src/bin/lttng-sessiond/ust-registry.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <assert.h>
  20 #include <inttypes.h>
  21
  22 #include <common/common.h>
  23 #include <common/hashtable/utils.h>
  24 #include <lttng/lttng.h>
  25
  26 #include "ust-registry.h"
  27 #include "ust-app.h"
  28 #include "utils.h"
  29
  30 /*
  31  * Hash table match function for event in the registry.
  32  */
  33 static int ht_match_event(struct cds_lfht_node *node, const void *_key)
  34 {
  35         struct ust_registry_event *event;
  36         const struct ust_registry_event *key;
  37
  38         assert(node);
  39         assert(_key);
  40
  41         event = caa_container_of(node, struct ust_registry_event, node.node);
  42         assert(event);
  43         key = _key;
  44
  45         /* It has to be a perfect match. */
  46         if (strncmp(event->name, key->name, sizeof(event->name))) {
  47                 goto no_match;
  48         }
  49
  50         /* It has to be a perfect match. */
  51         if (strncmp(event->signature, key->signature,
  52                         strlen(event->signature))) {
  53                 goto no_match;
  54         }
  55
  56         /* Match */
  57         return 1;
  58
  59 no_match:
  60         return 0;
  61 }
  62
  63 static unsigned long ht_hash_event(void *_key, unsigned long seed)
  64 {
  65         uint64_t xored_key;
  66         struct ust_registry_event *key = _key;
  67
  68         assert(key);
  69
  70         xored_key = (uint64_t) (hash_key_str(key->name, seed) ^
  71                         hash_key_str(key->signature, seed));
  72
  73         return hash_key_u64(&xored_key, seed);
  74 }
  75
  76 static int compare_enums(const struct ust_registry_enum *reg_enum_a,
  77                 const struct ust_registry_enum *reg_enum_b)
  78 {
  79         int ret = 0;
  80         size_t i;
  81
  82         assert(strcmp(reg_enum_a->name, reg_enum_b->name) == 0);
  83         if (reg_enum_a->nr_entries != reg_enum_b->nr_entries) {
  84                 ret = -1;
  85                 goto end;
  86         }
  87         for (i = 0; i < reg_enum_a->nr_entries; i++) {
  88                 const struct ustctl_enum_entry *entries_a, *entries_b;
  89
  90                 entries_a = &reg_enum_a->entries[i];
  91                 entries_b = &reg_enum_b->entries[i];
  92                 if (entries_a->start != entries_b->start) {
  93                         ret = -1;
  94                         goto end;
  95                 }
  96                 if (entries_a->end != entries_b->end) {
  97                         ret = -1;
  98                         goto end;
  99                 }
 100                 if (strcmp(entries_a->string, entries_b->string)) {
 101                         ret = -1;
 102                         goto end;
 103                 }
 104         }
 105 end:
 106         return ret;
 107 }
 108
 109 /*
 110  * Hash table match function for enumerations in the session. Match is
 111  * performed on enumeration name, and confirmed by comparing the enum
 112  * entries.
 113  */
 114 static int ht_match_enum(struct cds_lfht_node *node, const void *_key)
 115 {
 116         struct ust_registry_enum *_enum;
 117         const struct ust_registry_enum *key;
 118
 119         assert(node);
 120         assert(_key);
 121
 122         _enum = caa_container_of(node, struct ust_registry_enum,
 123                         node.node);
 124         assert(_enum);
 125         key = _key;
 126
 127         if (strncmp(_enum->name, key->name, LTTNG_UST_SYM_NAME_LEN)) {
 128                 goto no_match;
 129         }
 130         if (compare_enums(_enum, key)) {
 131                 goto no_match;
 132         }
 133
 134         /* Match. */
 135         return 1;
 136
 137 no_match:
 138         return 0;
 139 }
 140
 141 /*
 142  * Hash table match function for enumerations in the session. Match is
 143  * performed by enumeration ID.
 144  */
 145 static int ht_match_enum_id(struct cds_lfht_node *node, const void *_key)
 146 {
 147         struct ust_registry_enum *_enum;
 148         const struct ust_registry_enum *key = _key;
 149
 150         assert(node);
 151         assert(_key);
 152
 153         _enum = caa_container_of(node, struct ust_registry_enum, node.node);
 154         assert(_enum);
 155
 156         if (_enum->id != key->id) {
 157                 goto no_match;
 158         }
 159
 160         /* Match. */
 161         return 1;
 162
 163 no_match:
 164         return 0;
 165 }
 166
 167 /*
 168  * Hash table hash function for enumerations in the session. The
 169  * enumeration name is used for hashing.
