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1 | --- |
2 | title: CUPS Programming Manual | |
3 | author: Michael R Sweet | |
9c44e2cb | 4 | copyright: Copyright © 2007-2017 by Apple Inc. All Rights Reserved. |
f1175a5a | 5 | version: 2.2.5 |
abacc52b MS |
6 | ... |
7 | ||
1da024d1 MS |
8 | > Please [file issues on Github](https://github.com/apple/cups/issues) to |
9 | > provide feedback on this document. | |
798d6e29 MS |
10 | |
11 | ||
abacc52b MS |
12 | # Introduction |
13 | ||
14 | CUPS provides the "cups" library to talk to the different parts of CUPS and with | |
15 | Internet Printing Protocol (IPP) printers. The "cups" library functions are | |
16 | accessed by including the `<cups/cups.h>` header. | |
17 | ||
18 | CUPS is based on the Internet Printing Protocol ("IPP"), which allows clients | |
19 | (applications) to communicate with a server (the scheduler, printers, etc.) to | |
20 | get a list of destinations, send print jobs, and so forth. You identify which | |
21 | server you want to communicate with using a pointer to the opaque structure | |
22 | `http_t`. The `CUPS_HTTP_DEFAULT` constant can be used when you want to talk to | |
23 | the CUPS scheduler. | |
24 | ||
25 | ||
26 | ## Guidelines | |
27 | ||
28 | When writing software that uses the "cups" library: | |
29 | ||
30 | - Do not use undocumented or deprecated APIs, | |
31 | - Do not rely on pre-configured printers, | |
32 | - Do not assume that printers support specific features or formats, and | |
33 | - Do not rely on implementation details (PPDs, etc.) | |
34 | ||
35 | CUPS is designed to insulate users and developers from the implementation | |
36 | details of printers and file formats. The goal is to allow an application to | |
37 | supply a print file in a standard format with the user intent ("print four | |
38 | copies, two-sided on A4 media, and staple each copy") and have the printing | |
39 | system manage the printer communication and format conversion needed. | |
40 | ||
41 | Similarly, printer and job management applications can use standard query | |
42 | operations to obtain the status information in a common, generic form and use | |
43 | standard management operations to control the state of those printers and jobs. | |
44 | ||
45 | ||
46 | ## Terms Used in This Document | |
47 | ||
48 | A *Destination* is a printer or print queue that accepts print jobs. A | |
49 | *Print Job* is one or more documents that are processed by a destination | |
50 | using options supplied when creating the job. A *Document* is a file (JPEG | |
51 | image, PDF file, etc.) suitable for printing. An *Option* controls some aspect | |
52 | of printing, such as the media used. *Media* is the sheets or roll that is | |
53 | printed on. An *Attribute* is an option encoded for an Internet Printing | |
54 | Protocol (IPP) request. | |
55 | ||
56 | ||
57 | ## Compiling Programs That Use the CUPS API | |
58 | ||
59 | The CUPS libraries can be used from any C, C++, or Objective C program. | |
60 | The method of compiling against the libraries varies depending on the | |
61 | operating system and installation of CUPS. The following sections show how | |
62 | to compile a simple program (shown below) in two common environments. | |
63 | ||
64 | The following simple program lists the available destinations: | |
65 | ||
66 | #include <stdio.h> | |
67 | #include <cups/cups.h> | |
68 | ||
69 | int print_dest(void *user_data, unsigned flags, cups_dest_t *dest) | |
70 | { | |
71 | if (dest->instance) | |
72 | printf("%s/%s\n", dest->name, dest->instance); | |
73 | else | |
74 | puts(dest->name); | |
75 | ||
76 | return (1); | |
77 | } | |
78 | ||
79 | int main(void) | |
80 | { | |
81 | cupsEnumDests(CUPS_DEST_FLAGS_NONE, 1000, NULL, 0, 0, print_dest, NULL); | |
82 | ||
83 | return (0); | |
84 | } | |
85 | ||
86 | ||
87 | ### Compiling with Xcode | |
88 | ||
89 | In Xcode, choose *New Project...* from the *File* menu (or press SHIFT+CMD+N), | |
90 | then select the *Command Line Tool* under the macOS Application project type. | |
91 | Click *Next* and enter a name for the project, for example "firstcups". Click | |
92 | *Next* and choose a project directory. The click *Next* to create the project. | |
93 | ||
94 | In the project window, click on the *Build Phases* group and expand the | |
95 | *Link Binary with Libraries* section. Click *+*, type "libcups" to show the | |
96 | library, and then double-click on `libcups.tbd`. | |
97 | ||
98 | Finally, click on the `main.c` file in the sidebar and copy the example program | |
99 | to the file. Build and run (CMD+R) to see the list of destinations. | |
100 | ||
101 | ||
102 | ### Compiling with GCC | |
103 | ||
104 | From the command-line, create a file called `sample.c` using your favorite | |
105 | editor, copy the example to this file, and save. Then run the following command | |
106 | to compile it with GCC and run it: | |
107 | ||
108 | gcc -o simple `cups-config --cflags` simple.c `cups-config --libs` | |
109 | ./simple | |
110 | ||
111 | The `cups-config` command provides the compiler flags (`cups-config --cflags`) | |
112 | and libraries (`cups-config --libs`) needed for the local system. | |
113 | ||
114 | ||
115 | # Working with Destinations | |
116 | ||
798d6e29 | 117 | Destinations, which in CUPS represent individual printers or classes |
9c44e2cb MS |
118 | (collections or pools) of printers, are represented by the `cups_dest_t` |
119 | structure which includes the name \(`name`), instance \(`instance`, saved | |
120 | options/settings), whether the destination is the default for the user | |
121 | \(`is_default`), and the options and basic information associated with that | |
