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5a738aea | 339 | --></style> |
ef416fc2 | 340 | </head> |
341 | <body> | |
5a738aea | 342 | <div class='body'> |
ef416fc2 | 343 | <!-- |
9c0e8e5d | 344 | "$Id: api-filter.header 7616 2008-05-28 00:34:13Z mike $" |
ef416fc2 | 345 | |
321d8d57 | 346 | Filter and backend programming header for CUPS. |
ef416fc2 | 347 | |
321d8d57 | 348 | Copyright 2008-2011 by Apple Inc. |
ef416fc2 | 349 | |
350 | These coded instructions, statements, and computer programs are the | |
bc44d920 | 351 | property of Apple Inc. and are protected by Federal copyright |
352 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
353 | which should have been included with this file. If this file is | |
354 | file is missing or damaged, see the license at "http://www.cups.org/". | |
ef416fc2 | 355 | --> |
356 | ||
178cb736 MS |
357 | <h1 class='title'>Filter and Backend Programming</h1> |
358 | ||
5a738aea MS |
359 | <div class='summary'><table summary='General Information'> |
360 | <thead> | |
361 | <tr> | |
ac884b6a | 362 | <th>Headers</th> |
5a738aea | 363 | <th>cups/backend.h<br> |
79e1d494 | 364 | cups/sidechannel.h</th> |
5a738aea MS |
365 | </tr> |
366 | </thead> | |
367 | <tbody> | |
368 | <tr> | |
369 | <th>Library</th> | |
370 | <td>-lcups</td> | |
371 | </tr> | |
372 | <tr> | |
373 | <th>See Also</th> | |
374 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
375 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
376 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
79e1d494 | 377 | Programming: <a href='api-raster.html' target='_top'>Raster API</a><br> |
b0f6947b MS |
378 | Programming: <a href='postscript-driver.html' target='_top'>Developing PostScript Printer Drivers</a><br> |
379 | Programming: <a href='raster-driver.html' target='_top'>Developing Raster Printer Drivers</a><br> | |
10d09e33 | 380 | Specifications: <a href='spec-design.html' target='_top'>CUPS Design Description</a></td> |
5a738aea MS |
381 | </tr> |
382 | </tbody> | |
383 | </table></div> | |
384 | <h2 class="title">Contents</h2> | |
385 | <ul class="contents"> | |
5a738aea | 386 | <li><a href="#OVERVIEW">Overview</a><ul class="subcontents"> |
0268488e | 387 | <li><a href="#SECURITY">Security Considerations</a></li> |
88f9aafc | 388 | <li><a href="#SIGNALS">Canceled Jobs and Signal Handling</a></li> |
f228370c | 389 | <li><a href="#PERMISSIONS">File Permissions</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 | <!-- |
9c0e8e5d | 429 | "$Id: api-filter.shtml 7677 2008-06-19 23:22:19Z mike $" |
ef416fc2 | 430 | |
22c9029b | 431 | Filter and backend programming introduction for CUPS. |
ef416fc2 | 432 | |
f3c17241 | 433 | Copyright 2007-2012 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 | |
eac3a0a0 | 487 | most backends are run as a non-privileged user, so the major security |
ac884b6a MS |
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 |
f3c17241 | 511 | OS X, for example, no backend may write to a user's home directory.</p> |
ac884b6a MS |
512 | </blockquote> |
513 | ||
f228370c | 514 | <h3><a name="SIGNALS">Canceled Jobs and Signal Handling</a></h3> |
22c9029b MS |
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 | |
88f9aafc MS |
520 | end the output on the current page, preferably on the current line or object |
521 | being printed.</p> | |
22c9029b | 522 | |
88f9aafc | 523 | <p>Filters and backends may also receive <code>SIGPIPE</code> when an upstream or downstream filter/backend exits with a non-zero status. Developers should generally ignore <code>SIGPIPE</code> at the beginning of <code>main()</code> with the following function call:</p> |
eac3a0a0 MS |
524 | |
525 | <pre class="example"> | |
526 | #include <signal.h>> | |
527 | ||
528 | ... | |
529 | ||
530 | int | |
531 | main(int argc, char *argv[]) | |
532 | { | |
533 | signal(SIGPIPE, SIG_IGN); | |
534 | ||
535 | ... | |
536 | } | |
537 | </pre> | |
538 | ||
178cb736 MS |
539 | <h3><a name="PERMISSIONS">File Permissions</a></h3> |
540 | ||
541 | <p>For security reasons, CUPS will only run filters and backends that are owned | |
4d301e69 MS |
542 | by root and do not have world or group write permissions. The recommended |
543 | permissions for filters and backends are 0555 - read and execute but no write. | |
544 | Backends that must run as root should use permissions of 0500 - read and execute | |
545 | by root, no access for other users. Write permissions can be enabled for the | |
546 | root user only.</p> | |
178cb736 MS |
547 | |
548 | <p>To avoid a warning message, the directory containing your filter(s) must also | |
4d301e69 MS |
549 | be owned by root and have world and group write disabled - permissions of 0755 |
550 | or 0555 are strongly encouraged.</p> | |
178cb736 | 551 | |
ac884b6a MS |
552 | <h3><a name="TEMPFILES">Temporary Files</a></h3> |
553 | ||
554 | <p>Temporary files should be created in the directory specified by the | |
555 | "TMPDIR" environment variable. The | |
556 | <a href="#cupsTempFile2"><code>cupsTempFile2</code></a> function can be | |
557 | used to safely create temporary files in this directory.</p> | |
558 | ||
559 | <h3><a name="COPIES">Copy Generation</a></h3> | |
560 | ||
561 | <p>The <code>argv[4]</code> argument specifies the number of copies to produce | |
562 | of the input file. In general, you should only generate copies if the | |
563 | <em>filename</em> argument is supplied. The only exception to this are | |
564 | filters that produce device-independent PostScript output, since the PostScript | |
565 | filter <var>pstops</var> is responsible for generating copies of PostScript | |
566 | files.</p> | |
567 | ||
5a738aea | 568 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 569 | |
5a738aea MS |
570 | <p>Filters must exit with status 0 when they successfully generate print data |
571 | or 1 when they encounter an error. Backends can return any of the | |
572 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 573 | |
5a738aea | 574 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 575 | |
79e1d494 MS |
576 | <p>The following environment variables are defined by the printing system |
577 | when running print filters and backends:</p> | |
f7deaa1a | 578 | |
5a738aea | 579 | <dl class="code"> |
f7deaa1a | 580 | |
acb056cb | 581 | <dt>APPLE_LANGUAGE</dt> |
5a738aea | 582 | <dd>The Apple language identifier associated with the job |
f3c17241 | 583 | (OS X only).</dd> |
f7deaa1a | 584 | |
5a738aea MS |
585 | <dt>CHARSET</dt> |
586 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 587 | |
5a738aea MS |
588 | <dt>CLASS</dt> |
589 | <dd>When a job is submitted to a printer class, contains the name of | |
590 | the destination printer class. Otherwise this environment | |
591 | variable will not be set.</dd> | |
f7deaa1a | 592 | |
5a738aea MS |