 170  */
 171 static unsigned long ht_hash_enum(void *_key, unsigned long seed)
 172 {
 173         struct ust_registry_enum *key = _key;
 174
 175         assert(key);
 176         return hash_key_str(key->name, seed);
 177 }
 178
 179 /*
 180  * Return negative value on error, 0 if OK.
 181  *
 182  * TODO: we could add stricter verification of more types to catch
 183  * errors in liblttng-ust implementation earlier than consumption by the
 184  * trace reader.
 185  */
 186 static
 187 int validate_event_field(struct ustctl_field *field,
 188                 const char *event_name,
 189                 struct ust_app *app)
 190 {
 191         int ret = 0;
 192
 193         switch(field->type.atype) {
 194         case ustctl_atype_integer:
 195         case ustctl_atype_enum:
 196         case ustctl_atype_array:
 197         case ustctl_atype_sequence:
 198         case ustctl_atype_string:
 199         case ustctl_atype_variant:
 200                 break;
 201         case ustctl_atype_struct:
 202                 if (field->type.u._struct.nr_fields != 0) {
 203                         WARN("Unsupported non-empty struct field.");
 204                         ret = -EINVAL;
 205                         goto end;
 206                 }
 207                 break;
 208
 209         case ustctl_atype_float:
 210                 switch (field->type.u.basic._float.mant_dig) {
 211                 case 0:
 212                         WARN("UST application '%s' (pid: %d) has unknown float mantissa '%u' "
 213                                 "in field '%s', rejecting event '%s'",
 214                                 app->name, app->pid,
 215                                 field->type.u.basic._float.mant_dig,
 216                                 field->name,
 217                                 event_name);
 218                         ret = -EINVAL;
 219                         goto end;
 220                 default:
 221                         break;
 222                 }
 223                 break;
 224
 225         default:
 226                 ret = -ENOENT;
 227                 goto end;
 228         }
 229 end:
 230         return ret;
 231 }
 232
 233 static
 234 int validate_event_fields(size_t nr_fields, struct ustctl_field *fields,
 235                 const char *event_name, struct ust_app *app)
 236 {
 237         unsigned int i;
 238
 239         for (i = 0; i < nr_fields; i++) {
 240                 if (validate_event_field(&fields[i], event_name, app) < 0)
 241                         return -EINVAL;
 242         }
 243         return 0;
 244 }
 245
 246 /*
 247  * Allocate event and initialize it. This does NOT set a valid event id from a
 248  * registry.
 249  */
 250 static struct ust_registry_event *alloc_event(int session_objd,
 251                 int channel_objd, char *name, char *sig, size_t nr_fields,
 252                 struct ustctl_field *fields, int loglevel_value,
 253                 char *model_emf_uri, struct ust_app *app)
 254 {
 255         struct ust_registry_event *event = NULL;
 256
 257         /*
 258          * Ensure that the field content is valid.
 259          */
 260         if (validate_event_fields(nr_fields, fields, name, app) < 0) {
 261                 return NULL;
 262         }
 263
 264         event = zmalloc(sizeof(*event));
 265         if (!event) {
 266                 PERROR("zmalloc ust registry event");
 267                 goto error;
 268         }
 269
 270         event->session_objd = session_objd;
 271         event->channel_objd = channel_objd;
 272         /* Allocated by ustctl. */
 273         event->signature = sig;
 274         event->nr_fields = nr_fields;
 275         event->fields = fields;
 276         event->loglevel_value = loglevel_value;
 277         event->model_emf_uri = model_emf_uri;
 278         if (name) {
 279                 /* Copy event name and force NULL byte. */
 280                 strncpy(event->name, name, sizeof(event->name));
 281                 event->name[sizeof(event->name) - 1] = '\0';
 282         }
 283         cds_lfht_node_init(&event->node.node);
 284
 285 error:
 286         return event;
 287 }
 288
 289 /*
 290  * Free event data structure. This does NOT delete it from any hash table. It's
 291  * safe to pass a NULL pointer. This shoudl be called inside a call RCU if the
 292  * event is previously deleted from a rcu hash table.
