt> |
549 | <dd>The type of file being printed: "job-sheet" for a banner page and | |
550 | "document" for a regular print file.</dd> | |
551 | ||
5a738aea MS |
552 | <dt>CUPS_SERVERROOT</dt> |
553 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 554 | |
5a738aea MS |
555 | <dt>DEVICE_URI</dt> |
556 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 557 | |
5a738aea MS |
558 | <dt>FINAL_CONTENT_TYPE</dt> |
559 | <dd>The MIME type associated with the printer (e.g. | |
560 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 561 | |
5a738aea MS |
562 | <dt>LANG</dt> |
563 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 564 | |
5a738aea MS |
565 | <dt>PPD</dt> |
566 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
567 | file for this printer.</dd> | |
f7deaa1a | 568 | |
5a738aea | 569 | <dt>PRINTER</dt> |
79e1d494 | 570 | <dd>The queue name of the class or printer.</dd> |
f7deaa1a | 571 | |
5a738aea MS |
572 | <dt>RIP_CACHE</dt> |
573 | <dd>The recommended amount of memory to use for Raster Image | |
574 | Processors (RIPs).</dd> | |
f7deaa1a | 575 | |
79e1d494 MS |
576 | <dt>TMPDIR</dt> |
577 | <dd>The directory where temporary files should be created.</dd> | |
578 | ||
5a738aea | 579 | </dl> |
f7deaa1a | 580 | |
5a738aea | 581 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 582 | |
79e1d494 MS |
583 | <p>Filters and backends communicate with the scheduler by writing messages |
584 | to the standard error file. The scheduler reads messages from all filters in | |
585 | a job and processes the message based on its prefix. For example, the following | |
586 | code sets the current printer state message to "Printing page 5":</p> | |
f7deaa1a | 587 | |
5a738aea MS |
588 | <pre class="example"> |
589 | int page = 5; | |
f7deaa1a | 590 | |
5a738aea | 591 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 592 | </pre> |
593 | ||
5a738aea MS |
594 | <p>Each message is a single line of text starting with one of the following |
595 | prefix strings:</p> | |
596 | ||
597 | <dl class="code"> | |
598 | ||
599 | <dt>ALERT: message</dt> | |
600 | <dd>Sets the printer-state-message attribute and adds the specified | |
601 | message to the current error log file using the "alert" log level.</dd> | |
602 | ||
603 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
604 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
605 | to set the <code>marker-colors</code>, <code>marker-levels</code>, | |
75bd9771 MS |
606 | <code>marker-message</code>, <code>marker-names</code>, |
607 | <code>marker-types</code>, <code>printer-alert</code>, and | |
608 | <code>printer-alert-description</code> printer attributes. Standard | |
609 | <code>marker-types</code> values are listed in <a href='#TABLE1'>Table | |
610 | 1</a>.</dd> | |
5a738aea MS |
611 | |
612 | <dt>CRIT: message</dt> | |
613 | <dd>Sets the printer-state-message attribute and adds the specified | |
614 | message to the current error log file using the "critical" log | |
615 | level.</dd> | |
616 | ||
617 | <dt>DEBUG: message</dt> | |
618 | <dd>Sets the printer-state-message attribute and adds the specified | |
619 | message to the current error log file using the "debug" log level.</dd> | |
620 | ||
621 | <dt>DEBUG2: message</dt> | |
622 | <dd>Sets the printer-state-message attribute and adds the specified | |
623 | message to the current error log file using the "debug2" log level.</dd> | |
624 | ||
625 | <dt>EMERG: message</dt> | |
626 | <dd>Sets the printer-state-message attribute and adds the specified | |
627 | message to the current error log file using the "emergency" log | |
628 | level.</dd> | |
629 | ||
630 | <dt>ERROR: message</dt> | |
631 | <dd>Sets the printer-state-message attribute and adds the specified | |
79e1d494 MS |
632 | message to the current error log file using the "error" log level. |
633 | Use "ERROR:" messages for non-persistent processing errors.</dd> | |
5a738aea MS |
634 | |
635 | <dt>INFO: message</dt> | |
636 | <dd>Sets the printer-state-message attribute. If the current log level | |
637 | is set to "debug2", also adds the specified message to the current error | |
638 | log file using the "info" log level.</dd> | |
639 | ||
640 | <dt>NOTICE: message</dt> | |
641 | <dd>Sets the printer-state-message attribute and adds the specified | |
642 | message to the current error log file using the "notice" log level.</dd> | |
643 | ||
644 | <dt>PAGE: page-number #-copies</dt> | |
645 | <dt>PAGE: total #-pages</dt> | |
646 | <dd>Adds an entry to the current page log file. The first form adds | |
647 | #-copies to the job-media-sheets-completed attribute. The second | |
648 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
