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5a738aea MS |
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5a738aea | 251 | <div class='body'> |
ef416fc2 | 252 | <!-- |
5a738aea | 253 | "$Id: api-cups.header 7279 2008-01-31 01:50:44Z mike $" |
ef416fc2 | 254 | |
5a738aea MS |
255 | Filter and backend programming header for the Common UNIX Printing System |
256 | (CUPS). | |
ef416fc2 | 257 | |
5a738aea | 258 | Copyright 2008 by Apple Inc. |
ef416fc2 | 259 | |
260 | These coded instructions, statements, and computer programs are the | |
bc44d920 | 261 | property of Apple Inc. and are protected by Federal copyright |
262 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
263 | which should have been included with this file. If this file is | |
264 | file is missing or damaged, see the license at "http://www.cups.org/". | |
ef416fc2 | 265 | --> |
266 | ||
5a738aea | 267 | <h1 class="title">Filter and Backend Programming</h1> |
ef416fc2 | 268 | |
5a738aea MS |
269 | <div class='summary'><table summary='General Information'> |
270 | <thead> | |
271 | <tr> | |
272 | <th>Header</th> | |
273 | <th>cups/backend.h<br> | |
274 | cups/sidechannel.h</th> | |
275 | </tr> | |
276 | </thead> | |
277 | <tbody> | |
278 | <tr> | |
279 | <th>Library</th> | |
280 | <td>-lcups</td> | |
281 | </tr> | |
282 | <tr> | |
283 | <th>See Also</th> | |
284 | <td>Programming: <a href='api-overview.html' target='_top'>Introduction to CUPS Programming</a><br> | |
285 | Programming: <a href='api-cups.html' target='_top'>CUPS API</a><br> | |
286 | Programming: <a href='api-ppd.html' target='_top'>PPD API</a><br> | |
287 | Programming: <a href='api-raster.html' target='_top'>Raster API</a></td> | |
288 | </tr> | |
289 | </tbody> | |
290 | </table></div> | |
291 | <h2 class="title">Contents</h2> | |
292 | <ul class="contents"> | |
293 | </li> | |
294 | <li><a href="#OVERVIEW">Overview</a><ul class="subcontents"> | |
295 | <li><a href="#EXITCODES">Exit Codes</a></li> | |
296 | <li><a href="#ENVIRONMENT">Environment Variables</a></li> | |
297 | <li><a href="#MESSAGES">Communicating with the Scheduler</a></li> | |
298 | <li><a href="#COMMUNICATING">Communicating with the Backend</a></li> | |
299 | </ul></li> | |
300 | <li><a href="#FUNCTIONS">Functions</a><ul class="code"> | |
301 | <li><a href="#cupsBackChannelRead" title="Read data from the backchannel.">cupsBackChannelRead</a></li> | |
302 | <li><a href="#cupsBackChannelWrite" title="Write data to the backchannel.">cupsBackChannelWrite</a></li> | |
303 | <li><a href="#cupsSideChannelDoRequest" title="Send a side-channel command to a backend and wait for a response.">cupsSideChannelDoRequest</a></li> | |
304 | <li><a href="#cupsSideChannelRead" title="Read a side-channel message.">cupsSideChannelRead</a></li> | |
305 | <li><a href="#cupsSideChannelWrite" title="Write a side-channel message.">cupsSideChannelWrite</a></li> | |
306 | </ul> | |
307 | <li><a href="#TYPES">Data Types</a><ul class="code"> | |
308 | <li><a href="#cups_backend_t" title="Backend exit codes">cups_backend_t</a></li> | |
309 | <li><a href="#cups_sc_bidi_t" title="Bidirectional capabilities">cups_sc_bidi_t</a></li> | |
310 | <li><a href="#cups_sc_command_t" title="Request command codes">cups_sc_command_t</a></li> | |
311 | <li><a href="#cups_sc_state_t" title="Printer state bits">cups_sc_state_t</a></li> | |
312 | <li><a href="#cups_sc_status_t" title="Response status codes">cups_sc_status_t</a></li> | |
313 | </ul></li> | |
314 | <li><a href="#ENUMERATIONS">Constants</a><ul class="code"> | |
315 | <li><a href="#cups_backend_e" title="Backend exit codes">cups_backend_e</a></li> | |
316 | <li><a href="#cups_sc_bidi_e" title="Bidirectional capabilities">cups_sc_bidi_e</a></li> | |
317 | <li><a href="#cups_sc_command_e" title="Request command codes">cups_sc_command_e</a></li> | |
