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5a738aea | 339 | --></style> |
ef416fc2 | 340 | </head> |
341 | <body> | |
5a738aea | 342 | <div class='body'> |
ef416fc2 | 343 | <!-- |
68b10830 | 344 | "$Id$" |
ef416fc2 | 345 | |
5a738aea MS |
346 | Filter and backend programming header for the Common UNIX Printing System |
347 | (CUPS). | |
ef416fc2 | 348 | |
178cb736 | 349 | Copyright 2008-2009 by Apple Inc. |
ef416fc2 | 350 | |
351 | These coded instructions, statements, and computer programs are the | |
bc44d920 | 352 | property of Apple Inc. and are protected by Federal copyright |
353 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
354 | which should have been included with this file. If this file is | |
355 | file is missing or damaged, see the license at "http://www.cups.org/". | |
ef416fc2 | 356 | --> |
357 | ||
178cb736 MS |
358 | <h1 class='title'>Filter and Backend Programming</h1> |
359 | ||
5a738aea MS |
360 | <div class='summary'><table summary='General Information'> |
361 | <thead> | |
362 | <tr> | |
ac884b6a | 363 | <th>Headers</th> |
5a738aea | 364 | <th>cups/backend.h<br> |
79e1d494 | 365 | cups/sidechannel.h</th> |
5a738aea MS |
366 | </tr> |
367 | </thead> | |
368 | <tbody> | |
369 | <tr> | |
370 | <th>Library</th> | |
371 | <td>-lcups</td> | |
372 | </tr> | |
373 | <tr> | |
374 | <th>See Also</th> | |
375 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
376 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
377 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
79e1d494 | 378 | Programming: <a href='api-raster.html' target='_top'>Raster API</a><br> |
b0f6947b MS |
379 | Programming: <a href='postscript-driver.html' target='_top'>Developing PostScript Printer Drivers</a><br> |
380 | Programming: <a href='raster-driver.html' target='_top'>Developing Raster Printer Drivers</a><br> | |
10d09e33 | 381 | Specifications: <a href='spec-design.html' target='_top'>CUPS Design Description</a></td> |
5a738aea MS |
382 | </tr> |
383 | </tbody> | |
384 | </table></div> | |
385 | <h2 class="title">Contents</h2> | |
386 | <ul class="contents"> | |
5a738aea | 387 | <li><a href="#OVERVIEW">Overview</a><ul class="subcontents"> |
0268488e | 388 | <li><a href="#SECURITY">Security Considerations</a></li> |
22c9029b | 389 | <li><a href="#SIGNALS">Signal Handling</a></li> |
0268488e MS |
390 | <li><a href="#TEMPFILES">Temporary Files</a></li> |
391 | <li><a href="#COPIES">Copy Generation</a></li> | |
392 | <li><a href="#EXITCODES">Exit Codes</a></li> | |
393 | <li><a href="#ENVIRONMENT">Environment Variables</a></li> | |
394 | <li><a href="#MESSAGES">Communicating with the Scheduler</a></li> | |
395 | <li><a href="#COMMUNICATING_BACKEND">Communicating with the Backend</a></li> | |
396 | <li><a href="#COMMUNICATING_FILTER">Communicating with Filters</a></li> | |
397 | <li><a href="#SNMP">Doing SNMP Queries with Network Printers</a></li> | |
5a738aea MS |
398 | </ul></li> |
399 | <li><a href="#FUNCTIONS">Functions</a><ul class="code"> | |
0268488e MS |
400 | <li><a href="#cupsBackChannelRead" title="Read data from the backchannel.">cupsBackChannelRead</a></li> |
401 | <li><a href="#cupsBackChannelWrite" title="Write data to the backchannel.">cupsBackChannelWrite</a></li> | |
402 | <li><a href="#cupsBackendDeviceURI" title="Get the device URI for a backend.">cupsBackendDeviceURI</a></li> | |
403 | <li><a href="#cupsBackendReport" title="Write a device line from a backend.">cupsBackendReport</a></li> | |
404 | <li><a href="#cupsSideChannelDoRequest" title="Send a side-channel command to a backend and wait for a response.">cupsSideChannelDoRequest</a></li> | |
405 | <li><a href="#cupsSideChannelRead" title="Read a side-channel message.">cupsSideChannelRead</a></li> | |
406 | <li><a href="#cupsSideChannelSNMPGet" title="Query a SNMP OID's value.">cupsSideChannelSNMPGet</a></li> | |
407 | <li><a href="#cupsSideChannelSNMPWalk" title="Query multiple SNMP OID values.">cupsSideChannelSNMPWalk</a></li> | |
408 | <li><a href="#cupsSideChannelWrite" title="Write a side-channel message.">cupsSideChannelWrite</a></li> | |
8b450588 | 409 | </ul></li> |
5a738aea MS |
410 | <li><a href="#TYPES">Data Types</a><ul class="code"> |
411 | <li><a href="#cups_backend_t" title="Backend exit codes">cups_backend_t</a></li> | |
412 | <li><a href="#cups_sc_bidi_t" title="Bidirectional capabilities">cups_sc_bidi_t</a></li> | |
413 | <li><a href="#cups_sc_command_t" title="Request command codes">cups_sc_command_t</a></li> | |
82f97232 | 414 | <li><a href="#cups_sc_connected_t" title="Connectivity values">cups_sc_connected_t</a></li> |
5a738aea MS |
415 | <li><a href="#cups_sc_state_t" title="Printer state bits">cups_sc_state_t</a></li> |
416 | <li><a href="#cups_sc_status_t" title="Response status codes">cups_sc_status_t</a></li> | |
20fbc903 | 417 | <li><a href="#cups_sc_walk_func_t" title="SNMP walk callback">cups_sc_walk_func_t</a></li> |
5a738aea MS |
418 | </ul></li> |
419 | <li><a href="#ENUMERATIONS">Constants</a><ul class="code"> | |
420 | <li><a href="#cups_backend_e" title="Backend exit codes">cups_backend_e</a></li> | |
79e1d494 | 421 | <li><a href="#cups_sc_bidi_e" title="Bidirectional capability values">cups_sc_bidi_e</a></li> |
5a738aea | 422 | <li><a href="#cups_sc_command_e" title="Request command codes">cups_sc_command_e</a></li> |
82f97232 | 423 | <li><a href="#cups_sc_connected_e" title="Connectivity values">cups_sc_connected_e</a></li> |
5a738aea MS |
424 | <li><a href="#cups_sc_state_e" title="Printer state bits">cups_sc_state_e</a></li> |
425 | <li><a href="#cups_sc_status_e" title="Response status codes">cups_sc_status_e</a></li> | |
426 | </ul></li> | |
0268488e | 427 | </ul> |
5a738aea | 428 | <!-- |
68b10830 | 429 | "$Id$" |
ef416fc2 | 430 | |
22c9029b | 431 | Filter and backend programming introduction for CUPS. |
ef416fc2 | 432 | |
22c9029b | 433 | Copyright 2007-2011 by Apple Inc. |
5a738aea | 434 | Copyright 1997-2006 by Easy Software Products, all rights reserved. |
ef416fc2 | 435 | |
5a738aea MS |
436 | These coded instructions, statements, and computer programs are the |
437 | property of Apple Inc. and are protected by Federal copyright | |
438 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
439 | which should have been included with this file. If this file is | |
440 | file is missing or damaged, see the license at "http://www.cups.org/". | |
441 | --> | |
f7deaa1a | 442 | |
5a738aea | 443 | <h2 class='title'><a name="OVERVIEW">Overview</a></h2> |
ef416fc2 | 444 | |
79e1d494 MS |
445 | <p>Filters (which include printer drivers and port monitors) and backends |
446 | are used to convert job files to a printable format and send that data to the | |
