summaryrefslogtreecommitdiffstats
path: root/src/libsystemd/sd-bus/bus-track.c
blob: 5f8716e2aa6381e92424896f2aa7e83dad22091a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include "sd-bus.h"

#include "alloc-util.h"
#include "bus-internal.h"
#include "bus-track.h"
#include "bus-util.h"
#include "string-util.h"

struct track_item {
        unsigned n_ref;
        char *name;
        sd_bus_slot *slot;
};

struct sd_bus_track {
        unsigned n_ref;
        unsigned n_adding; /* are we in the process of adding a new name? */
        sd_bus *bus;
        sd_bus_track_handler_t handler;
        void *userdata;
        Hashmap *names;
        LIST_FIELDS(sd_bus_track, queue);
        Iterator iterator;
        bool in_list:1;    /* In bus->tracks? */
        bool in_queue:1;   /* In bus->track_queue? */
        bool modified:1;
        bool recursive:1;
        sd_bus_destroy_t destroy_callback;

        LIST_FIELDS(sd_bus_track, tracks);
};

#define MATCH_FOR_NAME(name)                            \
        strjoina("type='signal',"                       \
                 "sender='org.freedesktop.DBus',"       \
                 "path='/org/freedesktop/DBus',"        \
                 "interface='org.freedesktop.DBus',"    \
                 "member='NameOwnerChanged',"           \
                 "arg0='", name, "'")

static struct track_item* track_item_free(struct track_item *i) {

        if (!i)
                return NULL;

        sd_bus_slot_unref(i->slot);
        free(i->name);
        return mfree(i);
}

DEFINE_TRIVIAL_CLEANUP_FUNC(struct track_item*, track_item_free);
DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(track_item_hash_ops, char, string_hash_func, string_compare_func,
                                              struct track_item, track_item_free);

static void bus_track_add_to_queue(sd_bus_track *track) {
        assert(track);

        /* Adds the bus track object to the queue of objects we should dispatch next, subject to a number of
         * conditions. */

        /* Already in the queue? */
        if (track->in_queue)
                return;

        /* if we are currently in the process of adding a new name, then let's not enqueue this just yet, let's wait
         * until the addition is complete. */
        if (track->n_adding > 0)
                return;

        /* still referenced? */
        if (hashmap_size(track->names) > 0)
                return;

        /* Nothing to call? */
        if (!track->handler)
                return;

        /* Already closed? */
        if (!track->in_list)
                return;

        LIST_PREPEND(queue, track->bus->track_queue, track);
        track->in_queue = true;
}

static void bus_track_remove_from_queue(sd_bus_track *track) {
        assert(track);

        if (!track->in_queue)
                return;

        LIST_REMOVE(queue, track->bus->track_queue, track);
        track->in_queue = false;
}

static int bus_track_remove_name_fully(sd_bus_track *track, const char *name) {
        struct track_item *i;

        assert(track);
        assert(name);

        i = hashmap_remove(track->names, name);
        if (!i)
                return 0;

        track_item_free(i);

        bus_track_add_to_queue(track);

        track->modified = true;
        return 1;
}

_public_ int sd_bus_track_new(
                sd_bus *bus,
                sd_bus_track **track,
                sd_bus_track_handler_t handler,
                void *userdata) {

        sd_bus_track *t;

        assert_return(bus, -EINVAL);
        assert_return(bus = bus_resolve(bus), -ENOPKG);
        assert_return(track, -EINVAL);

        if (!bus->bus_client)
                return -EINVAL;

        t = new0(sd_bus_track, 1);
        if (!t)
                return -ENOMEM;

        t->n_ref = 1;
        t->handler = handler;
        t->userdata = userdata;
        t->bus = sd_bus_ref(bus);

        LIST_PREPEND(tracks, bus->tracks, t);
        t->in_list = true;

        bus_track_add_to_queue(t);

