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5a738aea | 251 | --></style> |
ef416fc2 | 252 | </head> |
253 | <body> | |
5a738aea | 254 | <div class='body'> |
ef416fc2 | 255 | <!-- |
79e1d494 | 256 | "$Id: api-filter.header 7615 2008-05-25 07:17:07Z mike $" |
ef416fc2 | 257 | |
5a738aea MS |
258 | Filter and backend programming header for the Common UNIX Printing System |
259 | (CUPS). | |
ef416fc2 | 260 | |
5a738aea | 261 | Copyright 2008 by Apple Inc. |
ef416fc2 | 262 | |
263 | These coded instructions, statements, and computer programs are the | |
bc44d920 | 264 | property of Apple Inc. and are protected by Federal copyright |
265 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
266 | which should have been included with this file. If this file is | |
267 | file is missing or damaged, see the license at "http://www.cups.org/". | |
ef416fc2 | 268 | --> |
269 | ||
5a738aea | 270 | <h1 class="title">Filter and Backend Programming</h1> |
ef416fc2 | 271 | |
5a738aea MS |
272 | <div class='summary'><table summary='General Information'> |
273 | <thead> | |
274 | <tr> | |
ac884b6a | 275 | <th>Headers</th> |
5a738aea | 276 | <th>cups/backend.h<br> |
79e1d494 | 277 | cups/sidechannel.h</th> |
5a738aea MS |
278 | </tr> |
279 | </thead> | |
280 | <tbody> | |
281 | <tr> | |
282 | <th>Library</th> | |
283 | <td>-lcups</td> | |
284 | </tr> | |
285 | <tr> | |
286 | <th>See Also</th> | |
287 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
288 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
289 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
79e1d494 MS |
290 | Programming: <a href='api-raster.html' target='_top'>Raster API</a><br> |
291 | Specifications: <a href='spec-design' target='_top'>CUPS Design Description</a></td> | |
5a738aea MS |
292 | </tr> |
293 | </tbody> | |
294 | </table></div> | |
295 | <h2 class="title">Contents</h2> | |
296 | <ul class="contents"> | |
297 | </li> | |
298 | <li><a href="#OVERVIEW">Overview</a><ul class="subcontents"> | |
ac884b6a MS |
299 | <li><a href="#SECURITY">Security Considerations</a></li> |
300 | <li><a href="#TEMPFILES">Temporary Files</a></li> | |
301 | <li><a href="#COPIES">Copy Generation</a></li> | |
5a738aea MS |
302 | <li><a href="#EXITCODES">Exit Codes</a></li> |
303 | <li><a href="#ENVIRONMENT">Environment Variables</a></li> | |
304 | <li><a href="#MESSAGES">Communicating with the Scheduler</a></li> | |
20fbc903 MS |
305 | <li><a href="#COMMUNICATING_BACKEND">Communicating with the Backend</a></li> |
306 | <li><a href="#COMMUNICATING_FILTER">Communicating with Filters</a></li> | |
ac884b6a | 307 | <li><a href="#SNMP">Doing SNMP Queries with Network Printers</a></li> |
5a738aea MS |
308 | </ul></li> |
309 | <li><a href="#FUNCTIONS">Functions</a><ul class="code"> | |
310 | <li><a href="#cupsBackChannelRead" title="Read data from the backchannel.">cupsBackChannelRead</a></li> | |
311 | <li><a href="#cupsBackChannelWrite" title="Write data to the backchannel.">cupsBackChannelWrite</a></li> | |
ac884b6a | 312 | <li><a href="#cupsBackendDeviceURI" title="Get the device URI for a backend.">cupsBackendDeviceURI</a></li> |
5a738aea MS |
313 | <li><a href="#cupsSideChannelDoRequest" title="Send a side-channel command to a backend and wait for a response.">cupsSideChannelDoRequest</a></li> |
314 | <li><a href="#cupsSideChannelRead" title="Read a side-channel message.">cupsSideChannelRead</a></li> | |
20fbc903 MS |
315 | <li><a href="#cupsSideChannelSNMPGet" title="Query a SNMP OID's value.">cupsSideChannelSNMPGet</a></li> |
316 | <li><a href="#cupsSideChannelSNMPWalk" title="Query multiple SNMP OID values.">cupsSideChannelSNMPWalk</a></li> | |
5a738aea MS |
317 | <li><a href="#cupsSideChannelWrite" title="Write a side-channel message.">cupsSideChannelWrite</a></li> |
318 | </ul> | |
319 | <li><a href="#TYPES">Data Types</a><ul class="code"> | |
320 | <li><a href="#cups_backend_t" title="Backend exit codes">cups_backend_t</a></li> | |
321 | <li><a href="#cups_sc_bidi_t" title="Bidirectional capabilities">cups_sc_bidi_t</a></li> | |
322 | <li><a href="#cups_sc_command_t" title="Request command codes">cups_sc_command_t</a></li> | |
323 | <li><a href="#cups_sc_state_t" title="Printer state bits">cups_sc_state_t</a></li> | |
324 | <li><a href="#cups_sc_status_t" title="Response status codes">cups_sc_status_t</a></li> | |
20fbc903 | 325 | <li><a href="#cups_sc_walk_func_t" title="SNMP walk callback">cups_sc_walk_func_t</a></li> |
5a738aea MS |
326 | </ul></li> |
327 | <li><a href="#ENUMERATIONS">Constants</a><ul class="code"> | |
328 | <li><a href="#cups_backend_e" title="Backend exit codes">cups_backend_e</a></li> | |
79e1d494 | 329 | <li><a href="#cups_sc_bidi_e" title="Bidirectional capability values">cups_sc_bidi_e</a></li> |
5a738aea MS |
330 | <li><a href="#cups_sc_command_e" title="Request command codes">cups_sc_command_e</a></li> |
331 | <li><a href="#cups_sc_state_e" title="Printer state bits">cups_sc_state_e</a></li> | |
332 | <li><a href="#cups_sc_status_e" title="Response status codes">cups_sc_status_e</a></li> | |
333 | </ul></li> | |
334 | </ul> | |
335 | <!-- | |
79e1d494 | 336 | "$Id: api-filter.shtml 7594 2008-05-19 23:16:03Z mike $" |
ef416fc2 | 337 | |
5a738aea MS |
338 | Filter and backend programming introduction for the Common UNIX Printing |
339 | System (CUPS). | |
ef416fc2 | 340 | |
5a738aea MS |
341 | Copyright 2007-2008 by Apple Inc. |
342 | Copyright 1997-2006 by Easy Software Products, all rights reserved. | |
ef416fc2 | 343 | |
5a738aea MS |
344 | These coded instructions, statements, and computer programs are the |
345 | property of Apple Inc. and are protected by Federal copyright | |
346 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
347 | which should have been included with this file. If this file is | |
348 | file is missing or damaged, see the license at "http://www.cups.org/". | |
349 | --> | |
