src/bin/lttng-sessiond/agent.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  * Copyright (C) 2016 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License, version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 51
  16  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <urcu/uatomic.h>
  22 #include <urcu/rculist.h>
  23
  24 #include <common/common.h>
  25 #include <common/sessiond-comm/agent.h>
  26
  27 #include <common/compat/endian.h>
  28
  29 #include "agent.h"
  30 #include "ust-app.h"
  31 #include "utils.h"
  32 #include "error.h"
  33
  34 #define AGENT_RET_CODE_INDEX(code) (code - AGENT_RET_CODE_SUCCESS)
  35
  36 /*
  37  * Agent application context representation.
  38  */
  39 struct agent_app_ctx {
  40         char *provider_name;
  41         char *ctx_name;
  42
  43         /* agent_app_ctx are part of the agent app_ctx_list. */
  44         struct cds_list_head list_node;
  45
  46         /* For call_rcu teardown. */
  47         struct rcu_head rcu_node;
  48 };
  49
  50 /*
  51  * Human readable agent return code.
  52  */
  53 static const char *error_string_array[] = {
  54         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_SUCCESS) ] = "Success",
  55         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_INVALID) ] = "Invalid command",
  56         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_UNKNOWN_NAME) ] = "Unknown logger name",
  57
  58         /* Last element */
  59         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_NR) ] = "Unknown code",
  60 };
  61
  62 static
  63 void log_reply_code(uint32_t in_reply_ret_code)
  64 {
  65         int level = PRINT_DBG3;
  66         /*
  67          * reply_ret_code and in_reply_ret_code are kept separate to have a
  68          * sanitized value (used to retrieve the human readable string) and the
  69          * original value which is logged as-is.
  70          */
  71         uint32_t reply_ret_code = in_reply_ret_code;
  72
  73         if (reply_ret_code < AGENT_RET_CODE_SUCCESS ||
  74                         reply_ret_code >= AGENT_RET_CODE_NR) {
  75                 reply_ret_code = AGENT_RET_CODE_NR;
  76                 level = PRINT_ERR;
  77         }
  78
  79         LOG(level, "Agent replied with retcode: %s (%"PRIu32")",
  80                         error_string_array[AGENT_RET_CODE_INDEX(
  81                         reply_ret_code)],
  82                         in_reply_ret_code);
  83 }
  84
  85 /*
  86  * Match function for the events hash table lookup by name.
  87  */
  88 static int ht_match_event_by_name(struct cds_lfht_node *node,
  89                 const void *_key)
  90 {
  91         struct agent_event *event;
  92         const struct agent_ht_key *key;
  93
  94         assert(node);
  95         assert(_key);
  96
  97         event = caa_container_of(node, struct agent_event, node.node);
  98         key = _key;
  99
 100         /* Match 1 elements of the key: name. */
 101
 102         /* Event name */
 103         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
 104                 goto no_match;
 105         }
 106         /* Match. */
 107         return 1;
 108
 109 no_match:
 110         return 0;
 111 }
 112
 113 /*
 114  * Match function for the events hash table lookup by name and loglevel.
 115  */
 116 static int ht_match_event(struct cds_lfht_node *node,
 117                 const void *_key)
 118 {
 119         struct agent_event *event;
 120         const struct agent_ht_key *key;
 121         int ll_match;
 122
 123         assert(node);
 124         assert(_key);
 125
 126         event = caa_container_of(node, struct agent_event, node.node);
 127         key = _key;
 128
 129         /* Match 2 elements of the key: name and loglevel. */
 130
 131         /* Event name */
 132         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
 133                 goto no_match;
 134         }
 135
 136         /* Event loglevel value and type. */
 137         ll_match = loglevels_match(event->loglevel_type,
 138                 event->loglevel_value, key->loglevel_type,
 139                 key->loglevel_value, LTTNG_EVENT_LOGLEVEL_ALL);
 140
 141         if (!ll_match) {
 142                 goto no_match;
 143         }
 144
 145         /* Filter expression */
 146         if (strncmp(event->filter_expression, key->filter_expression,
 147                         strlen(event->filter_expression)) != 0) {
 148                 goto no_match;
 149         }
 150
 151         return 1;
 152
 153 no_match:
 154         return 0;
 155 }
 156
 157 /*
 158  * Add unique agent event based on the event name and loglevel.
 159  */
 160 static void add_unique_agent_event(struct lttng_ht *ht,
 161                 struct agent_event *event)
 162 {
 163         struct cds_lfht_node *node_ptr;
 164         struct agent_ht_key key;
 165
 166         assert(ht);
 167         assert(ht->ht);
 168         assert(event);
 169
 170         key.name = event->name;
 171         key.loglevel_value = event->loglevel_value;
 172         key.loglevel_type = event->loglevel_type;
 173         key.filter_expression = event->filter_expression;
 174
 175         node_ptr = cds_lfht_add_unique(ht->ht,
 176                         ht->hash_fct(event->node.key, lttng_ht_seed),
 177                         ht_match_event, &key, &event->node.node);
 178         assert(node_ptr == &event->node.node);
 179 }
 180
 181 /*
 182  * URCU delayed agent event reclaim.