        *track = t;
        return 0;
}

static sd_bus_track *track_free(sd_bus_track *track) {
        assert(track);

        if (track->in_list)
                LIST_REMOVE(tracks, track->bus->tracks, track);

        bus_track_remove_from_queue(track);
        track->names = hashmap_free(track->names);
        track->bus = sd_bus_unref(track->bus);

        if (track->destroy_callback)
                track->destroy_callback(track->userdata);

        return mfree(track);
}

DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_bus_track, sd_bus_track, track_free);

static int on_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
        sd_bus_track *track = userdata;
        const char *name, *old, *new;
        int r;

        assert(message);
        assert(track);

        r = sd_bus_message_read(message, "sss", &name, &old, &new);
        if (r < 0)
                return 0;

        bus_track_remove_name_fully(track, name);
        return 0;
}

_public_ int sd_bus_track_add_name(sd_bus_track *track, const char *name) {
        _cleanup_(track_item_freep) struct track_item *n = NULL;
        struct track_item *i;
        const char *match;
        int r;

        assert_return(track, -EINVAL);
        assert_return(service_name_is_valid(name), -EINVAL);

        i = hashmap_get(track->names, name);
        if (i) {
                if (track->recursive) {
                        unsigned k = track->n_ref + 1;

                        if (k < track->n_ref) /* Check for overflow */
                                return -EOVERFLOW;

                        track->n_ref = k;
                }

                bus_track_remove_from_queue(track);
                return 0;
        }

        r = hashmap_ensure_allocated(&track->names, &track_item_hash_ops);
        if (r < 0)
                return r;

        n = new0(struct track_item, 1);
        if (!n)
                return -ENOMEM;
        n->name = strdup(name);
        if (!n->name)
                return -ENOMEM;

        /* First, subscribe to this name */
        match = MATCH_FOR_NAME(name);

        bus_track_remove_from_queue(track); /* don't dispatch this while we work in it */

        r = sd_bus_add_match_async(track->bus, &n->slot, match, on_name_owner_changed, NULL, track);
        if (r < 0) {
                bus_track_add_to_queue(track);
                return r;
        }

        r = hashmap_put(track->names, n->name, n);
        if (r < 0) {
                bus_track_add_to_queue(track);
                return r;
        }

        /* Second, check if it is currently existing, or maybe doesn't, or maybe disappeared already. */
        track->n_adding++; /* again, make sure this isn't dispatch while we are working in it */
        r = sd_bus_get_name_creds(track->bus, name, 0, NULL);
        track->n_adding--;
        if (r < 0) {
                hashmap_remove(track->names, name);
                bus_track_add_to_queue(track);
                return r;
        }

        n->n_ref = 1;
        n = NULL;

        bus_track_remove_from_queue(track);
        track->modified = true;

        return 1;
}

_public_ int sd_bus_track_remove_name(sd_bus_track *track, const char *name) {
        struct track_item *i;

        assert_return(name, -EINVAL);

        if (!track) /* Treat a NULL track object as an empty track object */
                return 0;

        if (!track->recursive)
                return bus_track_remove_name_fully(track, name);

        i = hashmap_get(track->names, name);
        if (!i)
                return -EUNATCH;
        if (i->n_ref <= 0)
                return -EUNATCH;

        i->n_ref--;

        if (i->n_ref <= 0)
                return bus_track_remove_name_fully(track, name);

        return 1;
}

_public_ unsigned sd_bus_track_count(sd_bus_track *track) {

        if (!track) /* Let's consider a NULL object equivalent to an empty object */
                return 0;

        /* This signature really should have returned an int, so that we can propagate errors. But well, ... Also, note
         * that this returns the number of names being watched, and multiple references to the same name are not
         * counted. */

        return hashmap_size(track->names);
}

_public_ const char* sd_bus_track_contains(sd_bus_track *track, const char *name) {
        assert_return(name, NULL);

        if (!track) /* Let's consider a NULL object equivalent to an empty object */
                return NULL;

        return hashmap_get(track->names, (void*) name) ? name : NULL;
}

_public_ const char* sd_bus_track_first(sd_bus_track *track) {
        const char *n = NULL;

        if (!track)
                return NULL;

        track->modified = false;
        track->iterator = ITERATOR_FIRST;

        (void) hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
        return n;
}

_public_ const char* sd_bus_track_next(sd_bus_track *track) {
        const char *n = NULL;

        if (!track)
                return NULL;

        if (track->modified)
                return NULL;

        (void) hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
        return n;
}