593 | <dt>CONTENT_TYPE</dt> |
594 | <dd>The MIME type associated with the file (e.g. | |
595 | application/postscript).</dd> | |
f7deaa1a | 596 | |
5a738aea | 597 | <dt>CUPS_CACHEDIR</dt> |
79e1d494 MS |
598 | <dd>The directory where cache files can be stored. Cache files can be |
599 | used to retain information between jobs or files in a job.</dd> | |
f7deaa1a | 600 | |
5a738aea | 601 | <dt>CUPS_DATADIR</dt> |
79e1d494 | 602 | <dd>The directory where (read-only) CUPS data files can be found.</dd> |
f7deaa1a | 603 | |
758a062f MS |
604 | <dt>CUPS_FILETYPE</dt> |
605 | <dd>The type of file being printed: "job-sheet" for a banner page and | |
606 | "document" for a regular print file.</dd> | |
607 | ||
5a738aea MS |
608 | <dt>CUPS_SERVERROOT</dt> |
609 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 610 | |
5a738aea MS |
611 | <dt>DEVICE_URI</dt> |
612 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 613 | |
5a738aea MS |
614 | <dt>FINAL_CONTENT_TYPE</dt> |
615 | <dd>The MIME type associated with the printer (e.g. | |
616 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 617 | |
5a738aea MS |
618 | <dt>LANG</dt> |
619 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 620 | |
5a738aea MS |
621 | <dt>PPD</dt> |
622 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
623 | file for this printer.</dd> | |
f7deaa1a | 624 | |
5a738aea | 625 | <dt>PRINTER</dt> |
79e1d494 | 626 | <dd>The queue name of the class or printer.</dd> |
f7deaa1a | 627 | |
5a738aea MS |
628 | <dt>RIP_CACHE</dt> |
629 | <dd>The recommended amount of memory to use for Raster Image | |
630 | Processors (RIPs).</dd> | |
f7deaa1a | 631 | |
79e1d494 MS |
632 | <dt>TMPDIR</dt> |
633 | <dd>The directory where temporary files should be created.</dd> | |
634 | ||
5a738aea | 635 | </dl> |
f7deaa1a | 636 | |
5a738aea | 637 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 638 | |
79e1d494 MS |
639 | <p>Filters and backends communicate with the scheduler by writing messages |
640 | to the standard error file. The scheduler reads messages from all filters in | |
641 | a job and processes the message based on its prefix. For example, the following | |
642 | code sets the current printer state message to "Printing page 5":</p> | |
f7deaa1a | 643 | |
5a738aea MS |
644 | <pre class="example"> |
645 | int page = 5; | |
f7deaa1a | 646 | |
5a738aea | 647 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 648 | </pre> |
649 | ||
5a738aea MS |
650 | <p>Each message is a single line of text starting with one of the following |
651 | prefix strings:</p> | |
652 | ||
653 | <dl class="code"> | |
654 | ||
655 | <dt>ALERT: message</dt> | |
656 | <dd>Sets the printer-state-message attribute and adds the specified | |
657 | message to the current error log file using the "alert" log level.</dd> | |
658 | ||
659 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
660 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
88f9aafc MS |
661 | to set the <code>marker-colors</code>, <code>marker-high-levels</code>, |
662 | <code>marker-levels</code>, <code>marker-low-levels</code>, | |
75bd9771 MS |
663 | <code>marker-message</code>, <code>marker-names</code>, |
664 | <code>marker-types</code>, <code>printer-alert</code>, and | |
665 | <code>printer-alert-description</code> printer attributes. Standard | |
666 | <code>marker-types</code> values are listed in <a href='#TABLE1'>Table | |
667 | 1</a>.</dd> | |
5a738aea MS |
668 | |
669 | <dt>CRIT: message</dt> | |
670 | <dd>Sets the printer-state-message attribute and adds the specified | |
671 | message to the current error log file using the "critical" log | |
672 | level.</dd> | |
673 | ||
674 | <dt>DEBUG: message</dt> | |
675 | <dd>Sets the printer-state-message attribute and adds the specified | |
676 | message to the current error log file using the "debug" log level.</dd> | |
677 | ||
678 | <dt>DEBUG2: message</dt> | |
679 | <dd>Sets the printer-state-message attribute and adds the specified | |
680 | message to the current error log file using the "debug2" log level.</dd> | |
681 | ||
682 | <dt>EMERG: message</dt> | |
683 | <dd>Sets the printer-state-message attribute and adds the specified | |
684 | message to the current error log file using the "emergency" log | |
685 | level.</dd> | |
686 | ||
687 | <dt>ERROR: message</dt> | |
688 | <dd>Sets the printer-state-message attribute and adds the specified | |
79e1d494 MS |
689 | message to the current error log file using the "error" log level. |
690 | Use "ERROR:" messages for non-persistent processing errors.</dd> | |
5a738aea MS |
691 | |
692 | <dt>INFO: message</dt> | |
693 | <dd>Sets the printer-state-message attribute. If the current log level | |
694 | is set to "debug2", also adds the specified message to the current error | |
695 | log file using the "info" log level.</dd> | |
696 | ||
697 | <dt>NOTICE: message</dt> | |
698 | <dd>Sets the printer-state-message attribute and adds the specified | |
699 | message to the current error log file using the "notice" log level.</dd> | |
700 | ||
701 | <dt>PAGE: page-number #-copies</dt> | |
702 | <dt>PAGE: total #-pages</dt> | |
703 | <dd>Adds an entry to the current page log file. The first form adds | |
704 | #-copies to the job-media-sheets-completed attribute. The second | |
705 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
706 | ||
20fbc903 MS |
707 | <dt>PPD: keyword=value [keyword=value ...]</dt> |
708 | <dd>Changes or adds keywords to the printer's PPD file. Typically | |
709 | this is used to update installable options or default media settings | |
710 | based on the printer configuration.</dd> | |
711 | ||
5a738aea MS |
712 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> |
713 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
88f9aafc MS |
714 | <dd>Sets or clears printer-state-reason keywords for the current queue. |
715 | Typically this is used to indicate persistent media, ink, toner, and | |
716 | configuration conditions or errors on a printer. | |
79e1d494 | 717 | <a href='#TABLE2'>Table 2</a> lists the standard state keywords - |
88f9aafc MS |
718 | use vendor-prefixed ("com.example.foo") keywords for custom states. See |
719 | <a href="#MANAGING_STATE">Managing Printer State in a Filter</a> for more | |
720 | information. | |
5a738aea MS |
721 | |
722 | <dt>WARNING: message</dt> | |
723 | <dd>Sets the printer-state-message attribute and adds the specified | |
724 | message to the current error log file using the "warning" log | |
725 | level.</dd> | |
726 | ||
727 | </dl> | |
728 | ||
729 | <p>Messages without one of these prefixes are treated as if they began with | |
730 | the "DEBUG:" prefix string.</p> | |
731 | ||
79e1d494 MS |
732 | <div class='table'><table width='80%' summary='Table 1: Standard marker-types Values'> |
