liblttng-ust-ctl/ustctl.c

   1 /*
   2  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; only version 2
   8  * of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <string.h>
  22 #include <lttng/ust-ctl.h>
  23 #include <lttng/ust-abi.h>
  24 #include <lttng/ust-events.h>
  25 #include <sys/mman.h>
  26
  27 #include <usterr-signal-safe.h>
  28 #include <ust-comm.h>
  29
  30 #include "../libringbuffer/backend.h"
  31 #include "../libringbuffer/frontend.h"
  32
  33 volatile enum ust_loglevel ust_loglevel;
  34
  35 static
  36 void init_object(struct lttng_ust_object_data *data)
  37 {
  38         data->handle = -1;
  39         data->shm_fd = -1;
  40         data->wait_fd = -1;
  41         data->memory_map_size = 0;
  42 }
  43
  44 int ustctl_release_handle(int sock, int handle)
  45 {
  46         struct ustcomm_ust_msg lum;
  47         struct ustcomm_ust_reply lur;
  48         int ret;
  49
  50         if (sock >= 0) {
  51                 memset(&lum, 0, sizeof(lum));
  52                 lum.handle = handle;
  53                 lum.cmd = LTTNG_UST_RELEASE;
  54                 ret = ustcomm_send_app_cmd(sock, &lum, &lur);
  55                 if (ret < 0) {
  56                         return ret;
  57                 }
  58         }
  59         return 0;
  60 }
  61 /*
  62  * If sock is negative, it means we don't have to notify the other side
  63  * (e.g. application has already vanished).
  64  */
  65 int ustctl_release_object(int sock, struct lttng_ust_object_data *data)
  66 {
  67         int ret;
  68
  69         if (!data)
  70                 return -EINVAL;
  71
  72         if (data->shm_fd >= 0) {
  73                 ret = close(data->shm_fd);
  74                 if (ret < 0) {
  75                         return ret;
  76                 }
  77         }
  78         if (data->wait_fd >= 0) {
  79                 ret = close(data->wait_fd);
  80                 if (ret < 0) {
  81                         return ret;
  82                 }
  83         }
  84         return ustctl_release_handle(sock, data->handle);
  85 }
  86
  87 /*
  88  * Send registration done packet to the application.
  89  */
  90 int ustctl_register_done(int sock)
  91 {
  92         struct ustcomm_ust_msg lum;
  93         struct ustcomm_ust_reply lur;
  94         int ret;
  95
  96         DBG("Sending register done command to %d", sock);
  97         memset(&lum, 0, sizeof(lum));
  98         lum.handle = LTTNG_UST_ROOT_HANDLE;
  99         lum.cmd = LTTNG_UST_REGISTER_DONE;
 100         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 101         if (ret)
 102                 return ret;
 103         if (lur.ret_code != USTCOMM_OK) {
 104                 DBG("Return code: %s", ustcomm_get_readable_code(lur.ret_code));
 105                 goto error;
 106         }
 107         return 0;
 108
 109 error:
 110         return -1;
 111 }
 112
 113 /*
 114  * returns session handle.
