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5a738aea | 251 | --></style> |
ef416fc2 | 252 | </head> |
253 | <body> | |
5a738aea | 254 | <div class='body'> |
ef416fc2 | 255 | <!-- |
ac884b6a | 256 | "$Id: api-filter.header 7285 2008-02-01 23:57:39Z 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> |
ac884b6a MS |
277 | cups/sidechannel.h<br> |
278 | cups/snmp.h</th> | |
5a738aea MS |
279 | </tr> |
280 | </thead> | |
281 | <tbody> | |
282 | <tr> | |
283 | <th>Library</th> | |
284 | <td>-lcups</td> | |
285 | </tr> | |
286 | <tr> | |
287 | <th>See Also</th> | |
288 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
289 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
290 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
291 | Programming: <a href='api-raster.html' target='_top'>Raster API</a></td> | |
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> | |
329 | <li><a href="#cups_sc_bidi_e" title="Bidirectional capabilities">cups_sc_bidi_e</a></li> | |
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 | <!-- | |
20fbc903 | 336 | "$Id: api-filter.shtml 7502 2008-04-28 21:30:12Z 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 | |
5a738aea MS |
353 | <p>Filters, printer drivers, port monitors, and backends use a common interface |
354 | for processing print jobs and communicating status information to the scheduler. | |
355 | Each filter is run with a standard set of command-line arguments:<p> | |
ef416fc2 | 356 | |
5a738aea | 357 | <dl class="code"> |
f7deaa1a | 358 | |
5a738aea MS |
359 | <dt>argv[1]</dt> |
360 | <dd>The job ID</dd> | |
ef416fc2 | 361 | |
5a738aea MS |
362 | <dt>argv[2]</dt> |
363 | <dd>The user printing the job</dd> | |
f7deaa1a | 364 | |
5a738aea MS |
365 | <dt>argv[3]</dt> |
366 | <dd>The job name/title</dd> | |
f7deaa1a | 367 | |
5a738aea MS |
368 | <dt>argv[4]</dt> |
369 | <dd>The number of copies to print</dd> | |
f7deaa1a | 370 | |
5a738aea MS |
371 | <dt>argv[5]</dt> |
372 | <dd>The options that were provided when the job was submitted</dd> | |
f7deaa1a | 373 | |
5a738aea MS |
374 | <dt>argv[6]</dt> |
375 | <dd>The file to print (first filter only)</dd> | |
376 | </dl> | |
f7deaa1a | 377 | |
5a738aea MS |
378 | <p>The scheduler runs one or more of these programs to print any given job. The |
379 | first filter reads from the print file and writes to the standard output, while | |
380 | the remaining filters read from the standard input and write to the standard | |
381 | output. The backend is the last filter in the chain and writes to the | |
382 | device.</p> | |
f7deaa1a | 383 | |
ac884b6a MS |
384 | <h3><a name="SECURITY">Security Considerations</a></h3> |
385 | ||
386 | <p>It is always important to use security programming practices. Filters and | |
387 | most backends are run as a non-priviledged user, so the major security | |
388 | consideration is resource utilization - filters should not depend on unlimited | |
389 | amounts of CPU, memory, or disk space, and should protect against conditions | |
390 | that could lead to excess usage of any resource like infinite loops and | |
391 | unbounded recursion. In addition, filters must <em>never</em> allow the user to | |
392 | specify an arbitrary file path to a separator page, template, or other file | |
393 | used by the filter since that can lead to an unauthorized disclosure of | |
394 | information. <em>Always</em> treat input as suspect and validate it!</p> | |
395 | ||
396 | <p>If you are developing a backend that runs as root, make sure to check for | |
397 | potential buffer overflows, integer under/overflow conditions, and file | |
398 | accesses since these can lead to privilege escalations. When writing files, | |
399 | always validate the file path and <em>never</em> allow a user to determine | |
400 | where to store a file.</p> | |
401 | ||
402 | <blockquote><b>Note:</b> | |
403 | ||
404 | <p><em>Never</em> write files to a user's home directory. Aside from the | |
405 | security implications, CUPS is a network print service and as such the network | |
406 | user may not be the same as the local user and/or there may not be a local home | |
407 | directory to write to.</p> | |
408 | ||
409 | <p>In addition, some operating systems provide additional security mechanisms | |
410 | that further limit file system access, even for backends running as root. On | |
411 | Mac OS X, for example, no backend may write to a user's home directory.</p> | |
412 | </blockquote> | |
413 | ||
414 | <h3><a name="TEMPFILES">Temporary Files</a></h3> | |
415 | ||
416 | <p>Temporary files should be created in the directory specified by the | |
417 | "TMPDIR" environment variable. The | |