f7deaa1a | 350 | |
5a738aea | 351 | <h2 class='title'><a name="OVERVIEW">Overview</a></h2> |
ef416fc2 | 352 | |
79e1d494 MS |
353 | <p>Filters (which include printer drivers and port monitors) and backends |
354 | are used to convert job files to a printable format and send that data to the | |
355 | printer itself. All of these programs use a common interface for processing | |
356 | print jobs and communicating status information to the scheduler. Each is run | |
357 | with a standard set of command-line arguments:<p> | |
ef416fc2 | 358 | |
5a738aea | 359 | <dl class="code"> |
f7deaa1a | 360 | |
5a738aea MS |
361 | <dt>argv[1]</dt> |
362 | <dd>The job ID</dd> | |
ef416fc2 | 363 | |
5a738aea MS |
364 | <dt>argv[2]</dt> |
365 | <dd>The user printing the job</dd> | |
f7deaa1a | 366 | |
5a738aea MS |
367 | <dt>argv[3]</dt> |
368 | <dd>The job name/title</dd> | |
f7deaa1a | 369 | |
5a738aea MS |
370 | <dt>argv[4]</dt> |
371 | <dd>The number of copies to print</dd> | |
f7deaa1a | 372 | |
5a738aea MS |
373 | <dt>argv[5]</dt> |
374 | <dd>The options that were provided when the job was submitted</dd> | |
f7deaa1a | 375 | |
5a738aea | 376 | <dt>argv[6]</dt> |
79e1d494 | 377 | <dd>The file to print (first program only)</dd> |
5a738aea | 378 | </dl> |
f7deaa1a | 379 | |
5a738aea MS |
380 | <p>The scheduler runs one or more of these programs to print any given job. The |
381 | first filter reads from the print file and writes to the standard output, while | |
382 | the remaining filters read from the standard input and write to the standard | |
383 | output. The backend is the last filter in the chain and writes to the | |
384 | device.</p> | |
f7deaa1a | 385 | |
ac884b6a MS |
386 | <h3><a name="SECURITY">Security Considerations</a></h3> |
387 | ||
388 | <p>It is always important to use security programming practices. Filters and | |
389 | most backends are run as a non-priviledged user, so the major security | |
390 | consideration is resource utilization - filters should not depend on unlimited | |
391 | amounts of CPU, memory, or disk space, and should protect against conditions | |
392 | that could lead to excess usage of any resource like infinite loops and | |
393 | unbounded recursion. In addition, filters must <em>never</em> allow the user to | |
394 | specify an arbitrary file path to a separator page, template, or other file | |
395 | used by the filter since that can lead to an unauthorized disclosure of | |
396 | information. <em>Always</em> treat input as suspect and validate it!</p> | |
397 | ||
398 | <p>If you are developing a backend that runs as root, make sure to check for | |
399 | potential buffer overflows, integer under/overflow conditions, and file | |
400 | accesses since these can lead to privilege escalations. When writing files, | |
401 | always validate the file path and <em>never</em> allow a user to determine | |
402 | where to store a file.</p> | |
403 | ||
404 | <blockquote><b>Note:</b> | |
405 | ||
406 | <p><em>Never</em> write files to a user's home directory. Aside from the | |
407 | security implications, CUPS is a network print service and as such the network | |
408 | user may not be the same as the local user and/or there may not be a local home | |
409 | directory to write to.</p> | |
410 | ||
411 | <p>In addition, some operating systems provide additional security mechanisms | |
412 | that further limit file system access, even for backends running as root. On | |
413 | Mac OS X, for example, no backend may write to a user's home directory.</p> | |
414 | </blockquote> | |
415 | ||
416 | <h3><a name="TEMPFILES">Temporary Files</a></h3> | |
417 | ||
418 | <p>Temporary files should be created in the directory specified by the | |
419 | "TMPDIR" environment variable. The | |
420 | <a href="#cupsTempFile2"><code>cupsTempFile2</code></a> function can be | |
421 | used to safely create temporary files in this directory.</p> | |
422 | ||
423 | <h3><a name="COPIES">Copy Generation</a></h3> | |
424 | ||
425 | <p>The <code>argv[4]</code> argument specifies the number of copies to produce | |
426 | of the input file. In general, you should only generate copies if the | |
427 | <em>filename</em> argument is supplied. The only exception to this are | |
428 | filters that produce device-independent PostScript output, since the PostScript | |
429 | filter <var>pstops</var> is responsible for generating copies of PostScript | |
430 | files.</p> | |
431 | ||
5a738aea | 432 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 433 | |
5a738aea MS |
434 | <p>Filters must exit with status 0 when they successfully generate print data |
435 | or 1 when they encounter an error. Backends can return any of the | |
436 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 437 | |
5a738aea | 438 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 439 | |
79e1d494 MS |
440 | <p>The following environment variables are defined by the printing system |
441 | when running print filters and backends:</p> | |
f7deaa1a | 442 | |
5a738aea | 443 | <dl class="code"> |
f7deaa1a | 444 | |
5a738aea MS |
445 | <dt>APPLE_LANGUAGES</dt> |
446 | <dd>The Apple language identifier associated with the job | |
447 | (Mac OS X only).</dd> | |
f7deaa1a | 448 | |
5a738aea MS |
449 | <dt>CHARSET</dt> |
450 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 451 | |
5a738aea MS |
452 | <dt>CLASS</dt> |
453 | <dd>When a job is submitted to a printer class, contains the name of | |
454 | the destination printer class. Otherwise this environment | |
455 | variable will not be set.</dd> | |
f7deaa1a | 456 | |
5a738aea MS |
457 | <dt>CONTENT_TYPE</dt> |
458 | <dd>The MIME type associated with the file (e.g. | |
459 | application/postscript).</dd> | |
f7deaa1a | 460 | |
5a738aea | 461 | <dt>CUPS_CACHEDIR</dt> |
79e1d494 MS |
462 | <dd>The directory where cache files can be stored. Cache files can be |