 115  */
 116 int ustctl_create_session(int sock)
 117 {
 118         struct ustcomm_ust_msg lum;
 119         struct ustcomm_ust_reply lur;
 120         int ret, session_handle;
 121
 122         /* Create session */
 123         memset(&lum, 0, sizeof(lum));
 124         lum.handle = LTTNG_UST_ROOT_HANDLE;
 125         lum.cmd = LTTNG_UST_SESSION;
 126         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 127         if (ret)
 128                 return ret;
 129         session_handle = lur.ret_val;
 130         DBG("received session handle %u", session_handle);
 131         return session_handle;
 132 }
 133
 134 /* open the metadata global channel */
 135 int ustctl_open_metadata(int sock, int session_handle,
 136                 struct lttng_ust_channel_attr *chops,
 137                 struct lttng_ust_object_data **_metadata_data)
 138 {
 139         struct ustcomm_ust_msg lum;
 140         struct ustcomm_ust_reply lur;
 141         struct lttng_ust_object_data *metadata_data;
 142         int ret, err = 0;
 143
 144         if (!chops || !_metadata_data)
 145                 return -EINVAL;
 146
 147         metadata_data = malloc(sizeof(*metadata_data));
 148         if (!metadata_data)
 149                 return -ENOMEM;
 150         init_object(metadata_data);
 151         /* Create metadata channel */
 152         memset(&lum, 0, sizeof(lum));
 153         lum.handle = session_handle;
 154         lum.cmd = LTTNG_UST_METADATA;
 155         lum.u.channel.overwrite = chops->overwrite;
 156         lum.u.channel.subbuf_size = chops->subbuf_size;
 157         lum.u.channel.num_subbuf = chops->num_subbuf;
 158         lum.u.channel.switch_timer_interval = chops->switch_timer_interval;
 159         lum.u.channel.read_timer_interval = chops->read_timer_interval;
 160         lum.u.channel.output = chops->output;
 161         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 162         if (ret) {
 163                 free(metadata_data);
 164                 return ret;
 165         }
 166         if (lur.ret_code != USTCOMM_OK) {
 167                 free(metadata_data);
 168                 return lur.ret_code;
 169         }
 170         metadata_data->handle = lur.ret_val;
 171         DBG("received metadata handle %u", metadata_data->handle);
 172         metadata_data->memory_map_size = lur.u.channel.memory_map_size;
 173         /* get shm fd */
 174         ret = ustcomm_recv_fd(sock);
 175         if (ret < 0)
 176                 err = 1;
 177         else
 178                 metadata_data->shm_fd = ret;
 179         /*
 180          * We need to get the second FD even if the first fails, because
 181          * libust expects us to read the two FDs.
 182          */
 183         /* get wait fd */
 184         ret = ustcomm_recv_fd(sock);
 185         if (ret < 0)
 186                 err = 1;
 187         else
 188                 metadata_data->wait_fd = ret;
 189         if (err)
 190                 goto error;
 191         *_metadata_data = metadata_data;
 192         return 0;
 193
 194 error:
 195         (void) ustctl_release_object(sock, metadata_data);
 196         free(metadata_data);
 197         return -EINVAL;
 198 }
 199
 200 int ustctl_create_channel(int sock, int session_handle,
 201                 struct lttng_ust_channel_attr *chops,
 202                 struct lttng_ust_object_data **_channel_data)
 203 {
 204         struct ustcomm_ust_msg lum;
 205         struct ustcomm_ust_reply lur;
 206         struct lttng_ust_object_data *channel_data;
 207         int ret, err = 0;
 208
 209         if (!chops || !_channel_data)
 210                 return -EINVAL;
 211
 212         channel_data = malloc(sizeof(*channel_data));
 213         if (!channel_data)
 214                 return -ENOMEM;
 215         init_object(channel_data);
 216         /* Create metadata channel */
 217         memset(&lum, 0, sizeof(lum));
 218         lum.handle = session_handle;
 219         lum.cmd = LTTNG_UST_CHANNEL;
 220         lum.u.channel.overwrite = chops->overwrite;
 221         lum.u.channel.subbuf_size = chops->subbuf_size;
 222         lum.u.channel.num_subbuf = chops->num_subbuf;
 223         lum.u.channel.switch_timer_interval = chops->switch_timer_interval;
 224         lum.u.channel.read_timer_interval = chops->read_timer_interval;
 225         lum.u.channel.output = chops->output;
 226         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 227         if (ret) {
 228                 free(channel_data);
 229                 return ret;
 230         }
 231         if (lur.ret_code != USTCOMM_OK) {
 232                 free(channel_data);
 233                 return lur.ret_code;
 234         }
 235         channel_data->handle = lur.ret_val;
 236         DBG("received channel handle %u", channel_data->handle);
 237         channel_data->memory_map_size = lur.u.channel.memory_map_size;
 238         /* get shm fd */
 239         ret = ustcomm_recv_fd(sock);
 240         if (ret < 0)
 241                 err = 1;
 242         else
 243                 channel_data->shm_fd = ret;
 244         /*
 245          * We need to get the second FD even if the first fails, because
 246          * libust expects us to read the two FDs.
