src/libsystemd/sd-bus/bus-track.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include "sd-bus.h"
   4
   5 #include "alloc-util.h"
   6 #include "bus-internal.h"
   7 #include "bus-track.h"
   8 #include "bus-util.h"
   9
  10 struct track_item {
  11         unsigned n_ref;
  12         char *name;
  13         sd_bus_slot *slot;
  14 };
  15
  16 struct sd_bus_track {
  17         unsigned n_ref;
  18         unsigned n_adding; /* are we in the process of adding a new name? */
  19         sd_bus *bus;
  20         sd_bus_track_handler_t handler;
  21         void *userdata;
  22         Hashmap *names;
  23         LIST_FIELDS(sd_bus_track, queue);
  24         Iterator iterator;
  25         bool in_list:1;    /* In bus->tracks? */
  26         bool in_queue:1;   /* In bus->track_queue? */
  27         bool modified:1;
  28         bool recursive:1;
  29         sd_bus_destroy_t destroy_callback;
  30
  31         LIST_FIELDS(sd_bus_track, tracks);
  32 };
  33
  34 #define MATCH_FOR_NAME(name)                            \
  35         strjoina("type='signal',"                       \
  36                  "sender='org.freedesktop.DBus',"       \
  37                  "path='/org/freedesktop/DBus',"        \
  38                  "interface='org.freedesktop.DBus',"    \
  39                  "member='NameOwnerChanged',"           \
  40                  "arg0='", name, "'")
  41
  42 static struct track_item* track_item_free(struct track_item *i) {
  43
  44         if (!i)
  45                 return NULL;
  46
  47         sd_bus_slot_unref(i->slot);
  48         free(i->name);
  49         return mfree(i);
  50 }
  51
  52 DEFINE_TRIVIAL_CLEANUP_FUNC(struct track_item*, track_item_free);
  53 DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR(track_item_hash_ops, char, string_hash_func, string_compare_func,
  54                                               struct track_item, track_item_free);
  55
  56 static void bus_track_add_to_queue(sd_bus_track *track) {
  57         assert(track);
  58
  59         /* Adds the bus track object to the queue of objects we should dispatch next, subject to a number of
  60          * conditions. */
  61
  62         /* Already in the queue? */
  63         if (track->in_queue)
  64                 return;
  65
  66         /* if we are currently in the process of adding a new name, then let's not enqueue this just yet, let's wait
  67          * until the addition is complete. */
  68         if (track->n_adding > 0)
  69                 return;
  70
  71         /* still referenced? */
  72         if (hashmap_size(track->names) > 0)
  73                 return;
  74
  75         /* Nothing to call? */
  76         if (!track->handler)
  77                 return;
  78
  79         /* Already closed? */
  80         if (!track->in_list)
  81                 return;
  82
  83         LIST_PREPEND(queue, track->bus->track_queue, track);
  84         track->in_queue = true;
  85 }
  86
  87 static void bus_track_remove_from_queue(sd_bus_track *track) {
  88         assert(track);
  89
  90         if (!track->in_queue)
  91                 return;
  92
  93         LIST_REMOVE(queue, track->bus->track_queue, track);
  94         track->in_queue = false;
  95 }
  96
  97 static int bus_track_remove_name_fully(sd_bus_track *track, const char *name) {
  98         struct track_item *i;
  99
 100         assert(track);
 101         assert(name);
 102
 103         i = hashmap_remove(track->names, name);
 104         if (!i)
 105                 return 0;
 106
 107         track_item_free(i);
 108
 109         bus_track_add_to_queue(track);
 110
 111         track->modified = true;
 112         return 1;
 113 }
 114
 115 _public_ int sd_bus_track_new(
 116                 sd_bus *bus,
 117                 sd_bus_track **track,
 118                 sd_bus_track_handler_t handler,
 119                 void *userdata) {
 120
 121         sd_bus_track *t;