733 | <caption>Table 1: <a name='TABLE1'>Standard marker-types Values</a></caption> | |
734 | <thead> | |
735 | <tr> | |
736 | <th>marker-type</th> | |
737 | <th>Description</th> | |
738 | </tr> | |
739 | </thead> | |
740 | <tbody> | |
741 | <tr> | |
742 | <td>developer</td> | |
743 | <td>Developer unit</td> | |
744 | </tr> | |
745 | <tr> | |
746 | <td>fuser</td> | |
747 | <td>Fuser unit</td> | |
748 | </tr> | |
749 | <tr> | |
750 | <td>fuserCleaningPad</td> | |
751 | <td>Fuser cleaning pad</td> | |
752 | </tr> | |
753 | <tr> | |
754 | <td>fuserOil</td> | |
755 | <td>Fuser oil</td> | |
756 | </tr> | |
757 | <tr> | |
758 | <td>ink</td> | |
759 | <td>Ink supply</td> | |
760 | </tr> | |
761 | <tr> | |
762 | <td>opc</td> | |
763 | <td>Photo conductor</td> | |
764 | </tr> | |
765 | <tr> | |
766 | <td>solidWax</td> | |
767 | <td>Wax supply</td> | |
768 | </tr> | |
769 | <tr> | |
770 | <td>staples</td> | |
771 | <td>Staple supply</td> | |
772 | </tr> | |
773 | <tr> | |
774 | <td>toner</td> | |
775 | <td>Toner supply</td> | |
776 | </tr> | |
777 | <tr> | |
778 | <td>transferUnit</td> | |
779 | <td>Transfer unit</td> | |
780 | </tr> | |
781 | <tr> | |
782 | <td>wasteInk</td> | |
783 | <td>Waste ink tank</td> | |
784 | </tr> | |
785 | <tr> | |
786 | <td>wasteToner</td> | |
787 | <td>Waste toner tank</td> | |
788 | </tr> | |
789 | <tr> | |
790 | <td>wasteWax</td> | |
791 | <td>Waste wax tank</td> | |
792 | </tr> | |
793 | </tbody> | |
794 | </table></div> | |
795 | ||
796 | <br> | |
797 | ||
798 | <div class='table'><table width='80%' summary='Table 2: Standard State Keywords'> | |
799 | <caption>Table 2: <a name='TABLE2'>Standard State Keywords</a></caption> | |
800 | <thead> | |
801 | <tr> | |
802 | <th>Keyword</th> | |
803 | <th>Description</th> | |
804 | </tr> | |
805 | </thead> | |
806 | <tbody> | |
807 | <tr> | |
808 | <td>connecting-to-device</td> | |
88f9aafc | 809 | <td>Connecting to printer but not printing yet.</td> |
79e1d494 MS |
810 | </tr> |
811 | <tr> | |
812 | <td>cover-open</td> | |
88f9aafc | 813 | <td>The printer's cover is open.</td> |
79e1d494 MS |
814 | </tr> |
815 | <tr> | |
816 | <td>input-tray-missing</td> | |
88f9aafc | 817 | <td>The paper tray is missing.</td> |
79e1d494 MS |
818 | </tr> |
819 | <tr> | |
820 | <td>marker-supply-empty</td> | |
88f9aafc | 821 | <td>The printer is out of ink.</td> |
79e1d494 MS |
822 | </tr> |
823 | <tr> | |
824 | <td>marker-supply-low</td> | |
88f9aafc | 825 | <td>The printer is almost out of ink.</td> |
79e1d494 MS |
826 | </tr> |
827 | <tr> | |
828 | <td>marker-waste-almost-full</td> | |
88f9aafc | 829 | <td>The printer's waste bin is almost full.</td> |
79e1d494 MS |
830 | </tr> |
831 | <tr> | |
832 | <td>marker-waste-full</td> | |
88f9aafc | 833 | <td>The printer's waste bin is full.</td> |
79e1d494 MS |
834 | </tr> |
835 | <tr> | |
836 | <td>media-empty</td> | |
88f9aafc | 837 | <td>The paper tray (any paper tray) is empty.</td> |
79e1d494 MS |
838 | </tr> |
839 | <tr> | |
840 | <td>media-jam</td> | |
88f9aafc | 841 | <td>There is a paper jam.</td> |
79e1d494 MS |
842 | </tr> |
843 | <tr> | |
844 | <td>media-low</td> | |
88f9aafc MS |
845 | <td>The paper tray (any paper tray) is almost empty.</td> |
846 | </tr> | |
847 | <tr> | |
848 | <td>media-needed</td> | |
849 | <td>The paper tray needs to be filled (for a job that is printing).</td> | |
79e1d494 MS |
850 | </tr> |
851 | <tr> | |
852 | <td>paused</td> | |
88f9aafc | 853 | <td>Stop the printer.</td> |
79e1d494 MS |
854 | </tr> |
855 | <tr> | |
856 | <td>timed-out</td> | |
88f9aafc | 857 | <td>Unable to connect to printer.</td> |
79e1d494 MS |
858 | </tr> |
859 | <tr> | |
860 | <td>toner-empty</td> | |
88f9aafc | 861 | <td>The printer is out of toner.</td> |
79e1d494 MS |
862 | </tr> |
863 | <tr> | |
864 | <td>toner-low</td> | |
88f9aafc MS |
865 | <td>The printer is low on toner.</td> |
866 | </tr> | |
867 | </tbody> | |
868 | </table></div> | |
869 | ||
870 | <h4><a name="MANAGING_STATE">Managing Printer State in a Filter</a></h4> | |
871 | ||
872 | <p>Filters are responsible for managing the state keywords they set using | |
873 | "STATE:" messages. Typically you will update <em>all</em> of the keywords that | |
874 | are used by the filter at startup, for example:</p> | |
875 | ||
876 | <pre class="example"> | |
877 | if (foo_condition != 0) | |
878 | fputs("STATE: +com.example.foo\n", stderr); | |
879 | else | |
880 | fputs("STATE: -com.example.foo\n", stderr); | |
881 | ||
882 | if (bar_condition != 0) | |
883 | fputs("STATE: +com.example.bar\n", stderr); | |
884 | else | |
885 | fputs("STATE: -com.example.bar\n", stderr); | |
886 | </pre> | |
887 | ||
888 | <p>Then as conditions change, your filter sends "STATE: +keyword" or "STATE: | |
889 | -keyword" messages as necessary to set or clear the corresponding keyword, | |
890 | respectively.</p> | |
891 | ||
892 | <p>State keywords are often used to notify the user of issues that span across | |
893 | jobs, for example "media-empty-warning" that indicates one or more paper trays | |
894 | are empty. These keywords should not be cleared unless the corresponding issue | |
895 | no longer exists.</p> | |
896 | ||
897 | <p>Filters should clear job-related keywords on startup and exit so that they | |
898 | do not remain set between jobs. For example, "connecting-to-device" is a job | |
899 | sub-state and not an issue that applies when a job is not printing.</p> | |
900 | ||
901 | <blockquote><b>Note:</b> | |
902 | ||
903 | <p>"STATE:" messages often provide visible alerts to the user. For example, | |
f3c17241 | 904 | on OS X setting a printer-state-reason value with an "-error" or |
88f9aafc MS |
905 | "-warning" suffix will cause the printer's dock item to bounce if the |
906 | corresponding reason is localized with a cupsIPPReason keyword in the | |
907 | printer's PPD file.</p> | |
908 | ||
909 | <p>When providing a vendor-prefixed keyword, <em>always</em> provide the | |
910 | corresponding standard keyword (if any) to allow clients to respond to the | |
911 | condition correctly. For example, if you provide a vendor-prefixed keyword | |
912 | for a low cyan ink condition ("com.example.cyan-ink-low") you must also set the | |
913 | "marker-supply-low-warning" keyword. In such cases you should also refrain | |
914 | from localizing the vendor-prefixed keyword in the PPD file - otherwise both | |
915 | the generic and vendor-specific keyword will be shown in the user | |
916 | interface.</p> | |
917 | ||
918 | </blockquote></dd> | |
919 | ||
920 | <h4><a name="REPORTING_SUPPLIES">Reporting Supply Levels</a></h4> | |
921 | ||
922 | <p>CUPS tracks several "marker-*" attributes for ink/toner supply level | |
923 | reporting. These attributes allow applications to display the current supply | |