 183  */
 184 static void destroy_event_agent_rcu(struct rcu_head *head)
 185 {
 186         struct lttng_ht_node_str *node =
 187                 caa_container_of(head, struct lttng_ht_node_str, head);
 188         struct agent_event *event =
 189                 caa_container_of(node, struct agent_event, node);
 190
 191         agent_destroy_event(event);
 192 }
 193
 194 /*
 195  * URCU delayed agent app reclaim.
 196  */
 197 static void destroy_app_agent_rcu(struct rcu_head *head)
 198 {
 199         struct lttng_ht_node_ulong *node =
 200                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 201         struct agent_app *app =
 202                 caa_container_of(node, struct agent_app, node);
 203
 204         free(app);
 205 }
 206
 207 /*
 208  * Communication with the agent. Send the message header to the given socket in
 209  * big endian.
 210  *
 211  * Return 0 on success or else a negative errno message of sendmsg() op.
 212  */
 213 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 214                 uint32_t cmd, uint32_t cmd_version)
 215 {
 216         int ret;
 217         ssize_t size;
 218         struct lttcomm_agent_hdr msg;
 219
 220         assert(sock);
 221
 222         memset(&msg, 0, sizeof(msg));
 223         msg.data_size = htobe64(data_size);
 224         msg.cmd = htobe32(cmd);
 225         msg.cmd_version = htobe32(cmd_version);
 226
 227         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 228         if (size < sizeof(msg)) {
 229                 ret = -errno;
 230                 goto error;
 231         }
 232         ret = 0;
 233
 234 error:
 235         return ret;
 236 }
 237
 238 /*
 239  * Communication call with the agent. Send the payload to the given socket. The
 240  * header MUST be sent prior to this call.
 241  *
 242  * Return 0 on success or else a negative errno value of sendmsg() op.
 243  */
 244 static int send_payload(struct lttcomm_sock *sock, const void *data,
 245                 size_t size)
 246 {
 247         int ret;
 248         ssize_t len;
 249
 250         assert(sock);
 251         assert(data);
 252
 253         len = sock->ops->sendmsg(sock, data, size, 0);
 254         if (len < size) {
 255                 ret = -errno;
 256                 goto error;
 257         }
 258         ret = 0;
 259
 260 error:
 261         return ret;
 262 }
 263
 264 /*
 265  * Communication call with the agent. Receive reply from the agent using the
 266  * given socket.
 267  *
 268  * Return 0 on success or else a negative errno value from recvmsg() op.
 269  */
 270 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 271 {
 272         int ret;
 273         ssize_t len;
 274
 275         assert(sock);
 276         assert(buf);
 277
 278         len = sock->ops->recvmsg(sock, buf, size, 0);
 279         if (len < size) {
 280                 ret = -errno;
 281                 goto error;
 282         }
 283         ret = 0;
 284
 285 error:
 286         return ret;
 287 }
 288
 289 /*
 290  * Internal event listing for a given app. Populate events.
 291  *
 292  * Return number of element in the list or else a negative LTTNG_ERR* code.
 293  * On success, the caller is responsible for freeing the memory
 294  * allocated for "events".
 295  */
 296 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 297 {
 298         int ret, i, len = 0, offset = 0;
 299         uint32_t nb_event;
 300         size_t data_size;
 301         uint32_t reply_ret_code;
 302         struct lttng_event *tmp_events = NULL;
 303         struct lttcomm_agent_list_reply *reply = NULL;
 304         struct lttcomm_agent_list_reply_hdr reply_hdr;
 305
 306         assert(app);
 307         assert(app->sock);
 308         assert(events);
 309
 310         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 311                         app->sock->fd);
 312
 313         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 314         if (ret < 0) {
 315                 goto error_io;
 316         }
 317
 318         /* Get list header so we know how much we'll receive. */
 319         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 320         if (ret < 0) {
 321                 goto error_io;
 322         }
 323
 324         reply_ret_code = be32toh(reply_hdr.ret_code);
 325         log_reply_code(reply_ret_code);
 326         switch (reply_ret_code) {
 327         case AGENT_RET_CODE_SUCCESS:
 328                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 329                 break;
 330         default:
 331                 ret = LTTNG_ERR_UNK;
 332                 goto error;
 333         }
 334
 335         reply = zmalloc(data_size);
 336         if (!reply) {
 337                 ret = LTTNG_ERR_NOMEM;
 338                 goto error;
 339         }
 340
 341         /* Get the list with the appropriate data size. */
 342         ret = recv_reply(app->sock, reply, data_size);
 343         if (ret < 0) {
 344                 goto error_io;
 345         }
 346
 347         nb_event = be32toh(reply->nb_event);
 348         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 349         if (!tmp_events) {
 350                 ret = LTTNG_ERR_NOMEM;
 351                 goto error;
 352         }
 353
 354         for (i = 0; i < nb_event; i++) {
 355                 offset += len;
 356                 strncpy(tmp_events[i].name, reply->payload + offset,
 357                                 sizeof(tmp_events[i].name));
 358                 tmp_events[i].pid = app->pid;
 359                 tmp_events[i].enabled = -1;
 360                 len = strlen(reply->payload + offset) + 1;
 361         }
 362
 363         *events = tmp_events;
 364
 365         free(reply);
 366         return nb_event;
 367
 368 error_io:
 369         ret = LTTNG_ERR_UST_LIST_FAIL;
 370 error:
 371         free(reply);
 372         free(tmp_events);
 373         return -ret;
 374
 375 }
 376
 377 /*
 378  * Internal enable agent event on a agent application. This function
 379  * communicates with the agent to enable a given event.
