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 #include <string.h>
  21 #include <lttng/ust-ctl.h>
  22 #include <lttng/ust-abi.h>
  23 #include <lttng/usterr-signal-safe.h>
  24 #include <lttng/ust-comm.h>
  25 #include <lttng/ust-events.h>
  26 #include <sys/mman.h>
  27
  28 #include "../libringbuffer/backend.h"
  29 #include "../libringbuffer/frontend.h"
  30
  31 volatile enum ust_loglevel ust_loglevel;
  32
  33 static
  34 void init_object(struct lttng_ust_object_data *data)
  35 {
  36         data->handle = -1;
  37         data->shm_fd = -1;
  38         data->wait_fd = -1;
  39         data->memory_map_size = 0;
  40 }
  41
  42 void ustctl_release_object(int sock, struct lttng_ust_object_data *data)
  43 {
  44         struct ustcomm_ust_msg lum;
  45         struct ustcomm_ust_reply lur;
  46         int ret;
  47
  48         if (data->shm_fd >= 0)
  49                 close(data->shm_fd);
  50         if (data->wait_fd >= 0)
  51                 close(data->wait_fd);
  52         memset(&lum, 0, sizeof(lum));
  53         lum.handle = data->handle;
  54         lum.cmd = LTTNG_UST_RELEASE;
  55         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
  56         assert(!ret);
  57         free(data);
  58 }
  59
  60 /*
  61  * Send registration done packet to the application.
  62  */
  63 int ustctl_register_done(int sock)
  64 {
  65         struct ustcomm_ust_msg lum;
  66         struct ustcomm_ust_reply lur;
  67         int ret;
  68
  69         DBG("Sending register done command to %d", sock);
  70         memset(&lum, 0, sizeof(lum));
  71         lum.handle = LTTNG_UST_ROOT_HANDLE;
  72         lum.cmd = LTTNG_UST_REGISTER_DONE;
  73         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
  74         if (ret)
  75                 return ret;
  76         if (lur.ret_code != USTCOMM_OK) {
  77                 DBG("Return code: %s", ustcomm_get_readable_code(lur.ret_code));
  78                 goto error;
  79         }
  80         return 0;
  81
  82 error:
  83         return -1;
  84 }
  85
  86 /*
  87  * returns session handle.
  88  */
  89 int ustctl_create_session(int sock)
  90 {
  91         struct ustcomm_ust_msg lum;
  92         struct ustcomm_ust_reply lur;
  93         int ret, session_handle;
  94
  95         /* Create session */
  96         memset(&lum, 0, sizeof(lum));
  97         lum.handle = LTTNG_UST_ROOT_HANDLE;
  98         lum.cmd = LTTNG_UST_SESSION;
  99         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 100         if (ret)
 101                 return ret;
 102         session_handle = lur.ret_val;
 103         DBG("received session handle %u", session_handle);
 104         return session_handle;
 105 }
 106
 107 /* open the metadata global channel */
 108 int ustctl_open_metadata(int sock, int session_handle,
 109                 struct lttng_ust_channel_attr *chops,
 110                 struct lttng_ust_object_data **_metadata_data)
 111 {
 112         struct ustcomm_ust_msg lum;
 113         struct ustcomm_ust_reply lur;
 114         struct lttng_ust_object_data *metadata_data;
 115         int ret;
 116
 117         metadata_data = malloc(sizeof(*metadata_data));
 118         if (!metadata_data)
 119                 return -ENOMEM;
 120         init_object(metadata_data);
 121         /* Create metadata channel */
 122         memset(&lum, 0, sizeof(lum));
 123         lum.handle = session_handle;
 124         lum.cmd = LTTNG_UST_METADATA;
 125         lum.u.channel.overwrite = chops->overwrite;
 126         lum.u.channel.subbuf_size = chops->subbuf_size;