418 | <a href="#cupsTempFile2"><code>cupsTempFile2</code></a> function can be | |
419 | used to safely create temporary files in this directory.</p> | |
420 | ||
421 | <h3><a name="COPIES">Copy Generation</a></h3> | |
422 | ||
423 | <p>The <code>argv[4]</code> argument specifies the number of copies to produce | |
424 | of the input file. In general, you should only generate copies if the | |
425 | <em>filename</em> argument is supplied. The only exception to this are | |
426 | filters that produce device-independent PostScript output, since the PostScript | |
427 | filter <var>pstops</var> is responsible for generating copies of PostScript | |
428 | files.</p> | |
429 | ||
5a738aea | 430 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 431 | |
5a738aea MS |
432 | <p>Filters must exit with status 0 when they successfully generate print data |
433 | or 1 when they encounter an error. Backends can return any of the | |
434 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 435 | |
5a738aea | 436 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 437 | |
5a738aea | 438 | <p>The following environment variables are defined by the printing system:</p> |
f7deaa1a | 439 | |
5a738aea | 440 | <dl class="code"> |
f7deaa1a | 441 | |
5a738aea MS |
442 | <dt>APPLE_LANGUAGES</dt> |
443 | <dd>The Apple language identifier associated with the job | |
444 | (Mac OS X only).</dd> | |
f7deaa1a | 445 | |
5a738aea MS |
446 | <dt>CHARSET</dt> |
447 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 448 | |
5a738aea MS |
449 | <dt>CLASS</dt> |
450 | <dd>When a job is submitted to a printer class, contains the name of | |
451 | the destination printer class. Otherwise this environment | |
452 | variable will not be set.</dd> | |
f7deaa1a | 453 | |
5a738aea MS |
454 | <dt>CONTENT_TYPE</dt> |
455 | <dd>The MIME type associated with the file (e.g. | |
456 | application/postscript).</dd> | |
f7deaa1a | 457 | |
5a738aea MS |
458 | <dt>CUPS_CACHEDIR</dt> |
459 | <dd>The directory where cache files can be stored.</dd> | |
f7deaa1a | 460 | |
5a738aea MS |
461 | <dt>CUPS_DATADIR</dt> |
462 | <dd>The directory where data files can be found.</dd> | |
f7deaa1a | 463 | |
5a738aea MS |
464 | <dt>CUPS_SERVERROOT</dt> |
465 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 466 | |
5a738aea MS |
467 | <dt>DEVICE_URI</dt> |
468 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 469 | |
5a738aea MS |
470 | <dt>FINAL_CONTENT_TYPE</dt> |
471 | <dd>The MIME type associated with the printer (e.g. | |
472 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 473 | |
5a738aea MS |
474 | <dt>LANG</dt> |
475 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 476 | |
5a738aea MS |
477 | <dt>PPD</dt> |
478 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
479 | file for this printer.</dd> | |
f7deaa1a | 480 | |
5a738aea MS |
481 | <dt>PRINTER</dt> |
482 | <dd>The name of the printer.</dd> | |
f7deaa1a | 483 | |
5a738aea MS |
484 | <dt>RIP_CACHE</dt> |
485 | <dd>The recommended amount of memory to use for Raster Image | |
486 | Processors (RIPs).</dd> | |
f7deaa1a | 487 | |
5a738aea | 488 | </dl> |
f7deaa1a | 489 | |
5a738aea | 490 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 491 | |
5a738aea MS |
492 | <p>Filters and backends communicate wih the scheduler by writing messages |
493 | to the standard error file. For example, the following code sets the current | |
494 | printer state message to "Printing page 5":</p> | |
f7deaa1a | 495 | |
5a738aea MS |
496 | <pre class="example"> |
497 | int page = 5; | |
f7deaa1a | 498 | |
5a738aea | 499 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 500 | </pre> |
501 | ||
5a738aea MS |
502 | <p>Each message is a single line of text starting with one of the following |
503 | prefix strings:</p> | |
504 | ||
505 | <dl class="code"> | |
506 | ||
507 | <dt>ALERT: message</dt> | |
508 | <dd>Sets the printer-state-message attribute and adds the specified | |
509 | message to the current error log file using the "alert" log level.</dd> | |
510 | ||
511 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
512 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
513 | to set the <code>marker-colors</code>, <code>marker-levels</code>, | |
514 | <code>marker-names</code>, <code>marker-types</code>, | |
515 | <code>printer-alert</code>, and <code>printer-alert-description</code> | |
516 | printer attributes.</dd> | |
517 | ||
518 | <dt>CRIT: message</dt> | |
519 | <dd>Sets the printer-state-message attribute and adds the specified | |
520 | message to the current error log file using the "critical" log | |
521 | level.</dd> | |
522 | ||
523 | <dt>DEBUG: message</dt> | |