 293  */
 294 static void destroy_event(struct ust_registry_event *event)
 295 {
 296         if (!event) {
 297                 return;
 298         }
 299
 300         free(event->fields);
 301         free(event->model_emf_uri);
 302         free(event->signature);
 303         free(event);
 304 }
 305
 306 /*
 307  * Destroy event function call of the call RCU.
 308  */
 309 static void destroy_event_rcu(struct rcu_head *head)
 310 {
 311         struct lttng_ht_node_u64 *node =
 312                 caa_container_of(head, struct lttng_ht_node_u64, head);
 313         struct ust_registry_event *event =
 314                 caa_container_of(node, struct ust_registry_event, node);
 315
 316         destroy_event(event);
 317 }
 318
 319 /*
 320  * Find an event using the name and signature in the given registry. RCU read
 321  * side lock MUST be acquired before calling this function and as long as the
 322  * event reference is kept by the caller.
 323  *
 324  * On success, the event pointer is returned else NULL.
 325  */
 326 struct ust_registry_event *ust_registry_find_event(
 327                 struct ust_registry_channel *chan, char *name, char *sig)
 328 {
 329         struct lttng_ht_node_u64 *node;
 330         struct lttng_ht_iter iter;
 331         struct ust_registry_event *event = NULL;
 332         struct ust_registry_event key;
 333
 334         assert(chan);
 335         assert(name);
 336         assert(sig);
 337
 338         /* Setup key for the match function. */
 339         strncpy(key.name, name, sizeof(key.name));
 340         key.name[sizeof(key.name) - 1] = '\0';
 341         key.signature = sig;
 342
 343         cds_lfht_lookup(chan->ht->ht, chan->ht->hash_fct(&key, lttng_ht_seed),
 344                         chan->ht->match_fct, &key, &iter.iter);
 345         node = lttng_ht_iter_get_node_u64(&iter);
 346         if (!node) {
 347                 goto end;
 348         }
 349         event = caa_container_of(node, struct ust_registry_event, node);
 350
 351 end:
 352         return event;
 353 }
 354
 355 /*
 356  * Create a ust_registry_event from the given parameters and add it to the
 357  * registry hash table. If event_id is valid, it is set with the newly created
 358  * event id.
 359  *
 360  * On success, return 0 else a negative value. The created event MUST be unique
 361  * so on duplicate entry -EINVAL is returned. On error, event_id is untouched.
 362  *
 363  * Should be called with session registry mutex held.
 364  */
 365 int ust_registry_create_event(struct ust_registry_session *session,
 366                 uint64_t chan_key, int session_objd, int channel_objd, char *name,
 367                 char *sig, size_t nr_fields, struct ustctl_field *fields,
 368                 int loglevel_value, char *model_emf_uri, int buffer_type,
 369                 uint32_t *event_id_p, struct ust_app *app)
 370 {
 371         int ret;
 372         uint32_t event_id;
 373         struct cds_lfht_node *nptr;
 374         struct ust_registry_event *event = NULL;
 375         struct ust_registry_channel *chan;
 376
 377         assert(session);
 378         assert(name);
 379         assert(sig);
 380         assert(event_id_p);
 381
 382         rcu_read_lock();
 383
 384         /*
 385          * This should not happen but since it comes from the UST tracer, an
 386          * external party, don't assert and simply validate values.
 387          */
 388         if (session_objd < 0 || channel_objd < 0) {
 389                 ret = -EINVAL;
 390                 goto error_free;
 391         }
 392
 393         chan = ust_registry_channel_find(session, chan_key);
 394         if (!chan) {
 395                 ret = -EINVAL;
 396                 goto error_free;
 397         }
 398
 399         /* Check if we've reached the maximum possible id. */
 400         if (ust_registry_is_max_id(chan->used_event_id)) {
 401                 ret = -ENOENT;
 402                 goto error_free;
 403         }
 404
 405         event = alloc_event(session_objd, channel_objd, name, sig, nr_fields,
 406                         fields, loglevel_value, model_emf_uri, app);
 407         if (!event) {
 408                 ret = -ENOMEM;
 409                 goto error_free;
 410         }
 411
 412         DBG3("UST registry creating event with event: %s, sig: %s, id: %u, "
 413                         "chan_objd: %u, sess_objd: %u, chan_id: %u", event->name,
 414                         event->signature, event->id, event->channel_objd,
 415                         event->session_objd, chan->chan_id);
 416
 417         /*
 418          * This is an add unique with a custom match function for event. The node
 419          * are matched using the event name and signature.