 127         lum.u.channel.num_subbuf = chops->num_subbuf;
 128         lum.u.channel.switch_timer_interval = chops->switch_timer_interval;
 129         lum.u.channel.read_timer_interval = chops->read_timer_interval;
 130         lum.u.channel.output = chops->output;
 131         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 132         if (ret) {
 133                 free(metadata_data);
 134                 return ret;
 135         }
 136         if (lur.ret_code != USTCOMM_OK) {
 137                 free(metadata_data);
 138                 return lur.ret_code;
 139         }
 140         metadata_data->handle = lur.ret_val;
 141         DBG("received metadata handle %u", metadata_data->handle);
 142         metadata_data->memory_map_size = lur.u.channel.memory_map_size;
 143         /* get shm fd */
 144         ret = ustcomm_recv_fd(sock);
 145         if (ret < 0)
 146                 goto error;
 147         metadata_data->shm_fd = ret;
 148         /* get wait fd */
 149         ret = ustcomm_recv_fd(sock);
 150         if (ret < 0)
 151                 goto error;
 152         metadata_data->wait_fd = ret;
 153         *_metadata_data = metadata_data;
 154         return 0;
 155
 156 error:
 157         ustctl_release_object(sock, metadata_data);
 158         return -EINVAL;
 159 }
 160
 161 int ustctl_create_channel(int sock, int session_handle,
 162                 struct lttng_ust_channel_attr *chops,
 163                 struct lttng_ust_object_data **_channel_data)
 164 {
 165         struct ustcomm_ust_msg lum;
 166         struct ustcomm_ust_reply lur;
 167         struct lttng_ust_object_data *channel_data;
 168         int ret;
 169
 170         channel_data = malloc(sizeof(*channel_data));
 171         if (!channel_data)
 172                 return -ENOMEM;
 173         init_object(channel_data);
 174         /* Create metadata channel */
 175         memset(&lum, 0, sizeof(lum));
 176         lum.handle = session_handle;
 177         lum.cmd = LTTNG_UST_CHANNEL;
 178         lum.u.channel.overwrite = chops->overwrite;
 179         lum.u.channel.subbuf_size = chops->subbuf_size;
 180         lum.u.channel.num_subbuf = chops->num_subbuf;
 181         lum.u.channel.switch_timer_interval = chops->switch_timer_interval;
 182         lum.u.channel.read_timer_interval = chops->read_timer_interval;
 183         lum.u.channel.output = chops->output;
 184         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 185         if (ret) {
 186                 free(channel_data);
 187                 return ret;
 188         }
 189         if (lur.ret_code != USTCOMM_OK) {
 190                 free(channel_data);
 191                 return lur.ret_code;
 192         }
 193         channel_data->handle = lur.ret_val;
 194         DBG("received channel handle %u", channel_data->handle);
 195         channel_data->memory_map_size = lur.u.channel.memory_map_size;
 196         /* get shm fd */
 197         ret = ustcomm_recv_fd(sock);
 198         if (ret < 0)
 199                 goto error;
 200         channel_data->shm_fd = ret;
 201         /* get wait fd */
 202         ret = ustcomm_recv_fd(sock);
 203         if (ret < 0)
 204                 goto error;
 205         channel_data->wait_fd = ret;
 206         *_channel_data = channel_data;
 207         return 0;
 208
 209 error:
 210         ustctl_release_object(sock, channel_data);
 211         return -EINVAL;
 212 }
 213
 214 /*
 215  * Return -ENOENT if no more stream is available for creation.
 216  * Return 0 on success.
 217  * Return negative error value on error.