463 | used to retain information between jobs or files in a job.</dd> | |
f7deaa1a | 464 | |
5a738aea | 465 | <dt>CUPS_DATADIR</dt> |
79e1d494 | 466 | <dd>The directory where (read-only) CUPS data files can be found.</dd> |
f7deaa1a | 467 | |
5a738aea MS |
468 | <dt>CUPS_SERVERROOT</dt> |
469 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 470 | |
5a738aea MS |
471 | <dt>DEVICE_URI</dt> |
472 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 473 | |
5a738aea MS |
474 | <dt>FINAL_CONTENT_TYPE</dt> |
475 | <dd>The MIME type associated with the printer (e.g. | |
476 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 477 | |
5a738aea MS |
478 | <dt>LANG</dt> |
479 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 480 | |
5a738aea MS |
481 | <dt>PPD</dt> |
482 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
483 | file for this printer.</dd> | |
f7deaa1a | 484 | |
5a738aea | 485 | <dt>PRINTER</dt> |
79e1d494 | 486 | <dd>The queue name of the class or printer.</dd> |
f7deaa1a | 487 | |
5a738aea MS |
488 | <dt>RIP_CACHE</dt> |
489 | <dd>The recommended amount of memory to use for Raster Image | |
490 | Processors (RIPs).</dd> | |
f7deaa1a | 491 | |
79e1d494 MS |
492 | <dt>TMPDIR</dt> |
493 | <dd>The directory where temporary files should be created.</dd> | |
494 | ||
5a738aea | 495 | </dl> |
f7deaa1a | 496 | |
5a738aea | 497 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 498 | |
79e1d494 MS |
499 | <p>Filters and backends communicate with the scheduler by writing messages |
500 | to the standard error file. The scheduler reads messages from all filters in | |
501 | a job and processes the message based on its prefix. For example, the following | |
502 | code sets the current printer state message to "Printing page 5":</p> | |
f7deaa1a | 503 | |
5a738aea MS |
504 | <pre class="example"> |
505 | int page = 5; | |
f7deaa1a | 506 | |
5a738aea | 507 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 508 | </pre> |
509 | ||
5a738aea MS |
510 | <p>Each message is a single line of text starting with one of the following |
511 | prefix strings:</p> | |
512 | ||
513 | <dl class="code"> | |
514 | ||
515 | <dt>ALERT: message</dt> | |
516 | <dd>Sets the printer-state-message attribute and adds the specified | |
517 | message to the current error log file using the "alert" log level.</dd> | |
518 | ||
519 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
520 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
521 | to set the <code>marker-colors</code>, <code>marker-levels</code>, | |
522 | <code>marker-names</code>, <code>marker-types</code>, | |
523 | <code>printer-alert</code>, and <code>printer-alert-description</code> | |
79e1d494 MS |
524 | printer attributes. Standard <code>marker-types</code> values are |
525 | listed in <a href='#TABLE1'>Table 1</a>.</dd> | |
5a738aea MS |
526 | |
527 | <dt>CRIT: message</dt> | |
528 | <dd>Sets the printer-state-message attribute and adds the specified | |
529 | message to the current error log file using the "critical" log | |
530 | level.</dd> | |
531 | ||
532 | <dt>DEBUG: message</dt> | |
533 | <dd>Sets the printer-state-message attribute and adds the specified | |
534 | message to the current error log file using the "debug" log level.</dd> | |
535 | ||
536 | <dt>DEBUG2: message</dt> | |
537 | <dd>Sets the printer-state-message attribute and adds the specified | |
538 | message to the current error log file using the "debug2" log level.</dd> | |
539 | ||
540 | <dt>EMERG: message</dt> | |
541 | <dd>Sets the printer-state-message attribute and adds the specified | |
542 | message to the current error log file using the "emergency" log | |
543 | level.</dd> | |
544 | ||
545 | <dt>ERROR: message</dt> | |
546 | <dd>Sets the printer-state-message attribute and adds the specified | |
79e1d494 MS |
547 | message to the current error log file using the "error" log level. |
548 | Use "ERROR:" messages for non-persistent processing errors.</dd> | |
5a738aea MS |
549 | |
550 | <dt>INFO: message</dt> | |
551 | <dd>Sets the printer-state-message attribute. If the current log level | |
552 | is set to "debug2", also adds the specified message to the current error | |
553 | log file using the "info" log level.</dd> | |
554 | ||
555 | <dt>NOTICE: message</dt> | |
556 | <dd>Sets the printer-state-message attribute and adds the specified | |
557 | message to the current error log file using the "notice" log level.</dd> | |
558 | ||
559 | <dt>PAGE: page-number #-copies</dt> | |
560 | <dt>PAGE: total #-pages</dt> | |
561 | <dd>Adds an entry to the current page log file. The first form adds | |
562 | #-copies to the job-media-sheets-completed attribute. The second | |
563 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
564 | ||
20fbc903 MS |
565 | <dt>PPD: keyword=value [keyword=value ...]</dt> |
566 | <dd>Changes or adds keywords to the printer's PPD file. Typically | |
567 | this is used to update installable options or default media settings | |
568 | based on the printer configuration.</dd> | |
569 | ||
5a738aea MS |
570 | <dt>STATE: printer-state-reason [printer-state-reason ...]</dt> |
571 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> | |
572 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
573 | <dd>Sets, adds, or removes printer-state-reason keywords to the | |
79e1d494 MS |
574 | current queue. Typically this is used to indicate persistent media, |
575 | ink, toner, and configuration conditions or errors on a printer. | |
576 | <a href='#TABLE2'>Table 2</a> lists the standard state keywords - | |
577 | use vendor-prefixed ("com.acme.foo") keywords for custom states.</dd> | |
5a738aea MS |
578 | |
579 | <dt>WARNING: message</dt> | |
580 | <dd>Sets the printer-state-message attribute and adds the specified | |
581 | message to the current error log file using the "warning" log | |
582 | level.</dd> | |
583 | ||
584 | </dl> | |