 420          */
 421         nptr = cds_lfht_add_unique(chan->ht->ht, chan->ht->hash_fct(event,
 422                                 lttng_ht_seed), chan->ht->match_fct, event, &event->node.node);
 423         if (nptr != &event->node.node) {
 424                 if (buffer_type == LTTNG_BUFFER_PER_UID) {
 425                         /*
 426                          * This is normal, we just have to send the event id of the
 427                          * returned node and make sure we destroy the previously allocated
 428                          * event object.
 429                          */
 430                         destroy_event(event);
 431                         event = caa_container_of(nptr, struct ust_registry_event,
 432                                         node.node);
 433                         assert(event);
 434                         event_id = event->id;
 435                 } else {
 436                         ERR("UST registry create event add unique failed for event: %s, "
 437                                         "sig: %s, id: %u, chan_objd: %u, sess_objd: %u",
 438                                         event->name, event->signature, event->id,
 439                                         event->channel_objd, event->session_objd);
 440                         ret = -EINVAL;
 441                         goto error_unlock;
 442                 }
 443         } else {
 444                 /* Request next event id if the node was successfully added. */
 445                 event_id = event->id = ust_registry_get_next_event_id(chan);
 446         }
 447
 448         *event_id_p = event_id;
 449
 450         if (!event->metadata_dumped) {
 451                 /* Append to metadata */
 452                 ret = ust_metadata_event_statedump(session, chan, event);
 453                 if (ret) {
 454                         ERR("Error appending event metadata (errno = %d)", ret);
 455                         rcu_read_unlock();
 456                         return ret;
 457                 }
 458         }
 459
 460         rcu_read_unlock();
 461         return 0;
 462
 463 error_free:
 464         free(sig);
 465         free(fields);
 466         free(model_emf_uri);
 467 error_unlock:
 468         rcu_read_unlock();
 469         destroy_event(event);
 470         return ret;
 471 }
 472
 473 /*
 474  * For a given event in a registry, delete the entry and destroy the event.
 475  * This MUST be called within a RCU read side lock section.
 476  */
 477 void ust_registry_destroy_event(struct ust_registry_channel *chan,
 478                 struct ust_registry_event *event)
 479 {
 480         int ret;
 481         struct lttng_ht_iter iter;
 482
 483         assert(chan);
 484         assert(event);
 485
 486         /* Delete the node first. */
 487         iter.iter.node = &event->node.node;
 488         ret = lttng_ht_del(chan->ht, &iter);
 489         assert(!ret);
 490
 491         call_rcu(&event->node.head, destroy_event_rcu);
 492
 493         return;
 494 }
 495
 496 static void destroy_enum(struct ust_registry_enum *reg_enum)
 497 {
 498         if (!reg_enum) {
 499                 return;
 500         }
 501         free(reg_enum->entries);
 502         free(reg_enum);
 503 }
 504
 505 static void destroy_enum_rcu(struct rcu_head *head)
 506 {
 507         struct ust_registry_enum *reg_enum =
 508                 caa_container_of(head, struct ust_registry_enum, rcu_head);
 509
 510         destroy_enum(reg_enum);
 511 }
 512
 513 /*
 514  * Lookup enumeration by name and comparing enumeration entries.
 515  * Needs to be called from RCU read-side critical section.
 516  */
 517 struct ust_registry_enum *
 518         ust_registry_lookup_enum(struct ust_registry_session *session,
 519                 const struct ust_registry_enum *reg_enum_lookup)
 520 {
 521         struct ust_registry_enum *reg_enum = NULL;
 522         struct lttng_ht_node_str *node;
 523         struct lttng_ht_iter iter;
 524
 525         cds_lfht_lookup(session->enums->ht,
 526                         ht_hash_enum((void *) &reg_enum_lookup, lttng_ht_seed),
 527                         ht_match_enum, &reg_enum_lookup, &iter.iter);
 528         node = lttng_ht_iter_get_node_str(&iter);
 529         if (!node) {
 530                 goto end;
 531         }
 532         reg_enum = caa_container_of(node, struct ust_registry_enum, node);
 533 end:
 534         return reg_enum;
 535 }
 536
 537 /*
 538  * Lookup enumeration by enum ID.