524 | <dd>Sets the printer-state-message attribute and adds the specified | |
525 | message to the current error log file using the "debug" log level.</dd> | |
526 | ||
527 | <dt>DEBUG2: message</dt> | |
528 | <dd>Sets the printer-state-message attribute and adds the specified | |
529 | message to the current error log file using the "debug2" log level.</dd> | |
530 | ||
531 | <dt>EMERG: message</dt> | |
532 | <dd>Sets the printer-state-message attribute and adds the specified | |
533 | message to the current error log file using the "emergency" log | |
534 | level.</dd> | |
535 | ||
536 | <dt>ERROR: message</dt> | |
537 | <dd>Sets the printer-state-message attribute and adds the specified | |
538 | message to the current error log file using the "error" log level.</dd> | |
539 | ||
540 | <dt>INFO: message</dt> | |
541 | <dd>Sets the printer-state-message attribute. If the current log level | |
542 | is set to "debug2", also adds the specified message to the current error | |
543 | log file using the "info" log level.</dd> | |
544 | ||
545 | <dt>NOTICE: message</dt> | |
546 | <dd>Sets the printer-state-message attribute and adds the specified | |
547 | message to the current error log file using the "notice" log level.</dd> | |
548 | ||
549 | <dt>PAGE: page-number #-copies</dt> | |
550 | <dt>PAGE: total #-pages</dt> | |
551 | <dd>Adds an entry to the current page log file. The first form adds | |
552 | #-copies to the job-media-sheets-completed attribute. The second | |
553 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
554 | ||
20fbc903 MS |
555 | <dt>PPD: keyword=value [keyword=value ...]</dt> |
556 | <dd>Changes or adds keywords to the printer's PPD file. Typically | |
557 | this is used to update installable options or default media settings | |
558 | based on the printer configuration.</dd> | |
559 | ||
5a738aea MS |
560 | <dt>STATE: printer-state-reason [printer-state-reason ...]</dt> |
561 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> | |
562 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
563 | <dd>Sets, adds, or removes printer-state-reason keywords to the | |
564 | current queue. Typically this is used to indicate media, ink, and | |
565 | toner conditions on a printer.</dd> | |
566 | ||
567 | <dt>WARNING: message</dt> | |
568 | <dd>Sets the printer-state-message attribute and adds the specified | |
569 | message to the current error log file using the "warning" log | |
570 | level.</dd> | |
571 | ||
572 | </dl> | |
573 | ||
574 | <p>Messages without one of these prefixes are treated as if they began with | |
575 | the "DEBUG:" prefix string.</p> | |
576 | ||
20fbc903 | 577 | <h3><a name="COMMUNICATING_BACKEND">Communicating with the Backend</a></h3> |
5a738aea MS |
578 | |
579 | <p>Filters can communicate with the backend via the | |
580 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
581 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
582 | functions. The | |
583 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function | |
584 | reads data that has been sent back from the device and is typically used to | |
585 | obtain status and configuration information. For example, the following code | |
586 | polls the backend for back-channel data:</p> | |
587 | ||
588 | <pre class="example"> | |
589 | #include <cups/cups.h> | |
590 | ||
591 | char buffer[8192]; | |
592 | ssize_t bytes; | |
593 | ||
594 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
595 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
596 | </pre> | |
f7deaa1a | 597 | |
5a738aea MS |
598 | The |
599 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
600 | function allows you to get out-of-band status information and do synchronization | |
601 | with the device. For example, the following code gets the current IEEE-1284 | |
602 | device ID string from the backend:</p> | |
603 | ||
604 | <pre class="example"> | |
f7deaa1a | 605 | #include <cups/sidechannel.h> |
606 | ||
607 | char data[2049]; | |
608 | int datalen; | |
5a738aea | 609 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 610 | |
611 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for nul-termination... */ | |
612 | datalen = sizeof(data) - 1; | |
613 | ||
614 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 615 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 616 | |
617 | /* Use the returned value if OK was returned and the length is non-zero */ | |
618 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
619 | data[datalen] = '\0'; | |
620 | else | |
621 | data[0] = '\0'; | |
622 | </pre> | |
623 | ||
20fbc903 MS |
624 | <h3><a name="COMMUNICATING_FILTER">Communicating with Filters</a></h3> |