318 | <li><a href="#cups_sc_state_e" title="Printer state bits">cups_sc_state_e</a></li> | |
319 | <li><a href="#cups_sc_status_e" title="Response status codes">cups_sc_status_e</a></li> | |
320 | </ul></li> | |
321 | </ul> | |
322 | <!-- | |
323 | "$Id: api-filter.shtml 6649 2007-07-11 21:46:42Z mike $" | |
ef416fc2 | 324 | |
5a738aea MS |
325 | Filter and backend programming introduction for the Common UNIX Printing |
326 | System (CUPS). | |
ef416fc2 | 327 | |
5a738aea MS |
328 | Copyright 2007-2008 by Apple Inc. |
329 | Copyright 1997-2006 by Easy Software Products, all rights reserved. | |
ef416fc2 | 330 | |
5a738aea MS |
331 | These coded instructions, statements, and computer programs are the |
332 | property of Apple Inc. and are protected by Federal copyright | |
333 | law. Distribution and use rights are outlined in the file "LICENSE.txt" | |
334 | which should have been included with this file. If this file is | |
335 | file is missing or damaged, see the license at "http://www.cups.org/". | |
336 | --> | |
f7deaa1a | 337 | |
5a738aea | 338 | <h2 class='title'><a name="OVERVIEW">Overview</a></h2> |
ef416fc2 | 339 | |
5a738aea MS |
340 | <p>Filters, printer drivers, port monitors, and backends use a common interface |
341 | for processing print jobs and communicating status information to the scheduler. | |
342 | Each filter is run with a standard set of command-line arguments:<p> | |
ef416fc2 | 343 | |
5a738aea | 344 | <dl class="code"> |
f7deaa1a | 345 | |
5a738aea MS |
346 | <dt>argv[1]</dt> |
347 | <dd>The job ID</dd> | |
ef416fc2 | 348 | |
5a738aea MS |
349 | <dt>argv[2]</dt> |
350 | <dd>The user printing the job</dd> | |
f7deaa1a | 351 | |
5a738aea MS |
352 | <dt>argv[3]</dt> |
353 | <dd>The job name/title</dd> | |
f7deaa1a | 354 | |
5a738aea MS |
355 | <dt>argv[4]</dt> |
356 | <dd>The number of copies to print</dd> | |
f7deaa1a | 357 | |
5a738aea MS |
358 | <dt>argv[5]</dt> |
359 | <dd>The options that were provided when the job was submitted</dd> | |
f7deaa1a | 360 | |
5a738aea MS |
361 | <dt>argv[6]</dt> |
362 | <dd>The file to print (first filter only)</dd> | |
363 | </dl> | |
f7deaa1a | 364 | |
5a738aea MS |
365 | <p>The scheduler runs one or more of these programs to print any given job. The |
366 | first filter reads from the print file and writes to the standard output, while | |
367 | the remaining filters read from the standard input and write to the standard | |
368 | output. The backend is the last filter in the chain and writes to the | |
369 | device.</p> | |
f7deaa1a | 370 | |
5a738aea | 371 | <h3><a name="EXITCODES">Exit Codes</a></h3> |
f7deaa1a | 372 | |
5a738aea MS |
373 | <p>Filters must exit with status 0 when they successfully generate print data |
374 | or 1 when they encounter an error. Backends can return any of the | |
375 | <a href="#cups_backend_t"><code>cups_backend_t</code></a> constants.</p> | |
f7deaa1a | 376 | |
5a738aea | 377 | <h3><a name="ENVIRONMENT">Environment Variables</a></h3> |
f7deaa1a | 378 | |
5a738aea | 379 | <p>The following environment variables are defined by the printing system:</p> |
f7deaa1a | 380 | |
5a738aea | 381 | <dl class="code"> |
f7deaa1a | 382 | |
5a738aea MS |
383 | <dt>APPLE_LANGUAGES</dt> |
384 | <dd>The Apple language identifier associated with the job | |
385 | (Mac OS X only).</dd> | |
f7deaa1a | 386 | |
5a738aea MS |
387 | <dt>CHARSET</dt> |
388 | <dd>The job character set, typically "utf-8".</dd> | |
f7deaa1a | 389 | |
5a738aea MS |
390 | <dt>CLASS</dt> |
391 | <dd>When a job is submitted to a printer class, contains the name of | |
392 | the destination printer class. Otherwise this environment | |
393 | variable will not be set.</dd> | |
f7deaa1a | 394 | |
5a738aea MS |
395 | <dt>CONTENT_TYPE</dt> |
396 | <dd>The MIME type associated with the file (e.g. | |
397 | application/postscript).</dd> | |
f7deaa1a | 398 | |
5a738aea MS |
399 | <dt>CUPS_CACHEDIR</dt> |