924 | levels for a printer without printer-specific software. <a href="#TABLE3">Table 3</a> lists the marker attributes and what they represent.</p> | |
925 | ||
926 | <p>Filters set marker attributes by sending "ATTR:" messages to stderr. For | |
927 | example, a filter supporting an inkjet printer with black and tri-color ink | |
928 | cartridges would use the following to initialize the supply attributes:</p> | |
929 | ||
930 | <pre class="example"> | |
931 | fputs("ATTR: marker-colors=#000000,#00FFFF#FF00FF#FFFF00\n", stderr); | |
932 | fputs("ATTR: marker-low-levels=5,10\n", stderr); | |
933 | fputs("ATTR: marker-names=Black,Tri-Color\n", stderr); | |
934 | fputs("ATTR: marker-types=ink,ink\n", stderr); | |
935 | </pre> | |
936 | ||
937 | <p>Then periodically the filter queries the printer for its current supply | |
938 | levels and updates them with a separate "ATTR:" message:</p> | |
939 | ||
940 | <pre class="example"> | |
941 | int black_level, tri_level; | |
942 | ... | |
943 | fprintf(stderr, "ATTR: marker-levels=%d,%d\n", black_level, tri_level); | |
944 | </pre> | |
945 | ||
946 | <div class='table'><table width='80%' summary='Table 3: Supply Level Attributes'> | |
947 | <caption>Table 3: <a name='TABLE3'>Supply Level Attributes</a></caption> | |
948 | <thead> | |
949 | <tr> | |
950 | <th>Attribute</th> | |
951 | <th>Description</th> | |
952 | </tr> | |
953 | </thead> | |
954 | <tbody> | |
955 | <tr> | |
956 | <td>marker-colors</td> | |
957 | <td>A list of comma-separated colors; each color is either "none" or one or | |
958 | more hex-encoded sRGB colors of the form "#RRGGBB".</td> | |
959 | </tr> | |
960 | <tr> | |
961 | <td>marker-high-levels</td> | |
962 | <td>A list of comma-separated "almost full" level values from 0 to 100; a | |
963 | value of 100 should be used for supplies that are consumed/emptied like ink | |
964 | cartridges.</td> | |
965 | </tr> | |
966 | <tr> | |
967 | <td>marker-levels</td> | |
968 | <td>A list of comma-separated level values for each supply. A value of -1 | |
969 | indicates the level is unavailable, -2 indicates unknown, and -3 indicates | |
970 | the level is unknown but has not yet reached capacity. Values from 0 to 100 | |
971 | indicate the corresponding percentage.</td> | |
972 | </tr> | |
973 | <tr> | |
974 | <td>marker-low-levels</td> | |
975 | <td>A list of comma-separated "almost empty" level values from 0 to 100; a | |
976 | value of 0 should be used for supplies that are filled like waste ink | |
977 | tanks.</td> | |
978 | </tr> | |
979 | <tr> | |
980 | <td>marker-message</td> | |
981 | <td>A human-readable supply status message for the user like "12 pages of | |
982 | ink remaining."</td> | |
983 | </tr> | |
984 | <tr> | |
985 | <td>marker-names</td> | |
986 | <td>A list of comma-separated supply names like "Cyan Ink", "Fuser", | |
987 | etc.</td> | |
988 | </tr> | |
989 | <tr> | |
990 | <td>marker-types</td> | |
991 | <td>A list of comma-separated supply types; the types are listed in | |
992 | <a href="#TABLE1">Table 1</a>.</td> | |
79e1d494 MS |
993 | </tr> |
994 | </tbody> | |
995 | </table></div> | |
996 | ||
20fbc903 | 997 | <h3><a name="COMMUNICATING_BACKEND">Communicating with the Backend</a></h3> |
5a738aea MS |
998 | |
999 | <p>Filters can communicate with the backend via the | |
1000 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
1001 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
22c9029b | 1002 | functions. The |
5a738aea MS |
1003 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function |
1004 | reads data that has been sent back from the device and is typically used to | |
1005 | obtain status and configuration information. For example, the following code | |
1006 | polls the backend for back-channel data:</p> | |
1007 | ||
1008 | <pre class="example"> | |
1009 | #include <cups/cups.h> | |
1010 | ||
1011 | char buffer[8192]; | |
1012 | ssize_t bytes; | |
1013 | ||
1014 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
1015 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
1016 | </pre> | |
f7deaa1a | 1017 | |
79e1d494 MS |
1018 | <p>Filters can also use <code>select()</code> or <code>poll()</code> on the |
1019 | back-channel file descriptor (3 or <code>CUPS_BC_FD</code>) to read data only | |
1020 | when it is available.</p> | |
1021 | ||
1022 | <p>The | |
5a738aea MS |
1023 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> |
1024 | function allows you to get out-of-band status information and do synchronization | |
1025 | with the device. For example, the following code gets the current IEEE-1284 | |
1026 | device ID string from the backend:</p> | |
1027 | ||
1028 | <pre class="example"> | |
f7deaa1a | 1029 | #include <cups/sidechannel.h> |
1030 | ||
1031 | char data[2049]; | |
1032 | int datalen; | |
5a738aea | 1033 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 1034 | |
79e1d494 MS |
1035 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for |
1036 | nul-termination... */ | |
f7deaa1a | 1037 | datalen = sizeof(data) - 1; |
1038 | ||
1039 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 1040 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 1041 | |
1042 | /* Use the returned value if OK was returned and the length is non-zero */ | |
1043 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
1044 | data[datalen] = '\0'; | |
1045 | else | |
1046 | data[0] = '\0'; | |
1047 | </pre> | |
1048 | ||
88f9aafc MS |
1049 | <h4><a name="DRAIN_OUTPUT">Forcing All Output to a Printer</a></h4> |
1050 | ||
1051 | <p>The | |
1052 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
1053 | function allows you to tell the backend to send all pending data to the printer. | |
1054 | This is most often needed when sending query commands to the printer. For example:</p> | |
1055 | ||
1056 | <pre class="example"> | |
1057 | #include <cups/cups.h> | |
1058 | #include <cups/sidechannel.h> | |
1059 | ||
1060 | char data[1024]; | |
1061 | int datalen = sizeof(data); | |
1062 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
1063 | ||
1064 | /* Flush pending output to stdout */ | |
1065 | fflush(stdout); | |
1066 | ||
1067 | /* Drain output to backend, waiting for up to 30 seconds */ | |
1068 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_DRAIN_OUTPUT, data, &datalen, 30.0); | |
1069 | ||
1070 | /* Read the response if the output was sent */ | |
1071 | if (status == CUPS_SC_STATUS_OK) | |
1072 | { | |
1073 | ssize_t bytes; | |
1074 | ||
1075 | /* Wait up to 10.0 seconds for back-channel data */ | |
1076 | bytes = cupsBackChannelRead(data, sizeof(data), 10.0); | |
1077 | /* do something with the data from the printer */ | |
1078 | } | |
1079 | </pre> | |
1080 | ||
20fbc903 MS |
1081 | <h3><a name="COMMUNICATING_FILTER">Communicating with Filters</a></h3> |
1082 | ||
5a738aea MS |
1083 | <p>Backends communicate with filters using the reciprocal functions |