 247          */
 248         /* get wait fd */
 249         ret = ustcomm_recv_fd(sock);
 250         if (ret < 0)
 251                 err = 1;
 252         else
 253                 channel_data->wait_fd = ret;
 254         if (err)
 255                 goto error;
 256         *_channel_data = channel_data;
 257         return 0;
 258
 259 error:
 260         (void) ustctl_release_object(sock, channel_data);
 261         free(channel_data);
 262         return -EINVAL;
 263 }
 264
 265 /*
 266  * Return -ENOENT if no more stream is available for creation.
 267  * Return 0 on success.
 268  * Return negative error value on error.
 269  */
 270 int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
 271                 struct lttng_ust_object_data **_stream_data)
 272 {
 273         struct ustcomm_ust_msg lum;
 274         struct ustcomm_ust_reply lur;
 275         struct lttng_ust_object_data *stream_data;
 276         int ret, fd, err = 0;
 277
 278         if (!channel_data || !_stream_data)
 279                 return -EINVAL;
 280
 281         stream_data = malloc(sizeof(*stream_data));
 282         if (!stream_data)
 283                 return -ENOMEM;
 284         init_object(stream_data);
 285         memset(&lum, 0, sizeof(lum));
 286         lum.handle = channel_data->handle;
 287         lum.cmd = LTTNG_UST_STREAM;
 288         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 289         if (ret) {
 290                 free(stream_data);
 291                 return ret;
 292         }
 293         if (lur.ret_code != USTCOMM_OK) {
 294                 free(stream_data);
 295                 return lur.ret_code;
 296         }
 297
 298         stream_data->handle = lur.ret_val;
 299         DBG("received stream handle %u", stream_data->handle);
 300         stream_data->memory_map_size = lur.u.stream.memory_map_size;
 301         /* get shm fd */
 302         fd = ustcomm_recv_fd(sock);
 303         if (fd < 0)
 304                 err = 1;
 305         else
 306                 stream_data->shm_fd = fd;
 307         /*
 308          * We need to get the second FD even if the first fails, because
 309          * libust expects us to read the two FDs.
 310          */
 311         /* get wait fd */
 312         fd = ustcomm_recv_fd(sock);
 313         if (fd < 0)
 314                 err = 1;
 315         else
 316                 stream_data->wait_fd = fd;
 317         if (err)
 318                 goto error;
 319         *_stream_data = stream_data;
 320         return ret;
 321
 322 error:
 323         (void) ustctl_release_object(sock, stream_data);
 324         free(stream_data);
 325         return -EINVAL;
 326 }
 327
 328 int ustctl_create_event(int sock, struct lttng_ust_event *ev,
 329                 struct lttng_ust_object_data *channel_data,
 330                 struct lttng_ust_object_data **_event_data)
 331 {
 332         struct ustcomm_ust_msg lum;
 333         struct ustcomm_ust_reply lur;
 334         struct lttng_ust_object_data *event_data;
 335         int ret;
 336
 337         if (!channel_data || !_event_data)
 338                 return -EINVAL;
 339
 340         event_data = malloc(sizeof(*event_data));
 341         if (!event_data)
 342                 return -ENOMEM;
 343         init_object(event_data);
 344         memset(&lum, 0, sizeof(lum));
 345         lum.handle = channel_data->handle;
 346         lum.cmd = LTTNG_UST_EVENT;
 347         strncpy(lum.u.event.name, ev->name,
 348                 LTTNG_UST_SYM_NAME_LEN);
 349         lum.u.event.instrumentation = ev->instrumentation;
 350         lum.u.event.loglevel_type = ev->loglevel_type;
 351         lum.u.event.loglevel = ev->loglevel;
 352         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 353         if (ret) {