447 | printer itself. All of these programs use a common interface for processing | |
448 | print jobs and communicating status information to the scheduler. Each is run | |
449 | with a standard set of command-line arguments:<p> | |
ef416fc2 | 450 | |
5a738aea | 451 | <dl class="code"> |
f7deaa1a | 452 | |
5a738aea MS |
453 | <dt>argv[1]</dt> |
454 | <dd>The job ID</dd> | |
ef416fc2 | 455 | |
5a738aea MS |
456 | <dt>argv[2]</dt> |
457 | <dd>The user printing the job</dd> | |
f7deaa1a | 458 | |
5a738aea MS |
459 | <dt>argv[3]</dt> |
460 | <dd>The job name/title</dd> | |
f7deaa1a | 461 | |
5a738aea MS |
462 | <dt>argv[4]</dt> |
463 | <dd>The number of copies to print</dd> | |
f7deaa1a | 464 | |
5a738aea MS |
465 | <dt>argv[5]</dt> |
466 | <dd>The options that were provided when the job was submitted</dd> | |
f7deaa1a | 467 | |
5a738aea | 468 | <dt>argv[6]</dt> |
79e1d494 | 469 | <dd>The file to print (first program only)</dd> |
5a738aea | 470 | </dl> |
f7deaa1a | 471 | |
5a738aea MS |
472 | <p>The scheduler runs one or more of these programs to print any given job. The |
473 | first filter reads from the print file and writes to the standard output, while | |
474 | the remaining filters read from the standard input and write to the standard | |
475 | output. The backend is the last filter in the chain and writes to the | |
476 | device.</p> | |
f7deaa1a | 477 | |
178cb736 MS |
478 | <p>Filters are always run as a non-privileged user, typically "lp", with no |
479 | connection to the user's desktop. Backends are run either as a non-privileged | |
480 | user or as root if the file permissions do not allow user or group execution. | |
481 | The <a href="#PERMISSIONS">file permissions</a> section talks about this in | |
482 | more detail.</p> | |
483 | ||
ac884b6a MS |
484 | <h3><a name="SECURITY">Security Considerations</a></h3> |
485 | ||
486 | <p>It is always important to use security programming practices. Filters and | |
487 | most backends are run as a non-priviledged user, so the major security | |
488 | consideration is resource utilization - filters should not depend on unlimited | |
489 | amounts of CPU, memory, or disk space, and should protect against conditions | |
490 | that could lead to excess usage of any resource like infinite loops and | |
491 | unbounded recursion. In addition, filters must <em>never</em> allow the user to | |
492 | specify an arbitrary file path to a separator page, template, or other file | |
493 | used by the filter since that can lead to an unauthorized disclosure of | |
494 | information. <em>Always</em> treat input as suspect and validate it!</p> | |
495 | ||
4d301e69 | 496 | <p>If you are developing a backend that runs as root, make sure to check for |
ac884b6a MS |
497 | potential buffer overflows, integer under/overflow conditions, and file |
498 | accesses since these can lead to privilege escalations. When writing files, | |
499 | always validate the file path and <em>never</em> allow a user to determine | |
500 | where to store a file.</p> | |
501 | ||
502 | <blockquote><b>Note:</b> | |
503 | ||
504 | <p><em>Never</em> write files to a user's home directory. Aside from the | |
505 | security implications, CUPS is a network print service and as such the network | |
506 | user may not be the same as the local user and/or there may not be a local home | |
507 | directory to write to.</p> | |
508 | ||
509 | <p>In addition, some operating systems provide additional security mechanisms | |
178cb736 | 510 | that further limit file system access, even for backends running as root. On |
ac884b6a MS |
511 | Mac OS X, for example, no backend may write to a user's home directory.</p> |
512 | </blockquote> | |
513 | ||
22c9029b MS |
514 | <h3><a name="SIGNALS">Signal Handling</a><h3> |
515 | ||
516 | <p>The scheduler sends <code>SIGTERM</code> when a printing job is canceled or | |
517 | held. Filters, backends, and port monitors <em>must</em> catch | |
518 | <code>SIGTERM</code> and perform any cleanup necessary to produce a valid output | |
519 | file or return the printer to a known good state. The recommended behavior is to | |
520 | end the output on the current page.</p> | |
521 | ||
178cb736 MS |
522 | <h3><a name="PERMISSIONS">File Permissions</a></h3> |
523 | ||
524 | <p>For security reasons, CUPS will only run filters and backends that are owned | |
4d301e69 MS |
525 | by root and do not have world or group write permissions. The recommended |
526 | permissions for filters and backends are 0555 - read and execute but no write. | |
527 | Backends that must run as root should use permissions of 0500 - read and execute | |
528 | by root, no access for other users. Write permissions can be enabled for the | |
529 | root user only.</p> | |
178cb736 MS |
530 | |
531 | <p>To avoid a warning message, the directory containing your filter(s) must also | |
4d301e69 MS |
532 | be owned by root and have world and group write disabled - permissions of 0755 |
533 | or 0555 are strongly encouraged.</p> | |
178cb736 | 534 | |
ac884b6a MS |
535 | <h3><a name="TEMPFILES">Temporary Files</a></h3> |
536 | ||
537 | <p>Temporary files should be created in the directory specified by the | |
538 | "TMPDIR" environment variable. The | |
539 | <a href="#cupsTempFile2"><code>cupsTempFile2</code></a> function can be | |
540 | used to safely create temporary files in this directory.</p> | |
541 | ||
542 | <h3><a name="COPIES">Copy Generation</a></h3> | |
543 | ||
544 | <p>The <code>argv[4]</code> argument specifies the number of copies to produce | |
545 | of the input file. In general, you should only generate copies if the | |
546 | <em>filename</em> argument is supplied. The only exception to this are | |
547 | filters that produce device-independent PostScript output, since the PostScript | |
548 | filter <var>pstops</var> is responsible for generating copies of PostScript | |
549 | files.</p> | |
550 | ||
5a738aea | 551 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 552 | |
5a738aea MS |
553 | <p>Filters must exit with status 0 when they successfully generate print data |
554 | or 1 when they encounter an error. Backends can return any of the | |
555 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 556 | |
5a738aea | 557 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 558 | |
79e1d494 MS |
559 | <p>The following environment variables are defined by the printing system |
560 | when running print filters and backends:</p> | |
f7deaa1a | 561 | |
5a738aea | 562 | <dl class="code"> |
f7deaa1a | 563 | |
acb056cb | 564 | <dt>APPLE_LANGUAGE</dt> |
5a738aea MS |
565 | <dd>The Apple language identifier associated with the job |
566 | (Mac OS X only).</dd> | |
f7deaa1a | 567 | |
5a738aea MS |
568 | <dt>CHARSET</dt> |