585 | ||
586 | <p>Messages without one of these prefixes are treated as if they began with | |
587 | the "DEBUG:" prefix string.</p> | |
588 | ||
79e1d494 MS |
589 | |
590 | <div class='table'><table width='80%' summary='Table 1: Standard marker-types Values'> | |
591 | <caption>Table 1: <a name='TABLE1'>Standard marker-types Values</a></caption> | |
592 | <thead> | |
593 | <tr> | |
594 | <th>marker-type</th> | |
595 | <th>Description</th> | |
596 | </tr> | |
597 | </thead> | |
598 | <tbody> | |
599 | <tr> | |
600 | <td>developer</td> | |
601 | <td>Developer unit</td> | |
602 | </tr> | |
603 | <tr> | |
604 | <td>fuser</td> | |
605 | <td>Fuser unit</td> | |
606 | </tr> | |
607 | <tr> | |
608 | <td>fuserCleaningPad</td> | |
609 | <td>Fuser cleaning pad</td> | |
610 | </tr> | |
611 | <tr> | |
612 | <td>fuserOil</td> | |
613 | <td>Fuser oil</td> | |
614 | </tr> | |
615 | <tr> | |
616 | <td>ink</td> | |
617 | <td>Ink supply</td> | |
618 | </tr> | |
619 | <tr> | |
620 | <td>opc</td> | |
621 | <td>Photo conductor</td> | |
622 | </tr> | |
623 | <tr> | |
624 | <td>solidWax</td> | |
625 | <td>Wax supply</td> | |
626 | </tr> | |
627 | <tr> | |
628 | <td>staples</td> | |
629 | <td>Staple supply</td> | |
630 | </tr> | |
631 | <tr> | |
632 | <td>toner</td> | |
633 | <td>Toner supply</td> | |
634 | </tr> | |
635 | <tr> | |
636 | <td>transferUnit</td> | |
637 | <td>Transfer unit</td> | |
638 | </tr> | |
639 | <tr> | |
640 | <td>wasteInk</td> | |
641 | <td>Waste ink tank</td> | |
642 | </tr> | |
643 | <tr> | |
644 | <td>wasteToner</td> | |
645 | <td>Waste toner tank</td> | |
646 | </tr> | |
647 | <tr> | |
648 | <td>wasteWax</td> | |
649 | <td>Waste wax tank</td> | |
650 | </tr> | |
651 | </tbody> | |
652 | </table></div> | |
653 | ||
654 | <br> | |
655 | ||
656 | <div class='table'><table width='80%' summary='Table 2: Standard State Keywords'> | |
657 | <caption>Table 2: <a name='TABLE2'>Standard State Keywords</a></caption> | |
658 | <thead> | |
659 | <tr> | |
660 | <th>Keyword</th> | |
661 | <th>Description</th> | |
662 | </tr> | |
663 | </thead> | |
664 | <tbody> | |
665 | <tr> | |
666 | <td>connecting-to-device</td> | |
667 | <td>Connecting to printer but not printing yet</td> | |
668 | </tr> | |
669 | <tr> | |
670 | <td>cover-open</td> | |
671 | <td>A cover is open on the printer</td> | |
672 | </tr> | |
673 | <tr> | |
674 | <td>input-tray-missing</td> | |
675 | <td>An input tray is missing from the printer</td> | |
676 | </tr> | |
677 | <tr> | |
678 | <td>marker-supply-empty</td> | |
679 | <td>Out of ink</td> | |
680 | </tr> | |
681 | <tr> | |
682 | <td>marker-supply-low</td> | |
683 | <td>Low on ink</td> | |
684 | </tr> | |
685 | <tr> | |
686 | <td>marker-waste-almost-full</td> | |
687 | <td>Waste tank almost full</td> | |
688 | </tr> | |
689 | <tr> | |
690 | <td>marker-waste-full</td> | |
691 | <td>Waste tank full</td> | |
692 | </tr> | |
693 | <tr> | |
694 | <td>media-empty</td> | |
695 | <td>Out of media</td> | |
696 | </tr> | |
697 | <tr> | |
698 | <td>media-jam</td> | |
699 | <td>Media is jammed in the printer</td> | |
700 | </tr> | |
701 | <tr> | |
702 | <td>media-low</td> | |
703 | <td>Low on media</td> | |
704 | </tr> | |
705 | <tr> | |
706 | <td>paused</td> | |
707 | <td>Stop the printer</td> | |
708 | </tr> | |
709 | <tr> | |
710 | <td>timed-out</td> | |
711 | <td>Unable to connect to printer</td> | |
712 | </tr> | |
713 | <tr> | |
714 | <td>toner-empty</td> | |
715 | <td>Out of toner</td> | |
716 | </tr> | |
717 | <tr> | |
718 | <td>toner-low</td> | |
719 | <td>Low on toner</td> | |
720 | </tr> | |
721 | </tbody> | |
722 | </table></div> | |
723 | ||
20fbc903 | 724 | <h3><a name="COMMUNICATING_BACKEND">Communicating with the Backend</a></h3> |
5a738aea MS |
725 | |
726 | <p>Filters can communicate with the backend via the | |
727 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
728 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
729 | functions. The | |
730 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function | |
731 | reads data that has been sent back from the device and is typically used to | |
732 | obtain status and configuration information. For example, the following code | |
733 | polls the backend for back-channel data:</p> | |
734 | ||
735 | <pre class="example"> | |
736 | #include <cups/cups.h> | |
737 | ||
738 | char buffer[8192]; | |
739 | ssize_t bytes; | |
740 | ||
741 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
742 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
743 | </pre> | |
f7deaa1a | 744 | |
79e1d494 MS |
745 | <p>Filters can also use <code>select()</code> or <code>poll()</code> on the |
746 | back-channel file descriptor (3 or <code>CUPS_BC_FD</code>) to read data only | |
747 | when it is available.</p> | |
748 | ||
749 | <p>The | |
5a738aea MS |
750 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> |
751 | function allows you to get out-of-band status information and do synchronization | |
752 | with the device. For example, the following code gets the current IEEE-1284 | |
753 | device ID string from the backend:</p> | |
754 | ||
755 | <pre class="example"> | |
f7deaa1a | 756 | #include <cups/sidechannel.h> |
757 | ||
758 | char data[2049]; | |
759 | int datalen; | |
5a738aea | 760 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 761 | |
79e1d494 MS |
762 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for |
763 | nul-termination... */ | |
f7deaa1a | 764 | datalen = sizeof(data) - 1; |
765 | ||
766 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 767 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 768 | |
769 | /* Use the returned value if OK was returned and the length is non-zero */ | |
770 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
771 | data[datalen] = '\0'; | |
772 | else | |
773 | data[0] = '\0'; | |
774 | </pre> | |
775 | ||
20fbc903 MS |
776 | <h3><a name="COMMUNICATING_FILTER">Communicating with Filters</a></h3> |