 380  *
 381  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 382  */
 383 static int enable_event(struct agent_app *app, struct agent_event *event)
 384 {
 385         int ret;
 386         char *bytes_to_send;
 387         uint64_t data_size;
 388         size_t filter_expression_length;
 389         uint32_t reply_ret_code;
 390         struct lttcomm_agent_enable_event msg;
 391         struct lttcomm_agent_generic_reply reply;
 392
 393         assert(app);
 394         assert(app->sock);
 395         assert(event);
 396
 397         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 398                         app->pid, app->sock->fd);
 399
 400         /*
 401          * Calculate the payload's size, which is the fixed-size struct followed
 402          * by the variable-length filter expression (+1 for the ending \0).
 403          */
 404         if (!event->filter_expression) {
 405                 filter_expression_length = 0;
 406         } else {
 407                 filter_expression_length = strlen(event->filter_expression) + 1;
 408         }
 409         data_size = sizeof(msg) + filter_expression_length;
 410
 411         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 412         if (ret < 0) {
 413                 goto error_io;
 414         }
 415
 416         memset(&msg, 0, sizeof(msg));
 417         msg.loglevel_value = htobe32(event->loglevel_value);
 418         msg.loglevel_type = htobe32(event->loglevel_type);
 419         strncpy(msg.name, event->name, sizeof(msg.name));
 420         msg.filter_expression_length = htobe32(filter_expression_length);
 421
 422         bytes_to_send = zmalloc(data_size);
 423         if (!bytes_to_send) {
 424                 ret = LTTNG_ERR_NOMEM;
 425                 goto error;
 426         }
 427
 428         memcpy(bytes_to_send, &msg, sizeof(msg));
 429         if (filter_expression_length > 0) {
 430                 memcpy(bytes_to_send + sizeof(msg), event->filter_expression,
 431                                 filter_expression_length);
 432         }
 433
 434         ret = send_payload(app->sock, bytes_to_send, data_size);
 435         free(bytes_to_send);
 436         if (ret < 0) {
 437                 goto error_io;
 438         }
 439
 440         ret = recv_reply(app->sock, &reply, sizeof(reply));
 441         if (ret < 0) {
 442                 goto error_io;
 443         }
 444
 445         reply_ret_code = be32toh(reply.ret_code);
 446         log_reply_code(reply_ret_code);
 447         switch (reply_ret_code) {
 448         case AGENT_RET_CODE_SUCCESS:
 449                 break;
 450         case AGENT_RET_CODE_UNKNOWN_NAME:
 451                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 452                 goto error;
 453         default:
 454                 ret = LTTNG_ERR_UNK;
 455                 goto error;
 456         }
 457
 458         return LTTNG_OK;
 459
 460 error_io:
 461         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 462 error:
 463         return ret;
 464 }
 465
 466 /*
 467  * Send Pascal-style string. Size is sent as a 32-bit big endian integer.
 468  */
 469 static
 470 int send_pstring(struct lttcomm_sock *sock, const char *str, uint32_t len)
 471 {
 472         int ret;
 473         uint32_t len_be;
 474
 475         len_be = htobe32(len);
 476         ret = send_payload(sock, &len_be, sizeof(len_be));
 477         if (ret) {
 478                 goto end;
 479         }
 480
 481         ret = send_payload(sock, str, len);
 482         if (ret) {
 483                 goto end;
 484         }
 485 end:
 486         return ret;
 487 }
 488
 489 /*
 490  * Internal enable application context on an agent application. This function
 491  * communicates with the agent to enable a given application context.
 492  *
 493  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 494  */
 495 static int app_context_op(struct agent_app *app,
 496                 struct agent_app_ctx *ctx, enum lttcomm_agent_command cmd)
 497 {
 498         int ret;
 499         uint32_t reply_ret_code;
 500         struct lttcomm_agent_generic_reply reply;
 501         size_t app_ctx_provider_name_len, app_ctx_name_len, data_size;
 502
 503         assert(app);
 504         assert(app->sock);
 505         assert(ctx);
 506         assert(cmd == AGENT_CMD_APP_CTX_ENABLE ||
 507                         cmd == AGENT_CMD_APP_CTX_DISABLE);
 508
 509         DBG2("Agent %s application %s:%s for app pid: %d and socket %d",
 510                         cmd == AGENT_CMD_APP_CTX_ENABLE ? "enabling" : "disabling",
 511                         ctx->provider_name, ctx->ctx_name,
 512                         app->pid, app->sock->fd);
 513
 514         /*
 515          * Calculate the payload's size, which consists of the size (u32, BE)
 516          * of the provider name, the NULL-terminated provider name string, the
 517          * size (u32, BE) of the context name, followed by the NULL-terminated
 518          * context name string.
