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460b9539 | 1 | .\" |
2 | .\" Copyright (C) 2004, 2005, 2006 Richard Kettlewell | |
3 | .\" | |
4 | .\" This program is free software; you can redistribute it and/or modify | |
5 | .\" it under the terms of the GNU General Public License as published by | |
6 | .\" the Free Software Foundation; either version 2 of the License, or | |
7 | .\" (at your option) any later version. | |
8 | .\" | |
9 | .\" This program is distributed in the hope that it will be useful, but | |
10 | .\" WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | .\" General Public License for more details. | |
13 | .\" | |
14 | .\" You should have received a copy of the GNU General Public License | |
15 | .\" along with this program; if not, write to the Free Software | |
16 | .\" Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 | |
17 | .\" USA | |
18 | .\" | |
19 | .TH disorder 3 | |
20 | .SH NAME | |
21 | disorder \- plugin interface to DisOrder jukebox | |
22 | .SH SYNOPSIS | |
23 | .B "#include <disorder.h>" | |
24 | .SH DESCRIPTION | |
25 | This header file defines the plugin interface to DisOrder. | |
26 | .PP | |
27 | The first half of this man page describes the functions DisOrder | |
28 | provides to plugins; the second half describes the functions that | |
29 | plugins must provide. | |
30 | .SH "MEMORY ALLOCATION" | |
c0c23a60 RK |
31 | DisOrder uses a garbage collector internally. |
32 | Therefore it is recommended that plugins use the provided memory | |
33 | allocation interface, rather than calling \fBmalloc\fR(3) etc directly. | |
460b9539 | 34 | .PP |
35 | .nf | |
36 | \fBvoid *disorder_malloc(size_t); | |
37 | void *disorder_realloc(void *, size_t); | |
38 | .fi | |
39 | .IP | |
40 | These functions behave much like \fBmalloc\fR(3) and \fBrealloc\fR(3) | |
41 | except that they never fail; they always zero out the memory | |
42 | allocated; and you do not need to free the result. | |
43 | .IP | |
44 | They may still return a null pointer if asked for a 0-sized | |
45 | allocation. | |
46 | .PP | |
47 | .nf | |
48 | \fBvoid *disorder_malloc_noptr(size_t); | |
49 | void *disorder_realloc_noptr(void *, size_t); | |
50 | .fi | |
51 | .IP | |
52 | These functions are like \fBmalloc\fR(3) and \fBrealloc\fR(3) | |
53 | except that they never fail and you must not put any pointer | |
54 | values in the allocated memory. | |
55 | .IP | |
56 | They may still return a null pointer if asked for a 0-sized | |
c0c23a60 RK |
57 | allocation. |
58 | They do not guarantee to zero out the memory allocated. | |
460b9539 | 59 | .PP |
60 | .nf | |
61 | \fBchar *disorder_strdup(const char *); | |
62 | char *disorder_strndup(const char *, size_t); | |
63 | .fi | |
64 | .IP | |
65 | These functions are like \fBstrdup\fR(3) and \fBstrndup\fR(3) except | |
66 | that they never fail and you do not need to free the result. | |
67 | .PP | |
68 | .nf | |
69 | \fBint disorder_asprintf(char **rp, const char *fmt, ...); | |
70 | int disorder_snprintf(char buffer[], size_t bufsize, | |
71 | const char *fmt, ...); | |
72 | .fi | |
73 | .IP | |
74 | These function are like \fBsnprintf\fR(3) and \fBasprintf\fR(3). | |
75 | .B disorder_asprintf | |
76 | never fails on memory allocation and | |
77 | you do not need to free the results. | |
78 | .IP | |
79 | Floating point conversions and wide character support are not | |
80 | currently implemented. | |
b6579a61 RK |
81 | .IP |
82 | These functions will cope with UTF-8 even if the current locale uses | |
83 | some other encoding. | |
460b9539 | 84 | .PP |
85 | "Never fail" in the above means that the process is terminated on error. | |
86 | .SH LOGGING | |
87 | Standard error doesn't reliably go anywhere in current versions of DisOrder, | |