 218  */
 219 int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
 220                 struct lttng_ust_object_data **_stream_data)
 221 {
 222         struct ustcomm_ust_msg lum;
 223         struct ustcomm_ust_reply lur;
 224         struct lttng_ust_object_data *stream_data;
 225         int ret, fd;
 226
 227         stream_data = malloc(sizeof(*stream_data));
 228         if (!stream_data)
 229                 return -ENOMEM;
 230         init_object(stream_data);
 231         memset(&lum, 0, sizeof(lum));
 232         lum.handle = channel_data->handle;
 233         lum.cmd = LTTNG_UST_STREAM;
 234         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 235         if (ret) {
 236                 free(stream_data);
 237                 return ret;
 238         }
 239         if (lur.ret_code != USTCOMM_OK) {
 240                 free(stream_data);
 241                 return lur.ret_code;
 242         }
 243
 244         stream_data->handle = lur.ret_val;
 245         DBG("received stream handle %u", stream_data->handle);
 246         stream_data->memory_map_size = lur.u.stream.memory_map_size;
 247         /* get shm fd */
 248         fd = ustcomm_recv_fd(sock);
 249         if (fd < 0)
 250                 goto error;
 251         stream_data->shm_fd = fd;
 252         /* get wait fd */
 253         fd = ustcomm_recv_fd(sock);
 254         if (fd < 0)
 255                 goto error;
 256         stream_data->wait_fd = fd;
 257         *_stream_data = stream_data;
 258         return ret;
 259
 260 error:
 261         ustctl_release_object(sock, stream_data);
 262         return -EINVAL;
 263 }
 264
 265 int ustctl_create_event(int sock, struct lttng_ust_event *ev,
 266                 struct lttng_ust_object_data *channel_data,
 267                 struct lttng_ust_object_data **_event_data)
 268 {
 269         struct ustcomm_ust_msg lum;
 270         struct ustcomm_ust_reply lur;
 271         struct lttng_ust_object_data *event_data;
 272         int ret;
 273
 274         event_data = malloc(sizeof(*event_data));
 275         if (!event_data)
 276                 return -ENOMEM;
 277         init_object(event_data);
 278         memset(&lum, 0, sizeof(lum));
 279         lum.handle = channel_data->handle;
 280         lum.cmd = LTTNG_UST_EVENT;
 281         strncpy(lum.u.event.name, ev->name,
 282                 LTTNG_UST_SYM_NAME_LEN);
 283         lum.u.event.instrumentation = ev->instrumentation;
 284         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 285         if (ret) {
 286                 free(event_data);
 287                 return ret;
 288         }
 289         event_data->handle = lur.ret_val;
 290         DBG("received event handle %u", event_data->handle);
 291         *_event_data = event_data;
 292         return 0;
 293 }
 294
 295 int ustctl_add_context(int sock, struct lttng_ust_context *ctx,
 296                 struct lttng_ust_object_data *obj_data,
 297                 struct lttng_ust_object_data **_context_data)
 298 {
 299         struct ustcomm_ust_msg lum;
 300         struct ustcomm_ust_reply lur;
 301         struct lttng_ust_object_data *context_data;
 302         int ret;
 303
 304         context_data = malloc(sizeof(*context_data));
 305         if (!context_data)
 306                 return -ENOMEM;
 307         init_object(context_data);
 308         memset(&lum, 0, sizeof(lum));
 309         lum.handle = obj_data->handle;
 310         lum.cmd = LTTNG_UST_CONTEXT;
 311         lum.u.context.ctx = ctx->ctx;
 312         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 313         if (ret) {
 314                 free(context_data);
 315                 return ret;
 316         }
 317         context_data->handle = lur.ret_val;
 318         DBG("received context handle %u", context_data->handle);
 319         *_context_data = context_data;
 320         return ret;
 321 }
 322
 323 /* Enable event, channel and session ioctl */
 324 int ustctl_enable(int sock, struct lttng_ust_object_data *object)
 325 {
 326         struct ustcomm_ust_msg lum;
 327         struct ustcomm_ust_reply lur;
 328         int ret;
 329
 330         memset(&lum, 0, sizeof(lum));
 331         lum.handle = object->handle;