 539  * Needs to be called from RCU read-side critical section.
 540  */
 541 struct ust_registry_enum *
 542         ust_registry_lookup_enum_by_id(struct ust_registry_session *session,
 543                 const char *enum_name, uint64_t enum_id)
 544 {
 545         struct ust_registry_enum *reg_enum = NULL;
 546         struct lttng_ht_node_str *node;
 547         struct lttng_ht_iter iter;
 548         struct ust_registry_enum reg_enum_lookup;
 549
 550         memset(&reg_enum_lookup, 0, sizeof(reg_enum_lookup));
 551         strncpy(reg_enum_lookup.name, enum_name, LTTNG_UST_SYM_NAME_LEN);
 552         reg_enum_lookup.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 553         reg_enum_lookup.id = enum_id;
 554         cds_lfht_lookup(session->enums->ht,
 555                         ht_hash_enum((void *) &reg_enum_lookup, lttng_ht_seed),
 556                         ht_match_enum_id, &reg_enum_lookup, &iter.iter);
 557         node = lttng_ht_iter_get_node_str(&iter);
 558         if (!node) {
 559                 goto end;
 560         }
 561         reg_enum = caa_container_of(node, struct ust_registry_enum, node);
 562 end:
 563         return reg_enum;
 564 }
 565
 566 /*
 567  * Create a ust_registry_enum from the given parameters and add it to the
 568  * registry hash table, or find it if already there.
 569  *
 570  * On success, return 0 else a negative value.
 571  *
 572  * Should be called with session registry mutex held.
 573  *
 574  * We receive ownership of entries.
 575  */
 576 int ust_registry_create_or_find_enum(struct ust_registry_session *session,
 577                 int session_objd, char *enum_name,
 578                 struct ustctl_enum_entry *entries, size_t nr_entries,
 579                 uint64_t *enum_id)
 580 {
 581         int ret = 0;
 582         struct cds_lfht_node *nodep;
 583         struct ust_registry_enum *reg_enum = NULL, *old_reg_enum;
 584
 585         assert(session);
 586         assert(enum_name);
 587
 588         rcu_read_lock();
 589
 590         /*
 591          * This should not happen but since it comes from the UST tracer, an
 592          * external party, don't assert and simply validate values.
 593          */
 594         if (session_objd < 0) {
 595                 ret = -EINVAL;
 596                 goto end;
 597         }
 598
 599         /* Check if the enumeration was already dumped */
 600         reg_enum = zmalloc(sizeof(*reg_enum));
 601         if (!reg_enum) {
 602                 PERROR("zmalloc ust registry enumeration");
 603                 ret = -ENOMEM;
 604                 goto end;
 605         }
 606         strncpy(reg_enum->name, enum_name, LTTNG_UST_SYM_NAME_LEN);
 607         reg_enum->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 608         /* entries will be owned by reg_enum. */
 609         reg_enum->entries = entries;
 610         reg_enum->nr_entries = nr_entries;
 611         entries = NULL;
 612
 613         old_reg_enum = ust_registry_lookup_enum(session, reg_enum);
 614         if (old_reg_enum) {
 615                 DBG("enum %s already in sess_objd: %u", enum_name, session_objd);
 616                 /* Fall through. Use prior enum. */
 617                 destroy_enum(reg_enum);
 618                 reg_enum = old_reg_enum;
 619         } else {
 620                 DBG("UST registry creating enum: %s, sess_objd: %u",
 621                                 enum_name, session_objd);
 622                 if (session->next_enum_id == -1ULL) {
 623                         ret = -EOVERFLOW;
 624                         destroy_enum(reg_enum);
 625                         goto end;
 626                 }
 627                 reg_enum->id = session->next_enum_id++;
 628                 cds_lfht_node_init(&reg_enum->node.node);
 629                 nodep = cds_lfht_add_unique(session->enums->ht,
 630                                 ht_hash_enum(reg_enum, lttng_ht_seed),
 631                                 ht_match_enum_id, reg_enum,
 632                                 &reg_enum->node.node);
 633                 assert(nodep == &reg_enum->node.node);
 634         }
 635         DBG("UST registry reply with enum %s with id %" PRIu64 " in sess_objd: %u",
 636                         enum_name, reg_enum->id, session_objd);
 637         *enum_id = reg_enum->id;
 638 end:
 639         free(entries);
 640         rcu_read_unlock();
 641         return ret;
 642 }
 643
 644 /*
 645  * For a given enumeration in a registry, delete the entry and destroy
 646  * the enumeration.