625 | ||
5a738aea MS |
626 | <p>Backends communicate with filters using the reciprocal functions |
627 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
628 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
629 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
630 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 631 | |
5a738aea MS |
632 | <pre class="example"> |
633 | #include <cups/cups.h> | |
f7deaa1a | 634 | |
5a738aea MS |
635 | char buffer[8192]; |
636 | ssize_t bytes; | |
f7deaa1a | 637 | |
5a738aea MS |
638 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
639 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 640 | </pre> |
641 | ||
5a738aea MS |
642 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
643 | function reads a side-channel command from a filter, driver, or port monitor. | |
644 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
645 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
646 | separate thread for that purpose), or use <code>select</code> or | |
647 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
20fbc903 | 648 | input and output on several file descriptors at the same time.</p> |
5a738aea MS |
649 | |
650 | <p>Once a command is processed, the backend uses the | |
651 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
652 | to send its response. For example, the following code shows how to poll for a | |
653 | side-channel command and respond to it:</p> | |
654 | ||
655 | <pre class="example"> | |
f7deaa1a | 656 | #include <cups/sidechannel.h> |
657 | ||
5a738aea MS |
658 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
659 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
20fbc903 MS |
660 | char data[2048]; |
661 | int datalen = sizeof(data); | |
f7deaa1a | 662 | |
663 | /* Poll for a command... */ | |
20fbc903 | 664 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, data, &datalen, 0.0)) |
f7deaa1a | 665 | { |
f7deaa1a | 666 | switch (command) |
667 | { | |
20fbc903 | 668 | /* handle supported commands, fill data/datalen/status with values as needed */ |
f7deaa1a | 669 | |
670 | default : | |
671 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
672 | datalen = 0; | |
673 | break; | |
674 | } | |
675 | ||
676 | /* Send a response... */ | |
5a738aea | 677 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 678 | } |
679 | </pre> | |
ac884b6a MS |
680 | |
681 | <h3><a name="SNMP">Doing SNMP Queries with Network Printers</a></h3> | |
682 | ||
683 | <p>The Simple Network Management Protocol (SNMP) allows you to get the current | |
684 | status, page counter, and supply levels from most network printers. Every | |
685 | piece of information is associated with an Object Identifier (OID), and | |
686 | every printer has a <em>community</em> name associated with it. OIDs can be | |
687 | queried directly or by "walking" over a range of OIDs with a common prefix.</p> | |
688 | ||
20fbc903 MS |
689 | <p>The two CUPS SNMP functions provide a simple API for querying network |
690 | printers through the side-channel interface. Each accepts a string containing | |
691 | an OID like ".1.3.6.1.2.1.43.10.2.1.4.1.1" (the standard page counter OID) | |
692 | along with a timeout for the query.</p> | |
ac884b6a | 693 | |
20fbc903 MS |
694 | <p>The <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a> |
695 | function queries a single OID and returns the value as a string in a buffer | |
696 | you supply:</p> | |
ac884b6a MS |
697 | |
698 | <pre class="example"> | |
20fbc903 | 699 | #include <cups/sidechannel.h> |
ac884b6a | 700 | |
20fbc903 MS |
701 | char data[512]; |
702 | int datalen = sizeof(data); | |
ac884b6a | 703 | |
20fbc903 MS |
704 | if (<a href="#cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a>(".1.3.6.1.2.1.43.10.2.1.4.1.1", data, &datalen, 5.0) |
705 | == CUPS_SC_STATUS_OK) | |
ac884b6a MS |
706 | { |
707 | /* Do something with the value */ | |
20fbc903 | 708 | printf("Page counter is: %s\n", data); |
ac884b6a MS |
709 | } |
710 | </pre> | |
711 | ||
20fbc903 MS |
712 | <p>The |
713 | <a href="#cupsSideChannelSNMPWalk"><code>cupsSideChannelSNMPWalk</code></a> | |
714 | function allows you to query a whole group of OIDs, calling a function of your | |
715 | choice for each OID that is found:</p> | |
ac884b6a MS |
716 | |
717 | <pre class="example"> | |
20fbc903 | 718 | #include <cups/sidechannel.h> |
ac884b6a MS |
719 | |
720 | void | |
20fbc903 | 721 | my_callback(const char *oid, const char *data, int datalen, void *context) |
ac884b6a MS |
722 | { |
723 | /* Do something with the value */ | |
20fbc903 | 724 | printf("%s=%s\n", oid, data); |
ac884b6a MS |
725 | } |