400 | <dd>The directory where cache files can be stored.</dd> | |
f7deaa1a | 401 | |
5a738aea MS |
402 | <dt>CUPS_DATADIR</dt> |
403 | <dd>The directory where data files can be found.</dd> | |
f7deaa1a | 404 | |
5a738aea MS |
405 | <dt>CUPS_SERVERROOT</dt> |
406 | <dd>The root directory of the server.</dd> | |
f7deaa1a | 407 | |
5a738aea MS |
408 | <dt>DEVICE_URI</dt> |
409 | <dd>The device-uri associated with the printer.</dd> | |
f7deaa1a | 410 | |
5a738aea MS |
411 | <dt>FINAL_CONTENT_TYPE</dt> |
412 | <dd>The MIME type associated with the printer (e.g. | |
413 | application/vnd.cups-postscript).</dd> | |
f7deaa1a | 414 | |
5a738aea MS |
415 | <dt>LANG</dt> |
416 | <dd>The language locale associated with the job.</dd> | |
f7deaa1a | 417 | |
5a738aea MS |
418 | <dt>PPD</dt> |
419 | <dd>The full pathname of the PostScript Printer Description (PPD) | |
420 | file for this printer.</dd> | |
f7deaa1a | 421 | |
5a738aea MS |
422 | <dt>PRINTER</dt> |
423 | <dd>The name of the printer.</dd> | |
f7deaa1a | 424 | |
5a738aea MS |
425 | <dt>RIP_CACHE</dt> |
426 | <dd>The recommended amount of memory to use for Raster Image | |
427 | Processors (RIPs).</dd> | |
f7deaa1a | 428 | |
5a738aea | 429 | </dl> |
f7deaa1a | 430 | |
5a738aea | 431 | <h3><a name="MESSAGES">Communicating with the Scheduler</a></h3> |
f7deaa1a | 432 | |
5a738aea MS |
433 | <p>Filters and backends communicate wih the scheduler by writing messages |
434 | to the standard error file. For example, the following code sets the current | |
435 | printer state message to "Printing page 5":</p> | |
f7deaa1a | 436 | |
5a738aea MS |
437 | <pre class="example"> |
438 | int page = 5; | |
f7deaa1a | 439 | |
5a738aea | 440 | fprintf(stderr, "INFO: Printing page %d\n", page); |
f7deaa1a | 441 | </pre> |
442 | ||
5a738aea MS |
443 | <p>Each message is a single line of text starting with one of the following |
444 | prefix strings:</p> | |
445 | ||
446 | <dl class="code"> | |
447 | ||
448 | <dt>ALERT: message</dt> | |
449 | <dd>Sets the printer-state-message attribute and adds the specified | |
450 | message to the current error log file using the "alert" log level.</dd> | |
451 | ||
452 | <dt>ATTR: attribute=value [attribute=value]</dt> | |
453 | <dd>Sets the named printer or job attribute(s). Typically this is used | |
454 | to set the <code>marker-colors</code>, <code>marker-levels</code>, | |
455 | <code>marker-names</code>, <code>marker-types</code>, | |
456 | <code>printer-alert</code>, and <code>printer-alert-description</code> | |
457 | printer attributes.</dd> | |
458 | ||
459 | <dt>CRIT: message</dt> | |
460 | <dd>Sets the printer-state-message attribute and adds the specified | |
461 | message to the current error log file using the "critical" log | |
462 | level.</dd> | |
463 | ||
464 | <dt>DEBUG: message</dt> | |
465 | <dd>Sets the printer-state-message attribute and adds the specified | |
466 | message to the current error log file using the "debug" log level.</dd> | |
467 | ||
468 | <dt>DEBUG2: message</dt> | |
469 | <dd>Sets the printer-state-message attribute and adds the specified | |
470 | message to the current error log file using the "debug2" log level.</dd> | |
471 | ||
472 | <dt>EMERG: message</dt> | |
473 | <dd>Sets the printer-state-message attribute and adds the specified | |
474 | message to the current error log file using the "emergency" log | |
475 | level.</dd> | |
476 | ||
477 | <dt>ERROR: message</dt> | |
478 | <dd>Sets the printer-state-message attribute and adds the specified | |
479 | message to the current error log file using the "error" log level.</dd> | |
480 | ||
481 | <dt>INFO: message</dt> | |
482 | <dd>Sets the printer-state-message attribute. If the current log level | |
483 | is set to "debug2", also adds the specified message to the current error | |
484 | log file using the "info" log level.</dd> | |
485 | ||
