1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: t -*-*/
2
3 /***
4 Copyright 2009 Lennart Poettering
5
6 Permission is hereby granted, free of charge, to any person
7 obtaining a copy of this software and associated documentation files
8 (the "Software"), to deal in the Software without restriction,
9 including without limitation the rights to use, copy, modify, merge,
10 publish, distribute, sublicense, and/or sell copies of the Software,
11 and to permit persons to whom the Software is furnished to do so,
12 subject to the following conditions:
13
14 The above copyright notice and this permission notice shall be
15 included in all copies or substantial portions of the Software.
16
17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
21 BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
22 ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
23 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24 SOFTWARE.
25 ***/
26
27 #include <string.h>
28 #include <unistd.h>
29 #include <errno.h>
30 #include <stdlib.h>
31 #include <stdio.h>
32 #include <assert.h>
33
34 #include "reserve.h"
35
36 struct rd_device {
37 int ref;
38
39 char *device_name;
40 char *application_name;
41 char *application_device_name;
42 char *service_name;
43 char *object_path;
44 int32_t priority;
45
46 DBusConnection *connection;
47
48 unsigned owning:1;
49 unsigned registered:1;
50 unsigned filtering:1;
51 unsigned gave_up:1;
52
53 rd_request_cb_t request_cb;
54 void *userdata;
55 };
56
57 #define SERVICE_PREFIX "org.freedesktop.ReserveDevice1."
58 #define OBJECT_PREFIX "/org/freedesktop/ReserveDevice1/"
59
60 static const char introspection[] =
61 DBUS_INTROSPECT_1_0_XML_DOCTYPE_DECL_NODE
62 "<node>"
63 " <!-- If you are looking for documentation make sure to check out\n"
64 " http://git.0pointer.de/?p=reserve.git;a=blob;f=reserve.txt -->\n"
65 " <interface name=\"org.freedesktop.ReserveDevice1\">"
66 " <method name=\"RequestRelease\">"
67 " <arg name=\"priority\" type=\"i\" direction=\"in\"/>"
68 " <arg name=\"result\" type=\"b\" direction=\"out\"/>"
69 " </method>"
70 " <property name=\"Priority\" type=\"i\" access=\"read\"/>"
71 " <property name=\"ApplicationName\" type=\"s\" access=\"read\"/>"
72 " <property name=\"ApplicationDeviceName\" type=\"s\" access=\"read\"/>"
73 " </interface>"
74 " <interface name=\"org.freedesktop.DBus.Properties\">"
75 " <method name=\"Get\">"
76 " <arg name=\"interface\" direction=\"in\" type=\"s\"/>"
77 " <arg name=\"property\" direction=\"in\" type=\"s\"/>"
78 " <arg name=\"value\" direction=\"out\" type=\"v\"/>"
79 " </method>"
80 " </interface>"
81 " <interface name=\"org.freedesktop.DBus.Introspectable\">"
82 " <method name=\"Introspect\">"
83 " <arg name=\"data\" type=\"s\" direction=\"out\"/>"
84 " </method>"
85 " </interface>"
86 "</node>";
87
add_variant(DBusMessage * m,int type,const void * data)88 static dbus_bool_t add_variant(
89 DBusMessage *m,
90 int type,
91 const void *data) {
92
93 DBusMessageIter iter, sub;
94 char t[2];
95
96 t[0] = (char) type;
97 t[1] = 0;
98
99 dbus_message_iter_init_append(m, &iter);
100
101 if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_VARIANT, t, &sub))