 332         lum.cmd = LTTNG_UST_ENABLE;
 333         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 334         if (ret)
 335                 return ret;
 336         DBG("enabled handle %u", object->handle);
 337         return 0;
 338 }
 339
 340 /* Disable event, channel and session ioctl */
 341 int ustctl_disable(int sock, struct lttng_ust_object_data *object)
 342 {
 343         struct ustcomm_ust_msg lum;
 344         struct ustcomm_ust_reply lur;
 345         int ret;
 346
 347         memset(&lum, 0, sizeof(lum));
 348         lum.handle = object->handle;
 349         lum.cmd = LTTNG_UST_DISABLE;
 350         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 351         if (ret)
 352                 return ret;
 353         DBG("disable handle %u", object->handle);
 354         return 0;
 355 }
 356
 357 int ustctl_start_session(int sock, int handle)
 358 {
 359         struct lttng_ust_object_data obj;
 360
 361         obj.handle = handle;
 362         return ustctl_enable(sock, &obj);
 363 }
 364
 365 int ustctl_stop_session(int sock, int handle)
 366 {
 367         struct lttng_ust_object_data obj;
 368
 369         obj.handle = handle;
 370         return ustctl_disable(sock, &obj);
 371 }
 372
 373
 374 int ustctl_tracepoint_list(int sock)
 375 {
 376         return -ENOSYS; /* not implemented */
 377 }
 378
 379 int ustctl_tracer_version(int sock, struct lttng_ust_tracer_version *v)
 380 {
 381         struct ustcomm_ust_msg lum;
 382         struct ustcomm_ust_reply lur;
 383         int ret;
 384
 385         memset(&lum, 0, sizeof(lum));
 386         lum.handle = LTTNG_UST_ROOT_HANDLE;
 387         lum.cmd = LTTNG_UST_TRACER_VERSION;
 388         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 389         if (ret)
 390                 return ret;
 391         memcpy(v, &lur.u.version, sizeof(*v));
 392         DBG("received tracer version");
 393         return 0;
 394 }
 395
 396 int ustctl_wait_quiescent(int sock)
 397 {
 398         struct ustcomm_ust_msg lum;
 399         struct ustcomm_ust_reply lur;
 400         int ret;
 401
 402         memset(&lum, 0, sizeof(lum));
 403         lum.handle = LTTNG_UST_ROOT_HANDLE;
 404         lum.cmd = LTTNG_UST_WAIT_QUIESCENT;
 405         ret = ustcomm_send_app_cmd(sock, &lum, &lur);
 406         if (ret)
 407                 return ret;
 408         DBG("waited for quiescent state");
 409         return 0;
 410 }
 411
 412 int ustctl_calibrate(int sock, struct lttng_ust_calibrate *calibrate)
 413 {
 414         return -ENOSYS;
 415 }
 416
 417 /* Buffer operations */
 418
 419 /* Map channel shm into process memory */
 420 struct lttng_ust_shm_handle *ustctl_map_channel(struct lttng_ust_object_data *chan_data)
 421 {
 422         struct lttng_ust_shm_handle *handle;
 423         struct channel *chan;
 424         size_t chan_size;
 425         struct lttng_ust_lib_ring_buffer_config *config;
 426         int ret;
 427
 428         handle = channel_handle_create(chan_data->shm_fd,
 429                 chan_data->wait_fd,
 430                 chan_data->memory_map_size);
 431         if (!handle) {
 432                 ERR("create handle error");
 433                 return NULL;
 434         }
 435         /*
 436          * Set to -1 because the lttng_ust_shm_handle destruction will take care
 437          * of closing shm_fd and wait_fd.
 438          */
 439         chan_data->shm_fd = -1;
 440         chan_data->wait_fd = -1;
 441
 442         /*
 443          * TODO: add consistency checks to be resilient if the
 444          * application try to feed us with incoherent channel structure
 445          * values.
 446          */
 447         chan = shmp(handle, handle->chan);
 448         /* chan is object 0. This is hardcoded. */
 449         chan_size = handle->table->objects[0].allocated_len;
 450         handle->shadow_chan = malloc(chan_size);
 451         if (!handle->shadow_chan) {
 452                 channel_destroy(chan, handle, 1);
 453                 return NULL;
 454         }
 455         memcpy(handle->shadow_chan, chan, chan_size);
 456         /*
 457          * The callback pointers in the producer are invalid in the
 458          * consumer. We need to look them up here.