 354                 free(event_data);
 355                 return ret;
 356         }
 357         event_data->handle = lur.ret_val;
 358         DBG("received event handle %u", event_data->handle);
 359         *_event_data = event_data;
 360         return 0;
 361 }
 362
 363 int ustctl_add_context(int sock, struct lttng_ust_context *ctx,
 364                 struct lttng_ust_object_data *obj_data,
 365                 struct lttng_ust_object_data **_context_data)
 366 {
 367         struct ustcomm_ust_msg lum;
 368         struct ustcomm_ust_reply lur;
 369         struct lttng_ust_object_data *context_data;
 370         int ret;
 371
 372         if (!obj_data || !_context_data)
 373                 return -EINVAL;
 374
 375         context_data = malloc(sizeof(*context_data));
 376         if (!context_data)
 377                 return -ENOMEM;
 378         init_object(context_data);
 379         memset(&lum, 0, sizeof(lum));
 380         lum.handle = obj_data->handle;
 381         lum.cmd = LTTNG_UST_CONTEXT;
 382         lum.u.context.ctx = ctx->ctx;
 383         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 384         if (ret) {
 385                 free(context_data);
 386                 return ret;
 387         }
 388         context_data->handle = lur.ret_val;
 389         DBG("received context handle %u", context_data->handle);
 390         *_context_data = context_data;
 391         return ret;
 392 }
 393
 394 /* Enable event, channel and session ioctl */
 395 int ustctl_enable(int sock, struct lttng_ust_object_data *object)
 396 {
 397         struct ustcomm_ust_msg lum;
 398         struct ustcomm_ust_reply lur;
 399         int ret;
 400
 401         if (!object)
 402                 return -EINVAL;
 403
 404         memset(&lum, 0, sizeof(lum));
 405         lum.handle = object->handle;
 406         lum.cmd = LTTNG_UST_ENABLE;
 407         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 408         if (ret)
 409                 return ret;
 410         DBG("enabled handle %u", object->handle);
 411         return 0;
 412 }
 413
 414 /* Disable event, channel and session ioctl */
 415 int ustctl_disable(int sock, struct lttng_ust_object_data *object)
 416 {
 417         struct ustcomm_ust_msg lum;
 418         struct ustcomm_ust_reply lur;
 419         int ret;
 420
 421         if (!object)
 422                 return -EINVAL;
 423
 424         memset(&lum, 0, sizeof(lum));
 425         lum.handle = object->handle;
 426         lum.cmd = LTTNG_UST_DISABLE;
 427         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 428         if (ret)
 429                 return ret;
 430         DBG("disable handle %u", object->handle);
 431         return 0;
 432 }
 433
 434 int ustctl_start_session(int sock, int handle)
 435 {
 436         struct lttng_ust_object_data obj;
 437
 438         obj.handle = handle;
 439         return ustctl_enable(sock, &obj);
 440 }
 441
 442 int ustctl_stop_session(int sock, int handle)
 443 {
 444         struct lttng_ust_object_data obj;
 445
 446         obj.handle = handle;
 447         return ustctl_disable(sock, &obj);
 448 }
 449
 450 int ustctl_tracepoint_list(int sock)
 451 {
 452         struct ustcomm_ust_msg lum;
 453         struct ustcomm_ust_reply lur;
 454         int ret, tp_list_handle;
 455
 456         memset(&lum, 0, sizeof(lum));
 457         lum.handle = LTTNG_UST_ROOT_HANDLE;
 458         lum.cmd = LTTNG_UST_TRACEPOINT_LIST;
 459         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 460         if (ret)
 461                 return ret;
 462         tp_list_handle = lur.ret_val;
 463         DBG("received tracepoint list handle %u", tp_list_handle);
 464         return tp_list_handle;
 465 }
 466
 467 int ustctl_tracepoint_list_get(int sock, int tp_list_handle,