122 | destination \(`num_options` and `options`). | |
abacc52b | 123 | |
798d6e29 MS |
124 | Historically destinations have been manually maintained by the administrator of |
125 | a system or network, but CUPS also supports dynamic discovery of destinations on | |
126 | the current network. | |
abacc52b | 127 | |
abacc52b | 128 | |
798d6e29 | 129 | ## Finding Available Destinations |
abacc52b | 130 | |
798d6e29 MS |
131 | The `cupsEnumDests` function finds all of the available destinations: |
132 | ||
133 | int | |
134 | cupsEnumDests(unsigned flags, int msec, int *cancel, | |
135 | cups_ptype_t type, cups_ptype_t mask, | |
136 | cups_dest_cb_t cb, void *user_data) | |
137 | ||
138 | The `flags` argument specifies enumeration options, which at present must be | |
139 | `CUPS_DEST_FLAGS_NONE`. | |
140 | ||
141 | The `msec` argument specifies the maximum amount of time that should be used for | |
142 | enumeration in milliseconds - interactive applications should keep this value to | |
143 | 5000 or less when run on the main thread. | |
144 | ||
145 | The `cancel` argument points to an integer variable that, when set to a non-zero | |
146 | value, will cause enumeration to stop as soon as possible. It can be `NULL` if | |
147 | not needed. | |
148 | ||
149 | The `type` and `mask` arguments are bitfields that allow the caller to filter | |
150 | the destinations based on categories and/or capabilities. The destination's | |
151 | "printer-type" value is masked by the `mask` value and compared to the `type` | |
152 | value when filtering. For example, to only enumerate destinations that are | |
153 | hosted on the local system, pass `CUPS_PRINTER_LOCAL` for the `type` argument | |
f50db552 MS |
154 | and `CUPS_PRINTER_DISCOVERED` for the `mask` argument. The following constants |
155 | can be used for filtering: | |
798d6e29 MS |
156 | |
157 | - `CUPS_PRINTER_CLASS`: A collection of destinations. | |
158 | - `CUPS_PRINTER_FAX`: A facsimile device. | |
159 | - `CUPS_PRINTER_LOCAL`: A local printer or class. This constant has the value 0 | |
160 | (no bits set) and is only used for the `type` argument and is paired with the | |
f50db552 MS |
161 | `CUPS_PRINTER_REMOTE` or `CUPS_PRINTER_DISCOVERED` constant passed in the |
162 | `mask` argument. | |
163 | - `CUPS_PRINTER_REMOTE`: A remote (shared) printer or class. | |
164 | - `CUPS_PRINTER_DISCOVERED`: An available network printer or class. | |
798d6e29 MS |
165 | - `CUPS_PRINTER_BW`: Can do B&W printing. |
166 | - `CUPS_PRINTER_COLOR`: Can do color printing. | |
167 | - `CUPS_PRINTER_DUPLEX`: Can do two-sided printing. | |
168 | - `CUPS_PRINTER_STAPLE`: Can staple output. | |
169 | - `CUPS_PRINTER_COLLATE`: Can quickly collate copies. | |
170 | - `CUPS_PRINTER_PUNCH`: Can punch output. | |
171 | - `CUPS_PRINTER_COVER`: Can cover output. | |
172 | - `CUPS_PRINTER_BIND`: Can bind output. | |
173 | - `CUPS_PRINTER_SORT`: Can sort output (mailboxes, etc.) | |
174 | - `CUPS_PRINTER_SMALL`: Can print on Letter/Legal/A4-size media. | |
175 | - `CUPS_PRINTER_MEDIUM`: Can print on Tabloid/B/C/A3/A2-size media. | |
176 | - `CUPS_PRINTER_LARGE`: Can print on D/E/A1/A0-size media. | |
177 | - `CUPS_PRINTER_VARIABLE`: Can print on rolls and custom-size media. | |
178 | ||
179 | The `cb` argument specifies a function to call for every destination that is | |
180 | found: | |
181 | ||
182 | typedef int (*cups_dest_cb_t)(void *user_data, | |
183 | unsigned flags, | |
184 | cups_dest_t *dest); | |
185 | ||
186 | The callback function receives a copy of the `user_data` argument along with a | |
187 | bitfield \(`flags`) and the destination that was found. The `flags` argument | |
188 | can have any of the following constant (bit) values set: | |
189 | ||
190 | - `CUPS_DEST_FLAGS_MORE`: There are more destinations coming. | |
191 | - `CUPS_DEST_FLAGS_REMOVED`: The destination has gone away and should be removed | |
192 | from the list of destinations a user can select. | |
193 | - `CUPS_DEST_FLAGS_ERROR`: An error occurred. The reason for the error can be | |
194 | found by calling the `cupsLastError` and/or `cupsLastErrorString` functions. | |
195 | ||
196 | The callback function returns 0 to stop enumeration or 1 to continue. | |
197 | ||
500fca27 MS |
198 | > Note that the callback function will likely be called multiple times for the |
199 | > same destination, so it is up to the caller to suppress any duplicate | |
200 | > destinations. | |
201 | ||
798d6e29 MS |
202 | The following example shows how to use `cupsEnumDests` to get a filtered array |
203 | of destinations: | |
204 | ||
205 | typedef struct | |
206 | { | |
207 | int num_dests; | |
208 | cups_dest_t *dests; | |
209 | } my_user_data_t; | |
abacc52b | 210 | |
798d6e29 MS |
211 | int |
212 | my_dest_cb(my_user_data_t *user_data, unsigned flags, | |
213 | cups_dest_t *dest) | |
214 | { | |
215 | if (flags & CUPS_DEST_FLAGS_REMOVED) | |
216 | { | |
217 | /* | |
218 | * Remove destination from array... | |
219 | */ | |
220 | ||
221 | user_data->num_dests = | |
222 | cupsRemoveDest(dest->name, dest->instance, | |
223 | user_data->num_dests, | |
224 | &(user_data->dests)); | |
225 | } | |
226 | else | |
227 | { | |
228 | /* | |
229 | * Add destination to array... | |
230 | */ | |
abacc52b | 231 | |
798d6e29 MS |
232 | user_data->num_dests = |
233 | cupsCopyDest(dest, user_data->num_dests, | |
234 | &(user_data->dests)); | |
235 | } | |
abacc52b | 236 | |
798d6e29 MS |
237 | return (1); |
238 | } | |
abacc52b | 239 | |
798d6e29 MS |
240 | int |
241 | my_get_dests(cups_ptype_t type, cups_ptype_t mask, | |
242 | cups_dest_t **dests) | |
243 | { | |
244 | my_user_data_t user_data = { 0, NULL }; | |
abacc52b | 245 | |
798d6e29 MS |