102 return FALSE;
103
104 if (!dbus_message_iter_append_basic(&sub, type, data))
105 return FALSE;
106
107 if (!dbus_message_iter_close_container(&iter, &sub))
108 return FALSE;
109
110 return TRUE;
111 }
112
object_handler(DBusConnection * c,DBusMessage * m,void * userdata)113 static DBusHandlerResult object_handler(
114 DBusConnection *c,
115 DBusMessage *m,
116 void *userdata) {
117
118 rd_device *d;
119 DBusError error;
120 DBusMessage *reply = NULL;
121
122 dbus_error_init(&error);
123
124 d = userdata;
125 assert(d->ref >= 1);
126
127 if (dbus_message_is_method_call(
128 m,
129 "org.freedesktop.ReserveDevice1",
130 "RequestRelease")) {
131
132 int32_t priority;
133 dbus_bool_t ret;
134
135 if (!dbus_message_get_args(
136 m,
137 &error,
138 DBUS_TYPE_INT32, &priority,
139 DBUS_TYPE_INVALID))
140 goto invalid;
141
142 ret = FALSE;
143
144 if (priority > d->priority && d->request_cb) {
145 d->ref++;
146
147 if (d->request_cb(d, 0) > 0) {
148 ret = TRUE;
149 d->gave_up = 1;
150 }
151
152 rd_release(d);
153 }
154
155 if (!(reply = dbus_message_new_method_return(m)))
156 goto oom;
157
158 if (!dbus_message_append_args(
159 reply,
160 DBUS_TYPE_BOOLEAN, &ret,
161 DBUS_TYPE_INVALID))
162 goto oom;
163
164 if (!dbus_connection_send(c, reply, NULL))
165 goto oom;
166
167 dbus_message_unref(reply);
168
169 return DBUS_HANDLER_RESULT_HANDLED;
170
171 } else if (dbus_message_is_method_call(
172 m,
173 "org.freedesktop.DBus.Properties",
174 "Get")) {
175
176 const char *interface, *property;
177
178 if (!dbus_message_get_args(
179 m,
180 &error,
181 DBUS_TYPE_STRING, &interface,
182 DBUS_TYPE_STRING, &property,
183 DBUS_TYPE_INVALID))
184 goto invalid;
185
186 if (strcmp(interface, "org.freedesktop.ReserveDevice1") == 0) {
187 const char *empty = "";
188
189 if (strcmp(property, "ApplicationName") == 0 && d->application_name) {
190 if (!(reply = dbus_message_new_method_return(m)))
191 goto oom;
192
193 if (!add_variant(
194 reply,
195 DBUS_TYPE_STRING,
196 d->application_name ? (const char**) &d->application_name : &empty))
197 goto oom;
198
199 } else if (strcmp(property, "ApplicationDeviceName") == 0) {
200 if (!(reply = dbus_message_new_method_return(m)))
201 goto oom;
202
203 if (!add_variant(
204 reply,
205 DBUS_TYPE_STRING,
206 d->application_device_name ? (const char**) &d->application_device_name : &empty))
207 goto oom;
208
209 } else if (strcmp(property, "Priority") == 0) {
210 if (!(reply = dbus_message_new_method_return(m)))
211 goto oom;
212
213 if (!add_variant(
214 reply,
215 DBUS_TYPE_INT32,
216 &d->priority))
217 goto oom;
218 } else {
219 if (!(reply = dbus_message_new_error_printf(
220 m,
221 DBUS_ERROR_UNKNOWN_METHOD,
222 "Unknown property %s",
223 property)))
224 goto oom;
225 }
226
227 if (!dbus_connection_send(c, reply, NULL))
228 goto oom;
229
230 dbus_message_unref(reply);
231
232 return DBUS_HANDLER_RESULT_HANDLED;
233 }
234
235 } else if (dbus_message_is_method_call(
236 m,
237 "org.freedesktop.DBus.Introspectable",
238 "Introspect")) {
239 const char *i = introspection;
240
241 if (!(reply = dbus_message_new_method_return(m)))
242 goto oom;
243
244 if (!dbus_message_append_args(