 468                 struct lttng_ust_tracepoint_iter *iter)
 469 {
 470         struct ustcomm_ust_msg lum;
 471         struct ustcomm_ust_reply lur;
 472         int ret;
 473
 474         if (!iter)
 475                 return -EINVAL;
 476
 477         memset(&lum, 0, sizeof(lum));
 478         lum.handle = tp_list_handle;
 479         lum.cmd = LTTNG_UST_TRACEPOINT_LIST_GET;
 480         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 481         if (ret)
 482                 return ret;
 483         DBG("received tracepoint list entry name %s loglevel %d",
 484                 lur.u.tracepoint.name,
 485                 lur.u.tracepoint.loglevel);
 486         memcpy(iter, &lur.u.tracepoint, sizeof(*iter));
 487         return 0;
 488 }
 489
 490 int ustctl_tracer_version(int sock, struct lttng_ust_tracer_version *v)
 491 {
 492         struct ustcomm_ust_msg lum;
 493         struct ustcomm_ust_reply lur;
 494         int ret;
 495
 496         if (!v)
 497                 return -EINVAL;
 498
 499         memset(&lum, 0, sizeof(lum));
 500         lum.handle = LTTNG_UST_ROOT_HANDLE;
 501         lum.cmd = LTTNG_UST_TRACER_VERSION;
 502         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 503         if (ret)
 504                 return ret;
 505         memcpy(v, &lur.u.version, sizeof(*v));
 506         DBG("received tracer version");
 507         return 0;
 508 }
 509
 510 int ustctl_wait_quiescent(int sock)
 511 {
 512         struct ustcomm_ust_msg lum;
 513         struct ustcomm_ust_reply lur;
 514         int ret;
 515
 516         memset(&lum, 0, sizeof(lum));
 517         lum.handle = LTTNG_UST_ROOT_HANDLE;
 518         lum.cmd = LTTNG_UST_WAIT_QUIESCENT;
 519         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 520         if (ret)
 521                 return ret;
 522         DBG("waited for quiescent state");
 523         return 0;
 524 }
 525
 526 int ustctl_calibrate(int sock, struct lttng_ust_calibrate *calibrate)
 527 {
 528         if (!calibrate)
 529                 return -EINVAL;
 530
 531         return -ENOSYS;
 532 }
 533
 534 int ustctl_sock_flush_buffer(int sock, struct lttng_ust_object_data *object)
 535 {
 536         struct ustcomm_ust_msg lum;
 537         struct ustcomm_ust_reply lur;
 538         int ret;
 539
 540         if (!object)
 541                 return -EINVAL;
 542
 543         memset(&lum, 0, sizeof(lum));
 544         lum.handle = object->handle;
 545         lum.cmd = LTTNG_UST_FLUSH_BUFFER;
 546         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 547         if (ret)
 548                 return ret;
 549         DBG("flushed buffer handle %u", object->handle);
 550         return 0;
 551 }
 552
 553 /* Buffer operations */
 554
 555 /* Map channel shm into process memory */
 556 struct lttng_ust_shm_handle *ustctl_map_channel(struct lttng_ust_object_data *chan_data)
 557 {
 558         struct lttng_ust_shm_handle *handle;
 559         struct channel *chan;
 560         size_t chan_size;
 561         struct lttng_ust_lib_ring_buffer_config *config;
 562         int ret;
 563
 564         if (!chan_data)
 565                 return NULL;
 566
 567         handle = channel_handle_create(chan_data->shm_fd,
 568                 chan_data->wait_fd,
 569                 chan_data->memory_map_size);
 570         if (!handle) {
 571                 ERR("create handle error");
 572                 return NULL;
 573         }
 574         /*
 575          * Set to -1, and then close the shm fd, and set the handle shm
 576          * fd to -1 too. We don't need the shm fds after they have been
 577          * mapped.
 578          * The wait_fd is set to -1 in chan_data because it is now owned
 579          * by the handle.