246 | if (!cupsEnumDests(CUPS_DEST_FLAGS_NONE, 1000, NULL, type, |
247 | mask, (cups_dest_cb_t)my_dest_cb, | |
248 | &user_data)) | |
249 | { | |
250 | /* | |
251 | * An error occurred, free all of the destinations and | |
252 | * return... | |
253 | */ | |
abacc52b | 254 | |
798d6e29 | 255 | cupsFreeDests(user_data.num_dests, user_dasta.dests); |
abacc52b | 256 | |
798d6e29 | 257 | *dests = NULL; |
abacc52b | 258 | |
798d6e29 MS |
259 | return (0); |
260 | } | |
abacc52b | 261 | |
798d6e29 MS |
262 | /* |
263 | * Return the destination array... | |
264 | */ | |
abacc52b | 265 | |
798d6e29 | 266 | *dests = user_data.dests; |
abacc52b | 267 | |
798d6e29 MS |
268 | return (user_data.num_dests); |
269 | } | |
abacc52b | 270 | |
abacc52b | 271 | |
798d6e29 MS |
272 | ## Basic Destination Information |
273 | ||
274 | The `num_options` and `options` members of the `cups_dest_t` structure provide | |
275 | basic attributes about the destination in addition to the user default options | |
276 | and values for that destination. The following names are predefined for various | |
277 | destination attributes: | |
278 | ||
279 | - "auth-info-required": The type of authentication required for printing to this | |
280 | destination: "none", "username,password", "domain,username,password", or | |
281 | "negotiate" (Kerberos). | |
282 | - "printer-info": The human-readable description of the destination such as "My | |
283 | Laser Printer". | |
284 | - "printer-is-accepting-jobs": "true" if the destination is accepting new jobs, | |
285 | "false" otherwise. | |
286 | - "printer-is-shared": "true" if the destination is being shared with other | |
287 | computers, "false" otherwise. | |
288 | - "printer-location": The human-readable location of the destination such as | |
289 | "Lab 4". | |
290 | - "printer-make-and-model": The human-readable make and model of the destination | |
291 | such as "ExampleCorp LaserPrinter 4000 Series". | |
292 | - "printer-state": "3" if the destination is idle, "4" if the destination is | |
293 | printing a job, and "5" if the destination is stopped. | |
294 | - "printer-state-change-time": The UNIX time when the destination entered the | |
295 | current state. | |
296 | - "printer-state-reasons": Additional comma-delimited state keywords for the | |
297 | destination such as "media-tray-empty-error" and "toner-low-warning". | |
298 | - "printer-type": The `cups_ptype_t` value associated with the destination. | |
53af7f21 MS |
299 | - "printer-uri-supported": The URI associated with the destination; if not set, |
300 | this destination was discovered but is not yet setup as a local printer. | |
798d6e29 MS |
301 | |
302 | Use the `cupsGetOption` function to retrieve the value. For example, the | |
303 | following code gets the make and model of a destination: | |
304 | ||
305 | const char *model = cupsGetOption("printer-make-and-model", | |
306 | dest->num_options, | |
307 | dest->options); | |
308 | ||
53af7f21 | 309 | |
798d6e29 MS |
310 | ## Detailed Destination Information |
311 | ||
312 | Once a destination has been chosen, the `cupsCopyDestInfo` function can be used | |
313 | to gather detailed information about the destination: | |
314 | ||
315 | cups_dinfo_t * | |
316 | cupsCopyDestInfo(http_t *http, cups_dest_t *dest); | |
317 | ||
318 | The `http` argument specifies a connection to the CUPS scheduler and is | |
319 | typically the constant `CUPS_HTTP_DEFAULT`. The `dest` argument specifies the | |
320 | destination to query. | |
321 | ||
322 | The `cups_dinfo_t` structure that is returned contains a snapshot of the | |
323 | supported options and their supported, ready, and default values. It also can | |
324 | report constraints between different options and values, and recommend changes | |
325 | to resolve those constraints. | |
abacc52b | 326 | |
53af7f21 | 327 | |
798d6e29 | 328 | ### Getting Supported Options and Values |
abacc52b | 329 | |
798d6e29 MS |
330 | The `cupsCheckDestSupported` function can be used to test whether a particular |
331 | option or option and value is supported: | |
332 | ||
333 | int | |
334 | cupsCheckDestSupported(http_t *http, cups_dest_t *dest, | |
335 | cups_dinfo_t *info, | |
336 | const char *option, | |
337 | const char *value); | |
338 | ||
339 | The `option` argument specifies the name of the option to check. The following | |
340 | constants can be used to check the various standard options: | |
341 | ||
342 | - `CUPS_COPIES`: Controls the number of copies that are produced. | |
343 | - `CUPS_FINISHINGS`: A comma-delimited list of integer constants that control | |
344 | the finishing processes that are applied to the job, including stapling, | |
345 | punching, and folding. | |
346 | - `CUPS_MEDIA`: Controls the media size that is used, typically one of the | |
347 | following: `CUPS_MEDIA_3X5`, `CUPS_MEDIA_4X6`, `CUPS_MEDIA_5X7`, | |
348 | `CUPS_MEDIA_8X10`, `CUPS_MEDIA_A3`, `CUPS_MEDIA_A4`, `CUPS_MEDIA_A5`, | |
349 | `CUPS_MEDIA_A6`, `CUPS_MEDIA_ENV10`, `CUPS_MEDIA_ENVDL`, `CUPS_MEDIA_LEGAL`, | |
350 | `CUPS_MEDIA_LETTER`, `CUPS_MEDIA_PHOTO_L`, `CUPS_MEDIA_SUPERBA3`, or | |
351 | `CUPS_MEDIA_TABLOID`. | |
352 | - `CUPS_MEDIA_SOURCE`: Controls where the media is pulled from, typically either | |
353 | `CUPS_MEDIA_SOURCE_AUTO` or `CUPS_MEDIA_SOURCE_MANUAL`. | |
354 | - `CUPS_MEDIA_TYPE`: Controls the type of media that is used, typically one of | |
355 | the following: `CUPS_MEDIA_TYPE_AUTO`, `CUPS_MEDIA_TYPE_ENVELOPE`, | |
356 | `CUPS_MEDIA_TYPE_LABELS`, `CUPS_MEDIA_TYPE_LETTERHEAD`, | |
357 | `CUPS_MEDIA_TYPE_PHOTO`, `CUPS_MEDIA_TYPE_PHOTO_GLOSSY`, | |
358 | `CUPS_MEDIA_TYPE_PHOTO_MATTE`, `CUPS_MEDIA_TYPE_PLAIN`, or | |
359 | `CUPS_MEDIA_TYPE_TRANSPARENCY`. | |