245 reply,
246 DBUS_TYPE_STRING,
247 &i,
248 DBUS_TYPE_INVALID))
249 goto oom;
250
251 if (!dbus_connection_send(c, reply, NULL))
252 goto oom;
253
254 dbus_message_unref(reply);
255
256 return DBUS_HANDLER_RESULT_HANDLED;
257 }
258
259 return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
260
261 invalid:
262 if (reply)
263 dbus_message_unref(reply);
264
265 if (!(reply = dbus_message_new_error(
266 m,
267 DBUS_ERROR_INVALID_ARGS,
268 "Invalid arguments")))
269 goto oom;
270
271 if (!dbus_connection_send(c, reply, NULL))
272 goto oom;
273
274 dbus_message_unref(reply);
275
276 dbus_error_free(&error);
277
278 return DBUS_HANDLER_RESULT_HANDLED;
279
280 oom:
281 if (reply)
282 dbus_message_unref(reply);
283
284 dbus_error_free(&error);
285
286 return DBUS_HANDLER_RESULT_NEED_MEMORY;
287 }
288
filter_handler(DBusConnection * c,DBusMessage * m,void * userdata)289 static DBusHandlerResult filter_handler(
290 DBusConnection *c,
291 DBusMessage *m,
292 void *userdata) {
293
294 rd_device *d;
295 DBusError error;
296 char *name_owner = NULL;
297
298 dbus_error_init(&error);
299
300 d = userdata;
301 assert(d->ref >= 1);
302
303 if (dbus_message_is_signal(m, "org.freedesktop.DBus", "NameLost")) {
304 const char *name;
305
306 if (!dbus_message_get_args(
307 m,
308 &error,
309 DBUS_TYPE_STRING, &name,
310 DBUS_TYPE_INVALID))
311 goto invalid;
312
313 if (strcmp(name, d->service_name) == 0 && d->owning) {
314 /* Verify the actual owner of the name to avoid leaked NameLost
315 * signals from previous reservations. The D-Bus daemon will send
316 * all messages asynchronously in the correct order, but we could
317 * potentially process them too late due to the pseudo-blocking
318 * call mechanism used during both acquisition and release. This
319 * can happen if we release the device and immediately after
320 * reacquire it before NameLost is processed. */
321 if (!d->gave_up) {
322 const char *un;
323
324 if ((un = dbus_bus_get_unique_name(c)) && rd_dbus_get_name_owner(c, d->service_name, &name_owner, &error) == 0)
325 if (strcmp(name_owner, un) == 0)
326 goto invalid; /* Name still owned by us */
327 }
328
329 d->owning = 0;
330
331 if (!d->gave_up) {
332 d->ref++;
333
334 if (d->request_cb)
335 d->request_cb(d, 1);
336 d->gave_up = 1;
337
338 rd_release(d);
339 }
340
341 }
342 }
343
344 invalid:
345 free(name_owner);
346 dbus_error_free(&error);
347
348 return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
349 }
350
351
352 static const struct DBusObjectPathVTable vtable ={
353 .message_function = object_handler
354 };
355
rd_acquire(rd_device ** _d,DBusConnection * connection,const char * device_name,const char * application_name,int32_t priority,rd_request_cb_t request_cb,DBusError * error)356 int rd_acquire(
357 rd_device **_d,
358 DBusConnection *connection,
359 const char *device_name,
360 const char *application_name,
361 int32_t priority,
362 rd_request_cb_t request_cb,
363 DBusError *error) {
364
365 rd_device *d = NULL;
366 int r, k;
367 DBusError _error;
368 DBusMessage *m = NULL, *reply = NULL;
369 dbus_bool_t good;
370
371 if (!error)
372 error = &_error;
373
374 dbus_error_init(error);
375
376 if (!_d)