569 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 570 | |
5a738aea MS |
571 | <dt>CLASS</dt> |
572 | <dd>When a job is submitted to a printer class, contains the name of | |
573 | the destination printer class. Otherwise this environment | |
574 | variable will not be set.</dd> | |
f7deaa1a | 575 | |
5a738aea MS |
576 | <dt>CONTENT_TYPE</dt> |
577 | <dd>The MIME type associated with the file (e.g. | |
578 | application/postscript).</dd> | |
f7deaa1a | 579 | |
5a738aea | 580 | <dt>CUPS_CACHEDIR</dt> |
79e1d494 MS |
581 | <dd>The directory where cache files can be stored. Cache files can be |
582 | used to retain information between jobs or files in a job.</dd> | |
f7deaa1a | 583 | |
5a738aea | 584 | <dt>CUPS_DATADIR</dt> |
79e1d494 | 585 | <dd>The directory where (read-only) CUPS data files can be found.</dd> |
f7deaa1a | 586 | |
758a062f MS |
587 | <dt>CUPS_FILETYPE</dt> |
588 | <dd>The type of file being printed: "job-sheet" for a banner page and | |
589 | "document" for a regular print file.</dd> | |
590 | ||
5a738aea MS |
591 | <dt>CUPS_SERVERROOT</dt> |
592 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 593 | |
5a738aea MS |
594 | <dt>DEVICE_URI</dt> |
595 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 596 | |
5a738aea MS |
597 | <dt>FINAL_CONTENT_TYPE</dt> |
598 | <dd>The MIME type associated with the printer (e.g. | |
599 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 600 | |
5a738aea MS |
601 | <dt>LANG</dt> |
602 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 603 | |
5a738aea MS |
604 | <dt>PPD</dt> |
605 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
606 | file for this printer.</dd> | |
f7deaa1a | 607 | |
5a738aea | 608 | <dt>PRINTER</dt> |
79e1d494 | 609 | <dd>The queue name of the class or printer.</dd> |
f7deaa1a | 610 | |
5a738aea MS |
611 | <dt>RIP_CACHE</dt> |
612 | <dd>The recommended amount of memory to use for Raster Image | |
613 | Processors (RIPs).</dd> | |
f7deaa1a | 614 | |
79e1d494 MS |
615 | <dt>TMPDIR</dt> |
616 | <dd>The directory where temporary files should be created.</dd> | |
617 | ||
5a738aea | 618 | </dl> |
f7deaa1a | 619 | |
5a738aea | 620 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 621 | |
79e1d494 MS |
622 | <p>Filters and backends communicate with the scheduler by writing messages |
623 | to the standard error file. The scheduler reads messages from all filters in | |
624 | a job and processes the message based on its prefix. For example, the following | |
625 | code sets the current printer state message to "Printing page 5":</p> | |
f7deaa1a | 626 | |
5a738aea MS |
627 | <pre class="example"> |
628 | int page = 5; | |
f7deaa1a | 629 | |
5a738aea | 630 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 631 | </pre> |
632 | ||
5a738aea MS |
633 | <p>Each message is a single line of text starting with one of the following |
634 | prefix strings:</p> | |
635 | ||
636 | <dl class="code"> | |
637 | ||
638 | <dt>ALERT: message</dt> | |
639 | <dd>Sets the printer-state-message attribute and adds the specified | |
640 | message to the current error log file using the "alert" log level.</dd> | |
641 | ||
642 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
643 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
644 | to set the <code>marker-colors</code>, <code>marker-levels</code>, | |
75bd9771 MS |
645 | <code>marker-message</code>, <code>marker-names</code>, |
646 | <code>marker-types</code>, <code>printer-alert</code>, and | |
647 | <code>printer-alert-description</code> printer attributes. Standard | |
648 | <code>marker-types</code> values are listed in <a href='#TABLE1'>Table | |
649 | 1</a>.</dd> | |
5a738aea MS |
650 | |
651 | <dt>CRIT: message</dt> | |
652 | <dd>Sets the printer-state-message attribute and adds the specified | |
653 | message to the current error log file using the "critical" log | |
654 | level.</dd> | |
655 | ||
656 | <dt>DEBUG: message</dt> | |
657 | <dd>Sets the printer-state-message attribute and adds the specified | |
658 | message to the current error log file using the "debug" log level.</dd> | |
659 | ||
660 | <dt>DEBUG2: message</dt> | |
661 | <dd>Sets the printer-state-message attribute and adds the specified | |
662 | message to the current error log file using the "debug2" log level.</dd> | |
663 | ||
664 | <dt>EMERG: message</dt> | |
665 | <dd>Sets the printer-state-message attribute and adds the specified | |
666 | message to the current error log file using the "emergency" log | |
667 | level.</dd> | |
668 | ||
669 | <dt>ERROR: message</dt> | |
670 | <dd>Sets the printer-state-message attribute and adds the specified | |
79e1d494 MS |
671 | message to the current error log file using the "error" log level. |
672 | Use "ERROR:" messages for non-persistent processing errors.</dd> | |
5a738aea MS |
673 | |
674 | <dt>INFO: message</dt> | |
675 | <dd>Sets the printer-state-message attribute. If the current log level | |
676 | is set to "debug2", also adds the specified message to the current error | |
677 | log file using the "info" log level.</dd> | |
678 | ||
679 | <dt>NOTICE: message</dt> | |
680 | <dd>Sets the printer-state-message attribute and adds the specified | |
681 | message to the current error log file using the "notice" log level.</dd> | |
682 | ||
683 | <dt>PAGE: page-number #-copies</dt> | |
684 | <dt>PAGE: total #-pages</dt> | |
685 | <dd>Adds an entry to the current page log file. The first form adds | |
686 | #-copies to the job-media-sheets-completed attribute. The second | |
687 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
688 | ||
20fbc903 MS |
689 | <dt>PPD: keyword=value [keyword=value ...]</dt> |
690 | <dd>Changes or adds keywords to the printer's PPD file. Typically | |
691 | this is used to update installable options or default media settings | |
692 | based on the printer configuration.</dd> | |
693 | ||
5a738aea MS |
694 | <dt>STATE: printer-state-reason [printer-state-reason ...]</dt> |
695 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> | |
696 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
697 | <dd>Sets, adds, or removes printer-state-reason keywords to the | |
79e1d494 MS |
698 | current queue. Typically this is used to indicate persistent media, |
699 | ink, toner, and configuration conditions or errors on a printer. | |
700 | <a href='#TABLE2'>Table 2</a> lists the standard state keywords - | |
acb056cb MS |
701 | use vendor-prefixed ("com.acme.foo") keywords for custom states. |
702 | ||
703 | <blockquote><b>Note:</b> | |
704 | ||
705 | <p>"STATE:" messages often provide visible alerts to the user. For example, on | |
706 | Mac OS X setting a printer-state-reason value with an "-error" or "-warning" | |