360 | - `CUPS_NUMBER_UP`: Controls the number of document pages that are placed on | |
361 | each media side. | |
362 | - `CUPS_ORIENTATION`: Controls the orientation of document pages placed on the | |
363 | media: `CUPS_ORIENTATION_PORTRAIT` or `CUPS_ORIENTATION_LANDSCAPE`. | |
364 | - `CUPS_PRINT_COLOR_MODE`: Controls whether the output is in color | |
365 | \(`CUPS_PRINT_COLOR_MODE_COLOR`), grayscale | |
366 | \(`CUPS_PRINT_COLOR_MODE_MONOCHROME`), or either | |
367 | \(`CUPS_PRINT_COLOR_MODE_AUTO`). | |
368 | - `CUPS_PRINT_QUALITY`: Controls the generate quality of the output: | |
369 | `CUPS_PRINT_QUALITY_DRAFT`, `CUPS_PRINT_QUALITY_NORMAL`, or | |
370 | `CUPS_PRINT_QUALITY_HIGH`. | |
371 | - `CUPS_SIDES`: Controls whether prints are placed on one or both sides of the | |
372 | media: `CUPS_SIDES_ONE_SIDED`, `CUPS_SIDES_TWO_SIDED_PORTRAIT`, or | |
373 | `CUPS_SIDES_TWO_SIDED_LANDSCAPE`. | |
374 | ||
375 | If the `value` argument is `NULL`, the `cupsCheckDestSupported` function returns | |
376 | whether the option is supported by the destination. Otherwise, the function | |
377 | returns whether the specified value of the option is supported. | |
378 | ||
379 | The `cupsFindDestSupported` function returns the IPP attribute containing the | |
380 | supported values for a given option: | |
381 | ||
382 | ipp_attribute_t * | |
383 | cupsFindDestSupported(http_t *http, cups_dest_t *dest, | |
384 | cups_dinfo_t *dinfo, | |
385 | const char *option); | |
386 | ||
387 | For example, the following code prints the supported finishing processes for a | |
388 | destination, if any, to the standard output: | |
389 | ||
390 | cups_dinfo_t *info = cupsCopyDestInfo(CUPS_HTTP_DEFAULT, | |
391 | dest); | |
392 | ||
393 | if (cupsCheckDestSupported(CUPS_HTTP_DEFAULT, dest, info, | |
394 | CUPS_FINISHINGS, NULL)) | |
395 | { | |
396 | ipp_attribute_t *finishings = | |
397 | cupsFindDestSupported(CUPS_HTTP_DEFAULT, dest, info, | |
398 | CUPS_FINISHINGS); | |
399 | int i, count = ippGetCount(finishings); | |
400 | ||
401 | puts("finishings supported:"); | |
402 | for (i = 0; i < count; i ++) | |
403 | printf(" %d\n", ippGetInteger(finishings, i)); | |
404 | } | |
405 | else | |
406 | puts("finishings not supported."); | |
abacc52b | 407 | |
798d6e29 MS |
408 | The "job-creation-attributes" option can be queried to get a list of supported |
409 | options. For example, the following code prints the list of supported options | |
410 | to the standard output: | |
abacc52b | 411 | |
798d6e29 MS |
412 | ipp_attribute_t *attrs = |
413 | cupsFindDestSupported(CUPS_HTTP_DEFAULT, dest, info, | |
414 | "job-creation-attributes"); | |
415 | int i, count = ippGetCount(attrs); | |
abacc52b | 416 | |
798d6e29 MS |
417 | for (i = 0; i < count; i ++) |
418 | puts(ippGetString(attrs, i, NULL)); | |
abacc52b MS |
419 | |
420 | ||
798d6e29 | 421 | ### Getting Default Values |
abacc52b | 422 | |
798d6e29 MS |
423 | There are two sets of default values - user defaults that are available via the |
424 | `num_options` and `options` members of the `cups_dest_t` structure, and | |
425 | destination defaults that available via the `cups_dinfo_t` structure and the | |
426 | `cupsFindDestDefault` function which returns the IPP attribute containing the | |
427 | default value(s) for a given option: | |
abacc52b | 428 | |
798d6e29 MS |
429 | ipp_attribute_t * |
430 | cupsFindDestDefault(http_t *http, cups_dest_t *dest, | |
431 | cups_dinfo_t *dinfo, | |
432 | const char *option); | |
abacc52b | 433 | |
798d6e29 MS |
434 | The user defaults from `cupsGetOption` should always take preference over the |
435 | destination defaults. For example, the following code prints the default | |
436 | finishings value(s) to the standard output: | |
abacc52b | 437 | |
798d6e29 MS |
438 | const char *def_value = |
439 | cupsGetOption(CUPS_FINISHINGS, dest->num_options, | |
440 | dest->options); | |
441 | ipp_attribute_t *def_attr = | |
442 | cupsFindDestDefault(CUPS_HTTP_DEFAULT, dest, info, | |
443 | CUPS_FINISHINGS); | |
abacc52b | 444 | |
798d6e29 MS |
445 | if (def_value != NULL) |
446 | { | |
447 | printf("Default finishings: %s\n", def_value); | |
448 | } | |
449 | else | |
450 | { | |
451 | int i, count = ippGetCount(def_attr); | |
abacc52b | 452 | |
798d6e29 MS |
453 | printf("Default finishings: %d", |
454 | ippGetInteger(def_attr, 0)); | |
455 | for (i = 1; i < count; i ++) | |
456 | printf(",%d", ippGetInteger(def_attr, i)); | |
457 | putchar('\n'); | |
458 | } | |
abacc52b MS |
459 | |
460 | ||
798d6e29 | 461 | ### Getting Ready (Loaded) Values |
abacc52b | 462 | |
798d6e29 MS |
463 | The finishings and media options also support queries for the ready, or loaded, |
464 | values. For example, a printer may have punch and staple finishers installed | |
465 | but be out of staples - the supported values will list both punch and staple | |
466 | finishing processes but the ready values will only list the punch processes. | |
467 | Similarly, a printer may support hundreds of different sizes of media but only | |
468 | have a single size loaded at any given time - the ready values are limited to | |
469 | the media that is actually in the printer. | |
abacc52b | 470 | |
798d6e29 MS |
471 | The `cupsFindDestReady` function finds the IPP attribute containing the ready |
472 | values for a given option: | |
abacc52b | 473 | |
798d6e29 MS |
474 | ipp_attribute_t * |
475 | cupsFindDestReady(http_t *http, cups_dest_t *dest, | |
476 | cups_dinfo_t *dinfo, const char *option); | |
abacc52b | 477 | |
798d6e29 | 478 | For example, the following code lists the ready finishing processes: |
abacc52b | 479 | |
798d6e29 MS |
480 | ipp_attribute_t *ready_finishings = |