 647  * This MUST be called within a RCU read side lock section.
 648  */
 649 void ust_registry_destroy_enum(struct ust_registry_session *reg_session,
 650                 struct ust_registry_enum *reg_enum)
 651 {
 652         int ret;
 653         struct lttng_ht_iter iter;
 654
 655         assert(reg_session);
 656         assert(reg_enum);
 657
 658         /* Delete the node first. */
 659         iter.iter.node = &reg_enum->node.node;
 660         ret = lttng_ht_del(reg_session->enums, &iter);
 661         assert(!ret);
 662         call_rcu(&reg_enum->rcu_head, destroy_enum_rcu);
 663 }
 664
 665 /*
 666  * We need to execute ht_destroy outside of RCU read-side critical
 667  * section and outside of call_rcu thread, so we postpone its execution
 668  * using ht_cleanup_push. It is simpler than to change the semantic of
 669  * the many callers of delete_ust_app_session().
 670  */
 671 static
 672 void destroy_channel_rcu(struct rcu_head *head)
 673 {
 674         struct ust_registry_channel *chan =
 675                 caa_container_of(head, struct ust_registry_channel, rcu_head);
 676
 677         if (chan->ht) {
 678                 ht_cleanup_push(chan->ht);
 679         }
 680         free(chan->ctx_fields);
 681         free(chan);
 682 }
 683
 684 /*
 685  * Destroy every element of the registry and free the memory. This does NOT
 686  * free the registry pointer since it might not have been allocated before so
 687  * it's the caller responsability.
 688  */
 689 static void destroy_channel(struct ust_registry_channel *chan)
 690 {
 691         struct lttng_ht_iter iter;
 692         struct ust_registry_event *event;
 693
 694         assert(chan);
 695
 696         rcu_read_lock();
 697         /* Destroy all event associated with this registry. */
 698         cds_lfht_for_each_entry(chan->ht->ht, &iter.iter, event, node.node) {
 699                 /* Delete the node from the ht and free it. */
 700                 ust_registry_destroy_event(chan, event);
 701         }
 702         rcu_read_unlock();
 703         call_rcu(&chan->rcu_head, destroy_channel_rcu);
 704 }
 705
 706 /*
 707  * Initialize registry with default values.
 708  */
 709 int ust_registry_channel_add(struct ust_registry_session *session,
 710                 uint64_t key)
 711 {
 712         int ret = 0;
 713         struct ust_registry_channel *chan;
 714
 715         assert(session);
 716
 717         chan = zmalloc(sizeof(*chan));
 718         if (!chan) {
 719                 PERROR("zmalloc ust registry channel");
 720                 ret = -ENOMEM;
 721                 goto error_alloc;
 722         }
 723
 724         chan->ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 725         if (!chan->ht) {
 726                 ret = -ENOMEM;
 727                 goto error;
 728         }
 729
 730         /* Set custom match function. */
 731         chan->ht->match_fct = ht_match_event;
 732         chan->ht->hash_fct = ht_hash_event;
 733
 734         /*
 735          * Assign a channel ID right now since the event notification comes
 736          * *before* the channel notify so the ID needs to be set at this point so
 737          * the metadata can be dumped for that event.
 738          */
 739         if (ust_registry_is_max_id(session->used_channel_id)) {
 740                 ret = -1;
 741                 goto error;
 742         }
 743         chan->chan_id = ust_registry_get_next_chan_id(session);
 744
 745         rcu_read_lock();
 746         lttng_ht_node_init_u64(&chan->node, key);
 747         lttng_ht_add_unique_u64(session->channels, &chan->node);
 748         rcu_read_unlock();
 749
 750         return 0;
 751
 752 error:
 753         destroy_channel(chan);
 754 error_alloc:
 755         return ret;
 756 }
 757
 758 /*
 759  * Find a channel in the given registry. RCU read side lock MUST be acquired
 760  * before calling this function and as long as the event reference is kept by
 761  * the caller.