707 | suffix will cause the printer's dock item to bounce if the corresponding reason | |
708 | is localized with a cupsIPPReason keyword in the printer's PPD file.</p> | |
709 | ||
710 | </blockquote></dd> | |
5a738aea MS |
711 | |
712 | <dt>WARNING: message</dt> | |
713 | <dd>Sets the printer-state-message attribute and adds the specified | |
714 | message to the current error log file using the "warning" log | |
715 | level.</dd> | |
716 | ||
717 | </dl> | |
718 | ||
719 | <p>Messages without one of these prefixes are treated as if they began with | |
720 | the "DEBUG:" prefix string.</p> | |
721 | ||
79e1d494 MS |
722 | <div class='table'><table width='80%' summary='Table 1: Standard marker-types Values'> |
723 | <caption>Table 1: <a name='TABLE1'>Standard marker-types Values</a></caption> | |
724 | <thead> | |
725 | <tr> | |
726 | <th>marker-type</th> | |
727 | <th>Description</th> | |
728 | </tr> | |
729 | </thead> | |
730 | <tbody> | |
731 | <tr> | |
732 | <td>developer</td> | |
733 | <td>Developer unit</td> | |
734 | </tr> | |
735 | <tr> | |
736 | <td>fuser</td> | |
737 | <td>Fuser unit</td> | |
738 | </tr> | |
739 | <tr> | |
740 | <td>fuserCleaningPad</td> | |
741 | <td>Fuser cleaning pad</td> | |
742 | </tr> | |
743 | <tr> | |
744 | <td>fuserOil</td> | |
745 | <td>Fuser oil</td> | |
746 | </tr> | |
747 | <tr> | |
748 | <td>ink</td> | |
749 | <td>Ink supply</td> | |
750 | </tr> | |
751 | <tr> | |
752 | <td>opc</td> | |
753 | <td>Photo conductor</td> | |
754 | </tr> | |
755 | <tr> | |
756 | <td>solidWax</td> | |
757 | <td>Wax supply</td> | |
758 | </tr> | |
759 | <tr> | |
760 | <td>staples</td> | |
761 | <td>Staple supply</td> | |
762 | </tr> | |
763 | <tr> | |
764 | <td>toner</td> | |
765 | <td>Toner supply</td> | |
766 | </tr> | |
767 | <tr> | |
768 | <td>transferUnit</td> | |
769 | <td>Transfer unit</td> | |
770 | </tr> | |
771 | <tr> | |
772 | <td>wasteInk</td> | |
773 | <td>Waste ink tank</td> | |
774 | </tr> | |
775 | <tr> | |
776 | <td>wasteToner</td> | |
777 | <td>Waste toner tank</td> | |
778 | </tr> | |
779 | <tr> | |
780 | <td>wasteWax</td> | |
781 | <td>Waste wax tank</td> | |
782 | </tr> | |
783 | </tbody> | |
784 | </table></div> | |
785 | ||
786 | <br> | |
787 | ||
788 | <div class='table'><table width='80%' summary='Table 2: Standard State Keywords'> | |
789 | <caption>Table 2: <a name='TABLE2'>Standard State Keywords</a></caption> | |
790 | <thead> | |
791 | <tr> | |
792 | <th>Keyword</th> | |
793 | <th>Description</th> | |
794 | </tr> | |
795 | </thead> | |
796 | <tbody> | |
797 | <tr> | |
798 | <td>connecting-to-device</td> | |
799 | <td>Connecting to printer but not printing yet</td> | |
800 | </tr> | |
801 | <tr> | |
802 | <td>cover-open</td> | |
803 | <td>A cover is open on the printer</td> | |
804 | </tr> | |
805 | <tr> | |
806 | <td>input-tray-missing</td> | |
807 | <td>An input tray is missing from the printer</td> | |
808 | </tr> | |
809 | <tr> | |
810 | <td>marker-supply-empty</td> | |
811 | <td>Out of ink</td> | |
812 | </tr> | |
813 | <tr> | |
814 | <td>marker-supply-low</td> | |
815 | <td>Low on ink</td> | |
816 | </tr> | |
817 | <tr> | |
818 | <td>marker-waste-almost-full</td> | |
819 | <td>Waste tank almost full</td> | |
820 | </tr> | |
821 | <tr> | |
822 | <td>marker-waste-full</td> | |
823 | <td>Waste tank full</td> | |
824 | </tr> | |
825 | <tr> | |
826 | <td>media-empty</td> | |
827 | <td>Out of media</td> | |
828 | </tr> | |
829 | <tr> | |
830 | <td>media-jam</td> | |
831 | <td>Media is jammed in the printer</td> | |
832 | </tr> | |
833 | <tr> | |
834 | <td>media-low</td> | |
835 | <td>Low on media</td> | |
836 | </tr> | |
837 | <tr> | |
838 | <td>paused</td> | |
839 | <td>Stop the printer</td> | |
840 | </tr> | |
841 | <tr> | |
842 | <td>timed-out</td> | |
843 | <td>Unable to connect to printer</td> | |
844 | </tr> | |
845 | <tr> | |
846 | <td>toner-empty</td> | |
847 | <td>Out of toner</td> | |
848 | </tr> | |
849 | <tr> | |
850 | <td>toner-low</td> | |
851 | <td>Low on toner</td> | |
852 | </tr> | |
853 | </tbody> | |
854 | </table></div> | |
855 | ||
20fbc903 | 856 | <h3><a name="COMMUNICATING_BACKEND">Communicating with the Backend</a></h3> |
5a738aea MS |
857 | |
858 | <p>Filters can communicate with the backend via the | |
859 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
860 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
22c9029b | 861 | functions. The |
5a738aea MS |
862 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function |
863 | reads data that has been sent back from the device and is typically used to | |
864 | obtain status and configuration information. For example, the following code | |
865 | polls the backend for back-channel data:</p> | |
866 | ||
867 | <pre class="example"> | |
868 | #include <cups/cups.h> | |
869 | ||
870 | char buffer[8192]; | |
871 | ssize_t bytes; | |
872 | ||
873 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
874 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
875 | </pre> | |
f7deaa1a | 876 | |
79e1d494 MS |
877 | <p>Filters can also use <code>select()</code> or <code>poll()</code> on the |
878 | back-channel file descriptor (3 or <code>CUPS_BC_FD</code>) to read data only | |
879 | when it is available.</p> | |
880 | ||
881 | <p>The | |
5a738aea MS |
882 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> |
883 | function allows you to get out-of-band status information and do synchronization | |
884 | with the device. For example, the following code gets the current IEEE-1284 | |
885 | device ID string from the backend:</p> | |
886 | ||
887 | <pre class="example"> | |
f7deaa1a | 888 | #include <cups/sidechannel.h> |
889 | ||
890 | char data[2049]; | |
891 | int datalen; | |
5a738aea | 892 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 893 | |
79e1d494 MS |
894 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for |
895 | nul-termination... */ | |
f7deaa1a | 896 | datalen = sizeof(data) - 1; |
897 | ||
898 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 899 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 900 | |
901 | /* Use the returned value if OK was returned and the length is non-zero */ | |
902 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
903 | data[datalen] = '\0'; | |
904 | else | |
905 | data[0] = '\0'; | |
906 | </pre> | |
907 | ||
20fbc903 MS |
908 | <h3><a name="COMMUNICATING_FILTER">Communicating with Filters</a></h3> |
909 | ||
5a738aea MS |
910 | <p>Backends communicate with filters using the reciprocal functions |
911 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
912 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
913 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
914 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 915 | |
5a738aea MS |