1084 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
1085 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
1086 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
1087 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 1088 | |
5a738aea MS |
1089 | <pre class="example"> |
1090 | #include <cups/cups.h> | |
f7deaa1a | 1091 | |
5a738aea MS |
1092 | char buffer[8192]; |
1093 | ssize_t bytes; | |
f7deaa1a | 1094 | |
79e1d494 MS |
1095 | /* Obtain data from printer/device */ |
1096 | ... | |
1097 | ||
5a738aea MS |
1098 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
1099 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 1100 | </pre> |
1101 | ||
5a738aea MS |
1102 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
1103 | function reads a side-channel command from a filter, driver, or port monitor. | |
1104 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
1105 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
1106 | separate thread for that purpose), or use <code>select</code> or | |
1107 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
20fbc903 | 1108 | input and output on several file descriptors at the same time.</p> |
5a738aea MS |
1109 | |
1110 | <p>Once a command is processed, the backend uses the | |
1111 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
1112 | to send its response. For example, the following code shows how to poll for a | |
1113 | side-channel command and respond to it:</p> | |
1114 | ||
1115 | <pre class="example"> | |
f7deaa1a | 1116 | #include <cups/sidechannel.h> |
1117 | ||
5a738aea MS |
1118 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
1119 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
20fbc903 MS |
1120 | char data[2048]; |
1121 | int datalen = sizeof(data); | |
f7deaa1a | 1122 | |
1123 | /* Poll for a command... */ | |
20fbc903 | 1124 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, data, &datalen, 0.0)) |
f7deaa1a | 1125 | { |
f7deaa1a | 1126 | switch (command) |
1127 | { | |
20fbc903 | 1128 | /* handle supported commands, fill data/datalen/status with values as needed */ |
f7deaa1a | 1129 | |
1130 | default : | |
1131 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
1132 | datalen = 0; | |
1133 | break; | |
1134 | } | |
1135 | ||
1136 | /* Send a response... */ | |
5a738aea | 1137 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 1138 | } |
1139 | </pre> | |
ac884b6a MS |
1140 | |
1141 | <h3><a name="SNMP">Doing SNMP Queries with Network Printers</a></h3> | |
1142 | ||
1143 | <p>The Simple Network Management Protocol (SNMP) allows you to get the current | |
1144 | status, page counter, and supply levels from most network printers. Every | |
1145 | piece of information is associated with an Object Identifier (OID), and | |
1146 | every printer has a <em>community</em> name associated with it. OIDs can be | |
1147 | queried directly or by "walking" over a range of OIDs with a common prefix.</p> | |
1148 | ||
20fbc903 MS |
1149 | <p>The two CUPS SNMP functions provide a simple API for querying network |
1150 | printers through the side-channel interface. Each accepts a string containing | |
1151 | an OID like ".1.3.6.1.2.1.43.10.2.1.4.1.1" (the standard page counter OID) | |
1152 | along with a timeout for the query.</p> | |
ac884b6a | 1153 | |
20fbc903 MS |
1154 | <p>The <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a> |
1155 | function queries a single OID and returns the value as a string in a buffer | |
1156 | you supply:</p> | |
ac884b6a MS |
1157 | |
1158 | <pre class="example"> | |
20fbc903 | 1159 | #include <cups/sidechannel.h> |
ac884b6a | 1160 | |
20fbc903 MS |
1161 | char data[512]; |
1162 | int datalen = sizeof(data); | |
ac884b6a | 1163 | |
20fbc903 MS |
1164 | if (<a href="#cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a>(".1.3.6.1.2.1.43.10.2.1.4.1.1", data, &datalen, 5.0) |
1165 | == CUPS_SC_STATUS_OK) | |
ac884b6a MS |
1166 | { |
1167 | /* Do something with the value */ | |
20fbc903 | 1168 | printf("Page counter is: %s\n", data); |
ac884b6a MS |
1169 | } |
1170 | </pre> | |
1171 | ||
20fbc903 MS |
1172 | <p>The |
1173 | <a href="#cupsSideChannelSNMPWalk"><code>cupsSideChannelSNMPWalk</code></a> | |
1174 | function allows you to query a whole group of OIDs, calling a function of your | |
1175 | choice for each OID that is found:</p> | |
ac884b6a MS |
1176 | |
1177 | <pre class="example"> | |
20fbc903 | 1178 | #include <cups/sidechannel.h> |
ac884b6a MS |
1179 | |
1180 | void | |
20fbc903 | 1181 | my_callback(const char *oid, const char *data, int datalen, void *context) |
ac884b6a MS |
1182 | { |
1183 | /* Do something with the value */ | |
20fbc903 | 1184 | printf("%s=%s\n", oid, data); |
ac884b6a MS |
1185 | } |
1186 | ||
20fbc903 MS |
1187 | ... |
1188 | ||
ac884b6a MS |
1189 | void *my_data; |
1190 | ||
20fbc903 | 1191 | <a href="#cupsSideChannelSNMPWalk">cupsSNMPSideChannelWalk</a>(".1.3.6.1.2.1.43", 5.0, my_callback, my_data); |
ac884b6a | 1192 | </pre> |
20fbc903 | 1193 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
f3c17241 | 1194 | <h3 class="function"><span class="info"> CUPS 1.2/OS X 10.5 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> |
5a738aea MS |
1195 | <p class="description">Read data from the backchannel.</p> |
1196 | <p class="code"> | |
1197 | ssize_t cupsBackChannelRead (<br> | |
1198 | char *buffer,<br> | |
1199 | size_t bytes,<br> | |
1200 | double timeout<br> | |
1201 | );</p> | |
1202 | <h4 class="parameters">Parameters</h4> | |
1203 | <dl> | |
1204 | <dt>buffer</dt> | |
79e1d494 | 1205 | <dd class="description">Buffer to read into</dd> |
5a738aea MS |
1206 | <dt>bytes</dt> |
1207 | <dd class="description">Bytes to read</dd> | |
1208 | <dt>timeout</dt> | |
79e1d494 | 1209 | <dd class="description">Timeout in seconds, typically 0.0 to poll</dd> |
5a738aea MS |
1210 | </dl> |
1211 | <h4 class="returnvalue">Return Value</h4> | |
1212 | <p class="description">Bytes read or -1 on error</p> | |
1213 | <h4 class="discussion">Discussion</h4> | |
79e1d494 MS |
1214 | <p class="discussion">Reads up to "bytes" bytes from the backchannel/backend. The "timeout" |
1215 | parameter controls how many seconds to wait for the data - use 0.0 to | |
1216 | return immediately if there is no data, -1.0 to wait for data indefinitely. | |
ef416fc2 | 1217 | |
5a738aea | 1218 | </p> |
f3c17241 | 1219 | <h3 class="function"><span class="info"> CUPS 1.2/OS X 10.5 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> |
5a738aea MS |
1220 | <p class="description">Write data to the backchannel.</p> |
1221 | <p class="code"> | |
1222 | ssize_t cupsBackChannelWrite (<br> | |
1223 | const char *buffer,<br> | |
1224 | size_t bytes,<br> | |
1225 | double timeout<br> | |
1226 | );</p> | |
1227 | <h4 class="parameters">Parameters</h4> | |
1228 | <dl> | |