 519          */
 520         app_ctx_provider_name_len = strlen(ctx->provider_name) + 1;
 521         app_ctx_name_len = strlen(ctx->ctx_name) + 1;
 522         data_size = sizeof(uint32_t) + app_ctx_provider_name_len +
 523                         sizeof(uint32_t) + app_ctx_name_len;
 524
 525         ret = send_header(app->sock, data_size, cmd, 0);
 526         if (ret < 0) {
 527                 goto error_io;
 528         }
 529
 530         if (app_ctx_provider_name_len > UINT32_MAX ||
 531                         app_ctx_name_len > UINT32_MAX) {
 532                 ERR("Application context name > MAX_UINT32");
 533                 ret = LTTNG_ERR_INVALID;
 534                 goto error;
 535         }
 536
 537         ret = send_pstring(app->sock, ctx->provider_name,
 538                         (uint32_t) app_ctx_provider_name_len);
 539         if (ret < 0) {
 540                 goto error_io;
 541         }
 542
 543         ret = send_pstring(app->sock, ctx->ctx_name,
 544                         (uint32_t) app_ctx_name_len);
 545         if (ret < 0) {
 546                 goto error_io;
 547         }
 548
 549         ret = recv_reply(app->sock, &reply, sizeof(reply));
 550         if (ret < 0) {
 551                 goto error_io;
 552         }
 553
 554         reply_ret_code = be32toh(reply.ret_code);
 555         log_reply_code(reply_ret_code);
 556         switch (reply_ret_code) {
 557         case AGENT_RET_CODE_SUCCESS:
 558                 break;
 559         default:
 560                 ret = LTTNG_ERR_UNK;
 561                 goto error;
 562         }
 563
 564         return LTTNG_OK;
 565
 566 error_io:
 567         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 568 error:
 569         return ret;
 570 }
 571
 572 /*
 573  * Internal disable agent event call on a agent application. This function
 574  * communicates with the agent to disable a given event.
 575  *
 576  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 577  */
 578 static int disable_event(struct agent_app *app, struct agent_event *event)
 579 {
 580         int ret;
 581         uint64_t data_size;
 582         uint32_t reply_ret_code;
 583         struct lttcomm_agent_disable_event msg;
 584         struct lttcomm_agent_generic_reply reply;
 585
 586         assert(app);
 587         assert(app->sock);
 588         assert(event);
 589
 590         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 591                         app->pid, app->sock->fd);
 592
 593         data_size = sizeof(msg);
 594
 595         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 596         if (ret < 0) {
 597                 goto error_io;
 598         }
 599
 600         memset(&msg, 0, sizeof(msg));
 601         strncpy(msg.name, event->name, sizeof(msg.name));
 602         ret = send_payload(app->sock, &msg, sizeof(msg));
 603         if (ret < 0) {
 604                 goto error_io;
 605         }
 606
 607         ret = recv_reply(app->sock, &reply, sizeof(reply));
 608         if (ret < 0) {
 609                 goto error_io;
 610         }
 611
 612         reply_ret_code = be32toh(reply.ret_code);
 613         log_reply_code(reply_ret_code);
 614         switch (reply_ret_code) {
 615         case AGENT_RET_CODE_SUCCESS:
 616                 break;
 617         case AGENT_RET_CODE_UNKNOWN_NAME:
 618                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 619                 goto error;
 620         default:
 621                 ret = LTTNG_ERR_UNK;
 622                 goto error;
 623         }
 624
 625         return LTTNG_OK;
 626
 627 error_io:
 628         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 629 error:
 630         return ret;
 631 }
 632
 633 /*
 634  * Send back the registration DONE command to a given agent application.
 635  *
 636  * Return 0 on success or else a negative value.
 637  */
 638 int agent_send_registration_done(struct agent_app *app)
 639 {
 640         assert(app);
 641         assert(app->sock);
 642
 643         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 644
 645         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 646 }
 647
 648 /*
 649  * Enable agent event on every agent applications registered with the session
 650  * daemon.
 651  *
 652  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 653  */
 654 int agent_enable_event(struct agent_event *event,
 655                 enum lttng_domain_type domain)
 656 {
 657         int ret;
 658         struct agent_app *app;
 659         struct lttng_ht_iter iter;
 660
 661         assert(event);
 662
 663         rcu_read_lock();
 664
 665         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 666                         node.node) {
 667                 if (app->domain != domain) {
 668                         continue;
 669                 }
 670
 671                 /* Enable event on agent application through TCP socket. */
 672                 ret = enable_event(app, event);
 673                 if (ret != LTTNG_OK) {
 674                         goto error;
 675                 }
 676         }
 677
 678         event->enabled = 1;
 679         ret = LTTNG_OK;
 680
 681 error:
 682         rcu_read_unlock();
 683         return ret;
 684 }
 685
 686 static
 687 void destroy_app_ctx(struct agent_app_ctx *ctx)
 688 {
 689         free(ctx->provider_name);
 690         free(ctx->ctx_name);
 691         free(ctx);
 692 }
 693
 694 static
 695 struct agent_app_ctx *create_app_ctx(struct lttng_event_context *ctx)
 696 {
 697         struct agent_app_ctx *agent_ctx = NULL;
 698
 699         if (!ctx) {
 700                 goto end;
 701         }
 702
 703         assert(ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
 704         agent_ctx = zmalloc(sizeof(*ctx));
 705         if (!agent_ctx) {
 706                 goto end;
 707         }
 708
 709         agent_ctx->provider_name = strdup(ctx->u.app_ctx.provider_name);
 710         agent_ctx->ctx_name = strdup(ctx->u.app_ctx.ctx_name);
 711         if (!agent_ctx->provider_name || !agent_ctx->ctx_name) {
 712                 destroy_app_ctx(agent_ctx);
 713                 agent_ctx = NULL;
 714         }
 715 end:
 716         return agent_ctx;
 717 }
 718
 719 /*
 720  * Enable agent context on every agent applications registered with the session
 721  * daemon.