649 | ||
20fbc903 MS |
650 | <dt>PPD: keyword=value [keyword=value ...]</dt> |
651 | <dd>Changes or adds keywords to the printer's PPD file. Typically | |
652 | this is used to update installable options or default media settings | |
653 | based on the printer configuration.</dd> | |
654 | ||
5a738aea MS |
655 | <dt>STATE: printer-state-reason [printer-state-reason ...]</dt> |
656 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> | |
657 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
658 | <dd>Sets, adds, or removes printer-state-reason keywords to the | |
79e1d494 MS |
659 | current queue. Typically this is used to indicate persistent media, |
660 | ink, toner, and configuration conditions or errors on a printer. | |
661 | <a href='#TABLE2'>Table 2</a> lists the standard state keywords - | |
662 | use vendor-prefixed ("com.acme.foo") keywords for custom states.</dd> | |
5a738aea MS |
663 | |
664 | <dt>WARNING: message</dt> | |
665 | <dd>Sets the printer-state-message attribute and adds the specified | |
666 | message to the current error log file using the "warning" log | |
667 | level.</dd> | |
668 | ||
669 | </dl> | |
670 | ||
671 | <p>Messages without one of these prefixes are treated as if they began with | |
672 | the "DEBUG:" prefix string.</p> | |
673 | ||
79e1d494 MS |
674 | |
675 | <div class='table'><table width='80%' summary='Table 1: Standard marker-types Values'> | |
676 | <caption>Table 1: <a name='TABLE1'>Standard marker-types Values</a></caption> | |
677 | <thead> | |
678 | <tr> | |
679 | <th>marker-type</th> | |
680 | <th>Description</th> | |
681 | </tr> | |
682 | </thead> | |
683 | <tbody> | |
684 | <tr> | |
685 | <td>developer</td> | |
686 | <td>Developer unit</td> | |
687 | </tr> | |
688 | <tr> | |
689 | <td>fuser</td> | |
690 | <td>Fuser unit</td> | |
691 | </tr> | |
692 | <tr> | |
693 | <td>fuserCleaningPad</td> | |
694 | <td>Fuser cleaning pad</td> | |
695 | </tr> | |
696 | <tr> | |
697 | <td>fuserOil</td> | |
698 | <td>Fuser oil</td> | |
699 | </tr> | |
700 | <tr> | |
701 | <td>ink</td> | |
702 | <td>Ink supply</td> | |
703 | </tr> | |
704 | <tr> | |
705 | <td>opc</td> | |
706 | <td>Photo conductor</td> | |
707 | </tr> | |
708 | <tr> | |
709 | <td>solidWax</td> | |
710 | <td>Wax supply</td> | |
711 | </tr> | |
712 | <tr> | |
713 | <td>staples</td> | |
714 | <td>Staple supply</td> | |
715 | </tr> | |
716 | <tr> | |
717 | <td>toner</td> | |
718 | <td>Toner supply</td> | |
719 | </tr> | |
720 | <tr> | |
721 | <td>transferUnit</td> | |
722 | <td>Transfer unit</td> | |
723 | </tr> | |
724 | <tr> | |
725 | <td>wasteInk</td> | |
726 | <td>Waste ink tank</td> | |
727 | </tr> | |
728 | <tr> | |
729 | <td>wasteToner</td> | |
730 | <td>Waste toner tank</td> | |
731 | </tr> | |
732 | <tr> | |
733 | <td>wasteWax</td> | |
734 | <td>Waste wax tank</td> | |
735 | </tr> | |
736 | </tbody> | |
737 | </table></div> | |
738 | ||
739 | <br> | |
740 | ||
741 | <div class='table'><table width='80%' summary='Table 2: Standard State Keywords'> | |
742 | <caption>Table 2: <a name='TABLE2'>Standard State Keywords</a></caption> | |
743 | <thead> | |
744 | <tr> | |
745 | <th>Keyword</th> | |
746 | <th>Description</th> | |
747 | </tr> | |
748 | </thead> | |
749 | <tbody> | |
750 | <tr> | |
751 | <td>connecting-to-device</td> | |
752 | <td>Connecting to printer but not printing yet</td> | |
753 | </tr> | |
754 | <tr> | |
755 | <td>cover-open</td> | |
756 | <td>A cover is open on the printer</td> | |
757 | </tr> | |
758 | <tr> | |
759 | <td>input-tray-missing</td> | |
760 | <td>An input tray is missing from the printer</td> | |
761 | </tr> | |
762 | <tr> | |
763 | <td>marker-supply-empty</td> | |
764 | <td>Out of ink</td> | |
765 | </tr> | |
766 | <tr> | |
767 | <td>marker-supply-low</td> | |
768 | <td>Low on ink</td> | |
769 | </tr> | |
770 | <tr> | |
771 | <td>marker-waste-almost-full</td> | |
772 | <td>Waste tank almost full</td> | |
773 | </tr> | |
774 | <tr> | |
775 | <td>marker-waste-full</td> | |
776 | <td>Waste tank full</td> | |
777 | </tr> | |
778 | <tr> | |
779 | <td>media-empty</td> | |
780 | <td>Out of media</td> | |
781 | </tr> | |
782 | <tr> | |
783 | <td>media-jam</td> | |
784 | <td>Media is jammed in the printer</td> | |
785 | </tr> | |
786 | <tr> | |
787 | <td>media-low</td> | |
788 | <td>Low on media</td> | |
789 | </tr> | |
790 | <tr> | |
791 | <td>paused</td> | |
792 | <td>Stop the printer</td> | |
793 | </tr> | |
794 | <tr> | |
795 | <td>timed-out</td> | |
796 | <td>Unable to connect to printer</td> | |
797 | </tr> | |
798 | <tr> | |
799 | <td>toner-empty</td> | |
800 | <td>Out of toner</td> | |
801 | </tr> | |
802 | <tr> | |
803 | <td>toner-low</td> | |