_public_ int sd_bus_track_add_sender(sd_bus_track *track, sd_bus_message *m) {
        const char *sender;

        assert_return(track, -EINVAL);
        assert_return(m, -EINVAL);

        if (sd_bus_message_get_bus(m) != track->bus)
                return -EINVAL;

        sender = sd_bus_message_get_sender(m);
        if (!sender)
                return -EINVAL;

        return sd_bus_track_add_name(track, sender);
}

_public_ int sd_bus_track_remove_sender(sd_bus_track *track, sd_bus_message *m) {
        const char *sender;

        assert_return(m, -EINVAL);

        if (!track) /* Treat a NULL track object as an empty track object */
                return 0;

        if (sd_bus_message_get_bus(m) != track->bus)
                return -EINVAL;

        sender = sd_bus_message_get_sender(m);
        if (!sender)
                return -EINVAL;

        return sd_bus_track_remove_name(track, sender);
}

_public_ sd_bus* sd_bus_track_get_bus(sd_bus_track *track) {
        assert_return(track, NULL);

        return track->bus;
}

void bus_track_dispatch(sd_bus_track *track) {
        int r;

        assert(track);
        assert(track->handler);

        bus_track_remove_from_queue(track);

        sd_bus_track_ref(track);

        r = track->handler(track, track->userdata);
        if (r < 0)
                log_debug_errno(r, "Failed to process track handler: %m");
        else if (r == 0)
                bus_track_add_to_queue(track);

        sd_bus_track_unref(track);
}

void bus_track_close(sd_bus_track *track) {
        assert(track);

        /* Called whenever our bus connected is closed. If so, and our track object is non-empty, dispatch it
         * immediately, as we are closing now, but first flush out all names. */

        if (!track->in_list)
                return; /* We already closed this one, don't close it again. */

        /* Remember that this one is closed now */
        LIST_REMOVE(tracks, track->bus->tracks, track);
        track->in_list = false;

        /* If there's no name in this one anyway, we don't have to dispatch */
        if (hashmap_isempty(track->names))
                return;

        /* Let's flush out all names */
        hashmap_clear(track->names);

        /* Invoke handler */
        if (track->handler)
                bus_track_dispatch(track);
}

_public_ void *sd_bus_track_get_userdata(sd_bus_track *track) {
        assert_return(track, NULL);

        return track->userdata;
}

_public_ void *sd_bus_track_set_userdata(sd_bus_track *track, void *userdata) {
        void *ret;

        assert_return(track, NULL);

        ret = track->userdata;
        track->userdata = userdata;

        return ret;
}

_public_ int sd_bus_track_set_destroy_callback(sd_bus_track *track, sd_bus_destroy_t callback) {
        assert_return(track, -EINVAL);

        track->destroy_callback = callback;
        return 0;
}

_public_ int sd_bus_track_get_destroy_callback(sd_bus_track *track, sd_bus_destroy_t *ret) {
        assert_return(track, -EINVAL);

        if (ret)
                *ret = track->destroy_callback;

        return !!track->destroy_callback;
}

_public_ int sd_bus_track_set_recursive(sd_bus_track *track, int b) {
        assert_return(track, -EINVAL);

        if (track->recursive == !!b)
                return 0;

        if (!hashmap_isempty(track->names))
                return -EBUSY;

        track->recursive = b;
        return 0;
}

_public_ int sd_bus_track_get_recursive(sd_bus_track *track) {
        assert_return(track, -EINVAL);

        return track->recursive;
}

_public_ int sd_bus_track_count_sender(sd_bus_track *track, sd_bus_message *m) {
        const char *sender;

        assert_return(m, -EINVAL);

        if (!track) /* Let's consider a NULL object equivalent to an empty object */
                return 0;

        if (sd_bus_message_get_bus(m) != track->bus)
                return -EINVAL;

        sender = sd_bus_message_get_sender(m);
        if (!sender)
                return -EINVAL;

        return sd_bus_track_count_name(track, sender);
}

_public_ int sd_bus_track_count_name(sd_bus_track *track, const char *name) {
        struct track_item *i;

        assert_return(service_name_is_valid(name), -EINVAL);

        if (!track) /* Let's consider a NULL object equivalent to an empty object */
                return 0;

        i = hashmap_get(track->names, name);
        if (!i)
                return 0;

        return i->n_ref;
}