 722  *
 723  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 724  */
 725 int agent_enable_context(struct lttng_event_context *ctx,
 726                 enum lttng_domain_type domain)
 727 {
 728         int ret;
 729         struct agent_app *app;
 730         struct lttng_ht_iter iter;
 731
 732         assert(ctx);
 733         if (ctx->ctx != LTTNG_EVENT_CONTEXT_APP_CONTEXT) {
 734                 ret = LTTNG_ERR_INVALID;
 735                 goto error;
 736         }
 737
 738         rcu_read_lock();
 739
 740         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 741                         node.node) {
 742                 struct agent_app_ctx *agent_ctx;
 743
 744                 if (app->domain != domain) {
 745                         continue;
 746                 }
 747
 748                 agent_ctx = create_app_ctx(ctx);
 749                 if (!agent_ctx) {
 750                         goto error_unlock;
 751                 }
 752
 753                 /* Enable event on agent application through TCP socket. */
 754                 ret = app_context_op(app, agent_ctx, AGENT_CMD_APP_CTX_ENABLE);
 755                 if (ret != LTTNG_OK) {
 756                         destroy_app_ctx(agent_ctx);
 757                         goto error_unlock;
 758                 }
 759         }
 760
 761         ret = LTTNG_OK;
 762
 763 error_unlock:
 764         rcu_read_unlock();
 765 error:
 766         return ret;
 767 }
 768
 769 /*
 770  * Disable agent event on every agent application registered with the session
 771  * daemon.
 772  *
 773  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 774  */
 775 int agent_disable_event(struct agent_event *event,
 776                 enum lttng_domain_type domain)
 777 {
 778         int ret = LTTNG_OK;
 779         struct agent_app *app;
 780         struct lttng_ht_iter iter;
 781
 782         assert(event);
 783         if (!event->enabled) {
 784                 goto end;
 785         }
 786
 787         rcu_read_lock();
 788
 789         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 790                         node.node) {
 791                 if (app->domain != domain) {
 792                         continue;
 793                 }
 794
 795                 /* Enable event on agent application through TCP socket. */
 796                 ret = disable_event(app, event);
 797                 if (ret != LTTNG_OK) {
 798                         goto error;
 799                 }
 800         }
 801
 802         event->enabled = 0;
 803
 804 error:
 805         rcu_read_unlock();
 806 end:
 807         return ret;
 808 }
 809
 810 /*
 811  * Disable agent context on every agent application registered with the session
 812  * daemon.
 813  *
 814  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 815  */
 816 int disable_context(struct agent_app_ctx *ctx, enum lttng_domain_type domain)
 817 {
 818         int ret = LTTNG_OK;
 819         struct agent_app *app;
 820         struct lttng_ht_iter iter;
 821
 822         assert(ctx);
 823
 824         rcu_read_lock();
 825         DBG2("Disabling agent application context %s:%s",
 826                         ctx->provider_name, ctx->ctx_name);
 827         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 828                         node.node) {
 829                 if (app->domain != domain) {
 830                         continue;
 831                 }
 832
 833                 ret = app_context_op(app, ctx, AGENT_CMD_APP_CTX_DISABLE);
 834                 if (ret != LTTNG_OK) {
 835                         goto end;
 836                 }
 837         }
 838 end:
 839         rcu_read_unlock();
 840         return ret;
 841 }
 842
 843 /*
 844  * Ask every agent for the list of possible event. Events is allocated with the
 845  * events of every agent application.
 846  *
 847  * Return the number of events or else a negative value.
 848  */
 849 int agent_list_events(struct lttng_event **events,
 850                 enum lttng_domain_type domain)
 851 {
 852         int ret;
 853         size_t nbmem, count = 0;
 854         struct agent_app *app;
 855         struct lttng_event *tmp_events = NULL;
 856         struct lttng_ht_iter iter;
 857
 858         assert(events);
 859
 860         DBG2("Agent listing events for domain %d", domain);
 861
 862         nbmem = UST_APP_EVENT_LIST_SIZE;
 863         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 864         if (!tmp_events) {
 865                 PERROR("zmalloc agent list events");
 866                 ret = -ENOMEM;
 867                 goto error;
 868         }
 869
 870         rcu_read_lock();
 871         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 872                         node.node) {
 873                 ssize_t nb_ev;
 874                 struct lttng_event *agent_events;
 875
 876                 /* Skip domain not asked by the list. */
 877                 if (app->domain != domain) {
 878                         continue;
 879                 }
 880
 881                 nb_ev = list_events(app, &agent_events);
 882                 if (nb_ev < 0) {
 883                         ret = nb_ev;
 884                         goto error_unlock;
 885                 }
 886
 887                 if (count + nb_ev > nbmem) {
 888                         /* In case the realloc fails, we free the memory */
 889                         struct lttng_event *new_tmp_events;
 890                         size_t new_nbmem;
 891
 892                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 893                         DBG2("Reallocating agent event list from %zu to %zu entries",
 894                                         nbmem, new_nbmem);
 895                         new_tmp_events = realloc(tmp_events,
 896                                 new_nbmem * sizeof(*new_tmp_events));
 897                         if (!new_tmp_events) {
 898                                 PERROR("realloc agent events");
 899                                 ret = -ENOMEM;
 900                                 free(agent_events);
 901                                 goto error_unlock;
 902                         }
 903                         /* Zero the new memory */
 904                         memset(new_tmp_events + nbmem, 0,
 905                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 906                         nbmem = new_nbmem;
 907                         tmp_events = new_tmp_events;
 908                 }
 909                 memcpy(tmp_events + count, agent_events,
 910                         nb_ev * sizeof(*tmp_events));
 911                 free(agent_events);
 912                 count += nb_ev;
 913         }
 914         rcu_read_unlock();
 915
 916         ret = count;
 917         *events = tmp_events;
 918         return ret;
 919
 920 error_unlock:
 921         rcu_read_unlock();
 922 error:
 923         free(tmp_events);
 924         return ret;
 925 }
 926
 927 /*
 928  * Create a agent app object using the given PID.