 580          */
 581         chan_data->shm_fd = -1;
 582         chan_data->wait_fd = -1;
 583
 584         /* chan is object 0. This is hardcoded. */
 585         if (handle->table->objects[0].shm_fd >= 0) {
 586                 ret = close(handle->table->objects[0].shm_fd);
 587                 if (ret) {
 588                         perror("Error closing shm_fd");
 589                 }
 590                 handle->table->objects[0].shm_fd = -1;
 591         }
 592
 593         /*
 594          * TODO: add consistency checks to be resilient if the
 595          * application try to feed us with incoherent channel structure
 596          * values.
 597          */
 598         chan = shmp(handle, handle->chan);
 599         /* chan is object 0. This is hardcoded. */
 600         chan_size = handle->table->objects[0].allocated_len;
 601         handle->shadow_chan = malloc(chan_size);
 602         if (!handle->shadow_chan) {
 603                 channel_destroy(chan, handle, 1);
 604                 return NULL;
 605         }
 606         memcpy(handle->shadow_chan, chan, chan_size);
 607         /*
 608          * The callback pointers in the producer are invalid in the
 609          * consumer. We need to look them up here.
 610          */
 611         config = &handle->shadow_chan->backend.config;
 612         switch (config->client_type) {
 613         case LTTNG_CLIENT_METADATA:
 614                 memcpy(&config->cb, lttng_client_callbacks_metadata,
 615                         sizeof(config->cb));
 616                 break;
 617         case LTTNG_CLIENT_DISCARD:
 618                 memcpy(&config->cb, lttng_client_callbacks_discard,
 619                         sizeof(config->cb));
 620                 break;
 621         case LTTNG_CLIENT_OVERWRITE:
 622                 memcpy(&config->cb, lttng_client_callbacks_overwrite,
 623                         sizeof(config->cb));
 624                 break;
 625         default:
 626                 ERR("Unknown client type %d", config->client_type);
 627                 channel_destroy(chan, handle, 1);
 628                 return NULL;
 629         }
 630         /* Replace the object table pointer. */
 631         ret = munmap(handle->table->objects[0].memory_map,
 632                 handle->table->objects[0].memory_map_size);
 633         if (ret) {
 634                 perror("munmap");
 635                 assert(0);
 636         }
 637         handle->table->objects[0].memory_map = (char *) handle->shadow_chan;
 638         handle->table->objects[0].is_shadow = 1;
 639         return handle;
 640 }
 641
 642 /* Add stream to channel shm and map its shm into process memory */
 643 int ustctl_add_stream(struct lttng_ust_shm_handle *handle,
 644                 struct lttng_ust_object_data *stream_data)
 645 {
 646         int ret;
 647
 648         if (!handle || !stream_data)
 649                 return -EINVAL;
 650
 651         if (!stream_data->handle)
 652                 return -ENOENT;
 653         /* map stream */
 654         ret = channel_handle_add_stream(handle,
 655                 stream_data->shm_fd,
 656                 stream_data->wait_fd,
 657                 stream_data->memory_map_size);
 658         if (ret) {
 659                 ERR("add stream error\n");
 660                 return ret;
 661         }
 662         /*
 663          * Set to -1 because the lttng_ust_shm_handle destruction will take care
 664          * of closing shm_fd and wait_fd.
 665          */
 666         stream_data->shm_fd = -1;
 667         stream_data->wait_fd = -1;
 668         return 0;
 669 }
 670
 671 void ustctl_unmap_channel(struct lttng_ust_shm_handle *handle)
 672 {
 673         struct channel *chan;
 674
 675         assert(handle);
 676         chan = shmp(handle, handle->chan);
 677         channel_destroy(chan, handle, 1);
 678 }
 679
 680 /*
 681  * ustctl closes the shm_fd fds after mapping it.