916 | <pre class="example"> |
917 | #include <cups/cups.h> | |
f7deaa1a | 918 | |
5a738aea MS |
919 | char buffer[8192]; |
920 | ssize_t bytes; | |
f7deaa1a | 921 | |
79e1d494 MS |
922 | /* Obtain data from printer/device */ |
923 | ... | |
924 | ||
5a738aea MS |
925 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
926 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 927 | </pre> |
928 | ||
5a738aea MS |
929 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
930 | function reads a side-channel command from a filter, driver, or port monitor. | |
931 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
932 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
933 | separate thread for that purpose), or use <code>select</code> or | |
934 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
20fbc903 | 935 | input and output on several file descriptors at the same time.</p> |
5a738aea MS |
936 | |
937 | <p>Once a command is processed, the backend uses the | |
938 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
939 | to send its response. For example, the following code shows how to poll for a | |
940 | side-channel command and respond to it:</p> | |
941 | ||
942 | <pre class="example"> | |
f7deaa1a | 943 | #include <cups/sidechannel.h> |
944 | ||
5a738aea MS |
945 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
946 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
20fbc903 MS |
947 | char data[2048]; |
948 | int datalen = sizeof(data); | |
f7deaa1a | 949 | |
950 | /* Poll for a command... */ | |
20fbc903 | 951 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, data, &datalen, 0.0)) |
f7deaa1a | 952 | { |
f7deaa1a | 953 | switch (command) |
954 | { | |
20fbc903 | 955 | /* handle supported commands, fill data/datalen/status with values as needed */ |
f7deaa1a | 956 | |
957 | default : | |
958 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
959 | datalen = 0; | |
960 | break; | |
961 | } | |
962 | ||
963 | /* Send a response... */ | |
5a738aea | 964 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 965 | } |
966 | </pre> | |
ac884b6a MS |
967 | |
968 | <h3><a name="SNMP">Doing SNMP Queries with Network Printers</a></h3> | |
969 | ||
970 | <p>The Simple Network Management Protocol (SNMP) allows you to get the current | |
971 | status, page counter, and supply levels from most network printers. Every | |
972 | piece of information is associated with an Object Identifier (OID), and | |
973 | every printer has a <em>community</em> name associated with it. OIDs can be | |
974 | queried directly or by "walking" over a range of OIDs with a common prefix.</p> | |
975 | ||
20fbc903 MS |
976 | <p>The two CUPS SNMP functions provide a simple API for querying network |
977 | printers through the side-channel interface. Each accepts a string containing | |
978 | an OID like ".1.3.6.1.2.1.43.10.2.1.4.1.1" (the standard page counter OID) | |
979 | along with a timeout for the query.</p> | |
ac884b6a | 980 | |
20fbc903 MS |
981 | <p>The <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a> |
982 | function queries a single OID and returns the value as a string in a buffer | |
983 | you supply:</p> | |
ac884b6a MS |
984 | |
985 | <pre class="example"> | |
20fbc903 | 986 | #include <cups/sidechannel.h> |
ac884b6a | 987 | |
20fbc903 MS |
988 | char data[512]; |
989 | int datalen = sizeof(data); | |
ac884b6a | 990 | |
20fbc903 MS |
991 | if (<a href="#cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a>(".1.3.6.1.2.1.43.10.2.1.4.1.1", data, &datalen, 5.0) |
992 | == CUPS_SC_STATUS_OK) | |
ac884b6a MS |
993 | { |
994 | /* Do something with the value */ | |
20fbc903 | 995 | printf("Page counter is: %s\n", data); |
ac884b6a MS |
996 | } |
997 | </pre> | |
998 | ||
20fbc903 MS |
999 | <p>The |
1000 | <a href="#cupsSideChannelSNMPWalk"><code>cupsSideChannelSNMPWalk</code></a> | |
1001 | function allows you to query a whole group of OIDs, calling a function of your | |
1002 | choice for each OID that is found:</p> | |
ac884b6a MS |
1003 | |
1004 | <pre class="example"> | |
20fbc903 | 1005 | #include <cups/sidechannel.h> |
ac884b6a MS |
1006 | |
1007 | void | |
20fbc903 | 1008 | my_callback(const char *oid, const char *data, int datalen, void *context) |
ac884b6a MS |
1009 | { |
1010 | /* Do something with the value */ | |
20fbc903 | 1011 | printf("%s=%s\n", oid, data); |
ac884b6a MS |
1012 | } |
1013 | ||
20fbc903 MS |
1014 | ... |
1015 | ||
ac884b6a MS |
1016 | void *my_data; |
1017 | ||
20fbc903 | 1018 | <a href="#cupsSideChannelSNMPWalk">cupsSNMPSideChannelWalk</a>(".1.3.6.1.2.1.43", 5.0, my_callback, my_data); |
ac884b6a | 1019 | </pre> |
20fbc903 | 1020 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
426c6a59 | 1021 | <h3 class="function"><span class="info"> CUPS 1.2/Mac OS X 10.5 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> |
5a738aea MS |
1022 | <p class="description">Read data from the backchannel.</p> |
1023 | <p class="code"> | |
1024 | ssize_t cupsBackChannelRead (<br> | |
1025 | char *buffer,<br> | |
1026 | size_t bytes,<br> | |
1027 | double timeout<br> | |
1028 | );</p> | |
1029 | <h4 class="parameters">Parameters</h4> | |
1030 | <dl> | |
1031 | <dt>buffer</dt> | |
79e1d494 | 1032 | <dd class="description">Buffer to read into</dd> |
5a738aea MS |
1033 | <dt>bytes</dt> |
1034 | <dd class="description">Bytes to read</dd> | |
1035 | <dt>timeout</dt> | |
79e1d494 | 1036 | <dd class="description">Timeout in seconds, typically 0.0 to poll</dd> |
5a738aea MS |
1037 | </dl> |
1038 | <h4 class="returnvalue">Return Value</h4> | |
1039 | <p class="description">Bytes read or -1 on error</p> | |
1040 | <h4 class="discussion">Discussion</h4> | |
79e1d494 MS |
1041 | <p class="discussion">Reads up to "bytes" bytes from the backchannel/backend. The "timeout" |
1042 | parameter controls how many seconds to wait for the data - use 0.0 to | |
1043 | return immediately if there is no data, -1.0 to wait for data indefinitely. | |
ef416fc2 | 1044 | |
5a738aea | 1045 | </p> |
426c6a59 | 1046 | <h3 class="function"><span class="info"> CUPS 1.2/Mac OS X 10.5 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> |
5a738aea MS |
1047 | <p class="description">Write data to the backchannel.</p> |
1048 | <p class="code"> | |
1049 | ssize_t cupsBackChannelWrite (<br> | |
1050 | const char *buffer,<br> | |
1051 | size_t bytes,<br> | |
1052 | double timeout<br> | |
1053 | );</p> | |
1054 | <h4 class="parameters">Parameters</h4> | |
1055 | <dl> | |
1056 | <dt>buffer</dt> | |
1057 | <dd class="description">Buffer to write</dd> | |
1058 | <dt>bytes</dt> | |
1059 | <dd class="description">Bytes to write</dd> | |
1060 | <dt>timeout</dt> | |
79e1d494 | 1061 | <dd class="description">Timeout in seconds, typically 1.0</dd> |