481 | cupsFindDestReady(CUPS_HTTP_DEFAULT, dest, info, | |
482 | CUPS_FINISHINGS); | |
abacc52b | 483 | |
798d6e29 MS |
484 | if (ready_finishings != NULL) |
485 | { | |
486 | int i, count = ippGetCount(ready_finishings); | |
abacc52b | 487 | |
798d6e29 MS |
488 | puts("finishings ready:"); |
489 | for (i = 0; i < count; i ++) | |
490 | printf(" %d\n", ippGetInteger(ready_finishings, i)); | |
491 | } | |
492 | else | |
493 | puts("no finishings are ready."); | |
abacc52b | 494 | |
abacc52b | 495 | |
798d6e29 | 496 | ### Media Size Options |
abacc52b | 497 | |
798d6e29 MS |
498 | CUPS provides functions for querying the dimensions and margins for each of the |
499 | supported media size options. The `cups_size_t` structure is used to describe a | |
500 | media size: | |
abacc52b | 501 | |
798d6e29 MS |
502 | typedef struct cups_size_s |
503 | { | |
504 | char media[128]; | |
505 | int width, length; | |
506 | int bottom, left, right, top; | |
507 | } cups_size_t; | |
508 | ||
509 | The `width` and `length` members specify the dimensions of the media in | |
510 | hundredths of millimeters (1/2540th of an inch). The `bottom`, `left`, `right`, | |
511 | and `top` members specify the margins of the printable area, also in hundredths | |
512 | of millimeters. | |
513 | ||
514 | The `cupsGetDestMediaByName` and `cupsGetDestMediaBySize` functions lookup the | |
515 | media size information using a standard media size name or dimensions in | |
516 | hundredths of millimeters: | |
517 | ||
518 | int | |
519 | cupsGetDestMediaByName(http_t *http, cups_dest_t *dest, | |
520 | cups_dinfo_t *dinfo, | |
521 | const char *media, | |
522 | unsigned flags, cups_size_t *size); | |
523 | ||
524 | int | |
525 | cupsGetDestMediaBySize(http_t *http, cups_dest_t *dest, | |
526 | cups_dinfo_t *dinfo, | |
527 | int width, int length, | |
528 | unsigned flags, cups_size_t *size); | |
529 | ||
530 | The `media`, `width`, and `length` arguments specify the size to lookup. The | |
531 | `flags` argument specifies a bitfield controlling various lookup options: | |
532 | ||
533 | - `CUPS_MEDIA_FLAGS_DEFAULT`: Find the closest size supported by the printer. | |
534 | - `CUPS_MEDIA_FLAGS_BORDERLESS`: Find a borderless size. | |
535 | - `CUPS_MEDIA_FLAGS_DUPLEX`: Find a size compatible with two-sided printing. | |
536 | - `CUPS_MEDIA_FLAGS_EXACT`: Find an exact match for the size. | |
537 | - `CUPS_MEDIA_FLAGS_READY`: If the printer supports media sensing or | |
538 | configuration of the media in each tray/source, find the size amongst the | |
539 | "ready" media. | |
540 | ||
541 | If a matching size is found for the destination, the size information is stored | |
542 | in the structure pointed to by the `size` argument and 1 is returned. Otherwise | |
543 | 0 is returned. | |
544 | ||
545 | For example, the following code prints the margins for two-sided printing on US | |
546 | Letter media: | |
547 | ||
548 | cups_size_t size; | |
549 | ||
550 | if (cupsGetDestMediaByName(CUPS_HTTP_DEFAULT, dest, info, | |
551 | CUPS_MEDIA_LETTER, | |
552 | CUPS_MEDIA_FLAGS_DUPLEX, &size)) | |
abacc52b | 553 | { |
798d6e29 MS |
554 | puts("Margins for duplex US Letter:"); |
555 | printf(" Bottom: %.2fin\n", size.bottom / 2540.0); | |
556 | printf(" Left: %.2fin\n", size.left / 2540.0); | |
557 | printf(" Right: %.2fin\n", size.right / 2540.0); | |
558 | printf(" Top: %.2fin\n", size.top / 2540.0); | |
abacc52b | 559 | } |
798d6e29 MS |
560 | else |
561 | puts("Margins for duplex US Letter are not available."); | |
abacc52b | 562 | |
798d6e29 MS |
563 | You can also enumerate all of the sizes that match a given `flags` value using |
564 | the `cupsGetDestMediaByIndex` and `cupsGetDestMediaCount` functions: | |
abacc52b | 565 | |
798d6e29 MS |
566 | int |
567 | cupsGetDestMediaByIndex(http_t *http, cups_dest_t *dest, | |
568 | cups_dinfo_t *dinfo, int n, | |
569 | unsigned flags, cups_size_t *size); | |
abacc52b | 570 | |
798d6e29 MS |
571 | int |
572 | cupsGetDestMediaCount(http_t *http, cups_dest_t *dest, | |
573 | cups_dinfo_t *dinfo, unsigned flags); | |
abacc52b | 574 | |
798d6e29 MS |
575 | For example, the following code prints the list of ready media and corresponding |
576 | margins: | |
abacc52b | 577 | |
798d6e29 MS |
578 | cups_size_t size; |
579 | int i; | |
580 | int count = cupsGetDestMediaCount(CUPS_HTTP_DEFAULT, | |
581 | dest, info, | |
582 | CUPS_MEDIA_FLAGS_READY); | |
abacc52b | 583 | |
798d6e29 MS |
584 | for (i = 0; i < count; i ++) |
585 | { | |
586 | if (cupsGetDestMediaByIndex(CUPS_HTTP_DEFAULT, dest, info, | |
587 | i, CUPS_MEDIA_FLAGS_READY, | |
588 | &size)) | |
589 | { | |
590 | printf("%s:\n", size.name); | |
591 | printf(" Width: %.2fin\n", size.width / 2540.0); | |
592 | printf(" Length: %.2fin\n", size.length / 2540.0); | |
593 | printf(" Bottom: %.2fin\n", size.bottom / 2540.0); | |
594 | printf(" Left: %.2fin\n", size.left / 2540.0); | |
595 | printf(" Right: %.2fin\n", size.right / 2540.0); | |
596 | printf(" Top: %.2fin\n", size.top / 2540.0); | |
597 | } | |
598 | } | |
abacc52b | 599 | |
798d6e29 | 600 | Finally, the `cupsGetDestMediaDefault` function returns the default media size: |
abacc52b | 601 | |
798d6e29 MS |
602 | int |
603 | cupsGetDestMediaDefault(http_t *http, cups_dest_t *dest, | |
604 | cups_dinfo_t *dinfo, unsigned flags, | |
605 | cups_size_t *size); | |
abacc52b | 606 | |
abacc52b | 607 | |
798d6e29 | 608 | ### Localizing Options and Values |
abacc52b | 609 | |
6ad44eeb MS |
610 | CUPS provides three functions to get localized, human-readable strings in the |
611 | user's current locale for options and values: `cupsLocalizeDestMedia`, | |
612 | `cupsLocalizeDestOption`, and `cupsLocalizeDestValue`: | |
abacc52b | 613 | |