 682  */
 683 struct lttng_ust_lib_ring_buffer *ustctl_open_stream_read(struct lttng_ust_shm_handle *handle,
 684         int cpu)
 685 {
 686         struct channel *chan = handle->shadow_chan;
 687         int *shm_fd, *wait_fd;
 688         uint64_t *memory_map_size;
 689         struct lttng_ust_lib_ring_buffer *buf;
 690         int ret;
 691
 692         if (!handle)
 693                 return NULL;
 694
 695         buf = channel_get_ring_buffer(&chan->backend.config,
 696                 chan, cpu, handle, &shm_fd, &wait_fd, &memory_map_size);
 697         if (!buf)
 698                 return NULL;
 699         ret = lib_ring_buffer_open_read(buf, handle, 1);
 700         if (ret)
 701                 return NULL;
 702         /*
 703          * We can close shm_fd early, right after is has been mapped.
 704          */
 705         if (*shm_fd >= 0) {
 706                 ret = close(*shm_fd);
 707                 if (ret) {
 708                         perror("Error closing shm_fd");
 709                 }
 710                 *shm_fd = -1;
 711         }
 712         return buf;
 713 }
 714
 715 void ustctl_close_stream_read(struct lttng_ust_shm_handle *handle,
 716                 struct lttng_ust_lib_ring_buffer *buf)
 717 {
 718         assert(handle && buf);
 719         lib_ring_buffer_release_read(buf, handle, 1);
 720 }
 721
 722 /* For mmap mode, readable without "get" operation */
 723
 724 void *ustctl_get_mmap_base(struct lttng_ust_shm_handle *handle,
 725                 struct lttng_ust_lib_ring_buffer *buf)
 726 {
 727         if (!handle || !buf)
 728                 return NULL;
 729         return shmp(handle, buf->backend.memory_map);
 730 }
 731
 732 /* returns the length to mmap. */
 733 int ustctl_get_mmap_len(struct lttng_ust_shm_handle *handle,
 734                 struct lttng_ust_lib_ring_buffer *buf,
 735                 unsigned long *len)
 736 {
 737         unsigned long mmap_buf_len;
 738         struct channel *chan = handle->shadow_chan;
 739
 740         if (!handle || !buf || !len)
 741                 return -EINVAL;
 742
 743         if (chan->backend.config.output != RING_BUFFER_MMAP)
 744                 return -EINVAL;
 745         mmap_buf_len = chan->backend.buf_size;
 746         if (chan->backend.extra_reader_sb)
 747                 mmap_buf_len += chan->backend.subbuf_size;
 748         if (mmap_buf_len > INT_MAX)
 749                 return -EFBIG;
 750         *len = mmap_buf_len;
 751         return 0;
 752 }
 753
 754 /* returns the maximum size for sub-buffers. */
 755 int ustctl_get_max_subbuf_size(struct lttng_ust_shm_handle *handle,
 756                 struct lttng_ust_lib_ring_buffer *buf,
 757                 unsigned long *len)
 758 {
 759         struct channel *chan = handle->shadow_chan;
 760
 761         if (!handle || !buf || !len)
 762                 return -EINVAL;
 763
 764         *len = chan->backend.subbuf_size;
 765         return 0;
 766 }
 767
 768 /*
 769  * For mmap mode, operate on the current packet (between get/put or
 770  * get_next/put_next).