777 | ||
5a738aea MS |
778 | <p>Backends communicate with filters using the reciprocal functions |
779 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
780 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
781 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
782 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 783 | |
5a738aea MS |
784 | <pre class="example"> |
785 | #include <cups/cups.h> | |
f7deaa1a | 786 | |
5a738aea MS |
787 | char buffer[8192]; |
788 | ssize_t bytes; | |
f7deaa1a | 789 | |
79e1d494 MS |
790 | /* Obtain data from printer/device */ |
791 | ... | |
792 | ||
5a738aea MS |
793 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
794 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 795 | </pre> |
796 | ||
5a738aea MS |
797 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
798 | function reads a side-channel command from a filter, driver, or port monitor. | |
799 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
800 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
801 | separate thread for that purpose), or use <code>select</code> or | |
802 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
20fbc903 | 803 | input and output on several file descriptors at the same time.</p> |
5a738aea MS |
804 | |
805 | <p>Once a command is processed, the backend uses the | |
806 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
807 | to send its response. For example, the following code shows how to poll for a | |
808 | side-channel command and respond to it:</p> | |
809 | ||
810 | <pre class="example"> | |
f7deaa1a | 811 | #include <cups/sidechannel.h> |
812 | ||
5a738aea MS |
813 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
814 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
20fbc903 MS |
815 | char data[2048]; |
816 | int datalen = sizeof(data); | |
f7deaa1a | 817 | |
818 | /* Poll for a command... */ | |
20fbc903 | 819 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, data, &datalen, 0.0)) |
f7deaa1a | 820 | { |
f7deaa1a | 821 | switch (command) |
822 | { | |
20fbc903 | 823 | /* handle supported commands, fill data/datalen/status with values as needed */ |
f7deaa1a | 824 | |
825 | default : | |
826 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
827 | datalen = 0; | |
828 | break; | |
829 | } | |
830 | ||
831 | /* Send a response... */ | |
5a738aea | 832 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 833 | } |
834 | </pre> | |
ac884b6a MS |
835 | |
836 | <h3><a name="SNMP">Doing SNMP Queries with Network Printers</a></h3> | |
837 | ||
838 | <p>The Simple Network Management Protocol (SNMP) allows you to get the current | |
839 | status, page counter, and supply levels from most network printers. Every | |
840 | piece of information is associated with an Object Identifier (OID), and | |
841 | every printer has a <em>community</em> name associated with it. OIDs can be | |
842 | queried directly or by "walking" over a range of OIDs with a common prefix.</p> | |
843 | ||
20fbc903 MS |
844 | <p>The two CUPS SNMP functions provide a simple API for querying network |
845 | printers through the side-channel interface. Each accepts a string containing | |
846 | an OID like ".1.3.6.1.2.1.43.10.2.1.4.1.1" (the standard page counter OID) | |
847 | along with a timeout for the query.</p> | |
ac884b6a | 848 | |
20fbc903 MS |
849 | <p>The <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a> |
850 | function queries a single OID and returns the value as a string in a buffer | |
851 | you supply:</p> | |
ac884b6a MS |
852 | |
853 | <pre class="example"> | |
20fbc903 | 854 | #include <cups/sidechannel.h> |
ac884b6a | 855 | |
20fbc903 MS |
856 | char data[512]; |
857 | int datalen = sizeof(data); | |
ac884b6a | 858 | |
20fbc903 MS |
859 | if (<a href="#cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a>(".1.3.6.1.2.1.43.10.2.1.4.1.1", data, &datalen, 5.0) |
860 | == CUPS_SC_STATUS_OK) | |
ac884b6a MS |
861 | { |
862 | /* Do something with the value */ | |
20fbc903 | 863 | printf("Page counter is: %s\n", data); |
ac884b6a MS |
864 | } |
865 | </pre> | |
866 | ||
20fbc903 MS |
867 | <p>The |
868 | <a href="#cupsSideChannelSNMPWalk"><code>cupsSideChannelSNMPWalk</code></a> | |
869 | function allows you to query a whole group of OIDs, calling a function of your | |
870 | choice for each OID that is found:</p> | |
ac884b6a MS |
871 | |
872 | <pre class="example"> | |
20fbc903 | 873 | #include <cups/sidechannel.h> |
ac884b6a MS |
874 | |
875 | void | |
20fbc903 | 876 | my_callback(const char *oid, const char *data, int datalen, void *context) |
ac884b6a MS |
877 | { |
878 | /* Do something with the value */ | |
20fbc903 | 879 | printf("%s=%s\n", oid, data); |
ac884b6a MS |
880 | } |
881 | ||
20fbc903 MS |
882 | ... |
883 | ||
ac884b6a MS |
884 | void *my_data; |
885 | ||
20fbc903 | 886 | <a href="#cupsSideChannelSNMPWalk">cupsSNMPSideChannelWalk</a>(".1.3.6.1.2.1.43", 5.0, my_callback, my_data); |
ac884b6a | 887 | </pre> |
20fbc903 | 888 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
5a738aea MS |
889 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> |
890 | <p class="description">Read data from the backchannel.</p> | |
891 | <p class="code"> | |
892 | ssize_t cupsBackChannelRead (<br> | |
893 | char *buffer,<br> | |
894 | size_t bytes,<br> | |
895 | double timeout<br> | |
896 | );</p> | |
897 | <h4 class="parameters">Parameters</h4> | |
898 | <dl> | |
899 | <dt>buffer</dt> | |
79e1d494 | 900 | <dd class="description">Buffer to read into</dd> |
5a738aea MS |
901 | <dt>bytes</dt> |
902 | <dd class="description">Bytes to read</dd> | |
903 | <dt>timeout</dt> | |
79e1d494 | 904 | <dd class="description">Timeout in seconds, typically 0.0 to poll</dd> |
5a738aea MS |
905 | </dl> |
906 | <h4 class="returnvalue">Return Value</h4> | |
907 | <p class="description">Bytes read or -1 on error</p> | |