726 | ||
20fbc903 MS |
727 | ... |
728 | ||
ac884b6a MS |
729 | void *my_data; |
730 | ||
20fbc903 | 731 | <a href="#cupsSideChannelSNMPWalk">cupsSNMPSideChannelWalk</a>(".1.3.6.1.2.1.43", 5.0, my_callback, my_data); |
ac884b6a | 732 | </pre> |
20fbc903 | 733 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
5a738aea MS |
734 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> |
735 | <p class="description">Read data from the backchannel.</p> | |
736 | <p class="code"> | |
737 | ssize_t cupsBackChannelRead (<br> | |
738 | char *buffer,<br> | |
739 | size_t bytes,<br> | |
740 | double timeout<br> | |
741 | );</p> | |
742 | <h4 class="parameters">Parameters</h4> | |
743 | <dl> | |
744 | <dt>buffer</dt> | |
745 | <dd class="description">Buffer to read</dd> | |
746 | <dt>bytes</dt> | |
747 | <dd class="description">Bytes to read</dd> | |
748 | <dt>timeout</dt> | |
749 | <dd class="description">Timeout in seconds</dd> | |
750 | </dl> | |
751 | <h4 class="returnvalue">Return Value</h4> | |
752 | <p class="description">Bytes read or -1 on error</p> | |
753 | <h4 class="discussion">Discussion</h4> | |
754 | <p class="discussion">Reads up to "bytes" bytes from the backchannel. The "timeout" | |
ef416fc2 | 755 | parameter controls how many seconds to wait for the data - use |
756 | 0.0 to return immediately if there is no data, -1.0 to wait | |
757 | for data indefinitely. | |
758 | ||
5a738aea MS |
759 | </p> |
760 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> | |
761 | <p class="description">Write data to the backchannel.</p> | |
762 | <p class="code"> | |
763 | ssize_t cupsBackChannelWrite (<br> | |
764 | const char *buffer,<br> | |
765 | size_t bytes,<br> | |
766 | double timeout<br> | |
767 | );</p> | |
768 | <h4 class="parameters">Parameters</h4> | |
769 | <dl> | |
770 | <dt>buffer</dt> | |
771 | <dd class="description">Buffer to write</dd> | |
772 | <dt>bytes</dt> | |
773 | <dd class="description">Bytes to write</dd> | |
774 | <dt>timeout</dt> | |
775 | <dd class="description">Timeout in seconds</dd> | |
776 | </dl> | |
777 | <h4 class="returnvalue">Return Value</h4> | |
778 | <p class="description">Bytes written or -1 on error</p> | |
779 | <h4 class="discussion">Discussion</h4> | |
780 | <p class="discussion">Writes "bytes" bytes to the backchannel. The "timeout" parameter | |
ef416fc2 | 781 | controls how many seconds to wait for the data to be written - use |
782 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
783 | indefinitely. | |
784 | ||
ac884b6a MS |
785 | </p> |
786 | <h3 class="function"><a name="cupsBackendDeviceURI">cupsBackendDeviceURI</a></h3> | |
787 | <p class="description">Get the device URI for a backend.</p> | |
788 | <p class="code"> | |
789 | const char *cupsBackendDeviceURI (<br> | |
790 | char **argv<br> | |
791 | );</p> | |
792 | <h4 class="parameters">Parameters</h4> | |
793 | <dl> | |
794 | <dt>argv</dt> | |
795 | <dd class="description">Command-line arguments</dd> | |
796 | </dl> | |
797 | <h4 class="returnvalue">Return Value</h4> | |
798 | <p class="description">Device URI or <code>NULL</code></p> | |
799 | <h4 class="discussion">Discussion</h4> | |
800 | <p class="discussion">The "argv" argument is the argv argument passed to main(). This | |
801 | function returns the device URI passed in the DEVICE_URI environment | |
802 | variable or the device URI passed in argv[0], whichever is found | |
803 | first.</p> | |
5a738aea MS |
804 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> |
805 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> | |
806 | <p class="code"> | |
807 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
808 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
809 | char *data,<br> | |
810 | int *datalen,<br> | |
811 | double timeout<br> | |
812 | );</p> | |
813 | <h4 class="parameters">Parameters</h4> | |
814 | <dl> | |
815 | <dt>command</dt> | |
816 | <dd class="description">Command to send</dd> | |
817 | <dt>data</dt> | |
818 | <dd class="description">Response data buffer pointer</dd> | |
819 | <dt>datalen</dt> | |
820 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
821 | <dt>timeout</dt> | |
822 | <dd class="description">Timeout in seconds</dd> | |
823 | </dl> | |
824 | <h4 class="returnvalue">Return Value</h4> | |
825 | <p class="description">Status of command</p> | |
826 | <h4 class="discussion">Discussion</h4> | |
827 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 828 | monitors in order to communicate with the backend used by the current |
829 | printer. Programs must be prepared to handle timeout or "not | |
830 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