5a738aea MS |
1062 | </dl> |
1063 | <h4 class="returnvalue">Return Value</h4> | |
1064 | <p class="description">Bytes written or -1 on error</p> | |
1065 | <h4 class="discussion">Discussion</h4> | |
79e1d494 | 1066 | <p class="discussion">Writes "bytes" bytes to the backchannel/filter. The "timeout" parameter |
ef416fc2 | 1067 | controls how many seconds to wait for the data to be written - use |
1068 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
1069 | indefinitely. | |
1070 | ||
ac884b6a | 1071 | </p> |
426c6a59 | 1072 | <h3 class="function"><span class="info"> CUPS 1.2/Mac OS X 10.5 </span><a name="cupsBackendDeviceURI">cupsBackendDeviceURI</a></h3> |
ac884b6a MS |
1073 | <p class="description">Get the device URI for a backend.</p> |
1074 | <p class="code"> | |
1075 | const char *cupsBackendDeviceURI (<br> | |
1076 | char **argv<br> | |
1077 | );</p> | |
1078 | <h4 class="parameters">Parameters</h4> | |
1079 | <dl> | |
1080 | <dt>argv</dt> | |
1081 | <dd class="description">Command-line arguments</dd> | |
1082 | </dl> | |
1083 | <h4 class="returnvalue">Return Value</h4> | |
1084 | <p class="description">Device URI or <code>NULL</code></p> | |
1085 | <h4 class="discussion">Discussion</h4> | |
1086 | <p class="discussion">The "argv" argument is the argv argument passed to main(). This | |
1087 | function returns the device URI passed in the DEVICE_URI environment | |
1088 | variable or the device URI passed in argv[0], whichever is found | |
426c6a59 MS |
1089 | first. |
1090 | ||
1091 | </p> | |
178cb736 | 1092 | <h3 class="function"><span class="info"> CUPS 1.4/Mac OS X 10.6 </span><a name="cupsBackendReport">cupsBackendReport</a></h3> |
06d4e77b MS |
1093 | <p class="description">Write a device line from a backend.</p> |
1094 | <p class="code"> | |
1095 | void cupsBackendReport (<br> | |
1096 | const char *device_scheme,<br> | |
1097 | const char *device_uri,<br> | |
1098 | const char *device_make_and_model,<br> | |
1099 | const char *device_info,<br> | |
1100 | const char *device_id,<br> | |
1101 | const char *device_location<br> | |
1102 | );</p> | |
1103 | <h4 class="parameters">Parameters</h4> | |
1104 | <dl> | |
1105 | <dt>device_scheme</dt> | |
1106 | <dd class="description">device-scheme string</dd> | |
1107 | <dt>device_uri</dt> | |
1108 | <dd class="description">device-uri string</dd> | |
1109 | <dt>device_make_and_model</dt> | |
1110 | <dd class="description">device-make-and-model string or <code>NULL</code></dd> | |
1111 | <dt>device_info</dt> | |
1112 | <dd class="description">device-info string or <code>NULL</code></dd> | |
1113 | <dt>device_id</dt> | |
1114 | <dd class="description">device-id string or <code>NULL</code></dd> | |
1115 | <dt>device_location</dt> | |
1116 | <dd class="description">device-location string or <code>NULL</code></dd> | |
1117 | </dl> | |
1118 | <h4 class="discussion">Discussion</h4> | |
1119 | <p class="discussion">This function writes a single device line to stdout for a backend. | |
1120 | It handles quoting of special characters in the device-make-and-model, | |
426c6a59 MS |
1121 | device-info, device-id, and device-location strings. |
1122 | ||
1123 | </p> | |
1124 | <h3 class="function"><span class="info"> CUPS 1.3/Mac OS X 10.5 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> | |
5a738aea MS |
1125 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> |
1126 | <p class="code"> | |
1127 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
1128 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1129 | char *data,<br> | |
1130 | int *datalen,<br> | |
1131 | double timeout<br> | |
1132 | );</p> | |
1133 | <h4 class="parameters">Parameters</h4> | |
1134 | <dl> | |
1135 | <dt>command</dt> | |
1136 | <dd class="description">Command to send</dd> | |
1137 | <dt>data</dt> | |
1138 | <dd class="description">Response data buffer pointer</dd> | |
1139 | <dt>datalen</dt> | |
1140 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1141 | <dt>timeout</dt> | |
1142 | <dd class="description">Timeout in seconds</dd> | |
1143 | </dl> | |
1144 | <h4 class="returnvalue">Return Value</h4> | |
1145 | <p class="description">Status of command</p> | |
1146 | <h4 class="discussion">Discussion</h4> | |
1147 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 1148 | monitors in order to communicate with the backend used by the current |
1149 | printer. Programs must be prepared to handle timeout or "not | |
1150 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
1151 | do not support the specified side-channel command.<br> |
1152 | <br> | |
1153 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1154 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1155 | update the value to contain the number of data bytes in the buffer. | |
1156 | ||
5a738aea | 1157 | </p> |
426c6a59 | 1158 | <h3 class="function"><span class="info"> CUPS 1.3/Mac OS X 10.5 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> |
5a738aea MS |
1159 | <p class="description">Read a side-channel message.</p> |
1160 | <p class="code"> | |
1161 | int cupsSideChannelRead (<br> | |
1162 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
1163 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
1164 | char *data,<br> | |
1165 | int *datalen,<br> | |
1166 | double timeout<br> | |
1167 | );</p> | |
1168 | <h4 class="parameters">Parameters</h4> | |
1169 | <dl> | |
1170 | <dt>command</dt> | |
1171 | <dd class="description">Command code</dd> | |
1172 | <dt>status</dt> | |
1173 | <dd class="description">Status code</dd> | |
1174 | <dt>data</dt> | |
1175 | <dd class="description">Data buffer pointer</dd> | |
1176 | <dt>datalen</dt> | |
1177 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1178 | <dt>timeout</dt> | |
1179 | <dd class="description">Timeout in seconds</dd> | |
1180 | </dl> | |
1181 | <h4 class="returnvalue">Return Value</h4> | |
1182 | <p class="description">0 on success, -1 on error</p> | |
1183 | <h4 class="discussion">Discussion</h4> | |
1184 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 1185 | commands from a filter, driver, or port monitor program. The |
1186 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
1187 | and return the corresponding status codes.<br> |
1188 | <br> | |
1189 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1190 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1191 | update the value to contain the number of data bytes in the buffer. | |
1192 | ||
20fbc903 | 1193 | </p> |
178cb736 | 1194 | <h3 class="function"><span class="info"> CUPS 1.4/Mac OS X 10.6 </span><a name="cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a></h3> |
20fbc903 MS |
1195 | <p class="description">Query a SNMP OID's value.</p> |