 929  *
 930  * Return newly allocated object or else NULL on error.
 931  */
 932 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 933                 struct lttcomm_sock *sock)
 934 {
 935         struct agent_app *app;
 936
 937         assert(sock);
 938
 939         app = zmalloc(sizeof(*app));
 940         if (!app) {
 941                 PERROR("zmalloc agent create");
 942                 goto error;
 943         }
 944
 945         app->pid = pid;
 946         app->domain = domain;
 947         app->sock = sock;
 948         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 949
 950 error:
 951         return app;
 952 }
 953
 954 /*
 955  * Lookup agent app by socket in the global hash table.
 956  *
 957  * RCU read side lock MUST be acquired.
 958  *
 959  * Return object if found else NULL.
 960  */
 961 struct agent_app *agent_find_app_by_sock(int sock)
 962 {
 963         struct lttng_ht_node_ulong *node;
 964         struct lttng_ht_iter iter;
 965         struct agent_app *app;
 966
 967         assert(sock >= 0);
 968
 969         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 970         node = lttng_ht_iter_get_node_ulong(&iter);
 971         if (node == NULL) {
 972                 goto error;
 973         }
 974         app = caa_container_of(node, struct agent_app, node);
 975
 976         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 977         return app;
 978
 979 error:
 980         DBG3("Agent app NOT found by sock %d.", sock);
 981         return NULL;
 982 }
 983
 984 /*
 985  * Add agent application object to the global hash table.
 986  */
 987 void agent_add_app(struct agent_app *app)
 988 {
 989         assert(app);
 990
 991         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 992         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 993 }
 994
 995 /*
 996  * Delete agent application from the global hash table.
 997  *
 998  * rcu_read_lock() must be held by the caller.
 999  */
1000 void agent_delete_app(struct agent_app *app)
1001 {
1002         int ret;
1003         struct lttng_ht_iter iter;
1004
1005         assert(app);
1006
1007         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
1008
1009         iter.iter.node = &app->node.node;
1010         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
1011         assert(!ret);
1012 }
1013
1014 /*
1015  * Destroy an agent application object by detaching it from its corresponding
1016  * UST app if one is connected by closing the socket. Finally, perform a
1017  * delayed memory reclaim.
1018  */
1019 void agent_destroy_app(struct agent_app *app)
1020 {
1021         assert(app);
1022
1023         if (app->sock) {
1024                 app->sock->ops->close(app->sock);
1025                 lttcomm_destroy_sock(app->sock);
1026         }
1027
1028         call_rcu(&app->node.head, destroy_app_agent_rcu);
1029 }
1030
1031 /*
1032  * Initialize an already allocated agent object.
1033  *
1034  * Return 0 on success or else a negative errno value.
1035  */
1036 int agent_init(struct agent *agt)
1037 {
1038         int ret;
1039
1040         assert(agt);
1041
1042         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
1043         if (!agt->events) {
1044                 ret = -ENOMEM;
1045                 goto error;
1046         }
1047         lttng_ht_node_init_u64(&agt->node, agt->domain);
1048
1049         CDS_INIT_LIST_HEAD(&agt->app_ctx_list);
1050         return 0;
1051
1052 error:
1053         return ret;
1054 }
1055
1056 /*
1057  * Add agent object to the given hash table.
1058  */
1059 void agent_add(struct agent *agt, struct lttng_ht *ht)
1060 {
1061         assert(agt);
1062         assert(ht);
1063
1064         DBG3("Agent adding from domain %d", agt->domain);
1065
1066         lttng_ht_add_unique_u64(ht, &agt->node);
1067 }
1068
1069 /*
1070  * Create an agent object for the given domain.
1071  *
1072  * Return the allocated agent or NULL on error.
1073  */
1074 struct agent *agent_create(enum lttng_domain_type domain)
1075 {
1076         int ret;
1077         struct agent *agt;
1078
1079         agt = zmalloc(sizeof(struct agent));
1080         if (!agt) {
1081                 goto error;
1082         }
1083         agt->domain = domain;
1084
1085         ret = agent_init(agt);
1086         if (ret < 0) {
1087                 free(agt);
1088                 agt = NULL;
1089                 goto error;
1090         }
1091
1092 error:
1093         return agt;
1094 }
1095
1096 /*
1097  * Create a newly allocated agent event data structure.
1098  * Ownership of filter_expression is taken.
1099  *
1100  * Return a new object else NULL on error.