804 | <td>Low on toner</td> | |
805 | </tr> | |
806 | </tbody> | |
807 | </table></div> | |
808 | ||
20fbc903 | 809 | <h3><a name="COMMUNICATING_BACKEND">Communicating with the Backend</a></h3> |
5a738aea MS |
810 | |
811 | <p>Filters can communicate with the backend via the | |
812 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
813 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
814 | functions. The | |
815 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function | |
816 | reads data that has been sent back from the device and is typically used to | |
817 | obtain status and configuration information. For example, the following code | |
818 | polls the backend for back-channel data:</p> | |
819 | ||
820 | <pre class="example"> | |
821 | #include <cups/cups.h> | |
822 | ||
823 | char buffer[8192]; | |
824 | ssize_t bytes; | |
825 | ||
826 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
827 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
828 | </pre> | |
f7deaa1a | 829 | |
79e1d494 MS |
830 | <p>Filters can also use <code>select()</code> or <code>poll()</code> on the |
831 | back-channel file descriptor (3 or <code>CUPS_BC_FD</code>) to read data only | |
832 | when it is available.</p> | |
833 | ||
834 | <p>The | |
5a738aea MS |
835 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> |
836 | function allows you to get out-of-band status information and do synchronization | |
837 | with the device. For example, the following code gets the current IEEE-1284 | |
838 | device ID string from the backend:</p> | |
839 | ||
840 | <pre class="example"> | |
f7deaa1a | 841 | #include <cups/sidechannel.h> |
842 | ||
843 | char data[2049]; | |
844 | int datalen; | |
5a738aea | 845 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 846 | |
79e1d494 MS |
847 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for |
848 | nul-termination... */ | |
f7deaa1a | 849 | datalen = sizeof(data) - 1; |
850 | ||
851 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 852 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 853 | |
854 | /* Use the returned value if OK was returned and the length is non-zero */ | |
855 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
856 | data[datalen] = '\0'; | |
857 | else | |
858 | data[0] = '\0'; | |
859 | </pre> | |
860 | ||
20fbc903 MS |
861 | <h3><a name="COMMUNICATING_FILTER">Communicating with Filters</a></h3> |
862 | ||
5a738aea MS |
863 | <p>Backends communicate with filters using the reciprocal functions |
864 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
865 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
866 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
867 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 868 | |
5a738aea MS |
869 | <pre class="example"> |
870 | #include <cups/cups.h> | |
f7deaa1a | 871 | |
5a738aea MS |
872 | char buffer[8192]; |
873 | ssize_t bytes; | |
f7deaa1a | 874 | |
79e1d494 MS |
875 | /* Obtain data from printer/device */ |
876 | ... | |
877 | ||
5a738aea MS |
878 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
879 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 880 | </pre> |
881 | ||
5a738aea MS |
882 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
883 | function reads a side-channel command from a filter, driver, or port monitor. | |
884 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
885 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
886 | separate thread for that purpose), or use <code>select</code> or | |
887 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
20fbc903 | 888 | input and output on several file descriptors at the same time.</p> |
5a738aea MS |
889 | |
890 | <p>Once a command is processed, the backend uses the | |
891 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
892 | to send its response. For example, the following code shows how to poll for a | |
893 | side-channel command and respond to it:</p> | |
894 | ||
895 | <pre class="example"> | |
f7deaa1a | 896 | #include <cups/sidechannel.h> |
897 | ||
5a738aea MS |
898 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
899 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
20fbc903 MS |
900 | char data[2048]; |
901 | int datalen = sizeof(data); | |
f7deaa1a | 902 | |
903 | /* Poll for a command... */ | |
20fbc903 | 904 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, data, &datalen, 0.0)) |
f7deaa1a | 905 | { |
f7deaa1a | 906 | switch (command) |
907 | { | |
20fbc903 | 908 | /* handle supported commands, fill data/datalen/status with values as needed */ |
f7deaa1a | 909 | |
910 | default : | |
911 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
912 | datalen = 0; | |