486 | <dt>NOTICE: message</dt> | |
487 | <dd>Sets the printer-state-message attribute and adds the specified | |
488 | message to the current error log file using the "notice" log level.</dd> | |
489 | ||
490 | <dt>PAGE: page-number #-copies</dt> | |
491 | <dt>PAGE: total #-pages</dt> | |
492 | <dd>Adds an entry to the current page log file. The first form adds | |
493 | #-copies to the job-media-sheets-completed attribute. The second | |
494 | form sets the job-media-sheets-completed attribute to #-pages.</dd> | |
495 | ||
496 | <dt>STATE: printer-state-reason [printer-state-reason ...]</dt> | |
497 | <dt>STATE: + printer-state-reason [printer-state-reason ...]</dt> | |
498 | <dt>STATE: - printer-state-reason [printer-state-reason ...]</dt> | |
499 | <dd>Sets, adds, or removes printer-state-reason keywords to the | |
500 | current queue. Typically this is used to indicate media, ink, and | |
501 | toner conditions on a printer.</dd> | |
502 | ||
503 | <dt>WARNING: message</dt> | |
504 | <dd>Sets the printer-state-message attribute and adds the specified | |
505 | message to the current error log file using the "warning" log | |
506 | level.</dd> | |
507 | ||
508 | </dl> | |
509 | ||
510 | <p>Messages without one of these prefixes are treated as if they began with | |
511 | the "DEBUG:" prefix string.</p> | |
512 | ||
513 | <h3><a name="COMMUNICATING">Communicating with the Backend</a></h3> | |
514 | ||
515 | <p>Filters can communicate with the backend via the | |
516 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> and | |
517 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
518 | functions. The | |
519 | <a href="#cupsBackChannelRead"><code>cupsBackChannelRead</code></a> function | |
520 | reads data that has been sent back from the device and is typically used to | |
521 | obtain status and configuration information. For example, the following code | |
522 | polls the backend for back-channel data:</p> | |
523 | ||
524 | <pre class="example"> | |
525 | #include <cups/cups.h> | |
526 | ||
527 | char buffer[8192]; | |
528 | ssize_t bytes; | |
529 | ||
530 | /* Use a timeout of 0.0 seconds to poll for back-channel data */ | |
531 | bytes = cupsBackChannelRead(buffer, sizeof(buffer), 0.0); | |
532 | </pre> | |
f7deaa1a | 533 | |
5a738aea MS |
534 | The |
535 | <a href="#cupsSideChannelDoRequest"><code>cupsSideChannelDoRequest</code></a> | |
536 | function allows you to get out-of-band status information and do synchronization | |
537 | with the device. For example, the following code gets the current IEEE-1284 | |
538 | device ID string from the backend:</p> | |
539 | ||
540 | <pre class="example"> | |
f7deaa1a | 541 | #include <cups/sidechannel.h> |
542 | ||
543 | char data[2049]; | |
544 | int datalen; | |
5a738aea | 545 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; |
f7deaa1a | 546 | |
547 | /* Tell cupsSideChannelDoRequest() how big our buffer is, less 1 byte for nul-termination... */ | |
548 | datalen = sizeof(data) - 1; | |
549 | ||
550 | /* Get the IEEE-1284 device ID, waiting for up to 1 second */ | |
5a738aea | 551 | status = <a href="#cupsSideChannelDoRequest">cupsSideChannelDoRequest</a>(CUPS_SC_CMD_GET_DEVICE_ID, data, &datalen, 1.0); |
f7deaa1a | 552 | |
553 | /* Use the returned value if OK was returned and the length is non-zero */ | |
554 | if (status == CUPS_SC_STATUS_OK && datalen > 0) | |
555 | data[datalen] = '\0'; | |
556 | else | |
557 | data[0] = '\0'; | |
558 | </pre> | |
559 | ||
5a738aea MS |
560 | <p>Backends communicate with filters using the reciprocal functions |
561 | <a href="#cupsBackChannelWrite"><code>cupsBackChannelWrite</code></a>, | |
562 | <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a>, and | |
563 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a>. We | |
564 | recommend writing back-channel data using a timeout of 1.0 seconds:</p> | |