798d6e29 MS |
614 | const char * |
615 | cupsLocalizeDestMedia(http_t *http, cups_dest_t *dest, | |
616 | cups_dinfo_t *info, unsigned flags, | |
617 | cups_size_t *size); | |
abacc52b | 618 | |
798d6e29 MS |
619 | const char * |
620 | cupsLocalizeDestOption(http_t *http, cups_dest_t *dest, | |
621 | cups_dinfo_t *info, | |
622 | const char *option); | |
abacc52b | 623 | |
798d6e29 MS |
624 | const char * |
625 | cupsLocalizeDestValue(http_t *http, cups_dest_t *dest, | |
626 | cups_dinfo_t *info, | |
627 | const char *option, const char *value); | |
abacc52b | 628 | |
abacc52b | 629 | |
798d6e29 | 630 | ## Submitting a Print Job |
abacc52b | 631 | |
798d6e29 MS |
632 | Once you are ready to submit a print job, you create a job using the |
633 | `cupsCreateDestJob` function: | |
634 | ||
635 | ipp_status_t | |
636 | cupsCreateDestJob(http_t *http, cups_dest_t *dest, | |
637 | cups_dinfo_t *info, int *job_id, | |
638 | const char *title, int num_options, | |
639 | cups_option_t *options); | |
640 | ||
641 | The `title` argument specifies a name for the print job such as "My Document". | |
642 | The `num_options` and `options` arguments specify the options for the print | |
643 | job which are allocated using the `cupsAddOption` function. | |
644 | ||
645 | When successful, the job's numeric identifier is stored in the integer pointed | |
646 | to by the `job_id` argument and `IPP_STATUS_OK` is returned. Otherwise, an IPP | |
647 | error status is returned. | |
648 | ||
649 | For example, the following code creates a new job that will print 42 copies of a | |
650 | two-sided US Letter document: | |
651 | ||
652 | int job_id = 0; | |
653 | int num_options = 0; | |
654 | cups_option_t *options = NULL; | |
655 | ||
656 | num_options = cupsAddOption(CUPS_COPIES, "42", | |
657 | num_options, &options); | |
658 | num_options = cupsAddOption(CUPS_MEDIA, CUPS_MEDIA_LETTER, | |
659 | num_options, &options); | |
660 | num_options = cupsAddOption(CUPS_SIDES, | |
661 | CUPS_SIDES_TWO_SIDED_PORTRAIT, | |
662 | num_options, &options); | |
663 | ||
664 | if (cupsCreateDestJob(CUPS_HTTP_DEFAULT, dest, info, | |
665 | &job_id, "My Document", num_options, | |
666 | options) == IPP_STATUS_OK) | |
667 | printf("Created job: %d\n", job_id); | |
668 | else | |
669 | printf("Unable to create job: %s\n", | |
670 | cupsLastErrorString()); | |
671 | ||
672 | Once the job is created, you submit documents for the job using the | |
673 | `cupsStartDestDocument`, `cupsWriteRequestData`, and `cupsFinishDestDocument` | |
674 | functions: | |
675 | ||
676 | http_status_t | |
677 | cupsStartDestDocument(http_t *http, cups_dest_t *dest, | |
678 | cups_dinfo_t *info, int job_id, | |
679 | const char *docname, | |
680 | const char *format, | |
681 | int num_options, | |
682 | cups_option_t *options, | |
683 | int last_document); | |
684 | ||
685 | http_status_t | |
686 | cupsWriteRequestData(http_t *http, const char *buffer, | |
687 | size_t length); | |
688 | ||
689 | ipp_status_t | |
690 | cupsFinishDestDocument(http_t *http, cups_dest_t *dest, | |
691 | cups_dinfo_t *info); | |
692 | ||
693 | The `docname` argument specifies the name of the document, typically the | |
694 | original filename. The `format` argument specifies the MIME media type of the | |
695 | document, including the following constants: | |
696 | ||
697 | - `CUPS_FORMAT_JPEG`: "image/jpeg" | |
698 | - `CUPS_FORMAT_PDF`: "application/pdf" | |
699 | - `CUPS_FORMAT_POSTSCRIPT`: "application/postscript" | |
700 | - `CUPS_FORMAT_TEXT`: "text/plain" | |
701 | ||
702 | The `num_options` and `options` arguments specify per-document print options, | |
703 | which at present must be 0 and `NULL`. The `last_document` argument specifies | |
704 | whether this is the last document in the job. | |
705 | ||
706 | For example, the following code submits a PDF file to the job that was just | |
707 | created: | |
708 | ||
709 | FILE *fp = fopen("filename.pdf", "rb"); | |
710 | size_t bytes; | |
711 | char buffer[65536]; | |
712 | ||
713 | if (cupsStartDestDocument(CUPS_HTTP_DEFAULT, dest, info, | |
714 | job_id, "filename.pdf", 0, NULL, | |
715 | 1) == HTTP_STATUS_CONTINUE) | |
abacc52b | 716 | { |
798d6e29 MS |
717 | while ((bytes = fread(buffer, 1, sizeof(buffer), fp)) > 0) |
718 | if (cupsWriteRequestData(CUPS_HTTP_DEFAULT, buffer, | |
719 | bytes) != HTTP_STATUS_CONTINUE) | |
720 | break; | |
721 | ||
722 | if (cupsFinishDestDocument(CUPS_HTTP_DEFAULT, dest, | |
723 | info) == IPP_STATUS_OK) | |
724 | puts("Document send succeeded."); | |
725 | else | |
726 | printf("Document send failed: %s\n", | |
727 | cupsLastErrorString()); | |
abacc52b | 728 | } |
798d6e29 MS |
729 | |
730 | fclose(fp); | |
65bebeac MS |
731 | |
732 | ||
733 | # Sending IPP Requests | |
734 | ||
b0fb2d75 MS |
735 | CUPS provides a rich API for sending IPP requests to the scheduler or printers, |
736 | typically from management or utility applications whose primary purpose is not | |
737 | to send print jobs. | |
738 | ||
739 | ||
65bebeac MS |
740 | ## Connecting to the Scheduler or Printer |
741 | ||
b0fb2d75 MS |
742 | The connection to the scheduler or printer is represented by the HTTP connection |
743 | type `http_t`. The `cupsConnectDest` function connects to the scheduler or | |
744 | printer associated with the destination: | |
745 | ||
746 | http_t * | |
747 | cupsConnectDest(cups_dest_t *dest, unsigned flags, int msec, | |
748 | int *cancel, char *resource, | |
749 | size_t resourcesize, cups_dest_cb_t cb, | |
750 | void *user_data); | |
751 | ||
752 | The `dest` argument specifies the destination to connect to. | |
753 | ||
754 | The `flags` argument specifies whether you want to connect to the scheduler | |