913 | break; | |
914 | } | |
915 | ||
916 | /* Send a response... */ | |
5a738aea | 917 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 918 | } |
919 | </pre> | |
ac884b6a MS |
920 | |
921 | <h3><a name="SNMP">Doing SNMP Queries with Network Printers</a></h3> | |
922 | ||
923 | <p>The Simple Network Management Protocol (SNMP) allows you to get the current | |
924 | status, page counter, and supply levels from most network printers. Every | |
925 | piece of information is associated with an Object Identifier (OID), and | |
926 | every printer has a <em>community</em> name associated with it. OIDs can be | |
927 | queried directly or by "walking" over a range of OIDs with a common prefix.</p> | |
928 | ||
20fbc903 MS |
929 | <p>The two CUPS SNMP functions provide a simple API for querying network |
930 | printers through the side-channel interface. Each accepts a string containing | |
931 | an OID like ".1.3.6.1.2.1.43.10.2.1.4.1.1" (the standard page counter OID) | |
932 | along with a timeout for the query.</p> | |
ac884b6a | 933 | |
20fbc903 MS |
934 | <p>The <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a> |
935 | function queries a single OID and returns the value as a string in a buffer | |
936 | you supply:</p> | |
ac884b6a MS |
937 | |
938 | <pre class="example"> | |
20fbc903 | 939 | #include <cups/sidechannel.h> |
ac884b6a | 940 | |
20fbc903 MS |
941 | char data[512]; |
942 | int datalen = sizeof(data); | |
ac884b6a | 943 | |
20fbc903 MS |
944 | if (<a href="#cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a>(".1.3.6.1.2.1.43.10.2.1.4.1.1", data, &datalen, 5.0) |
945 | == CUPS_SC_STATUS_OK) | |
ac884b6a MS |
946 | { |
947 | /* Do something with the value */ | |
20fbc903 | 948 | printf("Page counter is: %s\n", data); |
ac884b6a MS |
949 | } |
950 | </pre> | |
951 | ||
20fbc903 MS |
952 | <p>The |
953 | <a href="#cupsSideChannelSNMPWalk"><code>cupsSideChannelSNMPWalk</code></a> | |
954 | function allows you to query a whole group of OIDs, calling a function of your | |
955 | choice for each OID that is found:</p> | |
ac884b6a MS |
956 | |
957 | <pre class="example"> | |
20fbc903 | 958 | #include <cups/sidechannel.h> |
ac884b6a MS |
959 | |
960 | void | |
20fbc903 | 961 | my_callback(const char *oid, const char *data, int datalen, void *context) |
ac884b6a MS |
962 | { |
963 | /* Do something with the value */ | |
20fbc903 | 964 | printf("%s=%s\n", oid, data); |
ac884b6a MS |
965 | } |
966 | ||
20fbc903 MS |
967 | ... |
968 | ||
ac884b6a MS |
969 | void *my_data; |
970 | ||
20fbc903 | 971 | <a href="#cupsSideChannelSNMPWalk">cupsSNMPSideChannelWalk</a>(".1.3.6.1.2.1.43", 5.0, my_callback, my_data); |
ac884b6a | 972 | </pre> |
20fbc903 | 973 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
426c6a59 | 974 | <h3 class="function"><span class="info"> CUPS 1.2/Mac OS X 10.5 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> |
5a738aea MS |
975 | <p class="description">Read data from the backchannel.</p> |
976 | <p class="code"> | |
977 | ssize_t cupsBackChannelRead (<br> | |
978 | char *buffer,<br> | |
979 | size_t bytes,<br> | |
980 | double timeout<br> | |
981 | );</p> | |
982 | <h4 class="parameters">Parameters</h4> | |
983 | <dl> | |
984 | <dt>buffer</dt> | |
79e1d494 | 985 | <dd class="description">Buffer to read into</dd> |
5a738aea MS |
986 | <dt>bytes</dt> |
987 | <dd class="description">Bytes to read</dd> | |
988 | <dt>timeout</dt> | |
79e1d494 | 989 | <dd class="description">Timeout in seconds, typically 0.0 to poll</dd> |
5a738aea MS |
990 | </dl> |
991 | <h4 class="returnvalue">Return Value</h4> | |
992 | <p class="description">Bytes read or -1 on error</p> | |
993 | <h4 class="discussion">Discussion</h4> | |
79e1d494 MS |
994 | <p class="discussion">Reads up to "bytes" bytes from the backchannel/backend. The "timeout" |
995 | parameter controls how many seconds to wait for the data - use 0.0 to | |
996 | return immediately if there is no data, -1.0 to wait for data indefinitely. | |
ef416fc2 | 997 | |
5a738aea | 998 | </p> |
426c6a59 | 999 | <h3 class="function"><span class="info"> CUPS 1.2/Mac OS X 10.5 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> |
5a738aea MS |
1000 | <p class="description">Write data to the backchannel.</p> |
1001 | <p class="code"> | |
1002 | ssize_t cupsBackChannelWrite (<br> | |
1003 | const char *buffer,<br> | |
1004 | size_t bytes,<br> | |
1005 | double timeout<br> | |
1006 | );</p> | |
1007 | <h4 class="parameters">Parameters</h4> | |
1008 | <dl> | |
1009 | <dt>buffer</dt> | |
1010 | <dd class="description">Buffer to write</dd> | |
1011 | <dt>bytes</dt> | |
1012 | <dd class="description">Bytes to write</dd> | |
1013 | <dt>timeout</dt> | |