 122
 123         assert_return(bus, -EINVAL);
 124         assert_return(bus = bus_resolve(bus), -ENOPKG);
 125         assert_return(track, -EINVAL);
 126
 127         if (!bus->bus_client)
 128                 return -EINVAL;
 129
 130         t = new0(sd_bus_track, 1);
 131         if (!t)
 132                 return -ENOMEM;
 133
 134         t->n_ref = 1;
 135         t->handler = handler;
 136         t->userdata = userdata;
 137         t->bus = sd_bus_ref(bus);
 138
 139         LIST_PREPEND(tracks, bus->tracks, t);
 140         t->in_list = true;
 141
 142         bus_track_add_to_queue(t);
 143
 144         *track = t;
 145         return 0;
 146 }
 147
 148 static sd_bus_track *track_free(sd_bus_track *track) {
 149         assert(track);
 150
 151         if (track->in_list)
 152                 LIST_REMOVE(tracks, track->bus->tracks, track);
 153
 154         bus_track_remove_from_queue(track);
 155         track->names = hashmap_free(track->names);
 156         track->bus = sd_bus_unref(track->bus);
 157
 158         if (track->destroy_callback)
 159                 track->destroy_callback(track->userdata);
 160
 161         return mfree(track);
 162 }
 163
 164 DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_bus_track, sd_bus_track, track_free);
 165
 166 static int on_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
 167         sd_bus_track *track = userdata;
 168         const char *name, *old, *new;
 169         int r;
 170
 171         assert(message);
 172         assert(track);
 173
 174         r = sd_bus_message_read(message, "sss", &name, &old, &new);
 175         if (r < 0)
 176                 return 0;
 177
 178         bus_track_remove_name_fully(track, name);
 179         return 0;
 180 }
 181
 182 _public_ int sd_bus_track_add_name(sd_bus_track *track, const char *name) {
 183         _cleanup_(track_item_freep) struct track_item *n = NULL;
 184         struct track_item *i;
 185         const char *match;
 186         int r;
 187
 188         assert_return(track, -EINVAL);
 189         assert_return(service_name_is_valid(name), -EINVAL);
 190
 191         i = hashmap_get(track->names, name);
 192         if (i) {
 193                 if (track->recursive) {
 194                         unsigned k = track->n_ref + 1;
 195
 196                         if (k < track->n_ref) /* Check for overflow */
 197                                 return -EOVERFLOW;
 198
 199                         track->n_ref = k;
 200                 }
 201
 202                 bus_track_remove_from_queue(track);
 203                 return 0;
 204         }
 205
 206         r = hashmap_ensure_allocated(&track->names, &track_item_hash_ops);
 207         if (r < 0)
 208                 return r;
 209
 210         n = new0(struct track_item, 1);
 211         if (!n)
 212                 return -ENOMEM;
 213         n->name = strdup(name);
 214         if (!n->name)
 215                 return -ENOMEM;
 216
 217         /* First, subscribe to this name */
 218         match = MATCH_FOR_NAME(name);
 219
 220         bus_track_remove_from_queue(track); /* don't dispatch this while we work in it */
 221
 222         r = sd_bus_add_match_async(track->bus, &n->slot, match, on_name_owner_changed, NULL, track);
 223         if (r < 0) {
 224                 bus_track_add_to_queue(track);
 225                 return r;
 226         }
 227
 228         r = hashmap_put(track->names, n->name, n);
 229         if (r < 0) {
 230                 bus_track_add_to_queue(track);
 231                 return r;
 232         }
 233
 234         /* Second, check if it is currently existing, or maybe doesn't, or maybe disappeared already. */
 235         track->n_adding++; /* again, make sure this isn't dispatch while we are working in it */
 236         r = sd_bus_get_name_creds(track->bus, name, 0, NULL);
 237         track->n_adding--;
 238         if (r < 0) {
 239                 hashmap_remove(track->names, name);