908 | <h4 class="discussion">Discussion</h4> | |
79e1d494 MS |
909 | <p class="discussion">Reads up to "bytes" bytes from the backchannel/backend. The "timeout" |
910 | parameter controls how many seconds to wait for the data - use 0.0 to | |
911 | return immediately if there is no data, -1.0 to wait for data indefinitely. | |
ef416fc2 | 912 | |
5a738aea MS |
913 | </p> |
914 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> | |
915 | <p class="description">Write data to the backchannel.</p> | |
916 | <p class="code"> | |
917 | ssize_t cupsBackChannelWrite (<br> | |
918 | const char *buffer,<br> | |
919 | size_t bytes,<br> | |
920 | double timeout<br> | |
921 | );</p> | |
922 | <h4 class="parameters">Parameters</h4> | |
923 | <dl> | |
924 | <dt>buffer</dt> | |
925 | <dd class="description">Buffer to write</dd> | |
926 | <dt>bytes</dt> | |
927 | <dd class="description">Bytes to write</dd> | |
928 | <dt>timeout</dt> | |
79e1d494 | 929 | <dd class="description">Timeout in seconds, typically 1.0</dd> |
5a738aea MS |
930 | </dl> |
931 | <h4 class="returnvalue">Return Value</h4> | |
932 | <p class="description">Bytes written or -1 on error</p> | |
933 | <h4 class="discussion">Discussion</h4> | |
79e1d494 | 934 | <p class="discussion">Writes "bytes" bytes to the backchannel/filter. The "timeout" parameter |
ef416fc2 | 935 | controls how many seconds to wait for the data to be written - use |
936 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
937 | indefinitely. | |
938 | ||
ac884b6a MS |
939 | </p> |
940 | <h3 class="function"><a name="cupsBackendDeviceURI">cupsBackendDeviceURI</a></h3> | |
941 | <p class="description">Get the device URI for a backend.</p> | |
942 | <p class="code"> | |
943 | const char *cupsBackendDeviceURI (<br> | |
944 | char **argv<br> | |
945 | );</p> | |
946 | <h4 class="parameters">Parameters</h4> | |
947 | <dl> | |
948 | <dt>argv</dt> | |
949 | <dd class="description">Command-line arguments</dd> | |
950 | </dl> | |
951 | <h4 class="returnvalue">Return Value</h4> | |
952 | <p class="description">Device URI or <code>NULL</code></p> | |
953 | <h4 class="discussion">Discussion</h4> | |
954 | <p class="discussion">The "argv" argument is the argv argument passed to main(). This | |
955 | function returns the device URI passed in the DEVICE_URI environment | |
956 | variable or the device URI passed in argv[0], whichever is found | |
957 | first.</p> | |
5a738aea MS |
958 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> |
959 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> | |
960 | <p class="code"> | |
961 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
962 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
963 | char *data,<br> | |
964 | int *datalen,<br> | |
965 | double timeout<br> | |
966 | );</p> | |
967 | <h4 class="parameters">Parameters</h4> | |
968 | <dl> | |
969 | <dt>command</dt> | |
970 | <dd class="description">Command to send</dd> | |
971 | <dt>data</dt> | |
972 | <dd class="description">Response data buffer pointer</dd> | |
973 | <dt>datalen</dt> | |
974 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
975 | <dt>timeout</dt> | |
976 | <dd class="description">Timeout in seconds</dd> | |
977 | </dl> | |
978 | <h4 class="returnvalue">Return Value</h4> | |
979 | <p class="description">Status of command</p> | |
980 | <h4 class="discussion">Discussion</h4> | |
981 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 982 | monitors in order to communicate with the backend used by the current |
983 | printer. Programs must be prepared to handle timeout or "not | |
984 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
985 | do not support the specified side-channel command.<br> |
986 | <br> | |
987 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 988 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
989 | update the value to contain the number of data bytes in the buffer. | |
990 | ||
5a738aea MS |
991 | </p> |
992 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> | |
993 | <p class="description">Read a side-channel message.</p> | |
994 | <p class="code"> | |
995 | int cupsSideChannelRead (<br> | |
996 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
997 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
998 | char *data,<br> | |
999 | int *datalen,<br> | |
1000 | double timeout<br> | |
1001 | );</p> | |
1002 | <h4 class="parameters">Parameters</h4> | |
1003 | <dl> | |
1004 | <dt>command</dt> | |
1005 | <dd class="description">Command code</dd> | |
1006 | <dt>status</dt> | |
1007 | <dd class="description">Status code</dd> | |
1008 | <dt>data</dt> | |
1009 | <dd class="description">Data buffer pointer</dd> | |
1010 | <dt>datalen</dt> | |
1011 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1012 | <dt>timeout</dt> | |
1013 | <dd class="description">Timeout in seconds</dd> | |
1014 | </dl> | |
1015 | <h4 class="returnvalue">Return Value</h4> | |
1016 | <p class="description">0 on success, -1 on error</p> | |
1017 | <h4 class="discussion">Discussion</h4> | |
1018 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 1019 | commands from a filter, driver, or port monitor program. The |
1020 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
1021 | and return the corresponding status codes.<br> |
1022 | <br> | |
1023 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1024 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1025 | update the value to contain the number of data bytes in the buffer. | |
1026 | ||
20fbc903 MS |
1027 | </p> |
1028 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a></h3> | |
1029 | <p class="description">Query a SNMP OID's value.</p> | |
1030 | <p class="code"> | |
1031 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPGet (<br> | |
1032 | const char *oid,<br> | |
1033 | char *data,<br> | |
1034 | int *datalen,<br> | |
1035 | double timeout<br> | |