1101  */
1102 struct agent_event *agent_create_event(const char *name,
1103                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
1104                 struct lttng_filter_bytecode *filter, char *filter_expression)
1105 {
1106         struct agent_event *event = NULL;
1107
1108         DBG3("Agent create new event with name %s, loglevel type %d, \
1109                         loglevel value %d and filter %s",
1110                         name, loglevel_type, loglevel_value,
1111                         filter_expression ? filter_expression : "NULL");
1112
1113         if (!name) {
1114                 ERR("Failed to create agent event; no name provided.");
1115                 goto error;
1116         }
1117
1118         event = zmalloc(sizeof(*event));
1119         if (!event) {
1120                 goto error;
1121         }
1122
1123         strncpy(event->name, name, sizeof(event->name));
1124         event->name[sizeof(event->name) - 1] = '\0';
1125         lttng_ht_node_init_str(&event->node, event->name);
1126
1127         event->loglevel_value = loglevel_value;
1128         event->loglevel_type = loglevel_type;
1129         event->filter = filter;
1130         event->filter_expression = filter_expression;
1131 error:
1132         return event;
1133 }
1134
1135 /*
1136  * Unique add of a agent event to an agent object.
1137  */
1138 void agent_add_event(struct agent_event *event, struct agent *agt)
1139 {
1140         assert(event);
1141         assert(agt);
1142         assert(agt->events);
1143
1144         DBG3("Agent adding event %s", event->name);
1145         add_unique_agent_event(agt->events, event);
1146         agt->being_used = 1;
1147 }
1148
1149 /*
1150  * Unique add of a agent context to an agent object.
1151  */
1152 int agent_add_context(struct lttng_event_context *ctx, struct agent *agt)
1153 {
1154         int ret = LTTNG_OK;
1155         struct agent_app_ctx *agent_ctx = NULL;
1156
1157         assert(ctx);
1158         assert(agt);
1159         assert(agt->events);
1160         assert(ctx->ctx == LTTNG_EVENT_CONTEXT_APP_CONTEXT);
1161
1162         agent_ctx = create_app_ctx(ctx);
1163         if (!agent_ctx) {
1164                 ret = LTTNG_ERR_NOMEM;
1165                 goto end;
1166         }
1167
1168         DBG3("Agent adding context %s:%s", ctx->u.app_ctx.provider_name,
1169                         ctx->u.app_ctx.ctx_name);
1170         cds_list_add_tail_rcu(&agent_ctx->list_node, &agt->app_ctx_list);
1171 end:
1172         return ret;
1173 }
1174
1175 /*
1176  * Find multiple agent events sharing the given name.
1177  *
1178  * RCU read side lock MUST be acquired. It must be held for the
1179  * duration of the iteration.
1180  *
1181  * Sets the given iterator.
1182  */
1183 void agent_find_events_by_name(const char *name, struct agent *agt,
1184                 struct lttng_ht_iter* iter)
1185 {
1186         struct lttng_ht *ht;
1187         struct agent_ht_key key;
1188
1189         assert(name);
1190         assert(agt);
1191         assert(agt->events);
1192         assert(iter);
1193
1194         ht = agt->events;
1195         key.name = name;
1196
1197         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
1198                         ht_match_event_by_name, &key, &iter->iter);
1199 }
1200
1201 /*
1202  * Get the next agent event duplicate by name. This should be called
1203  * after a call to agent_find_events_by_name() to iterate on events.
1204  *
1205  * The RCU read lock must be held during the iteration and for as long
1206  * as the object the iterator points to remains in use.
1207  */
1208 void agent_event_next_duplicate(const char *name,
1209                 struct agent *agt, struct lttng_ht_iter* iter)
1210 {
1211         struct agent_ht_key key;
1212
1213         key.name = name;
1214
1215         cds_lfht_next_duplicate(agt->events->ht, ht_match_event_by_name,
1216                 &key, &iter->iter);
1217 }
1218
1219 /*
1220  * Find a agent event in the given agent using name, loglevel and filter.
1221  *
1222  * RCU read side lock MUST be acquired. It must be kept for as long as
1223  * the returned agent_event is used.
1224  *
1225  * Return object if found else NULL.
1226  */
1227 struct agent_event *agent_find_event(const char *name,
1228                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
1229                 char *filter_expression, struct agent *agt)
1230 {
1231         struct lttng_ht_node_str *node;
1232         struct lttng_ht_iter iter;
1233         struct lttng_ht *ht;
1234         struct agent_ht_key key;
1235
1236         assert(name);
1237         assert(agt);
1238         assert(agt->events);
1239
1240         ht = agt->events;
1241         key.name = name;
1242         key.loglevel_value = loglevel_value;
1243         key.loglevel_type = loglevel_type;
1244         key.filter_expression = filter_expression;
1245
1246         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
1247                         ht_match_event, &key, &iter.iter);
1248         node = lttng_ht_iter_get_node_str(&iter);
1249         if (node == NULL) {
1250                 goto error;
1251         }
1252
1253         DBG3("Agent event found %s.", name);
1254         return caa_container_of(node, struct agent_event, node);
1255
1256 error:
1257         DBG3("Agent event NOT found %s.", name);
1258         return NULL;
1259 }
1260
1261 /*
1262  * Free given agent event. This event must not be globally visible at this
1263  * point (only expected to be used on failure just after event creation). After
1264  * this call, the pointer is not usable anymore.