1196 | <p class="code"> | |
1197 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPGet (<br> | |
1198 | const char *oid,<br> | |
1199 | char *data,<br> | |
1200 | int *datalen,<br> | |
1201 | double timeout<br> | |
1202 | );</p> | |
1203 | <h4 class="parameters">Parameters</h4> | |
1204 | <dl> | |
1205 | <dt>oid</dt> | |
1206 | <dd class="description">OID to query</dd> | |
1207 | <dt>data</dt> | |
1208 | <dd class="description">Buffer for OID value</dd> | |
1209 | <dt>datalen</dt> | |
1210 | <dd class="description">Size of OID buffer on entry, size of value on return</dd> | |
1211 | <dt>timeout</dt> | |
1212 | <dd class="description">Timeout in seconds</dd> | |
1213 | </dl> | |
1214 | <h4 class="returnvalue">Return Value</h4> | |
1215 | <p class="description">Query status</p> | |
1216 | <h4 class="discussion">Discussion</h4> | |
1217 | <p class="discussion">This function asks the backend to do a SNMP OID query on behalf of the | |
1218 | filter, port monitor, or backend using the default community name.<br> | |
1219 | <br> | |
1220 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1221 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1222 | supported and must be converted to their numeric forms.<br> | |
1223 | <br> | |
1224 | On input, "data" and "datalen" provide the location and size of the | |
1225 | buffer to hold the OID value as a string. HEX-String (binary) values are | |
1226 | converted to hexadecimal strings representing the binary data, while | |
1227 | NULL-Value and unknown OID types are returned as the empty string. | |
1228 | The returned "datalen" does not include the trailing nul. | |
1229 | ||
1230 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1231 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1232 | the printer does not respond to the SNMP query. | |
1233 | ||
1234 | </p> | |
178cb736 | 1235 | <h3 class="function"><span class="info"> CUPS 1.4/Mac OS X 10.6 </span><a name="cupsSideChannelSNMPWalk">cupsSideChannelSNMPWalk</a></h3> |
20fbc903 MS |
1236 | <p class="description">Query multiple SNMP OID values.</p> |
1237 | <p class="code"> | |
1238 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPWalk (<br> | |
1239 | const char *oid,<br> | |
1240 | double timeout,<br> | |
1241 | <a href="#cups_sc_walk_func_t">cups_sc_walk_func_t</a> cb,<br> | |
1242 | void *context<br> | |
1243 | );</p> | |
1244 | <h4 class="parameters">Parameters</h4> | |
1245 | <dl> | |
1246 | <dt>oid</dt> | |
1247 | <dd class="description">First numeric OID to query</dd> | |
1248 | <dt>timeout</dt> | |
1249 | <dd class="description">Timeout for each query in seconds</dd> | |
1250 | <dt>cb</dt> | |
1251 | <dd class="description">Function to call with each value</dd> | |
1252 | <dt>context</dt> | |
1253 | <dd class="description">Application-defined pointer to send to callback</dd> | |
1254 | </dl> | |
1255 | <h4 class="returnvalue">Return Value</h4> | |
1256 | <p class="description">Status of first query of <code>CUPS_SC_STATUS_OK</code> on success</p> | |
1257 | <h4 class="discussion">Discussion</h4> | |
1258 | <p class="discussion">This function asks the backend to do multiple SNMP OID queries on behalf | |
1259 | of the filter, port monitor, or backend using the default community name. | |
1260 | All OIDs under the "parent" OID are queried and the results are sent to | |
1261 | the callback function you provide.<br> | |
1262 | <br> | |
1263 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1264 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1265 | supported and must be converted to their numeric forms.<br> | |
1266 | <br> | |
1267 | "timeout" specifies the timeout for each OID query. The total amount of | |
1268 | time will depend on the number of OID values found and the time required | |
1269 | for each query.<br> | |
1270 | <br> | |
1271 | "cb" provides a function to call for every value that is found. "context" | |
1272 | is an application-defined pointer that is sent to the callback function | |
1273 | along with the OID and current data. The data passed to the callback is the | |
1274 | same as returned by <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a>. | |
1275 | ||
1276 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1277 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1278 | the printer does not respond to the first SNMP query. | |
1279 | ||
5a738aea | 1280 | </p> |
426c6a59 | 1281 | <h3 class="function"><span class="info"> CUPS 1.3/Mac OS X 10.5 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> |
5a738aea MS |
1282 | <p class="description">Write a side-channel message.</p> |
1283 | <p class="code"> | |
1284 | int cupsSideChannelWrite (<br> | |
1285 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1286 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
1287 | const char *data,<br> | |
1288 | int datalen,<br> | |
1289 | double timeout<br> | |
1290 | );</p> | |
1291 | <h4 class="parameters">Parameters</h4> | |
1292 | <dl> | |
1293 | <dt>command</dt> | |
1294 | <dd class="description">Command code</dd> | |
1295 | <dt>status</dt> | |
1296 | <dd class="description">Status code</dd> | |
1297 | <dt>data</dt> | |
1298 | <dd class="description">Data buffer pointer</dd> | |
1299 | <dt>datalen</dt> | |
1300 | <dd class="description">Number of bytes of data</dd> | |
1301 | <dt>timeout</dt> | |
1302 | <dd class="description">Timeout in seconds</dd> | |
1303 | </dl> | |
1304 | <h4 class="returnvalue">Return Value</h4> | |
1305 | <p class="description">0 on success, -1 on error</p> | |
1306 | <h4 class="discussion">Discussion</h4> | |
1307 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 1308 | responses to a filter, driver, or port monitor program. |
1309 | ||
5a738aea MS |
1310 | </p> |
1311 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
1312 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> | |
1313 | <p class="description">Backend exit codes</p> | |
1314 | <p class="code"> | |
1315 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
1316 | </p> | |
1317 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
1318 | <p class="description">Bidirectional capabilities</p> | |
1319 | <p class="code"> | |
1320 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
1321 | </p> | |
1322 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
1323 | <p class="description">Request command codes</p> | |
1324 | <p class="code"> | |
1325 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
1326 | </p> | |
82f97232 MS |
1327 | <h3 class="typedef"><a name="cups_sc_connected_t">cups_sc_connected_t</a></h3> |
1328 | <p class="description">Connectivity values</p> | |
1329 | <p class="code"> | |
1330 | typedef enum <a href="#cups_sc_connected_e">cups_sc_connected_e</a> cups_sc_connected_t; | |