1036 | );</p> | |
1037 | <h4 class="parameters">Parameters</h4> | |
1038 | <dl> | |
1039 | <dt>oid</dt> | |
1040 | <dd class="description">OID to query</dd> | |
1041 | <dt>data</dt> | |
1042 | <dd class="description">Buffer for OID value</dd> | |
1043 | <dt>datalen</dt> | |
1044 | <dd class="description">Size of OID buffer on entry, size of value on return</dd> | |
1045 | <dt>timeout</dt> | |
1046 | <dd class="description">Timeout in seconds</dd> | |
1047 | </dl> | |
1048 | <h4 class="returnvalue">Return Value</h4> | |
1049 | <p class="description">Query status</p> | |
1050 | <h4 class="discussion">Discussion</h4> | |
1051 | <p class="discussion">This function asks the backend to do a SNMP OID query on behalf of the | |
1052 | filter, port monitor, or backend using the default community name.<br> | |
1053 | <br> | |
1054 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1055 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1056 | supported and must be converted to their numeric forms.<br> | |
1057 | <br> | |
1058 | On input, "data" and "datalen" provide the location and size of the | |
1059 | buffer to hold the OID value as a string. HEX-String (binary) values are | |
1060 | converted to hexadecimal strings representing the binary data, while | |
1061 | NULL-Value and unknown OID types are returned as the empty string. | |
1062 | The returned "datalen" does not include the trailing nul. | |
1063 | ||
1064 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1065 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1066 | the printer does not respond to the SNMP query. | |
1067 | ||
1068 | </p> | |
1069 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSideChannelSNMPWalk">cupsSideChannelSNMPWalk</a></h3> | |
1070 | <p class="description">Query multiple SNMP OID values.</p> | |
1071 | <p class="code"> | |
1072 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPWalk (<br> | |
1073 | const char *oid,<br> | |
1074 | double timeout,<br> | |
1075 | <a href="#cups_sc_walk_func_t">cups_sc_walk_func_t</a> cb,<br> | |
1076 | void *context<br> | |
1077 | );</p> | |
1078 | <h4 class="parameters">Parameters</h4> | |
1079 | <dl> | |
1080 | <dt>oid</dt> | |
1081 | <dd class="description">First numeric OID to query</dd> | |
1082 | <dt>timeout</dt> | |
1083 | <dd class="description">Timeout for each query in seconds</dd> | |
1084 | <dt>cb</dt> | |
1085 | <dd class="description">Function to call with each value</dd> | |
1086 | <dt>context</dt> | |
1087 | <dd class="description">Application-defined pointer to send to callback</dd> | |
1088 | </dl> | |
1089 | <h4 class="returnvalue">Return Value</h4> | |
1090 | <p class="description">Status of first query of <code>CUPS_SC_STATUS_OK</code> on success</p> | |
1091 | <h4 class="discussion">Discussion</h4> | |
1092 | <p class="discussion">This function asks the backend to do multiple SNMP OID queries on behalf | |
1093 | of the filter, port monitor, or backend using the default community name. | |
1094 | All OIDs under the "parent" OID are queried and the results are sent to | |
1095 | the callback function you provide.<br> | |
1096 | <br> | |
1097 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1098 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1099 | supported and must be converted to their numeric forms.<br> | |
1100 | <br> | |
1101 | "timeout" specifies the timeout for each OID query. The total amount of | |
1102 | time will depend on the number of OID values found and the time required | |
1103 | for each query.<br> | |
1104 | <br> | |
1105 | "cb" provides a function to call for every value that is found. "context" | |
1106 | is an application-defined pointer that is sent to the callback function | |
1107 | along with the OID and current data. The data passed to the callback is the | |
1108 | same as returned by <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a>. | |
1109 | ||
1110 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1111 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1112 | the printer does not respond to the first SNMP query. | |
1113 | ||
5a738aea MS |
1114 | </p> |
1115 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> | |
1116 | <p class="description">Write a side-channel message.</p> | |
1117 | <p class="code"> | |
1118 | int cupsSideChannelWrite (<br> | |
1119 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1120 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
1121 | const char *data,<br> | |
1122 | int datalen,<br> | |
1123 | double timeout<br> | |
1124 | );</p> | |
1125 | <h4 class="parameters">Parameters</h4> | |
1126 | <dl> | |
1127 | <dt>command</dt> | |
1128 | <dd class="description">Command code</dd> | |
1129 | <dt>status</dt> | |
1130 | <dd class="description">Status code</dd> | |
1131 | <dt>data</dt> | |
1132 | <dd class="description">Data buffer pointer</dd> | |
1133 | <dt>datalen</dt> | |
1134 | <dd class="description">Number of bytes of data</dd> | |
1135 | <dt>timeout</dt> | |
1136 | <dd class="description">Timeout in seconds</dd> | |
1137 | </dl> | |
1138 | <h4 class="returnvalue">Return Value</h4> | |
1139 | <p class="description">0 on success, -1 on error</p> | |
1140 | <h4 class="discussion">Discussion</h4> | |
1141 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 1142 | responses to a filter, driver, or port monitor program. |
1143 | ||
5a738aea MS |
1144 | </p> |
1145 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
1146 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> | |
1147 | <p class="description">Backend exit codes</p> | |
1148 | <p class="code"> | |
1149 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
1150 | </p> | |
1151 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
1152 | <p class="description">Bidirectional capabilities</p> | |
1153 | <p class="code"> | |
1154 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