88 | and whether syslog is to be used varies depending on how the program is | |
c0c23a60 RK |
89 | invoked. |
90 | Therefore plugins should use these functions to log any errors or | |
460b9539 | 91 | informational messages. |
92 | .PP | |
93 | .nf | |
94 | \fBvoid disorder_error(int errno_value, const char *fmt, ...); | |
95 | .fi | |
96 | .IP | |
c0c23a60 RK |
97 | Log an error message. |
98 | If \fBerrno_value\fR is not 0 then the relevant | |
460b9539 | 99 | string is included in the error message. |
100 | .PP | |
101 | .nf | |
102 | \fBvoid disorder_fatal(int errno_value, const char *fmt, ...); | |
103 | .fi | |
104 | .IP | |
c0c23a60 RK |
105 | Log an error message and then terminate the process. |
106 | If \fBerrno_value\fR is not 0 then the relevant string is included in the | |
460b9539 | 107 | error message. |
108 | .IP | |
109 | .B disorder_fatal | |
110 | is the right way to terminate the process if a fatal error arises. | |
111 | You shouldn't usually try to use \fBexit\fR(3) or \fB_exit\fR(2). | |
112 | .PP | |
113 | .nf | |
114 | \fBvoid disorder_info(const char *fmt, ...); | |
115 | .fi | |
116 | .IP | |
117 | Log a message. | |
118 | .IP | |
119 | .SH "TRACK DATABASE" | |
120 | The functions in this section provide a way of accessing the track database. | |
121 | In server plugins these access the database directly; in client plugins the | |
122 | requests are transmitted to the server over a socket. | |
123 | .PP | |
124 | All strings in this section are encoded using UTF-8. | |
125 | .PP | |
126 | .nf | |
127 | \fBint disorder_track_exists(const char *track); | |
128 | .fi | |
129 | .IP | |
130 | This function returns non-0 if \fBtrack\fR exists and 0 if it does | |
131 | not. | |
132 | .PP | |
133 | .nf | |
134 | \fBconst char *disorder_track_get_data(const char *track, | |
135 | const char *key); | |
136 | .fi | |
137 | .IP | |
138 | This function looks up the value of \fBkey\fR for \fBtrack\fR and | |
c0c23a60 RK |
139 | returns a pointer to a copy of it. |
140 | Do not bother to free the pointer. | |
460b9539 | 141 | If the track or key are not found a null pointer is returned. |
142 | .PP | |
143 | .nf | |
144 | \fBint disorder_track_set_data(const char *track, | |
145 | const char *key, | |
146 | const char *value); | |
147 | .fi | |
148 | .IP | |
149 | This function sets the value of \fBkey\fR for \fBtrack\fR to | |
c0c23a60 RK |
150 | \fBvalue\fR. |
151 | On success, 0 is returned; on error, -1 is returned. | |
460b9539 | 152 | .IP |
153 | If \fBvalue\fR is a null pointer then the preference is deleted. | |
154 | .IP | |
155 | Values starting with an underscore are stored in the tracks database, | |
156 | and are lost if the track is deleted; they should only ever have | |
c0c23a60 RK |
157 | values that can be regenerated on demand. |
158 | Other values are stored in the prefs database and never get | |
159 | automatically deleted. | |
460b9539 | 160 | .PP |
161 | .nf | |
162 | \fBconst char *disorder_track_random(void) | |
163 | .fi | |
164 | .IP | |
165 | Returns a pointer to a copy of the name of a randomly chosen track. | |
166 | Each non-alias track has an equal probability of being chosen. | |
167 | Aliases are never returned. | |
168 | Only available in server plugins. | |
169 | .SH "PLUGIN FUNCTIONS" | |
170 | This section describes the functions that you must implement to write various | |
c0c23a60 RK |
171 | plugins. |
172 | All of the plugins have at least one standard implementation available | |
173 | in the DisOrder source. | |
460b9539 | 174 | .PP |
175 | Some functions are listed as only available in server plugins. | |
176 | Currently this means that they are not even defined outside the | |
177 | server. | |
178 | .PP | |
179 | All strings in this section are encoded using UTF-8. | |