1229 | <dt>buffer</dt> | |
1230 | <dd class="description">Buffer to write</dd> | |
1231 | <dt>bytes</dt> | |
1232 | <dd class="description">Bytes to write</dd> | |
1233 | <dt>timeout</dt> | |
79e1d494 | 1234 | <dd class="description">Timeout in seconds, typically 1.0</dd> |
5a738aea MS |
1235 | </dl> |
1236 | <h4 class="returnvalue">Return Value</h4> | |
1237 | <p class="description">Bytes written or -1 on error</p> | |
1238 | <h4 class="discussion">Discussion</h4> | |
79e1d494 | 1239 | <p class="discussion">Writes "bytes" bytes to the backchannel/filter. The "timeout" parameter |
ef416fc2 | 1240 | controls how many seconds to wait for the data to be written - use |
1241 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
1242 | indefinitely. | |
1243 | ||
ac884b6a | 1244 | </p> |
f3c17241 | 1245 | <h3 class="function"><span class="info"> CUPS 1.2/OS X 10.5 </span><a name="cupsBackendDeviceURI">cupsBackendDeviceURI</a></h3> |
ac884b6a MS |
1246 | <p class="description">Get the device URI for a backend.</p> |
1247 | <p class="code"> | |
1248 | const char *cupsBackendDeviceURI (<br> | |
1249 | char **argv<br> | |
1250 | );</p> | |
1251 | <h4 class="parameters">Parameters</h4> | |
1252 | <dl> | |
1253 | <dt>argv</dt> | |
1254 | <dd class="description">Command-line arguments</dd> | |
1255 | </dl> | |
1256 | <h4 class="returnvalue">Return Value</h4> | |
1257 | <p class="description">Device URI or <code>NULL</code></p> | |
1258 | <h4 class="discussion">Discussion</h4> | |
1259 | <p class="discussion">The "argv" argument is the argv argument passed to main(). This | |
1260 | function returns the device URI passed in the DEVICE_URI environment | |
1261 | variable or the device URI passed in argv[0], whichever is found | |
426c6a59 MS |
1262 | first. |
1263 | ||
1264 | </p> | |
f3c17241 | 1265 | <h3 class="function"><span class="info"> CUPS 1.4/OS X 10.6 </span><a name="cupsBackendReport">cupsBackendReport</a></h3> |
06d4e77b MS |
1266 | <p class="description">Write a device line from a backend.</p> |
1267 | <p class="code"> | |
1268 | void cupsBackendReport (<br> | |
1269 | const char *device_scheme,<br> | |
1270 | const char *device_uri,<br> | |
1271 | const char *device_make_and_model,<br> | |
1272 | const char *device_info,<br> | |
1273 | const char *device_id,<br> | |
1274 | const char *device_location<br> | |
1275 | );</p> | |
1276 | <h4 class="parameters">Parameters</h4> | |
1277 | <dl> | |
1278 | <dt>device_scheme</dt> | |
1279 | <dd class="description">device-scheme string</dd> | |
1280 | <dt>device_uri</dt> | |
1281 | <dd class="description">device-uri string</dd> | |
1282 | <dt>device_make_and_model</dt> | |
1283 | <dd class="description">device-make-and-model string or <code>NULL</code></dd> | |
1284 | <dt>device_info</dt> | |
1285 | <dd class="description">device-info string or <code>NULL</code></dd> | |
1286 | <dt>device_id</dt> | |
1287 | <dd class="description">device-id string or <code>NULL</code></dd> | |
1288 | <dt>device_location</dt> | |
1289 | <dd class="description">device-location string or <code>NULL</code></dd> | |
1290 | </dl> | |
1291 | <h4 class="discussion">Discussion</h4> | |
1292 | <p class="discussion">This function writes a single device line to stdout for a backend. | |
1293 | It handles quoting of special characters in the device-make-and-model, | |
426c6a59 MS |
1294 | device-info, device-id, and device-location strings. |
1295 | ||
1296 | </p> | |
f3c17241 | 1297 | <h3 class="function"><span class="info"> CUPS 1.3/OS X 10.5 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> |
5a738aea MS |
1298 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> |
1299 | <p class="code"> | |
1300 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
1301 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1302 | char *data,<br> | |
1303 | int *datalen,<br> | |
1304 | double timeout<br> | |
1305 | );</p> | |
1306 | <h4 class="parameters">Parameters</h4> | |
1307 | <dl> | |
1308 | <dt>command</dt> | |
1309 | <dd class="description">Command to send</dd> | |
1310 | <dt>data</dt> | |
1311 | <dd class="description">Response data buffer pointer</dd> | |
1312 | <dt>datalen</dt> | |
1313 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1314 | <dt>timeout</dt> | |
1315 | <dd class="description">Timeout in seconds</dd> | |
1316 | </dl> | |
1317 | <h4 class="returnvalue">Return Value</h4> | |
1318 | <p class="description">Status of command</p> | |
1319 | <h4 class="discussion">Discussion</h4> | |
1320 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 1321 | monitors in order to communicate with the backend used by the current |
1322 | printer. Programs must be prepared to handle timeout or "not | |
1323 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
1324 | do not support the specified side-channel command.<br> |
1325 | <br> | |
1326 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1327 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1328 | update the value to contain the number of data bytes in the buffer. | |
1329 | ||
5a738aea | 1330 | </p> |
f3c17241 | 1331 | <h3 class="function"><span class="info"> CUPS 1.3/OS X 10.5 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> |
5a738aea MS |
1332 | <p class="description">Read a side-channel message.</p> |
1333 | <p class="code"> | |
1334 | int cupsSideChannelRead (<br> | |
1335 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
1336 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
1337 | char *data,<br> | |
1338 | int *datalen,<br> | |
1339 | double timeout<br> | |
1340 | );</p> | |
1341 | <h4 class="parameters">Parameters</h4> | |
1342 | <dl> | |
1343 | <dt>command</dt> | |
1344 | <dd class="description">Command code</dd> | |
1345 | <dt>status</dt> | |
1346 | <dd class="description">Status code</dd> | |
1347 | <dt>data</dt> | |
1348 | <dd class="description">Data buffer pointer</dd> | |
1349 | <dt>datalen</dt> | |
1350 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
1351 | <dt>timeout</dt> | |
1352 | <dd class="description">Timeout in seconds</dd> | |
1353 | </dl> | |
1354 | <h4 class="returnvalue">Return Value</h4> | |
1355 | <p class="description">0 on success, -1 on error</p> | |
1356 | <h4 class="discussion">Discussion</h4> | |
1357 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 1358 | commands from a filter, driver, or port monitor program. The |
1359 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
1360 | and return the corresponding status codes.<br> |
1361 | <br> | |
1362 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 1363 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
1364 | update the value to contain the number of data bytes in the buffer. | |
1365 | ||
20fbc903 | 1366 | </p> |
f3c17241 | 1367 | <h3 class="function"><span class="info"> CUPS 1.4/OS X 10.6 </span><a name="cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a></h3> |