 459          */
 460         config = &handle->shadow_chan->backend.config;
 461         switch (config->client_type) {
 462         case LTTNG_CLIENT_METADATA:
 463                 memcpy(&config->cb, lttng_client_callbacks_metadata,
 464                         sizeof(config->cb));
 465                 break;
 466         case LTTNG_CLIENT_DISCARD:
 467                 memcpy(&config->cb, lttng_client_callbacks_discard,
 468                         sizeof(config->cb));
 469                 break;
 470         case LTTNG_CLIENT_OVERWRITE:
 471                 memcpy(&config->cb, lttng_client_callbacks_overwrite,
 472                         sizeof(config->cb));
 473                 break;
 474         default:
 475                 ERR("Unknown client type %d", config->client_type);
 476                 channel_destroy(chan, handle, 1);
 477                 return NULL;
 478         }
 479         /* Replace the object table pointer. */
 480         ret = munmap(handle->table->objects[0].memory_map,
 481                 handle->table->objects[0].memory_map_size);
 482         if (ret) {
 483                 perror("munmap");
 484                 assert(0);
 485         }
 486         handle->table->objects[0].memory_map = (char *) handle->shadow_chan;
 487         handle->table->objects[0].is_shadow = 1;
 488         return handle;
 489 }
 490
 491 /* Add stream to channel shm and map its shm into process memory */
 492 int ustctl_add_stream(struct lttng_ust_shm_handle *handle,
 493                 struct lttng_ust_object_data *stream_data)
 494 {
 495         int ret;
 496
 497         if (!stream_data->handle)
 498                 return -ENOENT;
 499         /* map stream */
 500         ret = channel_handle_add_stream(handle,
 501                 stream_data->shm_fd,
 502                 stream_data->wait_fd,
 503                 stream_data->memory_map_size);
 504         if (ret) {
 505                 ERR("add stream error\n");
 506                 return ret;
 507         }
 508         /*
 509          * Set to -1 because the lttng_ust_shm_handle destruction will take care
 510          * of closing shm_fd and wait_fd.
 511          */
 512         stream_data->shm_fd = -1;
 513         stream_data->wait_fd = -1;
 514         return 0;
 515 }
 516
 517 void ustctl_unmap_channel(struct lttng_ust_shm_handle *handle)
 518 {
 519         struct channel *chan;
 520
 521         chan = shmp(handle, handle->chan);
 522         channel_destroy(chan, handle, 1);
 523 }
 524
 525 struct lttng_ust_lib_ring_buffer *ustctl_open_stream_read(struct lttng_ust_shm_handle *handle,
 526         int cpu)
 527 {
 528         struct channel *chan = handle->shadow_chan;
 529         int shm_fd, wait_fd;
 530         uint64_t memory_map_size;
 531         struct lttng_ust_lib_ring_buffer *buf;
 532         int ret;
 533
 534         buf = channel_get_ring_buffer(&chan->backend.config,
 535                 chan, cpu, handle, &shm_fd, &wait_fd, &memory_map_size);
 536         if (!buf)
 537                 return NULL;
 538         ret = lib_ring_buffer_open_read(buf, handle, 1);
 539         if (ret)
 540                 return NULL;
 541         return buf;
 542 }
 543
 544 void ustctl_close_stream_read(struct lttng_ust_shm_handle *handle,
 545                 struct lttng_ust_lib_ring_buffer *buf)
 546 {
 547         lib_ring_buffer_release_read(buf, handle, 1);
 548 }
 549
 550 /* For mmap mode, readable without "get" operation */
 551
 552 void *ustctl_get_mmap_base(struct lttng_ust_shm_handle *handle,
 553                 struct lttng_ust_lib_ring_buffer *buf)
 554 {
 555         return shmp(handle, buf->backend.memory_map);
 556 }
 557
 558 /* returns the length to mmap. */
 559 int ustctl_get_mmap_len(struct lttng_ust_shm_handle *handle,
 560                 struct lttng_ust_lib_ring_buffer *buf,
 561                 unsigned long *len)
 562 {
 563         unsigned long mmap_buf_len;
 564         struct channel *chan = handle->shadow_chan;
 565
 566         if (chan->backend.config.output != RING_BUFFER_MMAP)
 567                 return -EINVAL;
 568         mmap_buf_len = chan->backend.buf_size;
 569         if (chan->backend.extra_reader_sb)
 570                 mmap_buf_len += chan->backend.subbuf_size;
 571         if (mmap_buf_len > INT_MAX)
 572                 return -EFBIG;
 573         *len = mmap_buf_len;
 574         return 0;
 575 }
 576
 577 /* returns the maximum size for sub-buffers. */
 578 int ustctl_get_max_subbuf_size(struct lttng_ust_shm_handle *handle,
 579                 struct lttng_ust_lib_ring_buffer *buf,
 580                 unsigned long *len)
 581 {
 582         struct channel *chan = handle->shadow_chan;
 583
 584         *len = chan->backend.subbuf_size;
 585         return 0;
 586 }
 587
 588 /*
 589  * For mmap mode, operate on the current packet (between get/put or
 590  * get_next/put_next).