b6579a61 RK |
180 | .SS "Tracklength Plugins" |
181 | These are server plugins defined by the \fBtracklength\fR directive. | |
460b9539 | 182 | .PP |
183 | .nf | |
184 | \fBlong disorder_tracklength(const char *track, | |
185 | const char *path); | |
186 | .fi | |
187 | .IP | |
c0c23a60 RK |
188 | Called to calculate the length of a track. |
189 | \fBtrack\fR is the track name (UTF-8) and \fBpath\fR is the path | |
190 | name if there was one, or a null pointer otherwise. | |
191 | \fBpath\fR will be the same byte string return from | |
460b9539 | 192 | the scanner plugin, and so presumably encoded according to the |
193 | filesystem encoding. | |
194 | .IP | |
b6579a61 RK |
195 | To clarify this point, if the track must be opened to compute its |
196 | length, you would normally use \fBpath\fR and not \fBtrack\fR. | |
197 | .IP | |
460b9539 | 198 | If the return value is positive it should be the track length in |
199 | seconds (round up if it is not an integral number of seconds long). | |
200 | .IP | |
201 | If the return value is zero then the track length is unknown. | |
202 | .IP | |
203 | If the return value is negative then an error occurred determining the | |
204 | track length. | |
205 | .PP | |
206 | Tracklength plugins are invoked from a subprocess of the server, so | |
207 | they can block without disturbing the server's operation. | |
208 | .SS notify.so | |
209 | This is a server plugin. | |
210 | .PP | |
211 | .nf | |
212 | \fBvoid disorder_notify_play(const char *track, | |
213 | const char *submitter); | |
214 | .fi | |
215 | .IP | |
c0c23a60 RK |
216 | Called when \fBtrack\fR is about to be played. |
217 | \fBsubmitter\fR identifies the submitter or is a null pointer if | |
218 | the track was picked for random play. | |
460b9539 | 219 | .PP |
220 | .nf | |
221 | \fBvoid disorder_notify_scratch(const char *track, | |
222 | const char *submitter, | |
223 | const char *scratcher, | |
224 | int seconds); | |
225 | .fi | |
226 | .IP | |
c0c23a60 RK |
227 | Called when \fBtrack\fR is scratched by \fBscratcher\fR. |
228 | \fBsubmitter\fR identifies the submitter or is a null pointer if | |
229 | the track was picked for random play. | |
230 | \fBseconds\fR is the number of seconds since the track started playing. | |
460b9539 | 231 | .PP |
232 | .nf | |
233 | \fBvoid disorder_notify_not_scratched(const char *track, | |
234 | const char *submitter); | |
235 | .fi | |
236 | .IP | |
237 | Called when \fBtrack\fR completes without being scratched (an error might have | |
c0c23a60 RK |
238 | occurred though). |
239 | \fBsubmitter\fR identifies the submitter or is a null pointer if the | |
240 | track was picked for random play. | |
460b9539 | 241 | .PP |
242 | .nf | |
243 | \fBvoid disorder_notify_queue(const char *track, | |
244 | const char *submitter); | |
245 | .fi | |
246 | .IP | |
247 | Called when \fBtrack\fR is added to the queue by \fBsubmitter\fR | |
c0c23a60 RK |
248 | (which is never a null pointer). |
249 | Not called for scratches. | |
460b9539 | 250 | .PP |
251 | .nf | |
252 | \fBvoid disorder_notify_queue_remove(const char *track, | |
253 | const char *remover); | |
254 | .fi | |
255 | .IP | |
256 | Called when \fBtrack\fR is removed from queue by \fBremover\fR (which | |
257 | is never a null pointer). | |
258 | .PP | |
259 | .nf | |
260 | \fBvoid disorder_notify_queue_move(const char *track, | |
261 | const char *remover); | |
262 | .fi | |
263 | .IP | |
264 | Called when \fBtrack\fR is moved in the queue by \fBmover\fR | |
265 | (which is never a null pointer). | |
266 | .PP | |
267 | .nf | |
268 | \fBvoid disorder_notify_pause(const char *track, | |
269 | const char *who); | |
270 | .fi | |
271 | .IP | |
272 | Called when \fBtrack\fR is paused by \fBwho\fR | |