f7deaa1a | 565 | |
5a738aea MS |
566 | <pre class="example"> |
567 | #include <cups/cups.h> | |
f7deaa1a | 568 | |
5a738aea MS |
569 | char buffer[8192]; |
570 | ssize_t bytes; | |
f7deaa1a | 571 | |
5a738aea MS |
572 | /* Use a timeout of 1.0 seconds to give filters a chance to read */ |
573 | cupsBackChannelWrite(buffer, bytes, 1.0); | |
f7deaa1a | 574 | </pre> |
575 | ||
5a738aea MS |
576 | <p>The <a href="#cupsSideChannelRead"><code>cupsSideChannelRead</code></a> |
577 | function reads a side-channel command from a filter, driver, or port monitor. | |
578 | Backends can either poll for commands using a <code>timeout</code> of 0.0, wait | |
579 | indefinitely for commands using a <code>timeout</code> of -1.0 (probably in a | |
580 | separate thread for that purpose), or use <code>select</code> or | |
581 | <code>poll</code> on the <code>CUPS_SC_FD</code> file descriptor (4) to handle | |
582 | input and output on several file descriptors at the same time. Backends can pass | |
583 | <code>NULL</code> for the <code>data</code> and <code>datalen</code> parameters | |
584 | since none of the commands sent by upstream filters contain any data at this | |
585 | time.</p> | |
586 | ||
587 | <p>Once a command is processed, the backend uses the | |
588 | <a href="#cupsSideChannelWrite"><code>cupsSideChannelWrite</code></a> function | |
589 | to send its response. For example, the following code shows how to poll for a | |
590 | side-channel command and respond to it:</p> | |
591 | ||
592 | <pre class="example"> | |
f7deaa1a | 593 | #include <cups/sidechannel.h> |
594 | ||
5a738aea MS |
595 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command; |
596 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status; | |
f7deaa1a | 597 | |
598 | /* Poll for a command... */ | |
5a738aea | 599 | if (!<a href="#cupsSideChannelRead">cupsSideChannelRead</a>(&command, &status, NULL, NULL, 0.0)) |
f7deaa1a | 600 | { |
601 | char data[2048]; | |
602 | int datalen; | |
603 | ||
604 | switch (command) | |
605 | { | |
5a738aea | 606 | /* handle supported commands, file data/datalen/status with values as needed */ |
f7deaa1a | 607 | |
608 | default : | |
609 | status = CUPS_SC_STATUS_NOT_IMPLEMENTED; | |
610 | datalen = 0; | |
611 | break; | |
612 | } | |
613 | ||
614 | /* Send a response... */ | |
5a738aea | 615 | <a href="#cupsSideChannelWrite">cupsSideChannelWrite</a>(command, status, data, datalen, 1.0); |
f7deaa1a | 616 | } |
617 | </pre> | |
5a738aea MS |
618 | <h2 class="title"><a name="FUNCTIONS">Functions</a></h2> |
619 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelRead">cupsBackChannelRead</a></h3> | |
620 | <p class="description">Read data from the backchannel.</p> | |
621 | <p class="code"> | |
622 | ssize_t cupsBackChannelRead (<br> | |
623 | char *buffer,<br> | |
624 | size_t bytes,<br> | |
625 | double timeout<br> | |
626 | );</p> | |
627 | <h4 class="parameters">Parameters</h4> | |
628 | <dl> | |
629 | <dt>buffer</dt> | |
630 | <dd class="description">Buffer to read</dd> | |
631 | <dt>bytes</dt> | |
632 | <dd class="description">Bytes to read</dd> | |
633 | <dt>timeout</dt> | |
634 | <dd class="description">Timeout in seconds</dd> | |
635 | </dl> | |
636 | <h4 class="returnvalue">Return Value</h4> | |
637 | <p class="description">Bytes read or -1 on error</p> | |
638 | <h4 class="discussion">Discussion</h4> | |
639 | <p class="discussion">Reads up to "bytes" bytes from the backchannel. The "timeout" | |
ef416fc2 | 640 | parameter controls how many seconds to wait for the data - use |
641 | 0.0 to return immediately if there is no data, -1.0 to wait | |
642 | for data indefinitely. | |
643 | ||
5a738aea MS |
644 | </p> |
645 | <h3 class="function"><span class="info"> CUPS 1.2 </span><a name="cupsBackChannelWrite">cupsBackChannelWrite</a></h3> | |
646 | <p class="description">Write data to the backchannel.</p> | |