20fbc903 MS |
1368 | <p class="description">Query a SNMP OID's value.</p> |
1369 | <p class="code"> | |
1370 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPGet (<br> | |
1371 | const char *oid,<br> | |
1372 | char *data,<br> | |
1373 | int *datalen,<br> | |
1374 | double timeout<br> | |
1375 | );</p> | |
1376 | <h4 class="parameters">Parameters</h4> | |
1377 | <dl> | |
1378 | <dt>oid</dt> | |
1379 | <dd class="description">OID to query</dd> | |
1380 | <dt>data</dt> | |
1381 | <dd class="description">Buffer for OID value</dd> | |
1382 | <dt>datalen</dt> | |
1383 | <dd class="description">Size of OID buffer on entry, size of value on return</dd> | |
1384 | <dt>timeout</dt> | |
1385 | <dd class="description">Timeout in seconds</dd> | |
1386 | </dl> | |
1387 | <h4 class="returnvalue">Return Value</h4> | |
1388 | <p class="description">Query status</p> | |
1389 | <h4 class="discussion">Discussion</h4> | |
1390 | <p class="discussion">This function asks the backend to do a SNMP OID query on behalf of the | |
1391 | filter, port monitor, or backend using the default community name.<br> | |
1392 | <br> | |
1393 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1394 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1395 | supported and must be converted to their numeric forms.<br> | |
1396 | <br> | |
1397 | On input, "data" and "datalen" provide the location and size of the | |
1398 | buffer to hold the OID value as a string. HEX-String (binary) values are | |
1399 | converted to hexadecimal strings representing the binary data, while | |
1400 | NULL-Value and unknown OID types are returned as the empty string. | |
1401 | The returned "datalen" does not include the trailing nul. | |
1402 | ||
1403 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1404 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1405 | the printer does not respond to the SNMP query. | |
1406 | ||
1407 | </p> | |
f3c17241 | 1408 | <h3 class="function"><span class="info"> CUPS 1.4/OS X 10.6 </span><a name="cupsSideChannelSNMPWalk">cupsSideChannelSNMPWalk</a></h3> |
20fbc903 MS |
1409 | <p class="description">Query multiple SNMP OID values.</p> |
1410 | <p class="code"> | |
1411 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPWalk (<br> | |
1412 | const char *oid,<br> | |
1413 | double timeout,<br> | |
1414 | <a href="#cups_sc_walk_func_t">cups_sc_walk_func_t</a> cb,<br> | |
1415 | void *context<br> | |
1416 | );</p> | |
1417 | <h4 class="parameters">Parameters</h4> | |
1418 | <dl> | |
1419 | <dt>oid</dt> | |
1420 | <dd class="description">First numeric OID to query</dd> | |
1421 | <dt>timeout</dt> | |
1422 | <dd class="description">Timeout for each query in seconds</dd> | |
1423 | <dt>cb</dt> | |
1424 | <dd class="description">Function to call with each value</dd> | |
1425 | <dt>context</dt> | |
1426 | <dd class="description">Application-defined pointer to send to callback</dd> | |
1427 | </dl> | |
1428 | <h4 class="returnvalue">Return Value</h4> | |
1429 | <p class="description">Status of first query of <code>CUPS_SC_STATUS_OK</code> on success</p> | |
1430 | <h4 class="discussion">Discussion</h4> | |
1431 | <p class="discussion">This function asks the backend to do multiple SNMP OID queries on behalf | |
1432 | of the filter, port monitor, or backend using the default community name. | |
1433 | All OIDs under the "parent" OID are queried and the results are sent to | |
1434 | the callback function you provide.<br> | |
1435 | <br> | |
1436 | "oid" contains a numeric OID consisting of integers separated by periods, | |
1437 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
1438 | supported and must be converted to their numeric forms.<br> | |
1439 | <br> | |
1440 | "timeout" specifies the timeout for each OID query. The total amount of | |
1441 | time will depend on the number of OID values found and the time required | |
1442 | for each query.<br> | |
1443 | <br> | |
1444 | "cb" provides a function to call for every value that is found. "context" | |
1445 | is an application-defined pointer that is sent to the callback function | |
1446 | along with the OID and current data. The data passed to the callback is the | |
1447 | same as returned by <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a>. | |
1448 | ||
1449 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
1450 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
1451 | the printer does not respond to the first SNMP query. | |
1452 | ||
5a738aea | 1453 | </p> |
f3c17241 | 1454 | <h3 class="function"><span class="info"> CUPS 1.3/OS X 10.5 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> |
5a738aea MS |
1455 | <p class="description">Write a side-channel message.</p> |
1456 | <p class="code"> | |
1457 | int cupsSideChannelWrite (<br> | |
1458 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
1459 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
1460 | const char *data,<br> | |
1461 | int datalen,<br> | |
1462 | double timeout<br> | |
1463 | );</p> | |
1464 | <h4 class="parameters">Parameters</h4> | |
1465 | <dl> | |
1466 | <dt>command</dt> | |
1467 | <dd class="description">Command code</dd> | |
1468 | <dt>status</dt> | |
1469 | <dd class="description">Status code</dd> | |
1470 | <dt>data</dt> | |
1471 | <dd class="description">Data buffer pointer</dd> | |
1472 | <dt>datalen</dt> | |
1473 | <dd class="description">Number of bytes of data</dd> | |
1474 | <dt>timeout</dt> | |
1475 | <dd class="description">Timeout in seconds</dd> | |
1476 | </dl> | |
1477 | <h4 class="returnvalue">Return Value</h4> | |
1478 | <p class="description">0 on success, -1 on error</p> | |
1479 | <h4 class="discussion">Discussion</h4> | |
1480 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 1481 | responses to a filter, driver, or port monitor program. |
1482 | ||
5a738aea MS |
1483 | </p> |
1484 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
1485 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> | |
1486 | <p class="description">Backend exit codes</p> | |
1487 | <p class="code"> | |
1488 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
1489 | </p> | |
1490 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
1491 | <p class="description">Bidirectional capabilities</p> | |
1492 | <p class="code"> | |
1493 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
1494 | </p> | |
1495 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
1496 | <p class="description">Request command codes</p> | |
1497 | <p class="code"> | |
1498 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
1499 | </p> | |
82f97232 MS |
1500 | <h3 class="typedef"><a name="cups_sc_connected_t">cups_sc_connected_t</a></h3> |
1501 | <p class="description">Connectivity values</p> | |