273 | (which might be a null pointer). | |
274 | .PP | |
275 | .nf | |
276 | \fBvoid disorder_notify_resume(const char *track, | |
277 | const char *who); | |
278 | .fi | |
279 | .IP | |
280 | Called when \fBtrack\fR is resumed by \fBwho\fR | |
281 | (which might be a null pointer). | |
282 | .SS "Scanner Plugins" | |
283 | Scanner plugins are server plugins and may have any name; they are | |
284 | chosen via the configuration file. | |
285 | .PP | |
286 | .nf | |
287 | \fBvoid disorder_scan(const char *root); | |
288 | .fi | |
289 | .IP | |
c0c23a60 RK |
290 | Write a list of files below \fBroot\fR to standard output. |
291 | Each filename should be in the encoding defined for this root in the | |
460b9539 | 292 | configuration file and should be terminated by character 0. |
293 | .IP | |
294 | It is up to the plugin implementor whether they prefer to use stdio or | |
295 | write to file descriptor 1 directly. | |
296 | .IP | |
297 | All the filenames had better start with \fBroot\fR as this is used to | |
298 | match them back up to the right collection to call | |
299 | \fBdisorder_check\fR on. | |
300 | .PP | |
301 | .nf | |
302 | \fBint disorder_check(const char *root, const char *path); | |
303 | .fi | |
304 | .IP | |
c0c23a60 RK |
305 | Check whether file \fBpath\fR under \fBroot\fR still exists. |
306 | Should return 1 if it exists, 0 if it does not and -1 on error. | |
307 | This is run in the main server process. | |
460b9539 | 308 | .PP |
309 | Both scan and recheck are executed inside a subprocess, so it will not | |
310 | break the server if they block for an extended period (though of | |
311 | course, they should not gratuitously take longer than necessary to do | |
312 | their jobs). | |
313 | .SS "Player plugins" | |
314 | Player plugins are server plugins and may have any name; they are | |
315 | chosen via the configuration file. | |
316 | .PP | |
317 | .nf | |
318 | extern const unsigned long disorder_player_type; | |
319 | .fi | |
320 | .IP | |
c0c23a60 RK |
321 | This defines the player type and capabilities. |
322 | It should consist of a single type value ORed with any number of | |
323 | capability values. | |
324 | The following are known type values: | |
460b9539 | 325 | .RS |
326 | .TP | |
327 | .B DISORDER_PLAYER_STANDALONE | |
328 | A standalone player that writes directly to some suitable audio | |
329 | device. | |
330 | .TP | |
331 | .B DISORDER_PLAYER_RAW | |
332 | A player that writes raw samples to \fB$DISORDER_RAW_FD\fR, for | |
333 | instance by using the \fBdisorder\fR libao driver. | |
334 | .RE | |
335 | .IP | |
336 | Known capabilities are: | |
337 | .RS | |
338 | .TP | |
339 | .B DISORDER_PLAYER_PREFORK | |
340 | Supports the prefork and cleanup calls. | |
341 | .TP | |
342 | .B DISORDER_PLAYER_PAUSES | |
343 | Supports the pause and resume calls. | |
344 | .RE | |
345 | .PP | |
346 | .nf | |
347 | \fBvoid *disorder_play_prefork(const char *track); | |
348 | .fi | |
349 | .IP | |
350 | Called before a track is played, if \fB_PREFORK\fR is set. | |
c0c23a60 RK |
351 | \fBtrack\fR is the name of the track in UTF-8. |
352 | This function must never block, as it runs inside the main loop of the server. | |
460b9539 | 353 | .IP |
354 | The return value will be passed to the functions below as \fBdata\fR. | |
355 | On error, a null pointer should be returned. | |
356 | .PP | |
357 | .nf | |
358 | \fBvoid disorder_play_cleanup(void *data); | |
359 | .fi | |
360 | .IP | |
361 | Called after a track has been completed, if \fB_PREFORK\fR is set, for | |
c0c23a60 RK |
362 | instance to release the memory used by \fBdata\fR. |
363 | This function must never block, as it runs inside the main loop of the server. | |
460b9539 | 364 | .PP |
365 | .nf | |