647 | <p class="code"> | |
648 | ssize_t cupsBackChannelWrite (<br> | |
649 | const char *buffer,<br> | |
650 | size_t bytes,<br> | |
651 | double timeout<br> | |
652 | );</p> | |
653 | <h4 class="parameters">Parameters</h4> | |
654 | <dl> | |
655 | <dt>buffer</dt> | |
656 | <dd class="description">Buffer to write</dd> | |
657 | <dt>bytes</dt> | |
658 | <dd class="description">Bytes to write</dd> | |
659 | <dt>timeout</dt> | |
660 | <dd class="description">Timeout in seconds</dd> | |
661 | </dl> | |
662 | <h4 class="returnvalue">Return Value</h4> | |
663 | <p class="description">Bytes written or -1 on error</p> | |
664 | <h4 class="discussion">Discussion</h4> | |
665 | <p class="discussion">Writes "bytes" bytes to the backchannel. The "timeout" parameter | |
ef416fc2 | 666 | controls how many seconds to wait for the data to be written - use |
667 | 0.0 to return immediately if the data cannot be written, -1.0 to wait | |
668 | indefinitely. | |
669 | ||
5a738aea MS |
670 | </p> |
671 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelDoRequest">cupsSideChannelDoRequest</a></h3> | |
672 | <p class="description">Send a side-channel command to a backend and wait for a response.</p> | |
673 | <p class="code"> | |
674 | <a href="#cups_sc_status_t">cups_sc_status_t</a> cupsSideChannelDoRequest (<br> | |
675 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
676 | char *data,<br> | |
677 | int *datalen,<br> | |
678 | double timeout<br> | |
679 | );</p> | |
680 | <h4 class="parameters">Parameters</h4> | |
681 | <dl> | |
682 | <dt>command</dt> | |
683 | <dd class="description">Command to send</dd> | |
684 | <dt>data</dt> | |
685 | <dd class="description">Response data buffer pointer</dd> | |
686 | <dt>datalen</dt> | |
687 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
688 | <dt>timeout</dt> | |
689 | <dd class="description">Timeout in seconds</dd> | |
690 | </dl> | |
691 | <h4 class="returnvalue">Return Value</h4> | |
692 | <p class="description">Status of command</p> | |
693 | <h4 class="discussion">Discussion</h4> | |
694 | <p class="discussion">This function is normally only called by filters, drivers, or port | |
f7deaa1a | 695 | monitors in order to communicate with the backend used by the current |
696 | printer. Programs must be prepared to handle timeout or "not | |
697 | implemented" status codes, which indicate that the backend or device | |
5a738aea MS |
698 | do not support the specified side-channel command.<br> |
699 | <br> | |
700 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 701 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
702 | update the value to contain the number of data bytes in the buffer. | |
703 | ||
5a738aea MS |
704 | </p> |
705 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelRead">cupsSideChannelRead</a></h3> | |
706 | <p class="description">Read a side-channel message.</p> | |
707 | <p class="code"> | |
708 | int cupsSideChannelRead (<br> | |
709 | <a href="#cups_sc_command_t">cups_sc_command_t</a> *command,<br> | |
710 | <a href="#cups_sc_status_t">cups_sc_status_t</a> *status,<br> | |
711 | char *data,<br> | |
712 | int *datalen,<br> | |
713 | double timeout<br> | |
714 | );</p> | |
715 | <h4 class="parameters">Parameters</h4> | |
716 | <dl> | |
717 | <dt>command</dt> | |
718 | <dd class="description">Command code</dd> | |
719 | <dt>status</dt> | |
720 | <dd class="description">Status code</dd> | |
721 | <dt>data</dt> | |
722 | <dd class="description">Data buffer pointer</dd> | |
723 | <dt>datalen</dt> | |
724 | <dd class="description">Size of data buffer on entry, number of bytes in buffer on return</dd> | |
725 | <dt>timeout</dt> | |
726 | <dd class="description">Timeout in seconds</dd> | |
727 | </dl> | |
728 | <h4 class="returnvalue">Return Value</h4> | |
729 | <p class="description">0 on success, -1 on error</p> | |