755 | (`CUPS_DEST_FLAGS_NONE`) or device/printer (`CUPS_DEST_FLAGS_DEVICE`) associated | |
756 | with the destination. | |
757 | ||
758 | The `msec` argument specifies how long you are willing to wait for the | |
759 | connection to be established in milliseconds. Specify a value of `-1` to wait | |
760 | indefinitely. | |
761 | ||
762 | The `cancel` argument specifies the address of an integer variable that can be | |
763 | set to a non-zero value to cancel the connection. Specify a value of `NULL` | |
764 | to not provide a cancel variable. | |
765 | ||
766 | The `resource` and `resourcesize` arguments specify the address and size of a | |
767 | character string array to hold the path to use when sending an IPP request. | |
768 | ||
769 | The `cb` and `user_data` arguments specify a destination callback function that | |
770 | returns 1 to continue connecting or 0 to stop. The destination callback work | |
771 | the same way as the one used for the `cupsEnumDests` function. | |
65bebeac | 772 | |
b0fb2d75 MS |
773 | On success, a HTTP connection is returned that can be used to send IPP requests |
774 | and get IPP responses. | |
775 | ||
776 | For example, the following code connects to the printer associated with a | |
777 | destination with a 30 second timeout: | |
778 | ||
779 | char resource[256]; | |
780 | http_t *http = cupsConnectDest(dest, CUPS_DEST_FLAGS_DEVICE, | |
781 | 30000, NULL, resource, | |
782 | sizeof(resource), NULL, NULL); | |
65bebeac MS |
783 | |
784 | ||
785 | ## Creating an IPP Request | |
786 | ||
b0fb2d75 MS |
787 | IPP requests are represented by the IPP message type `ipp_t` and each IPP |
788 | attribute in the request is representing using the type `ipp_attribute_t`. Each | |
789 | IPP request includes an operation code (`IPP_OP_CREATE_JOB`, | |
790 | `IPP_OP_GET_PRINTER_ATTRIBUTES`, etc.) and a 32-bit integer identifier. | |
791 | ||
792 | The `ippNewRequest` function creates a new IPP request: | |
793 | ||
794 | ipp_t * | |
795 | ippNewRequest(ipp_op_t op); | |
796 | ||
797 | The `op` argument specifies the IPP operation code for the request. For | |
798 | example, the following code creates an IPP Get-Printer-Attributes request: | |
799 | ||
800 | ipp_t *request = ippNewRequest(IPP_OP_GET_PRINTER_ATTRIBUTES); | |
801 | ||
802 | The request identifier is automatically set to a unique value for the current | |
803 | process. | |
804 | ||
805 | Each IPP request starts with two IPP attributes, "attributes-charset" and | |
806 | "attributes-natural-language", followed by IPP attribute(s) that specify the | |
807 | target of the operation. The `ippNewRequest` automatically adds the correct | |
808 | "attributes-charset" and "attributes-natural-language" attributes, but you must | |
809 | add the target attribute(s). For example, the following code adds the | |
810 | "printer-uri" attribute to the IPP Get-Printer-Attributes request to specify | |
811 | which printer is being queried: | |
812 | ||
813 | const char *printer_uri = cupsGetOption("device-uri", | |
814 | dest->num_options, | |
815 | dest->options); | |
816 | ||
817 | ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI, | |
818 | "printer-uri", NULL, printer_uri); | |
819 | ||
820 | > Note: If we wanted to query the scheduler instead of the device, we would look | |
821 | > up the "printer-uri-supported" option instead of the "device-uri" value. | |
822 | ||
823 | The `ippAddString` function adds the "printer-uri" attribute the the IPP | |
824 | request. The `IPP_TAG_OPERATION` argument specifies that the attribute is part | |
825 | of the operation. The `IPP_TAG_URI` argument specifies that the value is a | |
826 | Universal Resource Identifier (URI) string. The `NULL` argument specifies there | |
827 | is no language (English, French, Japanese, etc.) associated with the string, and | |
828 | the `printer_uri` argument specifies the string value. | |
829 | ||
830 | The IPP Get-Printer-Attributes request also supports an IPP attribute called | |
831 | "requested-attributes" that lists the attributes and values you are interested | |
832 | in. For example, the following code requests the printer state attributes: | |
833 | ||
834 | static const char * const requested_attributes[] = | |
835 | { | |
836 | "printer-state", | |
837 | "printer-state-message", | |
838 | "printer-state-reasons" | |
839 | }; | |
840 | ||
841 | ippAddStrings(request, IPP_TAG_OPERATION, IPP_TAG_KEYWORD, | |
842 | "requested-attributes", 3, NULL, | |
843 | requested_attributes); | |
844 | ||
845 | The `ippAddStrings` function adds an attribute with one or more strings, in this | |
846 | case three. The `IPP_TAG_KEYWORD` argument specifies that the strings are | |
847 | keyword values, which are used for attribute names. All strings use the same | |
848 | language (`NULL`), and the attribute will contain the three strings in the | |
849 | array `requested_attributes`. | |
850 | ||
851 | CUPS provides many functions to adding attributes of different types: | |
852 | ||
853 | - `ippAddBoolean` adds a boolean (`IPP_TAG_BOOLEAN`) attribute with one value. | |
854 | - `ippAddInteger` adds an enum (`IPP_TAG_ENUM`) or integer (`IPP_TAG_INTEGER`) | |
855 | attribute with one value. | |
856 | - `ippAddIntegers` adds an enum or integer attribute with one or more values. | |
857 | - `ippAddOctetString` adds an octetString attribute with one value. | |
858 | - `ippAddOutOfBand` adds a admin-defined (`IPP_TAG_ADMINDEFINE`), default | |
859 | (`IPP_TAG_DEFAULT`), delete-attribute (`IPP_TAG_DELETEATTR`), no-value | |
860 | (`IPP_TAG_NOVALUE`), not-settable (`IPP_TAG_NOTSETTABLE`), unknown | |
861 | (`IPP_TAG_UNKNOWN`), or unsupported (`IPP_TAG_UNSUPPORTED_VALUE`) out-of-band | |