 762  *
 763  * On success, the pointer is returned else NULL.
 764  */
 765 struct ust_registry_channel *ust_registry_channel_find(
 766                 struct ust_registry_session *session, uint64_t key)
 767 {
 768         struct lttng_ht_node_u64 *node;
 769         struct lttng_ht_iter iter;
 770         struct ust_registry_channel *chan = NULL;
 771
 772         assert(session);
 773         assert(session->channels);
 774
 775         DBG3("UST registry channel finding key %" PRIu64, key);
 776
 777         lttng_ht_lookup(session->channels, &key, &iter);
 778         node = lttng_ht_iter_get_node_u64(&iter);
 779         if (!node) {
 780                 goto end;
 781         }
 782         chan = caa_container_of(node, struct ust_registry_channel, node);
 783
 784 end:
 785         return chan;
 786 }
 787
 788 /*
 789  * Remove channel using key from registry and free memory.
 790  */
 791 void ust_registry_channel_del_free(struct ust_registry_session *session,
 792                 uint64_t key)
 793 {
 794         struct lttng_ht_iter iter;
 795         struct ust_registry_channel *chan;
 796         int ret;
 797
 798         assert(session);
 799
 800         rcu_read_lock();
 801         chan = ust_registry_channel_find(session, key);
 802         if (!chan) {
 803                 rcu_read_unlock();
 804                 goto end;
 805         }
 806
 807         iter.iter.node = &chan->node.node;
 808         ret = lttng_ht_del(session->channels, &iter);
 809         assert(!ret);
 810         rcu_read_unlock();
 811         destroy_channel(chan);
 812
 813 end:
 814         return;
 815 }
 816
 817 /*
 818  * Initialize registry with default values and set the newly allocated session
 819  * pointer to sessionp.
 820  *
 821  * Return 0 on success and sessionp is set or else return -1 and sessionp is
 822  * kept untouched.
 823  */
 824 int ust_registry_session_init(struct ust_registry_session **sessionp,
 825                 struct ust_app *app,
 826                 uint32_t bits_per_long,
 827                 uint32_t uint8_t_alignment,
 828                 uint32_t uint16_t_alignment,
 829                 uint32_t uint32_t_alignment,
 830                 uint32_t uint64_t_alignment,
 831                 uint32_t long_alignment,
 832                 int byte_order,
 833                 uint32_t major,
 834                 uint32_t minor,
 835                 const char *root_shm_path,
 836                 const char *shm_path,
 837                 uid_t euid,
 838                 gid_t egid)
 839 {
 840         int ret;
 841         struct ust_registry_session *session;
 842
 843         assert(sessionp);
 844
 845         session = zmalloc(sizeof(*session));
 846         if (!session) {
 847                 PERROR("zmalloc ust registry session");
 848                 goto error_alloc;
 849         }
 850
 851         pthread_mutex_init(&session->lock, NULL);
 852         session->bits_per_long = bits_per_long;
 853         session->uint8_t_alignment = uint8_t_alignment;
 854         session->uint16_t_alignment = uint16_t_alignment;
 855         session->uint32_t_alignment = uint32_t_alignment;
 856         session->uint64_t_alignment = uint64_t_alignment;
 857         session->long_alignment = long_alignment;
 858         session->byte_order = byte_order;
 859         session->metadata_fd = -1;
 860         session->uid = euid;
 861         session->gid = egid;
 862         session->next_enum_id = 0;
 863         strncpy(session->root_shm_path, root_shm_path,
 864                 sizeof(session->root_shm_path));
 865         session->root_shm_path[sizeof(session->root_shm_path) - 1] = '\0';
 866         if (shm_path[0]) {
 867                 strncpy(session->shm_path, shm_path,
 868                         sizeof(session->shm_path));
 869                 session->shm_path[sizeof(session->shm_path) - 1] = '\0';
 870                 strncpy(session->metadata_path, shm_path,
 871                         sizeof(session->metadata_path));
 872                 session->metadata_path[sizeof(session->metadata_path) - 1] = '\0';
 873                 strncat(session->metadata_path, "/metadata",
 874                         sizeof(session->metadata_path)
 875                                 - strlen(session->metadata_path) - 1);
 876         }
 877         if (session->shm_path[0]) {
 878                 ret = run_as_mkdir_recursive(session->shm_path,
 879                         S_IRWXU | S_IRWXG,
 880                         euid, egid);
 881                 if (ret) {