730 | <h4 class="discussion">Discussion</h4> | |
731 | <p class="discussion">This function is normally only called by backend programs to read | |
f7deaa1a | 732 | commands from a filter, driver, or port monitor program. The |
733 | caller must be prepared to handle incomplete or invalid messages | |
5a738aea MS |
734 | and return the corresponding status codes.<br> |
735 | <br> | |
736 | The "datalen" parameter must be initialized to the size of the buffer | |
f7deaa1a | 737 | pointed to by the "data" parameter. cupsSideChannelDoRequest() will |
738 | update the value to contain the number of data bytes in the buffer. | |
739 | ||
5a738aea MS |
740 | </p> |
741 | <h3 class="function"><span class="info"> CUPS 1.3 </span><a name="cupsSideChannelWrite">cupsSideChannelWrite</a></h3> | |
742 | <p class="description">Write a side-channel message.</p> | |
743 | <p class="code"> | |
744 | int cupsSideChannelWrite (<br> | |
745 | <a href="#cups_sc_command_t">cups_sc_command_t</a> command,<br> | |
746 | <a href="#cups_sc_status_t">cups_sc_status_t</a> status,<br> | |
747 | const char *data,<br> | |
748 | int datalen,<br> | |
749 | double timeout<br> | |
750 | );</p> | |
751 | <h4 class="parameters">Parameters</h4> | |
752 | <dl> | |
753 | <dt>command</dt> | |
754 | <dd class="description">Command code</dd> | |
755 | <dt>status</dt> | |
756 | <dd class="description">Status code</dd> | |
757 | <dt>data</dt> | |
758 | <dd class="description">Data buffer pointer</dd> | |
759 | <dt>datalen</dt> | |
760 | <dd class="description">Number of bytes of data</dd> | |
761 | <dt>timeout</dt> | |
762 | <dd class="description">Timeout in seconds</dd> | |
763 | </dl> | |
764 | <h4 class="returnvalue">Return Value</h4> | |
765 | <p class="description">0 on success, -1 on error</p> | |
766 | <h4 class="discussion">Discussion</h4> | |
767 | <p class="discussion">This function is normally only called by backend programs to send | |
f7deaa1a | 768 | responses to a filter, driver, or port monitor program. |
769 | ||
5a738aea MS |
770 | </p> |
771 | <h2 class="title"><a name="TYPES">Data Types</a></h2> | |
772 | <h3 class="typedef"><a name="cups_backend_t">cups_backend_t</a></h3> | |
773 | <p class="description">Backend exit codes</p> | |
774 | <p class="code"> | |
775 | typedef enum <a href="#cups_backend_e">cups_backend_e</a> cups_backend_t; | |
776 | </p> | |
777 | <h3 class="typedef"><a name="cups_sc_bidi_t">cups_sc_bidi_t</a></h3> | |
778 | <p class="description">Bidirectional capabilities</p> | |
779 | <p class="code"> | |
780 | typedef enum <a href="#cups_sc_bidi_e">cups_sc_bidi_e</a> cups_sc_bidi_t; | |
781 | </p> | |
782 | <h3 class="typedef"><a name="cups_sc_command_t">cups_sc_command_t</a></h3> | |
783 | <p class="description">Request command codes</p> | |
784 | <p class="code"> | |
785 | typedef enum <a href="#cups_sc_command_e">cups_sc_command_e</a> cups_sc_command_t; | |
786 | </p> | |
787 | <h3 class="typedef"><a name="cups_sc_state_t">cups_sc_state_t</a></h3> | |
788 | <p class="description">Printer state bits</p> | |
789 | <p class="code"> | |
790 | typedef enum <a href="#cups_sc_state_e">cups_sc_state_e</a> cups_sc_state_t; | |
791 | </p> | |
792 | <h3 class="typedef"><a name="cups_sc_status_t">cups_sc_status_t</a></h3> | |
793 | <p class="description">Response status codes</p> | |
794 | <p class="code"> | |
795 | typedef enum <a href="#cups_sc_status_e">cups_sc_status_e</a> cups_sc_status_t; | |
796 | </p> | |
797 | <h2 class="title"><a name="ENUMERATIONS">Constants</a></h2> | |
798 | <h3 class="enumeration"><a name="cups_backend_e">cups_backend_e</a></h3> | |
799 | <p class="description">Backend exit codes</p> | |
800 | <h4 class="constants">Constants</h4> | |
801 | <dl> | |
802 | <dt>CUPS_BACKEND_AUTH_REQUIRED </dt> | |
803 | <dd class="description">Job failed, authentication required</dd> | |
804 | <dt>CUPS_BACKEND_CANCEL </dt> | |