862 | attribute. | |
863 | - `ippAddRange` adds a rangeOfInteger attribute with one range. | |
864 | - `ippAddRanges` adds a rangeOfInteger attribute with one or more ranges. | |
865 | - `ippAddResolution` adds a resolution attribute with one resolution. | |
866 | - `ippAddResolutions` adds a resolution attribute with one or more resolutions. | |
867 | - `ippAddString` adds a charset (`IPP_TAG_CHARSET`), keyword (`IPP_TAG_KEYWORD`), | |
868 | mimeMediaType (`IPP_TAG_MIMETYPE`), name (`IPP_TAG_NAME` and | |
869 | `IPP_TAG_NAMELANG`), naturalLanguage (`IPP_TAG_NATURAL_LANGUAGE`), text | |
870 | (`IPP_TAG_TEXT` and `IPP_TAG_TEXTLANG`), uri (`IPP_TAG_URI`), or uriScheme | |
871 | (`IPP_TAG_URISCHEME`) attribute with one value. | |
872 | - `ippAddStrings` adds a charset, keyword, mimeMediaType, name, naturalLanguage, | |
873 | text, uri, or uriScheme attribute with one or more values. | |
874 | ||
875 | ||
65bebeac MS |
876 | ## Sending the IPP Request |
877 | ||
b0fb2d75 MS |
878 | Once you have created the IPP request, you can send it using the |
879 | `cupsDoRequest` function. For example, the following code sends the IPP | |
880 | Get-Printer-Attributes request to the destination and saves the response: | |
881 | ||
882 | ipp_t *response = cupsDoRequest(http, request, resource); | |
883 | ||
884 | For requests like Send-Document that include a file, the `cupsDoFileRequest` | |
885 | function should be used: | |
886 | ||
887 | ipp_t *response = cupsDoFileRequest(http, request, resource, | |
888 | filename); | |
889 | ||
890 | Both `cupsDoRequest` and `cupsDoFileRequest` free the IPP request. If a valid | |
891 | IPP response is received, it is stored in a new IPP message (`ipp_t`) and | |
892 | returned to the caller. Otherwise `NULL` is returned. | |
893 | ||
894 | The status from the most recent request can be queried using the `cupsLastError` | |
895 | function, for example: | |
896 | ||
897 | if (cupsLastError() >= IPP_STATUS_ERROR_BAD_REQUEST) | |
898 | { | |
899 | /* request failed */ | |
900 | } | |
901 | ||
902 | A human-readable error message is also available using the `cupsLastErrorString` | |
903 | function: | |
904 | ||
905 | if (cupsLastError() >= IPP_STATUS_ERROR_BAD_REQUEST) | |
906 | { | |
907 | /* request failed */ | |
908 | printf("Request failed: %s\n", cupsLastErrorString()); | |
909 | } | |
910 | ||
911 | ||
912 | ## Processing the IPP Response | |
913 | ||
914 | Each response to an IPP request is also an IPP message (`ipp_t`) with its own | |
915 | IPP attributes (`ipp_attribute_t`) that includes a status code (`IPP_STATUS_OK`, | |
916 | `IPP_STATUS_ERROR_BAD_REQUEST`, etc.) and the corresponding 32-bit integer | |
917 | identifier from the request. | |
918 | ||
919 | For example, the following code finds the printer state attributes and prints | |
920 | their values: | |
921 | ||
922 | ipp_attribute_t *attr; | |
923 | ||
924 | if ((attr = ippFindAttribute(response, "printer-state", | |
925 | IPP_TAG_ENUM)) != NULL) | |
926 | { | |
927 | printf("printer-state=%s\n", | |
db5424ea | 928 | ippEnumString("printer-state", ippGetInteger(attr, 0))); |
b0fb2d75 MS |
929 | } |
930 | else | |
931 | puts("printer-state=unknown"); | |
932 | ||
933 | if ((attr = ippFindAttribute(response, "printer-state-message", | |
934 | IPP_TAG_TEXT)) != NULL) | |
935 | { | |
936 | printf("printer-state-message=\"%s\"\n", | |
937 | ippGetString(attr, 0, NULL))); | |
938 | } | |
939 | ||
940 | if ((attr = ippFindAttribute(response, "printer-state-reasons", | |
941 | IPP_TAG_KEYWORD)) != NULL) | |
942 | { | |
943 | int i, count = ippGetCount(attr); | |
944 | ||
945 | puts("printer-state-reasons="); | |
946 | for (i = 0; i < count; i ++) | |
947 | printf(" %s\n", ippGetString(attr, i, NULL))); | |
948 | } | |
949 | ||
950 | The `ippGetCount` function returns the number of values in an attribute. | |
951 | ||
952 | The `ippGetInteger` and `ippGetString` functions return a single integer or | |
953 | string value from an attribute. | |
954 | ||
db5424ea | 955 | The `ippEnumString` function converts a enum value to its keyword (string) |
b0fb2d75 MS |
956 | equivalent. |
957 | ||
958 | Once you are done using the IPP response message, free it using the `ippDelete` | |
959 | function: | |
960 | ||
961 | ippDelete(response); | |
962 | ||
65bebeac MS |
963 | |
964 | ## Authentication | |
b0fb2d75 MS |
965 | |
966 | CUPS normally handles authentication through the console. GUI applications | |
967 | should set a password callback using the `cupsSetPasswordCB2` function: | |
968 | ||
969 | void | |
970 | cupsSetPasswordCB2(cups_password_cb2_t cb, void *user_data); | |
971 | ||
972 | The password callback will be called when needed and is responsible for setting | |
973 | the current user name using `cupsSetUser` and returning a string: | |
974 | ||
975 | const char * | |
976 | cups_password_cb2(const char *prompt, http_t *http, | |
977 | const char *method, const char *resource, | |
978 | void *user_data); | |
979 | ||
980 | The `prompt` argument is a string from CUPS that should be displayed to the | |
981 | user. | |
982 | ||
983 | The `http` argument is the connection hosting the request that is being | |
984 | authenticated. The password callback can call the `httpGetField` and | |
985 | `httpGetSubField` functions to look for additional details concerning the | |
986 | authentication challenge. | |
987 | ||
988 | The `method` argument specifies the HTTP method used for the request and is | |
989 | typically "POST". | |
990 | ||
991 | The `resource` argument specifies the path used for the request. | |
992 | ||
993 | The `user_data` argument provides the user data pointer from the | |
994 | `cupsSetPasswordCB2` call. |