831 | do not support the specified side-channel command.<br> |
832 | <br> | |
833 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 834 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
835 | update the value to contain the number of data bytes in the buffer. | |
836 | ||
5a738aea MS |
837 | </p> |
838 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> | |
839 | <p class="description">Read a side-channel message.</p> | |
840 | <p class="code"> | |
841 | int cupsSideChannelRead (<br> | |
842 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
843 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
844 | char *data,<br> | |
845 | int *datalen,<br> | |
846 | double timeout<br> | |
847 | );</p> | |
848 | <h4 class="parameters">Parameters</h4> | |
849 | <dl> | |
850 | <dt>command</dt> | |
851 | <dd class="description">Command code</dd> | |
852 | <dt>status</dt> | |
853 | <dd class="description">Status code</dd> | |
854 | <dt>data</dt> | |
855 | <dd class="description">Data buffer pointer</dd> | |
856 | <dt>datalen</dt> | |
857 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
858 | <dt>timeout</dt> | |
859 | <dd class="description">Timeout in seconds</dd> | |
860 | </dl> | |
861 | <h4 class="returnvalue">Return Value</h4> | |
862 | <p class="description">0 on success, -1 on error</p> | |
863 | <h4 class="discussion">Discussion</h4> | |
864 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 865 | commands from a filter, driver, or port monitor program. The |
866 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
867 | and return the corresponding status codes.<br> |
868 | <br> | |
869 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 870 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
871 | update the value to contain the number of data bytes in the buffer. | |
872 | ||
20fbc903 MS |
873 | </p> |
874 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSideChannelSNMPGet">cupsSideChannelSNMPGet</a></h3> | |
875 | <p class="description">Query a SNMP OID's value.</p> | |
876 | <p class="code"> | |
877 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPGet (<br> | |
878 | const char *oid,<br> | |
879 | char *data,<br> | |
880 | int *datalen,<br> | |
881 | double timeout<br> | |
882 | );</p> | |
883 | <h4 class="parameters">Parameters</h4> | |
884 | <dl> | |
885 | <dt>oid</dt> | |
886 | <dd class="description">OID to query</dd> | |
887 | <dt>data</dt> | |
888 | <dd class="description">Buffer for OID value</dd> | |
889 | <dt>datalen</dt> | |
890 | <dd class="description">Size of OID buffer on entry, size of value on return</dd> | |
891 | <dt>timeout</dt> | |
892 | <dd class="description">Timeout in seconds</dd> | |
893 | </dl> | |
894 | <h4 class="returnvalue">Return Value</h4> | |
895 | <p class="description">Query status</p> | |
896 | <h4 class="discussion">Discussion</h4> | |
897 | <p class="discussion">This function asks the backend to do a SNMP OID query on behalf of the | |
898 | filter, port monitor, or backend using the default community name.<br> | |
899 | <br> | |
900 | "oid" contains a numeric OID consisting of integers separated by periods, | |
901 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
902 | supported and must be converted to their numeric forms.<br> | |
903 | <br> | |
904 | On input, "data" and "datalen" provide the location and size of the | |
905 | buffer to hold the OID value as a string. HEX-String (binary) values are | |
906 | converted to hexadecimal strings representing the binary data, while | |
907 | NULL-Value and unknown OID types are returned as the empty string. | |
908 | The returned "datalen" does not include the trailing nul. | |
909 | ||
910 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
911 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
912 | the printer does not respond to the SNMP query. | |
913 | ||
914 | </p> | |
915 | <h3 class="function"><span class="info"> CUPS 1.4 </span><a name="cupsSideChannelSNMPWalk">cupsSideChannelSNMPWalk</a></h3> | |
916 | <p class="description">Query multiple SNMP OID values.</p> | |
917 | <p class="code"> | |
918 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelSNMPWalk (<br> | |
919 | const char *oid,<br> | |
920 | double timeout,<br> | |
921 | <a href="#cups_sc_walk_func_t">cups_sc_walk_func_t</a> cb,<br> | |
922 | void *context<br> | |
923 | );</p> | |
924 | <h4 class="parameters">Parameters</h4> | |
925 | <dl> | |
926 | <dt>oid</dt> | |
927 | <dd class="description">First numeric OID to query</dd> | |
928 | <dt>timeout</dt> | |
929 | <dd class="description">Timeout for each query in seconds</dd> | |
930 | <dt>cb</dt> | |
931 | <dd class="description">Function to call with each value</dd> | |