1331 | </p> | |
5a738aea MS |
1332 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> |
1333 | <p class="description">Printer state bits</p> | |
1334 | <p class="code"> | |
1335 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
1336 | </p> | |
1337 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
1338 | <p class="description">Response status codes</p> | |
1339 | <p class="code"> | |
1340 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
1341 | </p> | |
20fbc903 MS |
1342 | <h3 class="typedef"><a name="cups_sc_walk_func_t">cups_sc_walk_func_t</a></h3> |
1343 | <p class="description">SNMP walk callback</p> | |
1344 | <p class="code"> | |
1345 | typedef void (*cups_sc_walk_func_t)(const char *oid, const char *data, int datalen, void *context); | |
1346 | </p> | |
5a738aea MS |
1347 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> |
1348 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> | |
1349 | <p class="description">Backend exit codes</p> | |
1350 | <h4 class="constants">Constants</h4> | |
1351 | <dl> | |
1352 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
1353 | <dd class="description">Job failed, authentication required</dd> | |
1354 | <dt>CUPS_BACKEND_CANCEL </dt> | |
1355 | <dd class="description">Job failed, cancel job</dd> | |
1356 | <dt>CUPS_BACKEND_FAILED </dt> | |
1357 | <dd class="description">Job failed, use error-policy</dd> | |
1358 | <dt>CUPS_BACKEND_HOLD </dt> | |
1359 | <dd class="description">Job failed, hold job</dd> | |
1360 | <dt>CUPS_BACKEND_OK </dt> | |
1361 | <dd class="description">Job completed successfully</dd> | |
22c9029b MS |
1362 | <dt>CUPS_BACKEND_RETRY </dt> |
1363 | <dd class="description">Job failed, retry this job later</dd> | |
1364 | <dt>CUPS_BACKEND_RETRY_CURRENT </dt> | |
1365 | <dd class="description">Job failed, retry this job immediately</dd> | |
5a738aea MS |
1366 | <dt>CUPS_BACKEND_STOP </dt> |
1367 | <dd class="description">Job failed, stop queue</dd> | |
1368 | </dl> | |
1369 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
79e1d494 | 1370 | <p class="description">Bidirectional capability values</p> |
5a738aea MS |
1371 | <h4 class="constants">Constants</h4> |
1372 | <dl> | |
1373 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
1374 | <dd class="description">Bidirectional I/O is not supported</dd> | |
1375 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
1376 | <dd class="description">Bidirectional I/O is supported</dd> | |
1377 | </dl> | |
1378 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
1379 | <p class="description">Request command codes</p> | |
1380 | <h4 class="constants">Constants</h4> | |
1381 | <dl> | |
1382 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
1383 | <dd class="description">Drain all pending output</dd> | |
1384 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
1385 | <dd class="description">Return bidirectional capabilities</dd> | |
82f97232 MS |
1386 | <dt>CUPS_SC_CMD_GET_CONNECTED <span class="info"> CUPS 1.5 </span></dt> |
1387 | <dd class="description">Return whether the backend is "connected" to the printer </dd> | |
5a738aea MS |
1388 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> |
1389 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
1390 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
1391 | <dd class="description">Return the device state</dd> | |
178cb736 | 1392 | <dt>CUPS_SC_CMD_SNMP_GET <span class="info"> CUPS 1.4/Mac OS X 10.6 </span></dt> |
20fbc903 | 1393 | <dd class="description">Query an SNMP OID </dd> |
178cb736 | 1394 | <dt>CUPS_SC_CMD_SNMP_GET_NEXT <span class="info"> CUPS 1.4/Mac OS X 10.6 </span></dt> |
20fbc903 | 1395 | <dd class="description">Query the next SNMP OID </dd> |
5a738aea MS |
1396 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> |
1397 | <dd class="description">Do a soft reset</dd> | |
1398 | </dl> | |
82f97232 MS |
1399 | <h3 class="enumeration"><a name="cups_sc_connected_e">cups_sc_connected_e</a></h3> |
1400 | <p class="description">Connectivity values</p> | |
1401 | <h4 class="constants">Constants</h4> | |
1402 | <dl> | |
1403 | <dt>CUPS_SC_CONNECTED </dt> | |
1404 | <dd class="description">Backend is "connected" to printer</dd> | |
1405 | <dt>CUPS_SC_NOT_CONNECTED </dt> | |
1406 | <dd class="description">Backend is not "connected" to printer</dd> | |
1407 | </dl> | |
5a738aea MS |
1408 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> |
1409 | <p class="description">Printer state bits</p> | |
1410 | <h4 class="constants">Constants</h4> | |
1411 | <dl> | |
1412 | <dt>CUPS_SC_STATE_BUSY </dt> | |
1413 | <dd class="description">Device is busy</dd> | |
1414 | <dt>CUPS_SC_STATE_ERROR </dt> | |
1415 | <dd class="description">Other error condition</dd> | |
1416 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
1417 | <dd class="description">Toner/ink out condition</dd> | |
1418 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
1419 | <dd class="description">Toner/ink low condition</dd> | |
1420 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
1421 | <dd class="description">Paper out condition</dd> | |
1422 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
1423 | <dd class="description">Paper low condition</dd> | |
1424 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
79e1d494 | 1425 | <dd class="description">Device is offline</dd> |
5a738aea | 1426 | <dt>CUPS_SC_STATE_ONLINE </dt> |
79e1d494 | 1427 | <dd class="description">Device is online</dd> |
5a738aea MS |
1428 | </dl> |
1429 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
1430 | <p class="description">Response status codes</p> | |
1431 | <h4 class="constants">Constants</h4> | |
1432 | <dl> | |
1433 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
1434 | <dd class="description">The command/response message was invalid</dd> | |
1435 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
1436 | <dd class="description">An I/O error occurred</dd> | |
1437 | <dt>CUPS_SC_STATUS_NONE </dt> | |
1438 | <dd class="description">No status</dd> | |
1439 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
1440 | <dd class="description">Command not implemented</dd> | |
1441 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
1442 | <dd class="description">The device did not respond</dd> | |
1443 | <dt>CUPS_SC_STATUS_OK </dt> | |
1444 | <dd class="description">Operation succeeded</dd> | |
1445 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
1446 | <dd class="description">The backend did not respond</dd> | |
1447 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
1448 | <dd class="description">Response too big</dd> | |
1449 | </dl> | |
1450 | </div> | |
ef416fc2 | 1451 | </body> |
1452 | </html> |