79e1d494 | 1014 | <dd class="description">Timeout in seconds, typically 1.0</dd> |
5a738aea MS |
1015 | </dl> |
1016 | <h4 class="returnvalue">Return Value</h4> | |
1017 | <p class="description">Bytes written or -1 on error</p> | |
1018 | <h4 class="discussion">Discussion</h4> | |
79e1d494 | 1019 | <p class="discussion">Writes "bytes" bytes to the backchannel/filter. The "timeout" parameter |
ef416fc2 | 1020 | controls how many seconds to wait for the data to be written - use |
1021 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
1022 | indefinitely. | |
1023 | ||
ac884b6a | 1024 | </p> |
426c6a59 | 1025 | <h3 class="function"><span class="info"> CUPS 1.2/Mac OS X 10.5 </span><a name="cupsBackendDeviceURI">cupsBackendDeviceURI</a></h3> |
ac884b6a MS |
1026 | <p class="description">Get the device URI for a backend.</p> |
1027 | <p class="code"> | |
1028 | const char *cupsBackendDeviceURI (<br> | |
1029 | char **argv<br> | |
1030 | );</p> | |
1031 | <h4 class="parameters">Parameters</h4> | |
1032 | <dl> | |
1033 | <dt>argv</dt> | |
1034 | <dd class="description">Command-line arguments</dd> | |
1035 | </dl> | |
1036 | <h4 class="returnvalue">Return Value</h4> | |
1037 | <p class="description">Device URI or <code>NULL</code></p> | |
1038 | <h4 class="discussion">Discussion</h4> | |
1039 | <p class="discussion">The "argv" argument is the argv argument passed to main(). This | |
1040 | function returns the device URI passed in the DEVICE_URI environment | |
1041 | variable or the device URI passed in argv[0], whichever is found | |
426c6a59 MS |
1042 | first. |
1043 | ||
1044 | </p> | |
1045 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsBackendReport">cupsBackendReport</a></h3> | |
06d4e77b MS |
1046 | <p class="description">Write a device line from a backend.</p> |
1047 | <p class="code"> | |
1048 | void cupsBackendReport (<br> | |
1049 | const char *device_scheme,<br> | |
1050 | const char *device_uri,<br> | |
1051 | const char *device_make_and_model,<br> | |
1052 | const char *device_info,<br> | |
1053 | const char *device_id,<br> | |
1054 | const char *device_location<br> | |
1055 | );</p> | |
1056 | <h4 class="parameters">Parameters</h4> | |
1057 | <dl> | |
1058 | <dt>device_scheme</dt> | |
1059 | <dd class="description">device-scheme string</dd> | |
1060 | <dt>device_uri</dt> | |
1061 | <dd class="description">device-uri string</dd> | |
1062 | <dt>device_make_and_model</dt> | |
1063 | <dd class="description">device-make-and-model string or <code>NULL</code></dd> | |
1064 | <dt>device_info</dt> | |
1065 | <dd class="description">device-info string or <code>NULL</code></dd> | |
1066 | <dt>device_id</dt> | |
1067 | <dd class="description">device-id string or <code>NULL</code></dd> | |
1068 | <dt>device_location</dt> | |
1069 | <dd class="description">device-location string or <code>NULL</code></dd> | |
1070 | </dl> | |
1071 | <h4 class="discussion">Discussion</h4> | |
1072 | <p class="discussion">This function writes a single device line to stdout for a backend. | |
1073 | It handles quoting of special characters in the device-make-and-model, | |
426c6a59 MS |
1074 | device-info, device-id, and device-location strings. |
1075 | ||
1076 | </p> | |
1077 | <h3 class="function"><span class="info"> CUPS 1.3/Mac OS X 10.5 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> | |
5a738aea MS |
1078 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> |
1079 | <p class="code"> | |
1080 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
1081 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1082 | char *data,<br> | |
1083 | int *datalen,<br> | |
1084 | double timeout<br> | |
1085 | );</p> | |
1086 | <h4 class="parameters">Parameters</h4> | |
1087 | <dl> | |
1088 | <dt>command</dt> | |
1089 | <dd class="description">Command to send</dd> | |
1090 | <dt>data</dt> | |
1091 | <dd class="description">Response data buffer pointer</dd> | |
1092 | <dt>datalen</dt> | |
1093 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1094 | <dt>timeout</dt> | |
1095 | <dd class="description">Timeout in seconds</dd> | |
1096 | </dl> | |
1097 | <h4 class="returnvalue">Return Value</h4> | |
1098 | <p class="description">Status of command</p> | |
1099 | <h4 class="discussion">Discussion</h4> | |
1100 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 1101 | monitors in order to communicate with the backend used by the current |
1102 | printer. Programs must be prepared to handle timeout or "not | |
1103 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
1104 | do not support the specified side-channel command.<br> |
1105 | <br> | |