805 | <dd class="description">Job failed, cancel job</dd> | |
806 | <dt>CUPS_BACKEND_FAILED </dt> | |
807 | <dd class="description">Job failed, use error-policy</dd> | |
808 | <dt>CUPS_BACKEND_HOLD </dt> | |
809 | <dd class="description">Job failed, hold job</dd> | |
810 | <dt>CUPS_BACKEND_OK </dt> | |
811 | <dd class="description">Job completed successfully</dd> | |
812 | <dt>CUPS_BACKEND_STOP </dt> | |
813 | <dd class="description">Job failed, stop queue</dd> | |
814 | </dl> | |
815 | <h3 class="enumeration"><a name="cups_sc_bidi_e">cups_sc_bidi_e</a></h3> | |
816 | <p class="description">Bidirectional capabilities</p> | |
817 | <h4 class="constants">Constants</h4> | |
818 | <dl> | |
819 | <dt>CUPS_SC_BIDI_NOT_SUPPORTED </dt> | |
820 | <dd class="description">Bidirectional I/O is not supported</dd> | |
821 | <dt>CUPS_SC_BIDI_SUPPORTED </dt> | |
822 | <dd class="description">Bidirectional I/O is supported</dd> | |
823 | </dl> | |
824 | <h3 class="enumeration"><a name="cups_sc_command_e">cups_sc_command_e</a></h3> | |
825 | <p class="description">Request command codes</p> | |
826 | <h4 class="constants">Constants</h4> | |
827 | <dl> | |
828 | <dt>CUPS_SC_CMD_DRAIN_OUTPUT </dt> | |
829 | <dd class="description">Drain all pending output</dd> | |
830 | <dt>CUPS_SC_CMD_GET_BIDI </dt> | |
831 | <dd class="description">Return bidirectional capabilities</dd> | |
832 | <dt>CUPS_SC_CMD_GET_DEVICE_ID </dt> | |
833 | <dd class="description">Return the IEEE-1284 device ID</dd> | |
834 | <dt>CUPS_SC_CMD_GET_STATE </dt> | |
835 | <dd class="description">Return the device state</dd> | |
836 | <dt>CUPS_SC_CMD_SOFT_RESET </dt> | |
837 | <dd class="description">Do a soft reset</dd> | |
838 | </dl> | |
839 | <h3 class="enumeration"><a name="cups_sc_state_e">cups_sc_state_e</a></h3> | |
840 | <p class="description">Printer state bits</p> | |
841 | <h4 class="constants">Constants</h4> | |
842 | <dl> | |
843 | <dt>CUPS_SC_STATE_BUSY </dt> | |
844 | <dd class="description">Device is busy</dd> | |
845 | <dt>CUPS_SC_STATE_ERROR </dt> | |
846 | <dd class="description">Other error condition</dd> | |
847 | <dt>CUPS_SC_STATE_MARKER_EMPTY </dt> | |
848 | <dd class="description">Toner/ink out condition</dd> | |
849 | <dt>CUPS_SC_STATE_MARKER_LOW </dt> | |
850 | <dd class="description">Toner/ink low condition</dd> | |
851 | <dt>CUPS_SC_STATE_MEDIA_EMPTY </dt> | |
852 | <dd class="description">Paper out condition</dd> | |
853 | <dt>CUPS_SC_STATE_MEDIA_LOW </dt> | |
854 | <dd class="description">Paper low condition</dd> | |
855 | <dt>CUPS_SC_STATE_OFFLINE </dt> | |
856 | <dd class="description">Device is off-line</dd> | |
857 | <dt>CUPS_SC_STATE_ONLINE </dt> | |
858 | <dd class="description">Device is on-line</dd> | |
859 | </dl> | |
860 | <h3 class="enumeration"><a name="cups_sc_status_e">cups_sc_status_e</a></h3> | |
861 | <p class="description">Response status codes</p> | |
862 | <h4 class="constants">Constants</h4> | |
863 | <dl> | |
864 | <dt>CUPS_SC_STATUS_BAD_MESSAGE </dt> | |
865 | <dd class="description">The command/response message was invalid</dd> | |
866 | <dt>CUPS_SC_STATUS_IO_ERROR </dt> | |
867 | <dd class="description">An I/O error occurred</dd> | |
868 | <dt>CUPS_SC_STATUS_NONE </dt> | |
869 | <dd class="description">No status</dd> | |
870 | <dt>CUPS_SC_STATUS_NOT_IMPLEMENTED </dt> | |
871 | <dd class="description">Command not implemented</dd> | |
872 | <dt>CUPS_SC_STATUS_NO_RESPONSE </dt> | |
873 | <dd class="description">The device did not respond</dd> | |
874 | <dt>CUPS_SC_STATUS_OK </dt> | |
875 | <dd class="description">Operation succeeded</dd> | |
876 | <dt>CUPS_SC_STATUS_TIMEOUT </dt> | |
877 | <dd class="description">The backend did not respond</dd> | |
878 | <dt>CUPS_SC_STATUS_TOO_BIG </dt> | |
879 | <dd class="description">Response too big</dd> | |
880 | </dl> | |
881 | </div> | |
ef416fc2 | 882 | </body> |
883 | </html> |