377 return -EINVAL;
378
379 if (!connection)
380 return -EINVAL;
381
382 if (!device_name)
383 return -EINVAL;
384
385 if (!request_cb && priority != INT32_MAX)
386 return -EINVAL;
387
388 if (!(d = calloc(sizeof(rd_device), 1)))
389 return -ENOMEM;
390
391 d->ref = 1;
392
393 if (!(d->device_name = strdup(device_name))) {
394 r = -ENOMEM;
395 goto fail;
396 }
397
398 if (!(d->application_name = strdup(application_name))) {
399 r = -ENOMEM;
400 goto fail;
401 }
402
403 d->priority = priority;
404 d->connection = dbus_connection_ref(connection);
405 d->request_cb = request_cb;
406
407 if (!(d->service_name = malloc(sizeof(SERVICE_PREFIX) + strlen(device_name)))) {
408 r = -ENOMEM;
409 goto fail;
410 }
411 sprintf(d->service_name, SERVICE_PREFIX "%s", d->device_name);
412
413 if (!(d->object_path = malloc(sizeof(OBJECT_PREFIX) + strlen(device_name)))) {
414 r = -ENOMEM;
415 goto fail;
416 }
417 sprintf(d->object_path, OBJECT_PREFIX "%s", d->device_name);
418
419 if ((k = dbus_bus_request_name(
420 d->connection,
421 d->service_name,
422 DBUS_NAME_FLAG_DO_NOT_QUEUE|
423 (priority < INT32_MAX ? DBUS_NAME_FLAG_ALLOW_REPLACEMENT : 0),
424 error)) < 0) {
425 r = -EIO;
426 goto fail;
427 }
428
429 if (k == DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER)
430 goto success;
431
432 if (k != DBUS_REQUEST_NAME_REPLY_EXISTS) {
433 r = -EIO;
434 goto fail;
435 }
436
437 if (priority <= INT32_MIN) {
438 r = -EBUSY;
439 goto fail;
440 }
441
442 if (!(m = dbus_message_new_method_call(
443 d->service_name,
444 d->object_path,
445 "org.freedesktop.ReserveDevice1",
446 "RequestRelease"))) {
447 r = -ENOMEM;
448 goto fail;
449 }
450
451 if (!dbus_message_append_args(
452 m,
453 DBUS_TYPE_INT32, &d->priority,
454 DBUS_TYPE_INVALID)) {
455 r = -ENOMEM;
456 goto fail;
457 }
458
459 if (!(reply = dbus_connection_send_with_reply_and_block(
460 d->connection,
461 m,
462 5000, /* 5s */
463 error))) {
464
465 if (dbus_error_has_name(error, DBUS_ERROR_TIMED_OUT) ||
466 dbus_error_has_name(error, DBUS_ERROR_UNKNOWN_METHOD) ||
467 dbus_error_has_name(error, DBUS_ERROR_NO_REPLY)) {
468 /* This must be treated as denied. */
469 r = -EBUSY;
470 goto fail;
471 }
472
473 r = -EIO;
474 goto fail;
475 }
476
477 dbus_message_unref(m);
478 m = NULL;
479
480 if (!dbus_message_get_args(
481 reply,
482 error,
483 DBUS_TYPE_BOOLEAN, &good,
484 DBUS_TYPE_INVALID)) {
485 r = -EIO;
486 goto fail;
487 }
488
489 dbus_message_unref(reply);
490 reply = NULL;
491
492 if (!good) {
493 r = -EBUSY;
494 goto fail;
495 }
496
497 if ((k = dbus_bus_request_name(
498 d->connection,
499 d->service_name,
500 DBUS_NAME_FLAG_DO_NOT_QUEUE|
501 (priority < INT32_MAX ? DBUS_NAME_FLAG_ALLOW_REPLACEMENT : 0)|
502 DBUS_NAME_FLAG_REPLACE_EXISTING,
503 error)) < 0) {
504 r = -EIO;
505 goto fail;
506 }
507
508 if (k != DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER) {
509 r = -EIO;
510 goto fail;
511 }
512
513 success:
514 d->owning = 1;
515
516 if (!(dbus_connection_register_object_path(
517 d->connection,
518 d->object_path,
519 &vtable,
520 d))) {
521 r = -ENOMEM;
522 goto fail;
523 }
524
525 d->registered = 1;
526
527 if (!dbus_connection_add_filter(
528 d->connection,