1106 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1107 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1108 | update the value to contain the number of data bytes in the buffer. | |
1109 | ||
5a738aea | 1110 | </p> |
426c6a59 | 1111 | <h3 class="function"><span class="info"> CUPS 1.3/Mac OS X 10.5 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> |
5a738aea MS |
1112 | <p class="description">Read a side-channel message.</p> |
1113 | <p class="code"> | |
1114 | int cupsSideChannelRead (<br> | |
1115 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
1116 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
1117 | char *data,<br> | |
1118 | int *datalen,<br> | |
1119 | double timeout<br> | |
1120 | );</p> | |
1121 | <h4 class="parameters">Parameters</h4> | |
1122 | <dl> | |
1123 | <dt>command</dt> | |
1124 | <dd class="description">Command code</dd> | |
1125 | <dt>status</dt> | |
1126 | <dd class="description">Status code</dd> | |
1127 | <dt>data</dt> | |
1128 | <dd class="description">Data buffer pointer</dd> | |
1129 | <dt>datalen</dt> | |
1130 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1131 | <dt>timeout</dt> | |
1132 | <dd class="description">Timeout in seconds</dd> | |
1133 | </dl> | |
1134 | <h4 class="returnvalue">Return Value</h4> | |
1135 | <p class="description">0 on success, -1 on error</p> | |
1136 | <h4 class="discussion">Discussion</h4> | |
1137 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 1138 | commands from a filter, driver, or port monitor program. The |
1139 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
1140 | and return the corresponding status codes.<br> |
1141 | <br> | |
1142 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1143 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1144 | update the value to contain the number of data bytes in the buffer. | |
1145 | ||
20fbc903 MS |
1146 | </p> |
1147 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a></h3> | |
1148 | <p class="description">Query a SNMP OID's value.</p> | |
1149 | <p class="code"> | |
1150 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPGet (<br> | |
1151 | const char *oid,<br> | |
1152 | char *data,<br> | |
1153 | int *datalen,<br> | |
1154 | double timeout<br> | |
1155 | );</p> | |
1156 | <h4 class="parameters">Parameters</h4> | |
1157 | <dl> | |
1158 | <dt>oid</dt> | |
1159 | <dd class="description">OID to query</dd> | |
1160 | <dt>data</dt> | |
1161 | <dd class="description">Buffer for OID value</dd> | |
1162 | <dt>datalen</dt> | |
1163 | <dd class="description">Size of OID buffer on entry, size of value on return</dd> | |
1164 | <dt>timeout</dt> | |
1165 | <dd class="description">Timeout in seconds</dd> | |
1166 | </dl> | |
1167 | <h4 class="returnvalue">Return Value</h4> | |
1168 | <p class="description">Query status</p> | |
1169 | <h4 class="discussion">Discussion</h4> | |
1170 | <p class="discussion">This function asks the backend to do a SNMP OID query on behalf of the | |
1171 | filter, port monitor, or backend using the default community name.<br> | |
1172 | <br> | |
1173 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1174 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1175 | supported and must be converted to their numeric forms.<br> | |
1176 | <br> | |
1177 | On input, "data" and "datalen" provide the location and size of the | |
1178 | buffer to hold the OID value as a string. HEX-String (binary) values are | |
1179 | converted to hexadecimal strings representing the binary data, while | |
1180 | NULL-Value and unknown OID types are returned as the empty string. | |
1181 | The returned "datalen" does not include the trailing nul. | |
1182 | ||
1183 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1184 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1185 | the printer does not respond to the SNMP query. | |
1186 | ||
1187 | </p> | |
1188 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSideChannelSNMPWalk">cupsSideChannelSNMPWalk</a></h3> | |
1189 | <p class="description">Query multiple SNMP OID values.</p> | |
1190 | <p class="code"> | |
1191 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPWalk (<br> | |
1192 | const char *oid,<br> | |
1193 | double timeout,<br> | |
1194 | <a href="#cups_sc_walk_func_t">cups_sc_walk_func_t</a> cb,<br> | |
1195 | void *context<br> | |
1196 | );</p> | |
1197 | <h4 class="parameters">Parameters</h4> | |
1198 | <dl> | |
1199 | <dt>oid</dt> | |
1200 | <dd class="description">First numeric OID to query</dd> | |
1201 | <dt>timeout</dt> | |
1202 | <dd class="description">Timeout for each query in seconds</dd> | |
1203 | <dt>cb</dt> | |
1204 | <dd class="description">Function to call with each value</dd> | |
1205 | <dt>context</dt> | |