 240                 bus_track_add_to_queue(track);
 241                 return r;
 242         }
 243
 244         n->n_ref = 1;
 245         n = NULL;
 246
 247         bus_track_remove_from_queue(track);
 248         track->modified = true;
 249
 250         return 1;
 251 }
 252
 253 _public_ int sd_bus_track_remove_name(sd_bus_track *track, const char *name) {
 254         struct track_item *i;
 255
 256         assert_return(name, -EINVAL);
 257
 258         if (!track) /* Treat a NULL track object as an empty track object */
 259                 return 0;
 260
 261         if (!track->recursive)
 262                 return bus_track_remove_name_fully(track, name);
 263
 264         i = hashmap_get(track->names, name);
 265         if (!i)
 266                 return -EUNATCH;
 267         if (i->n_ref <= 0)
 268                 return -EUNATCH;
 269
 270         i->n_ref--;
 271
 272         if (i->n_ref <= 0)
 273                 return bus_track_remove_name_fully(track, name);
 274
 275         return 1;
 276 }
 277
 278 _public_ unsigned sd_bus_track_count(sd_bus_track *track) {
 279
 280         if (!track) /* Let's consider a NULL object equivalent to an empty object */
 281                 return 0;
 282
 283         /* This signature really should have returned an int, so that we can propagate errors. But well, ... Also, note
 284          * that this returns the number of names being watched, and multiple references to the same name are not
 285          * counted. */
 286
 287         return hashmap_size(track->names);
 288 }
 289
 290 _public_ const char* sd_bus_track_contains(sd_bus_track *track, const char *name) {
 291         assert_return(name, NULL);
 292
 293         if (!track) /* Let's consider a NULL object equivalent to an empty object */
 294                 return NULL;
 295
 296         return hashmap_get(track->names, (void*) name) ? name : NULL;
 297 }
 298
 299 _public_ const char* sd_bus_track_first(sd_bus_track *track) {
 300         const char *n = NULL;
 301
 302         if (!track)
 303                 return NULL;
 304
 305         track->modified = false;
 306         track->iterator = ITERATOR_FIRST;
 307
 308         hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
 309         return n;
 310 }
 311
 312 _public_ const char* sd_bus_track_next(sd_bus_track *track) {
 313         const char *n = NULL;
 314
 315         if (!track)
 316                 return NULL;
 317
 318         if (track->modified)
 319                 return NULL;
 320
 321         hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
 322         return n;
 323 }
 324
 325 _public_ int sd_bus_track_add_sender(sd_bus_track *track, sd_bus_message *m) {
 326         const char *sender;
 327
 328         assert_return(track, -EINVAL);
 329         assert_return(m, -EINVAL);
 330
 331         if (sd_bus_message_get_bus(m) != track->bus)
 332                 return -EINVAL;
 333
 334         sender = sd_bus_message_get_sender(m);
 335         if (!sender)
 336                 return -EINVAL;
 337
 338         return sd_bus_track_add_name(track, sender);
 339 }
 340
 341 _public_ int sd_bus_track_remove_sender(sd_bus_track *track, sd_bus_message *m) {
 342         const char *sender;
 343
 344         assert_return(m, -EINVAL);
 345
 346         if (!track) /* Treat a NULL track object as an empty track object */
 347                 return 0;
 348
 349         if (sd_bus_message_get_bus(m) != track->bus)
 350                 return -EINVAL;
 351
 352         sender = sd_bus_message_get_sender(m);
 353         if (!sender)
 354                 return -EINVAL;
 355
 356         return sd_bus_track_remove_name(track, sender);
 357 }
 358
 359 _public_ sd_bus* sd_bus_track_get_bus(sd_bus_track *track) {
 360         assert_return(track, NULL);
 361
 362         return track->bus;
 363 }
 364
 365 void bus_track_dispatch(sd_bus_track *track) {
 366         int r;