529 filter_handler,
530 d,
531 NULL)) {
532 r = -ENOMEM;
533 goto fail;
534 }
535
536 d->filtering = 1;
537
538 *_d = d;
539 return 0;
540
541 fail:
542 if (m)
543 dbus_message_unref(m);
544
545 if (reply)
546 dbus_message_unref(reply);
547
548 if (&_error == error)
549 dbus_error_free(&_error);
550
551 if (d)
552 rd_release(d);
553
554 return r;
555 }
556
rd_release(rd_device * d)557 void rd_release(
558 rd_device *d) {
559
560 if (!d)
561 return;
562
563 assert(d->ref > 0);
564
565 if (--d->ref > 0)
566 return;
567
568
569 if (d->filtering)
570 dbus_connection_remove_filter(
571 d->connection,
572 filter_handler,
573 d);
574
575 if (d->registered)
576 dbus_connection_unregister_object_path(
577 d->connection,
578 d->object_path);
579
580 if (d->owning)
581 dbus_bus_release_name(
582 d->connection,
583 d->service_name,
584 NULL);
585
586 free(d->device_name);
587 free(d->application_name);
588 free(d->application_device_name);
589 free(d->service_name);
590 free(d->object_path);
591
592 if (d->connection)
593 dbus_connection_unref(d->connection);
594
595 free(d);
596 }
597
rd_set_application_device_name(rd_device * d,const char * n)598 int rd_set_application_device_name(rd_device *d, const char *n) {
599 char *t;
600
601 if (!d)
602 return -EINVAL;
603
604 assert(d->ref > 0);
605
606 if (!(t = strdup(n)))
607 return -ENOMEM;
608
609 free(d->application_device_name);
610 d->application_device_name = t;
611 return 0;
612 }
613
rd_set_userdata(rd_device * d,void * userdata)614 void rd_set_userdata(rd_device *d, void *userdata) {
615
616 if (!d)
617 return;
618
619 assert(d->ref > 0);
620 d->userdata = userdata;
621 }
622
rd_get_userdata(rd_device * d)623 void* rd_get_userdata(rd_device *d) {
624
625 if (!d)
626 return NULL;
627
628 assert(d->ref > 0);
629
630 return d->userdata;
631 }
632
rd_dbus_get_name_owner(DBusConnection * connection,const char * name,char ** name_owner,DBusError * error)633 int rd_dbus_get_name_owner(
634 DBusConnection *connection,
635 const char *name,
636 char **name_owner,
637 DBusError *error) {
638
639 DBusMessage *msg, *reply;
640 int r;
641
642 *name_owner = NULL;
643
644 if (!(msg = dbus_message_new_method_call(DBUS_SERVICE_DBUS, DBUS_PATH_DBUS, DBUS_INTERFACE_DBUS, "GetNameOwner"))) {
645 r = -ENOMEM;
646 goto fail;
647 }
648
649 if (!dbus_message_append_args(msg, DBUS_TYPE_STRING, &name, DBUS_TYPE_INVALID)) {
650 r = -ENOMEM;
651 goto fail;
652 }
653
654 reply = dbus_connection_send_with_reply_and_block(connection, msg, DBUS_TIMEOUT_USE_DEFAULT, error);
655 dbus_message_unref(msg);
656 msg = NULL;
657
658 if (reply) {
659 if (!dbus_message_get_args(reply, error, DBUS_TYPE_STRING, name_owner, DBUS_TYPE_INVALID)) {
660 dbus_message_unref(reply);
661 r = -EIO;
662 goto fail;
663 }
664
665 *name_owner = strdup(*name_owner);
666 dbus_message_unref(reply);
667
668 if (!*name_owner) {
669 r = -ENOMEM;
670 goto fail;
671 }
672
673 } else if (dbus_error_has_name(error, "org.freedesktop.DBus.Error.NameHasNoOwner"))
674 dbus_error_free(error);
675 else {
676 r = -EIO;
677 goto fail;
678 }
679
680 return 0;
681
682 fail:
683 if (msg)
684 dbus_message_unref(msg);
685
686 return r;
687 }
688