1206 | <dd class="description">Application-defined pointer to send to callback</dd> | |
1207 | </dl> | |
1208 | <h4 class="returnvalue">Return Value</h4> | |
1209 | <p class="description">Status of first query of <code>CUPS_SC_STATUS_OK</code> on success</p> | |
1210 | <h4 class="discussion">Discussion</h4> | |
1211 | <p class="discussion">This function asks the backend to do multiple SNMP OID queries on behalf | |
1212 | of the filter, port monitor, or backend using the default community name. | |
1213 | All OIDs under the "parent" OID are queried and the results are sent to | |
1214 | the callback function you provide.<br> | |
1215 | <br> | |
1216 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1217 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1218 | supported and must be converted to their numeric forms.<br> | |
1219 | <br> | |
1220 | "timeout" specifies the timeout for each OID query. The total amount of | |
1221 | time will depend on the number of OID values found and the time required | |
1222 | for each query.<br> | |
1223 | <br> | |
1224 | "cb" provides a function to call for every value that is found. "context" | |
1225 | is an application-defined pointer that is sent to the callback function | |
1226 | along with the OID and current data. The data passed to the callback is the | |
1227 | same as returned by <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a>. | |
1228 | ||
1229 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1230 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1231 | the printer does not respond to the first SNMP query. | |
1232 | ||
5a738aea | 1233 | </p> |
426c6a59 | 1234 | <h3 class="function"><span class="info"> CUPS 1.3/Mac OS X 10.5 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> |
5a738aea MS |
1235 | <p class="description">Write a side-channel message.</p> |
1236 | <p class="code"> | |
1237 | int cupsSideChannelWrite (<br> | |
1238 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1239 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
1240 | const char *data,<br> | |
1241 | int datalen,<br> | |
1242 | double timeout<br> | |
1243 | );</p> | |
1244 | <h4 class="parameters">Parameters</h4> | |
1245 | <dl> | |
1246 | <dt>command</dt> | |
1247 | <dd class="description">Command code</dd> | |
1248 | <dt>status</dt> | |
1249 | <dd class="description">Status code</dd> | |
1250 | <dt>data</dt> | |
1251 | <dd class="description">Data buffer pointer</dd> | |
1252 | <dt>datalen</dt> | |
1253 | <dd class="description">Number of bytes of data</dd> | |
1254 | <dt>timeout</dt> | |
1255 | <dd class="description">Timeout in seconds</dd> | |
1256 | </dl> | |
1257 | <h4 class="returnvalue">Return Value</h4> | |
1258 | <p class="description">0 on success, -1 on error</p> | |
1259 | <h4 class="discussion">Discussion</h4> | |
1260 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 1261 | responses to a filter, driver, or port monitor program. |
1262 | ||
5a738aea MS |
1263 | </p> |
1264 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
1265 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> | |
1266 | <p class="description">Backend exit codes</p> | |
1267 | <p class="code"> | |
1268 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
1269 | </p> | |
1270 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
1271 | <p class="description">Bidirectional capabilities</p> | |
1272 | <p class="code"> | |
1273 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
1274 | </p> | |
1275 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
1276 | <p class="description">Request command codes</p> | |
1277 | <p class="code"> | |
1278 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
1279 | </p> | |
1280 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> | |
1281 | <p class="description">Printer state bits</p> | |
1282 | <p class="code"> | |
1283 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
1284 | </p> | |
1285 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
1286 | <p class="description">Response status codes</p> | |
1287 | <p class="code"> | |
1288 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
1289 | </p> | |
20fbc903 MS |
1290 | <h3 class="typedef"><a name="cups_sc_walk_func_t">cups_sc_walk_func_t</a></h3> |
1291 | <p class="description">SNMP walk callback</p> | |
1292 | <p class="code"> | |
1293 | typedef void (*cups_sc_walk_func_t)(const char *oid, const char *data, int datalen, void *context); | |
1294 | </p> | |
5a738aea MS |
1295 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> |
1296 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> | |
1297 | <p class="description">Backend exit codes</p> | |