 882                         PERROR("run_as_mkdir_recursive");
 883                         goto error;
 884                 }
 885         }
 886         if (session->metadata_path[0]) {
 887                 /* Create metadata file */
 888                 ret = run_as_open(session->metadata_path,
 889                         O_WRONLY | O_CREAT | O_EXCL,
 890                         S_IRUSR | S_IWUSR, euid, egid);
 891                 if (ret < 0) {
 892                         PERROR("Opening metadata file");
 893                         goto error;
 894                 }
 895                 session->metadata_fd = ret;
 896         }
 897
 898         session->enums = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 899         if (!session->enums) {
 900                 ret = -ENOMEM;
 901                 goto error;
 902         }
 903         /* hash/match functions are specified at call site. */
 904         session->enums->match_fct = NULL;
 905         session->enums->hash_fct = NULL;
 906
 907         session->channels = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 908         if (!session->channels) {
 909                 goto error;
 910         }
 911
 912         ret = lttng_uuid_generate(session->uuid);
 913         if (ret) {
 914                 ERR("Failed to generate UST uuid (errno = %d)", ret);
 915                 goto error;
 916         }
 917
 918         pthread_mutex_lock(&session->lock);
 919         ret = ust_metadata_session_statedump(session, app, major, minor);
 920         pthread_mutex_unlock(&session->lock);
 921         if (ret) {
 922                 ERR("Failed to generate session metadata (errno = %d)", ret);
 923                 goto error;
 924         }
 925
 926         *sessionp = session;
 927
 928         return 0;
 929
 930 error:
 931         ust_registry_session_destroy(session);
 932         free(session);
 933 error_alloc:
 934         return -1;
 935 }
 936
 937 /*
 938  * Destroy session registry. This does NOT free the given pointer since it
 939  * might get passed as a reference. The registry lock should NOT be acquired.
 940  */
 941 void ust_registry_session_destroy(struct ust_registry_session *reg)
 942 {
 943         int ret;
 944         struct lttng_ht_iter iter;
 945         struct ust_registry_channel *chan;
 946         struct ust_registry_enum *reg_enum;
 947
 948         if (!reg) {
 949                 return;
 950         }
 951
 952         /* On error, EBUSY can be returned if lock. Code flow error. */
 953         ret = pthread_mutex_destroy(&reg->lock);
 954         assert(!ret);
 955
 956         if (reg->channels) {
 957                 rcu_read_lock();
 958                 /* Destroy all event associated with this registry. */
 959                 cds_lfht_for_each_entry(reg->channels->ht, &iter.iter, chan,
 960                                 node.node) {
 961                         /* Delete the node from the ht and free it. */
 962                         ret = lttng_ht_del(reg->channels, &iter);
 963                         assert(!ret);
 964                         destroy_channel(chan);
 965                 }
 966                 rcu_read_unlock();
 967                 ht_cleanup_push(reg->channels);
 968         }
 969
 970         free(reg->metadata);
 971         if (reg->metadata_fd >= 0) {
 972                 ret = close(reg->metadata_fd);
 973                 if (ret) {
 974                         PERROR("close");
 975                 }
 976                 ret = run_as_unlink(reg->metadata_path,
 977                                 reg->uid, reg->gid);
 978                 if (ret) {
 979                         PERROR("unlink");
 980                 }
 981         }
 982         if (reg->root_shm_path[0]) {
 983                 /*
 984                  * Try deleting the directory hierarchy.
 985                  */
 986                 (void) run_as_recursive_rmdir(reg->root_shm_path,
 987                                 reg->uid, reg->gid);
 988         }
 989         /* Destroy the enum hash table */
 990         if (reg->enums) {
 991                 rcu_read_lock();
 992                 /* Destroy all enum entries associated with this registry. */
 993                 cds_lfht_for_each_entry(reg->enums->ht, &iter.iter, reg_enum,
 994                                 node.node) {
 995                         ust_registry_destroy_enum(reg, reg_enum);
 996                 }
 997                 rcu_read_unlock();
 998                 ht_cleanup_push(reg->enums);
 999         }
1000 }