1502 | <p class="code"> | |
1503 | typedef enum <a href="#cups_sc_connected_e">cups_sc_connected_e</a> cups_sc_connected_t; | |
1504 | </p> | |
5a738aea MS |
1505 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> |
1506 | <p class="description">Printer state bits</p> | |
1507 | <p class="code"> | |
1508 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
1509 | </p> | |
1510 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
1511 | <p class="description">Response status codes</p> | |
1512 | <p class="code"> | |
1513 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
1514 | </p> | |
20fbc903 MS |
1515 | <h3 class="typedef"><a name="cups_sc_walk_func_t">cups_sc_walk_func_t</a></h3> |
1516 | <p class="description">SNMP walk callback</p> | |
1517 | <p class="code"> | |
1518 | typedef void (*cups_sc_walk_func_t)(const char *oid, const char *data, int datalen, void *context); | |
1519 | </p> | |
5a738aea MS |
1520 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> |
1521 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> | |
1522 | <p class="description">Backend exit codes</p> | |
1523 | <h4 class="constants">Constants</h4> | |
1524 | <dl> | |
1525 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
1526 | <dd class="description">Job failed, authentication required</dd> | |
1527 | <dt>CUPS_BACKEND_CANCEL </dt> | |
1528 | <dd class="description">Job failed, cancel job</dd> | |
1529 | <dt>CUPS_BACKEND_FAILED </dt> | |
1530 | <dd class="description">Job failed, use error-policy</dd> | |
1531 | <dt>CUPS_BACKEND_HOLD </dt> | |
1532 | <dd class="description">Job failed, hold job</dd> | |
1533 | <dt>CUPS_BACKEND_OK </dt> | |
1534 | <dd class="description">Job completed successfully</dd> | |
22c9029b MS |
1535 | <dt>CUPS_BACKEND_RETRY </dt> |
1536 | <dd class="description">Job failed, retry this job later</dd> | |
1537 | <dt>CUPS_BACKEND_RETRY_CURRENT </dt> | |
1538 | <dd class="description">Job failed, retry this job immediately</dd> | |
5a738aea MS |
1539 | <dt>CUPS_BACKEND_STOP </dt> |
1540 | <dd class="description">Job failed, stop queue</dd> | |
1541 | </dl> | |
1542 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
79e1d494 | 1543 | <p class="description">Bidirectional capability values</p> |
5a738aea MS |
1544 | <h4 class="constants">Constants</h4> |
1545 | <dl> | |
1546 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
1547 | <dd class="description">Bidirectional I/O is not supported</dd> | |
1548 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
1549 | <dd class="description">Bidirectional I/O is supported</dd> | |
1550 | </dl> | |
1551 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
1552 | <p class="description">Request command codes</p> | |
1553 | <h4 class="constants">Constants</h4> | |
1554 | <dl> | |
1555 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
1556 | <dd class="description">Drain all pending output</dd> | |
1557 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
1558 | <dd class="description">Return bidirectional capabilities</dd> | |
f3c17241 | 1559 | <dt>CUPS_SC_CMD_GET_CONNECTED <span class="info"> CUPS 1.5/OS X 10.7 </span></dt> |
82f97232 | 1560 | <dd class="description">Return whether the backend is "connected" to the printer </dd> |
5a738aea MS |
1561 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> |
1562 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
1563 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
1564 | <dd class="description">Return the device state</dd> | |
f3c17241 | 1565 | <dt>CUPS_SC_CMD_SNMP_GET <span class="info"> CUPS 1.4/OS X 10.6 </span></dt> |
20fbc903 | 1566 | <dd class="description">Query an SNMP OID </dd> |
f3c17241 | 1567 | <dt>CUPS_SC_CMD_SNMP_GET_NEXT <span class="info"> CUPS 1.4/OS X 10.6 </span></dt> |
20fbc903 | 1568 | <dd class="description">Query the next SNMP OID </dd> |
5a738aea MS |
1569 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> |
1570 | <dd class="description">Do a soft reset</dd> | |
1571 | </dl> | |
82f97232 MS |
1572 | <h3 class="enumeration"><a name="cups_sc_connected_e">cups_sc_connected_e</a></h3> |
1573 | <p class="description">Connectivity values</p> | |
1574 | <h4 class="constants">Constants</h4> | |
1575 | <dl> | |
1576 | <dt>CUPS_SC_CONNECTED </dt> | |
1577 | <dd class="description">Backend is "connected" to printer</dd> | |
1578 | <dt>CUPS_SC_NOT_CONNECTED </dt> | |
1579 | <dd class="description">Backend is not "connected" to printer</dd> | |
1580 | </dl> | |
5a738aea MS |
1581 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> |
1582 | <p class="description">Printer state bits</p> | |
1583 | <h4 class="constants">Constants</h4> | |
1584 | <dl> | |
1585 | <dt>CUPS_SC_STATE_BUSY </dt> | |
1586 | <dd class="description">Device is busy</dd> | |
1587 | <dt>CUPS_SC_STATE_ERROR </dt> | |
1588 | <dd class="description">Other error condition</dd> | |
1589 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
1590 | <dd class="description">Toner/ink out condition</dd> | |
1591 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
1592 | <dd class="description">Toner/ink low condition</dd> | |
1593 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
1594 | <dd class="description">Paper out condition</dd> | |
1595 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
1596 | <dd class="description">Paper low condition</dd> | |
1597 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
79e1d494 | 1598 | <dd class="description">Device is offline</dd> |
5a738aea | 1599 | <dt>CUPS_SC_STATE_ONLINE </dt> |
79e1d494 | 1600 | <dd class="description">Device is online</dd> |
5a738aea MS |
1601 | </dl> |
1602 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
1603 | <p class="description">Response status codes</p> | |
1604 | <h4 class="constants">Constants</h4> | |
1605 | <dl> | |
1606 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
1607 | <dd class="description">The command/response message was invalid</dd> | |
1608 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
1609 | <dd class="description">An I/O error occurred</dd> | |
1610 | <dt>CUPS_SC_STATUS_NONE </dt> | |
1611 | <dd class="description">No status</dd> | |
1612 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
1613 | <dd class="description">Command not implemented</dd> | |
1614 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
1615 | <dd class="description">The device did not respond</dd> | |
1616 | <dt>CUPS_SC_STATUS_OK </dt> | |
1617 | <dd class="description">Operation succeeded</dd> | |
1618 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
1619 | <dd class="description">The backend did not respond</dd> | |
1620 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
1621 | <dd class="description">Response too big</dd> | |
1622 | </dl> | |
1623 | </div> | |
ef416fc2 | 1624 | </body> |
1625 | </html> |