932 | <dt>context</dt> | |
933 | <dd class="description">Application-defined pointer to send to callback</dd> | |
934 | </dl> | |
935 | <h4 class="returnvalue">Return Value</h4> | |
936 | <p class="description">Status of first query of <code>CUPS_SC_STATUS_OK</code> on success</p> | |
937 | <h4 class="discussion">Discussion</h4> | |
938 | <p class="discussion">This function asks the backend to do multiple SNMP OID queries on behalf | |
939 | of the filter, port monitor, or backend using the default community name. | |
940 | All OIDs under the "parent" OID are queried and the results are sent to | |
941 | the callback function you provide.<br> | |
942 | <br> | |
943 | "oid" contains a numeric OID consisting of integers separated by periods, | |
944 | for example ".1.3.6.1.2.1.43". Symbolic names from SNMP MIBs are not | |
945 | supported and must be converted to their numeric forms.<br> | |
946 | <br> | |
947 | "timeout" specifies the timeout for each OID query. The total amount of | |
948 | time will depend on the number of OID values found and the time required | |
949 | for each query.<br> | |
950 | <br> | |
951 | "cb" provides a function to call for every value that is found. "context" | |
952 | is an application-defined pointer that is sent to the callback function | |
953 | along with the OID and current data. The data passed to the callback is the | |
954 | same as returned by <a href="#cupsSideChannelSNMPGet"><code>cupsSideChannelSNMPGet</code></a>. | |
955 | ||
956 | <code>CUPS_SC_STATUS_NOT_IMPLEMENTED</code> is returned by backends that do not | |
957 | support SNMP queries. <code>CUPS_SC_STATUS_NO_RESPONSE</code> is returned when | |
958 | the printer does not respond to the first SNMP query. | |
959 | ||
5a738aea MS |
960 | </p> |
961 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> | |
962 | <p class="description">Write a side-channel message.</p> | |
963 | <p class="code"> | |
964 | int cupsSideChannelWrite (<br> | |
965 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
966 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
967 | const char *data,<br> | |
968 | int datalen,<br> | |
969 | double timeout<br> | |
970 | );</p> | |
971 | <h4 class="parameters">Parameters</h4> | |
972 | <dl> | |
973 | <dt>command</dt> | |
974 | <dd class="description">Command code</dd> | |
975 | <dt>status</dt> | |
976 | <dd class="description">Status code</dd> | |
977 | <dt>data</dt> | |
978 | <dd class="description">Data buffer pointer</dd> | |
979 | <dt>datalen</dt> | |
980 | <dd class="description">Number of bytes of data</dd> | |
981 | <dt>timeout</dt> | |
982 | <dd class="description">Timeout in seconds</dd> | |
983 | </dl> | |
984 | <h4 class="returnvalue">Return Value</h4> | |
985 | <p class="description">0 on success, -1 on error</p> | |
986 | <h4 class="discussion">Discussion</h4> | |
987 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 988 | responses to a filter, driver, or port monitor program. |
989 | ||
5a738aea MS |
990 | </p> |
991 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
992 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> | |
993 | <p class="description">Backend exit codes</p> | |
994 | <p class="code"> | |
995 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
996 | </p> | |
997 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
998 | <p class="description">Bidirectional capabilities</p> | |
999 | <p class="code"> | |
1000 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
1001 | </p> | |
1002 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
1003 | <p class="description">Request command codes</p> | |
1004 | <p class="code"> | |
1005 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
1006 | </p> | |
1007 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> | |
1008 | <p class="description">Printer state bits</p> | |
1009 | <p class="code"> | |
1010 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
1011 | </p> | |
1012 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
1013 | <p class="description">Response status codes</p> | |
1014 | <p class="code"> | |
1015 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
1016 | </p> | |
20fbc903 MS |
1017 | <h3 class="typedef"><a name="cups_sc_walk_func_t">cups_sc_walk_func_t</a></h3> |
1018 | <p class="description">SNMP walk callback</p> | |
1019 | <p class="code"> | |
1020 | typedef void (*cups_sc_walk_func_t)(const char *oid, const char *data, int datalen, void *context); | |
1021 | </p> | |
5a738aea MS |
1022 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> |
1023 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> | |