 771  */
 772
 773 /* returns the offset of the subbuffer belonging to the mmap reader. */
 774 int ustctl_get_mmap_read_offset(struct lttng_ust_shm_handle *handle,
 775                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *off)
 776 {
 777         struct channel *chan = handle->shadow_chan;
 778         unsigned long sb_bindex;
 779
 780         if (!handle || !buf || !off)
 781                 return -EINVAL;
 782
 783         if (chan->backend.config.output != RING_BUFFER_MMAP)
 784                 return -EINVAL;
 785         sb_bindex = subbuffer_id_get_index(&chan->backend.config,
 786                                            buf->backend.buf_rsb.id);
 787         *off = shmp(handle, shmp_index(handle, buf->backend.array, sb_bindex)->shmp)->mmap_offset;
 788         return 0;
 789 }
 790
 791 /* returns the size of the current sub-buffer, without padding (for mmap). */
 792 int ustctl_get_subbuf_size(struct lttng_ust_shm_handle *handle,
 793                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *len)
 794 {
 795         struct channel *chan = handle->shadow_chan;
 796
 797         if (!handle || !buf || !len)
 798                 return -EINVAL;
 799
 800         *len = lib_ring_buffer_get_read_data_size(&chan->backend.config, buf,
 801                 handle);
 802         return 0;
 803 }
 804
 805 /* returns the size of the current sub-buffer, without padding (for mmap). */
 806 int ustctl_get_padded_subbuf_size(struct lttng_ust_shm_handle *handle,
 807                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *len)
 808 {
 809         struct channel *chan = handle->shadow_chan;
 810
 811         if (!handle || !buf || !len)
 812                 return -EINVAL;
 813
 814         *len = lib_ring_buffer_get_read_data_size(&chan->backend.config, buf,
 815                 handle);
 816         *len = PAGE_ALIGN(*len);
 817         return 0;
 818 }
 819
 820 /* Get exclusive read access to the next sub-buffer that can be read. */
 821 int ustctl_get_next_subbuf(struct lttng_ust_shm_handle *handle,
 822                 struct lttng_ust_lib_ring_buffer *buf)
 823 {
 824         if (!handle || !buf)
 825                 return -EINVAL;
 826
 827         return lib_ring_buffer_get_next_subbuf(buf, handle);
 828 }
 829
 830
 831 /* Release exclusive sub-buffer access, move consumer forward. */
 832 int ustctl_put_next_subbuf(struct lttng_ust_shm_handle *handle,
 833                 struct lttng_ust_lib_ring_buffer *buf)
 834 {
 835         if (!handle || !buf)
 836                 return -EINVAL;
 837
 838         lib_ring_buffer_put_next_subbuf(buf, handle);
 839         return 0;
 840 }
 841
 842 /* snapshot */
 843
 844 /* Get a snapshot of the current ring buffer producer and consumer positions */
 845 int ustctl_snapshot(struct lttng_ust_shm_handle *handle,
 846                 struct lttng_ust_lib_ring_buffer *buf)
 847 {
 848         if (!handle || !buf)
 849                 return -EINVAL;
 850
 851         return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 852                         &buf->prod_snapshot, handle);
 853 }
 854
 855 /* Get the consumer position (iteration start) */
 856 int ustctl_snapshot_get_consumed(struct lttng_ust_shm_handle *handle,
 857                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 858 {
 859         if (!handle || !buf || !pos)
 860                 return -EINVAL;
 861
 862         *pos = buf->cons_snapshot;
 863         return 0;
 864 }
 865
 866 /* Get the producer position (iteration end) */
 867 int ustctl_snapshot_get_produced(struct lttng_ust_shm_handle *handle,
 868                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 869 {
 870         if (!handle || !buf || !pos)
 871                 return -EINVAL;
 872
 873         *pos = buf->prod_snapshot;
 874         return 0;
 875 }
 876
 877 /* Get exclusive read access to the specified sub-buffer position */
 878 int ustctl_get_subbuf(struct lttng_ust_shm_handle *handle,
 879                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 880 {
 881         if (!handle || !buf || !pos)
 882                 return -EINVAL;
 883
 884         return lib_ring_buffer_get_subbuf(buf, *pos, handle);
 885 }
 886
 887 /* Release exclusive sub-buffer access */
 888 int ustctl_put_subbuf(struct lttng_ust_shm_handle *handle,
 889                 struct lttng_ust_lib_ring_buffer *buf)
 890 {
 891         if (!handle || !buf)
 892                 return -EINVAL;
 893
 894         lib_ring_buffer_put_subbuf(buf, handle);
 895         return 0;
 896 }
 897
 898 void ustctl_flush_buffer(struct lttng_ust_shm_handle *handle,
 899                 struct lttng_ust_lib_ring_buffer *buf,
 900                 int producer_active)
 901 {
 902         assert(handle && buf);
 903         lib_ring_buffer_switch_slow(buf,
 904                 producer_active ? SWITCH_ACTIVE : SWITCH_FLUSH,
 905                 handle);
 906 }