 591  */
 592
 593 /* returns the offset of the subbuffer belonging to the mmap reader. */
 594 int ustctl_get_mmap_read_offset(struct lttng_ust_shm_handle *handle,
 595                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *off)
 596 {
 597         struct channel *chan = handle->shadow_chan;
 598         unsigned long sb_bindex;
 599
 600         if (chan->backend.config.output != RING_BUFFER_MMAP)
 601                 return -EINVAL;
 602         sb_bindex = subbuffer_id_get_index(&chan->backend.config,
 603                                            buf->backend.buf_rsb.id);
 604         *off = shmp(handle, shmp_index(handle, buf->backend.array, sb_bindex)->shmp)->mmap_offset;
 605         return 0;
 606 }
 607
 608 /* returns the size of the current sub-buffer, without padding (for mmap). */
 609 int ustctl_get_subbuf_size(struct lttng_ust_shm_handle *handle,
 610                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *len)
 611 {
 612         struct channel *chan = handle->shadow_chan;
 613
 614         *len = lib_ring_buffer_get_read_data_size(&chan->backend.config, buf,
 615                 handle);
 616         return 0;
 617 }
 618
 619 /* returns the size of the current sub-buffer, without padding (for mmap). */
 620 int ustctl_get_padded_subbuf_size(struct lttng_ust_shm_handle *handle,
 621                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *len)
 622 {
 623         struct channel *chan = handle->shadow_chan;
 624
 625         *len = lib_ring_buffer_get_read_data_size(&chan->backend.config, buf,
 626                 handle);
 627         *len = PAGE_ALIGN(*len);
 628         return 0;
 629 }
 630
 631 /* Get exclusive read access to the next sub-buffer that can be read. */
 632 int ustctl_get_next_subbuf(struct lttng_ust_shm_handle *handle,
 633                 struct lttng_ust_lib_ring_buffer *buf)
 634 {
 635         return lib_ring_buffer_get_next_subbuf(buf, handle);
 636 }
 637
 638
 639 /* Release exclusive sub-buffer access, move consumer forward. */
 640 int ustctl_put_next_subbuf(struct lttng_ust_shm_handle *handle,
 641                 struct lttng_ust_lib_ring_buffer *buf)
 642 {
 643         lib_ring_buffer_put_next_subbuf(buf, handle);
 644         return 0;
 645 }
 646
 647 /* snapshot */
 648
 649 /* Get a snapshot of the current ring buffer producer and consumer positions */
 650 int ustctl_snapshot(struct lttng_ust_shm_handle *handle,
 651                 struct lttng_ust_lib_ring_buffer *buf)
 652 {
 653         return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 654                         &buf->prod_snapshot, handle);
 655 }
 656
 657 /* Get the consumer position (iteration start) */
 658 int ustctl_snapshot_get_consumed(struct lttng_ust_shm_handle *handle,
 659                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 660 {
 661         *pos = buf->cons_snapshot;
 662         return 0;
 663 }
 664
 665 /* Get the producer position (iteration end) */
 666 int ustctl_snapshot_get_produced(struct lttng_ust_shm_handle *handle,
 667                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 668 {
 669         *pos = buf->prod_snapshot;
 670         return 0;
 671 }
 672
 673 /* Get exclusive read access to the specified sub-buffer position */
 674 int ustctl_get_subbuf(struct lttng_ust_shm_handle *handle,
 675                 struct lttng_ust_lib_ring_buffer *buf, unsigned long *pos)
 676 {
 677         return lib_ring_buffer_get_subbuf(buf, *pos, handle);
 678 }
 679
 680 /* Release exclusive sub-buffer access */
 681 int ustctl_put_subbuf(struct lttng_ust_shm_handle *handle,
 682                 struct lttng_ust_lib_ring_buffer *buf)
 683 {
 684         lib_ring_buffer_put_subbuf(buf, handle);
 685         return 0;
 686 }
 687
 688 void ustctl_flush_buffer(struct lttng_ust_shm_handle *handle,
 689                 struct lttng_ust_lib_ring_buffer *buf,
 690                 int producer_active)
 691 {
 692         lib_ring_buffer_switch_slow(buf,
 693                 producer_active ? SWITCH_ACTIVE : SWITCH_FLUSH,
 694                 handle);
 695 }