366 | \fBvoid disorder_play_track(const char *const *parameters, | |
367 | int nparameters, | |
368 | const char *path, | |
369 | const char *track, | |
370 | void *data); | |
371 | .fi | |
372 | .IP | |
373 | Play a track. | |
374 | .IP | |
375 | \fBpath\fR is the path name as originally encoded in the filesystem. | |
376 | This is the value you should ultimately pass to \fBopen\fR(2). | |
377 | .IP | |
c0c23a60 RK |
378 | \fBtrack\fR is the path name converted to UTF-8. |
379 | This value (possibly converted to some other encoding) should be used | |
380 | in any logs, etc. | |
460b9539 | 381 | .IP |
382 | If there is no meaningful path, or if the track is a scratch (where no | |
383 | filename encoding information is available), \fBpath\fR will be equal | |
384 | to \fBtrack\fR. | |
385 | .IP | |
386 | The parameters are any additional arguments | |
387 | supplied to the \fBplayer\fR configuration file command. | |
388 | .IP | |
389 | This function is always called inside a fork, and it should not return | |
390 | until playing has finished. | |
391 | .IP | |
392 | DisOrder sends the subprocess a signal if the track is to be scratched | |
c0c23a60 RK |
393 | (and when \fBdisorderd\fR is shut down). |
394 | By default this signal is \fBSIGKILL\fR but it can be reconfigured. | |
460b9539 | 395 | .PP |
396 | .nf | |
397 | \fBint disorder_play_pause(long *playedp, | |
398 | void *data); | |
399 | .fi | |
400 | .IP | |
c0c23a60 RK |
401 | Pauses the current track, for players that support pausing. |
402 | This function must never block, as it runs inside the main loop of the | |
460b9539 | 403 | server. |
404 | .IP | |
405 | On success, should return 0 and set \fB*playedp\fR to the number of | |
406 | seconds played so far of this track, or to -1 if this cannot be | |
407 | determined. | |
408 | .IP | |
409 | On error, should return -1. | |
410 | .PP | |
411 | .nf | |
412 | \fBvoid disorder_play_resume(void *data); | |
413 | .fi | |
414 | .IP | |
c0c23a60 RK |
415 | Resume playing the current track after a pause. |
416 | This function must never block, as it runs inside the main loop of the server. | |
460b9539 | 417 | .SH NOTES |
418 | There is no special DisOrder library to link against; the symbols are | |
c0c23a60 | 419 | exported by the executables themselves. |
460b9539 | 420 | (You should NOT try to link against \fB-ldisorder\fR.) |
421 | Plugins must be separately | |
422 | linked against any other libraries they require, even if the DisOrder | |
423 | executables are already linked against them. | |
424 | .PP | |
425 | The easiest approach is probably to develop the plugin inside the | |
c0c23a60 RK |
426 | DisOrder tree; then you can just use DisOrder's build system. |
427 | This might also make it easier to submit patches if you write something of | |
460b9539 | 428 | general utility. |
429 | .PP | |
430 | Failing that you can use Libtool, if you make sure to pass the | |
c0c23a60 RK |
431 | \fB-module\fR option. |
432 | For current versions of DisOrder you only need the shared object | |
433 | itself, not the \fB.la\fR file. | |
460b9539 | 434 | .PP |
435 | If you know the right runes for your toolchain you could also build | |
436 | the modules more directly. | |
437 | .PP | |
438 | It is possible, up to a point, to implement several plugin interfaces | |
c0c23a60 RK |
439 | from within a single shared object. |
440 | If you ever use any of the functions that are listed as only being | |
441 | available in server plugins, though, then you can only use the | |
442 | resulting shared object as a server plugin. | |
460b9539 | 443 | .SH "SEE ALSO" |
444 | .BR disorderd (8), | |
445 | .BR disorder (1), | |
446 | .BR disorder_config (5) | |
447 | .\" Local Variables: | |
448 | .\" mode:nroff | |
449 | .\" End: |