1265  */
1266 void agent_destroy_event(struct agent_event *event)
1267 {
1268         assert(event);
1269
1270         free(event->filter);
1271         free(event->filter_expression);
1272         free(event->exclusion);
1273         free(event);
1274 }
1275
1276 static
1277 void destroy_app_ctx_rcu(struct rcu_head *head)
1278 {
1279         struct agent_app_ctx *ctx =
1280                         caa_container_of(head, struct agent_app_ctx, rcu_node);
1281
1282         destroy_app_ctx(ctx);
1283 }
1284
1285 /*
1286  * Destroy an agent completely.
1287  */
1288 void agent_destroy(struct agent *agt)
1289 {
1290         struct lttng_ht_node_str *node;
1291         struct lttng_ht_iter iter;
1292         struct agent_app_ctx *ctx;
1293
1294         assert(agt);
1295
1296         DBG3("Agent destroy");
1297
1298         rcu_read_lock();
1299         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
1300                 int ret;
1301                 struct agent_event *event;
1302
1303                 /*
1304                  * When destroying an event, we have to try to disable it on the
1305                  * agent side so the event stops generating data. The return
1306                  * value is not important since we have to continue anyway
1307                  * destroying the object.
1308                  */
1309                 event = caa_container_of(node, struct agent_event, node);
1310                 (void) agent_disable_event(event, agt->domain);
1311
1312                 ret = lttng_ht_del(agt->events, &iter);
1313                 assert(!ret);
1314                 call_rcu(&node->head, destroy_event_agent_rcu);
1315         }
1316
1317         cds_list_for_each_entry_rcu(ctx, &agt->app_ctx_list, list_node) {
1318                 (void) disable_context(ctx, agt->domain);
1319                 cds_list_del(&ctx->list_node);
1320                 call_rcu(&ctx->rcu_node, destroy_app_ctx_rcu);
1321         }
1322         rcu_read_unlock();
1323         ht_cleanup_push(agt->events);
1324         free(agt);
1325 }
1326
1327 /*
1328  * Allocate agent_apps_ht_by_sock.
1329  */
1330 int agent_app_ht_alloc(void)
1331 {
1332         int ret = 0;
1333
1334         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1335         if (!agent_apps_ht_by_sock) {
1336                 ret = -1;
1337         }
1338
1339         return ret;
1340 }
1341
1342 /*
1343  * Destroy a agent application by socket.
1344  */
1345 void agent_destroy_app_by_sock(int sock)
1346 {
1347         struct agent_app *app;
1348
1349         assert(sock >= 0);
1350
1351         /*
1352          * Not finding an application is a very important error that should NEVER
1353          * happen. The hash table deletion is ONLY done through this call when the
1354          * main sessiond thread is torn down.
1355          */
1356         rcu_read_lock();
1357         app = agent_find_app_by_sock(sock);
1358         assert(app);
1359
1360         /* RCU read side lock is assumed to be held by this function. */
1361         agent_delete_app(app);
1362
1363         /* The application is freed in a RCU call but the socket is closed here. */
1364         agent_destroy_app(app);
1365         rcu_read_unlock();
1366 }
1367
1368 /*
1369  * Clean-up the agent app hash table and destroy it.
1370  */
1371 void agent_app_ht_clean(void)
1372 {
1373         struct lttng_ht_node_ulong *node;
1374         struct lttng_ht_iter iter;
1375
1376         if (!agent_apps_ht_by_sock) {
1377                 return;
1378         }
1379         rcu_read_lock();
1380         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1381                 struct agent_app *app;
1382
1383                 app = caa_container_of(node, struct agent_app, node);
1384                 agent_destroy_app_by_sock(app->sock->fd);
1385         }
1386         rcu_read_unlock();
1387
1388         lttng_ht_destroy(agent_apps_ht_by_sock);
1389 }
1390
1391 /*
1392  * Update a agent application (given socket) using the given agent.
1393  *
1394  * Note that this function is most likely to be used with a tracing session
1395  * thus the caller should make sure to hold the appropriate lock(s).
1396  */
1397 void agent_update(struct agent *agt, int sock)
1398 {
1399         int ret;
1400         struct agent_app *app;
1401         struct agent_event *event;
1402         struct lttng_ht_iter iter;
1403         struct agent_app_ctx *ctx;
1404
1405         assert(agt);
1406         assert(sock >= 0);
1407
1408         DBG("Agent updating app socket %d", sock);
1409
1410         rcu_read_lock();
1411         app = agent_find_app_by_sock(sock);
1412         /*
1413          * We are in the registration path thus if the application is gone,
1414          * there is a serious code flow error.
1415          */
1416         assert(app);
1417         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1418                 /* Skip event if disabled. */
1419                 if (!event->enabled) {
1420                         continue;
1421                 }
1422
1423                 ret = enable_event(app, event);
1424                 if (ret != LTTNG_OK) {
1425                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1426                                         event->name, app->pid, app->sock->fd);
1427                         /* Let's try the others here and don't assume the app is dead. */
1428                         continue;
1429                 }
1430         }
1431
1432         cds_list_for_each_entry_rcu(ctx, &agt->app_ctx_list, list_node) {
1433                 ret = app_context_op(app, ctx, AGENT_CMD_APP_CTX_ENABLE);
1434                 if (ret != LTTNG_OK) {
1435                         DBG2("Agent update unable to add application context %s:%s on app pid: %d sock %d",
1436                                         ctx->provider_name, ctx->ctx_name,
1437                                         app->pid, app->sock->fd);
1438                         continue;
1439                 }
1440         }
1441
1442         rcu_read_unlock();
1443 }