1298 | <h4 class="constants">Constants</h4> | |
1299 | <dl> | |
1300 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
1301 | <dd class="description">Job failed, authentication required</dd> | |
1302 | <dt>CUPS_BACKEND_CANCEL </dt> | |
1303 | <dd class="description">Job failed, cancel job</dd> | |
1304 | <dt>CUPS_BACKEND_FAILED </dt> | |
1305 | <dd class="description">Job failed, use error-policy</dd> | |
1306 | <dt>CUPS_BACKEND_HOLD </dt> | |
1307 | <dd class="description">Job failed, hold job</dd> | |
1308 | <dt>CUPS_BACKEND_OK </dt> | |
1309 | <dd class="description">Job completed successfully</dd> | |
1310 | <dt>CUPS_BACKEND_STOP </dt> | |
1311 | <dd class="description">Job failed, stop queue</dd> | |
1312 | </dl> | |
1313 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
79e1d494 | 1314 | <p class="description">Bidirectional capability values</p> |
5a738aea MS |
1315 | <h4 class="constants">Constants</h4> |
1316 | <dl> | |
1317 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
1318 | <dd class="description">Bidirectional I/O is not supported</dd> | |
1319 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
1320 | <dd class="description">Bidirectional I/O is supported</dd> | |
1321 | </dl> | |
1322 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
1323 | <p class="description">Request command codes</p> | |
1324 | <h4 class="constants">Constants</h4> | |
1325 | <dl> | |
1326 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
1327 | <dd class="description">Drain all pending output</dd> | |
1328 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
1329 | <dd class="description">Return bidirectional capabilities</dd> | |
1330 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> | |
1331 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
1332 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
1333 | <dd class="description">Return the device state</dd> | |
20fbc903 MS |
1334 | <dt>CUPS_SC_CMD_SNMP_GET <span class="info"> CUPS 1.4 </span></dt> |
1335 | <dd class="description">Query an SNMP OID </dd> | |
1336 | <dt>CUPS_SC_CMD_SNMP_GET_NEXT <span class="info"> CUPS 1.4 </span></dt> | |
1337 | <dd class="description">Query the next SNMP OID </dd> | |
5a738aea MS |
1338 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> |
1339 | <dd class="description">Do a soft reset</dd> | |
1340 | </dl> | |
1341 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> | |
1342 | <p class="description">Printer state bits</p> | |
1343 | <h4 class="constants">Constants</h4> | |
1344 | <dl> | |
1345 | <dt>CUPS_SC_STATE_BUSY </dt> | |
1346 | <dd class="description">Device is busy</dd> | |
1347 | <dt>CUPS_SC_STATE_ERROR </dt> | |
1348 | <dd class="description">Other error condition</dd> | |
1349 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
1350 | <dd class="description">Toner/ink out condition</dd> | |
1351 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
1352 | <dd class="description">Toner/ink low condition</dd> | |
1353 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
1354 | <dd class="description">Paper out condition</dd> | |
1355 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
1356 | <dd class="description">Paper low condition</dd> | |
1357 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
79e1d494 | 1358 | <dd class="description">Device is offline</dd> |
5a738aea | 1359 | <dt>CUPS_SC_STATE_ONLINE </dt> |
79e1d494 | 1360 | <dd class="description">Device is online</dd> |
5a738aea MS |
1361 | </dl> |
1362 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
1363 | <p class="description">Response status codes</p> | |
1364 | <h4 class="constants">Constants</h4> | |
1365 | <dl> | |
1366 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
1367 | <dd class="description">The command/response message was invalid</dd> | |
1368 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
1369 | <dd class="description">An I/O error occurred</dd> | |
1370 | <dt>CUPS_SC_STATUS_NONE </dt> | |
1371 | <dd class="description">No status</dd> | |
1372 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
1373 | <dd class="description">Command not implemented</dd> | |
1374 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
1375 | <dd class="description">The device did not respond</dd> | |
1376 | <dt>CUPS_SC_STATUS_OK </dt> | |
1377 | <dd class="description">Operation succeeded</dd> | |
1378 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
1379 | <dd class="description">The backend did not respond</dd> | |
1380 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
1381 | <dd class="description">Response too big</dd> | |
1382 | </dl> | |
1383 | </div> | |
ef416fc2 | 1384 | </body> |
1385 | </html> |