1155 | </p> | |
1156 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
1157 | <p class="description">Request command codes</p> | |
1158 | <p class="code"> | |
1159 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
1160 | </p> | |
1161 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> | |
1162 | <p class="description">Printer state bits</p> | |
1163 | <p class="code"> | |
1164 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
1165 | </p> | |
1166 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
1167 | <p class="description">Response status codes</p> | |
1168 | <p class="code"> | |
1169 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
1170 | </p> | |
20fbc903 MS |
1171 | <h3 class="typedef"><a name="cups_sc_walk_func_t">cups_sc_walk_func_t</a></h3> |
1172 | <p class="description">SNMP walk callback</p> | |
1173 | <p class="code"> | |
1174 | typedef void (*cups_sc_walk_func_t)(const char *oid, const char *data, int datalen, void *context); | |
1175 | </p> | |
5a738aea MS |
1176 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> |
1177 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> | |
1178 | <p class="description">Backend exit codes</p> | |
1179 | <h4 class="constants">Constants</h4> | |
1180 | <dl> | |
1181 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
1182 | <dd class="description">Job failed, authentication required</dd> | |
1183 | <dt>CUPS_BACKEND_CANCEL </dt> | |
1184 | <dd class="description">Job failed, cancel job</dd> | |
1185 | <dt>CUPS_BACKEND_FAILED </dt> | |
1186 | <dd class="description">Job failed, use error-policy</dd> | |
1187 | <dt>CUPS_BACKEND_HOLD </dt> | |
1188 | <dd class="description">Job failed, hold job</dd> | |
1189 | <dt>CUPS_BACKEND_OK </dt> | |
1190 | <dd class="description">Job completed successfully</dd> | |
1191 | <dt>CUPS_BACKEND_STOP </dt> | |
1192 | <dd class="description">Job failed, stop queue</dd> | |
1193 | </dl> | |
1194 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
79e1d494 | 1195 | <p class="description">Bidirectional capability values</p> |
5a738aea MS |
1196 | <h4 class="constants">Constants</h4> |
1197 | <dl> | |
1198 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
1199 | <dd class="description">Bidirectional I/O is not supported</dd> | |
1200 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
1201 | <dd class="description">Bidirectional I/O is supported</dd> | |
1202 | </dl> | |
1203 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
1204 | <p class="description">Request command codes</p> | |
1205 | <h4 class="constants">Constants</h4> | |
1206 | <dl> | |
1207 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
1208 | <dd class="description">Drain all pending output</dd> | |
1209 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
1210 | <dd class="description">Return bidirectional capabilities</dd> | |
1211 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> | |
1212 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
1213 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
1214 | <dd class="description">Return the device state</dd> | |
20fbc903 MS |
1215 | <dt>CUPS_SC_CMD_SNMP_GET <span class="info"> CUPS 1.4 </span></dt> |
1216 | <dd class="description">Query an SNMP OID </dd> | |
1217 | <dt>CUPS_SC_CMD_SNMP_GET_NEXT <span class="info"> CUPS 1.4 </span></dt> | |
1218 | <dd class="description">Query the next SNMP OID </dd> | |
5a738aea MS |
1219 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> |
1220 | <dd class="description">Do a soft reset</dd> | |
1221 | </dl> | |
1222 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> | |
1223 | <p class="description">Printer state bits</p> | |
1224 | <h4 class="constants">Constants</h4> | |
1225 | <dl> | |
1226 | <dt>CUPS_SC_STATE_BUSY </dt> | |
1227 | <dd class="description">Device is busy</dd> | |
1228 | <dt>CUPS_SC_STATE_ERROR </dt> | |
1229 | <dd class="description">Other error condition</dd> | |
1230 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
1231 | <dd class="description">Toner/ink out condition</dd> | |
1232 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
1233 | <dd class="description">Toner/ink low condition</dd> | |
1234 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
1235 | <dd class="description">Paper out condition</dd> | |
1236 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
1237 | <dd class="description">Paper low condition</dd> | |
1238 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
79e1d494 | 1239 | <dd class="description">Device is offline</dd> |
5a738aea | 1240 | <dt>CUPS_SC_STATE_ONLINE </dt> |
79e1d494 | 1241 | <dd class="description">Device is online</dd> |
5a738aea MS |
1242 | </dl> |
1243 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
1244 | <p class="description">Response status codes</p> | |
1245 | <h4 class="constants">Constants</h4> | |
1246 | <dl> | |
1247 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
1248 | <dd class="description">The command/response message was invalid</dd> | |
1249 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
1250 | <dd class="description">An I/O error occurred</dd> | |
1251 | <dt>CUPS_SC_STATUS_NONE </dt> | |
1252 | <dd class="description">No status</dd> | |
1253 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
1254 | <dd class="description">Command not implemented</dd> | |
1255 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
1256 | <dd class="description">The device did not respond</dd> | |
1257 | <dt>CUPS_SC_STATUS_OK </dt> | |
1258 | <dd class="description">Operation succeeded</dd> | |
1259 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
1260 | <dd class="description">The backend did not respond</dd> | |
1261 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
1262 | <dd class="description">Response too big</dd> | |
1263 | </dl> | |
1264 | </div> | |
ef416fc2 | 1265 | </body> |
1266 | </html> |