 367
 368         assert(track);
 369         assert(track->handler);
 370
 371         bus_track_remove_from_queue(track);
 372
 373         sd_bus_track_ref(track);
 374
 375         r = track->handler(track, track->userdata);
 376         if (r < 0)
 377                 log_debug_errno(r, "Failed to process track handler: %m");
 378         else if (r == 0)
 379                 bus_track_add_to_queue(track);
 380
 381         sd_bus_track_unref(track);
 382 }
 383
 384 void bus_track_close(sd_bus_track *track) {
 385         assert(track);
 386
 387         /* Called whenever our bus connected is closed. If so, and our track object is non-empty, dispatch it
 388          * immediately, as we are closing now, but first flush out all names. */
 389
 390         if (!track->in_list)
 391                 return; /* We already closed this one, don't close it again. */
 392
 393         /* Remember that this one is closed now */
 394         LIST_REMOVE(tracks, track->bus->tracks, track);
 395         track->in_list = false;
 396
 397         /* If there's no name in this one anyway, we don't have to dispatch */
 398         if (hashmap_isempty(track->names))
 399                 return;
 400
 401         /* Let's flush out all names */
 402         hashmap_clear(track->names);
 403
 404         /* Invoke handler */
 405         if (track->handler)
 406                 bus_track_dispatch(track);
 407 }
 408
 409 _public_ void *sd_bus_track_get_userdata(sd_bus_track *track) {
 410         assert_return(track, NULL);
 411
 412         return track->userdata;
 413 }
 414
 415 _public_ void *sd_bus_track_set_userdata(sd_bus_track *track, void *userdata) {
 416         void *ret;
 417
 418         assert_return(track, NULL);
 419
 420         ret = track->userdata;
 421         track->userdata = userdata;
 422
 423         return ret;
 424 }
 425
 426 _public_ int sd_bus_track_set_destroy_callback(sd_bus_track *track, sd_bus_destroy_t callback) {
 427         assert_return(track, -EINVAL);
 428
 429         track->destroy_callback = callback;
 430         return 0;
 431 }
 432
 433 _public_ int sd_bus_track_get_destroy_callback(sd_bus_track *track, sd_bus_destroy_t *ret) {
 434         assert_return(track, -EINVAL);
 435
 436         if (ret)
 437                 *ret = track->destroy_callback;
 438
 439         return !!track->destroy_callback;
 440 }
 441
 442 _public_ int sd_bus_track_set_recursive(sd_bus_track *track, int b) {
 443         assert_return(track, -EINVAL);
 444
 445         if (track->recursive == !!b)
 446                 return 0;
 447
 448         if (!hashmap_isempty(track->names))
 449                 return -EBUSY;
 450
 451         track->recursive = b;
 452         return 0;
 453 }
 454
 455 _public_ int sd_bus_track_get_recursive(sd_bus_track *track) {
 456         assert_return(track, -EINVAL);
 457
 458         return track->recursive;
 459 }
 460
 461 _public_ int sd_bus_track_count_sender(sd_bus_track *track, sd_bus_message *m) {
 462         const char *sender;
 463
 464         assert_return(m, -EINVAL);
 465
 466         if (!track) /* Let's consider a NULL object equivalent to an empty object */
 467                 return 0;
 468
 469         if (sd_bus_message_get_bus(m) != track->bus)
 470                 return -EINVAL;
 471
 472         sender = sd_bus_message_get_sender(m);
 473         if (!sender)
 474                 return -EINVAL;
 475
 476         return sd_bus_track_count_name(track, sender);
 477 }
 478
 479 _public_ int sd_bus_track_count_name(sd_bus_track *track, const char *name) {
 480         struct track_item *i;
 481
 482         assert_return(service_name_is_valid(name), -EINVAL);
 483
 484         if (!track) /* Let's consider a NULL object equivalent to an empty object */
 485                 return 0;
 486
 487         i = hashmap_get(track->names, name);
 488         if (!i)
 489                 return 0;
 490
 491         return i->n_ref;
 492 }