1024 | <p class="description">Backend exit codes</p> | |
1025 | <h4 class="constants">Constants</h4> | |
1026 | <dl> | |
1027 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
1028 | <dd class="description">Job failed, authentication required</dd> | |
1029 | <dt>CUPS_BACKEND_CANCEL </dt> | |
1030 | <dd class="description">Job failed, cancel job</dd> | |
1031 | <dt>CUPS_BACKEND_FAILED </dt> | |
1032 | <dd class="description">Job failed, use error-policy</dd> | |
1033 | <dt>CUPS_BACKEND_HOLD </dt> | |
1034 | <dd class="description">Job failed, hold job</dd> | |
1035 | <dt>CUPS_BACKEND_OK </dt> | |
1036 | <dd class="description">Job completed successfully</dd> | |
1037 | <dt>CUPS_BACKEND_STOP </dt> | |
1038 | <dd class="description">Job failed, stop queue</dd> | |
1039 | </dl> | |
1040 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
1041 | <p class="description">Bidirectional capabilities</p> | |
1042 | <h4 class="constants">Constants</h4> | |
1043 | <dl> | |
1044 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
1045 | <dd class="description">Bidirectional I/O is not supported</dd> | |
1046 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
1047 | <dd class="description">Bidirectional I/O is supported</dd> | |
1048 | </dl> | |
1049 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
1050 | <p class="description">Request command codes</p> | |
1051 | <h4 class="constants">Constants</h4> | |
1052 | <dl> | |
1053 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
1054 | <dd class="description">Drain all pending output</dd> | |
1055 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
1056 | <dd class="description">Return bidirectional capabilities</dd> | |
1057 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> | |
1058 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
1059 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
1060 | <dd class="description">Return the device state</dd> | |
20fbc903 MS |
1061 | <dt>CUPS_SC_CMD_SNMP_GET <span class="info"> CUPS 1.4 </span></dt> |
1062 | <dd class="description">Query an SNMP OID </dd> | |
1063 | <dt>CUPS_SC_CMD_SNMP_GET_NEXT <span class="info"> CUPS 1.4 </span></dt> | |
1064 | <dd class="description">Query the next SNMP OID </dd> | |
5a738aea MS |
1065 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> |
1066 | <dd class="description">Do a soft reset</dd> | |
1067 | </dl> | |
1068 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> | |
1069 | <p class="description">Printer state bits</p> | |
1070 | <h4 class="constants">Constants</h4> | |
1071 | <dl> | |
1072 | <dt>CUPS_SC_STATE_BUSY </dt> | |
1073 | <dd class="description">Device is busy</dd> | |
1074 | <dt>CUPS_SC_STATE_ERROR </dt> | |
1075 | <dd class="description">Other error condition</dd> | |
1076 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
1077 | <dd class="description">Toner/ink out condition</dd> | |
1078 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
1079 | <dd class="description">Toner/ink low condition</dd> | |
1080 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
1081 | <dd class="description">Paper out condition</dd> | |
1082 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
1083 | <dd class="description">Paper low condition</dd> | |
1084 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
1085 | <dd class="description">Device is off-line</dd> | |
1086 | <dt>CUPS_SC_STATE_ONLINE </dt> | |
1087 | <dd class="description">Device is on-line</dd> | |
1088 | </dl> | |
1089 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
1090 | <p class="description">Response status codes</p> | |
1091 | <h4 class="constants">Constants</h4> | |
1092 | <dl> | |
1093 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
1094 | <dd class="description">The command/response message was invalid</dd> | |
1095 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
1096 | <dd class="description">An I/O error occurred</dd> | |
1097 | <dt>CUPS_SC_STATUS_NONE </dt> | |
1098 | <dd class="description">No status</dd> | |
1099 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
1100 | <dd class="description">Command not implemented</dd> | |
1101 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
1102 | <dd class="description">The device did not respond</dd> | |
1103 | <dt>CUPS_SC_STATUS_OK </dt> | |
1104 | <dd class="description">Operation succeeded</dd> | |
1105 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
1106 | <dd class="description">The backend did not respond</dd> | |
1107 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
1108 | <dd class="description">Response too big</dd> | |
1109 | </dl> | |
1110 | </div> | |
ef416fc2 | 1111 | </body> |
1112 | </html> |