liblttng-ust-comm/lttng-ust-comm.c

   1 /*
   2  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C)  2011-2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; only
   8  * version 2.1 of the License.
   9  *
  10  * This library 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 GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/socket.h>
  26 #include <sys/stat.h>
  27 #include <sys/types.h>
  28 #include <sys/un.h>
  29 #include <unistd.h>
  30 #include <assert.h>
  31 #include <errno.h>
  32 #include <fcntl.h>
  33
  34 #include <lttng/ust-ctl.h>
  35 #include <ust-comm.h>
  36 #include <ust-fd.h>
  37 #include <helper.h>
  38 #include <lttng/ust-error.h>
  39 #include <lttng/ust-events.h>
  40 #include <lttng/ust-dynamic-type.h>
  41 #include <usterr-signal-safe.h>
  42
  43 #include "../liblttng-ust/compat.h"
  44
  45 #define USTCOMM_CODE_OFFSET(code)       \
  46         (code == LTTNG_UST_OK ? 0 : (code - LTTNG_UST_ERR + 1))
  47
  48 #define USTCOMM_MAX_SEND_FDS    4
  49
  50 static
  51 ssize_t count_fields_recursive(size_t nr_fields,
  52                 const struct lttng_event_field *lttng_fields);
  53 static
  54 int serialize_one_field(struct lttng_session *session,
  55                 struct ustctl_field *fields, size_t *iter_output,
  56                 const struct lttng_event_field *lf);
  57
  58 /*
  59  * Human readable error message.
  60  */
  61 static const char *ustcomm_readable_code[] = {
  62         [ USTCOMM_CODE_OFFSET(LTTNG_UST_OK) ] = "Success",
  63         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR) ] = "Unknown error",
  64         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_NOENT) ] = "No entry",
  65         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_EXIST) ] = "Object already exists",
  66         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_INVAL) ] = "Invalid argument",
  67         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_PERM) ] = "Permission denied",
  68         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_NOSYS) ] = "Not implemented",
  69         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_EXITING) ] = "Process is exiting",
  70
  71         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_INVAL_MAGIC) ] = "Invalid magic number",
  72         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_INVAL_SOCKET_TYPE) ] = "Invalid socket type",
  73         [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_UNSUP_MAJOR) ] = "Unsupported major version",
  74 };
  75
  76 /*
  77  * lttng_ust_strerror
  78  *
  79  * Receives positive error value.
  80  * Return ptr to string representing a human readable
  81  * error code from the ustcomm_return_code enum.
  82  */
  83 const char *lttng_ust_strerror(int code)
  84 {
  85         if (code == LTTNG_UST_OK)
  86                 return ustcomm_readable_code[USTCOMM_CODE_OFFSET(code)];
  87         if (code < LTTNG_UST_ERR)
  88                 return strerror(code);
  89         if (code >= LTTNG_UST_ERR_NR)
  90                 code = LTTNG_UST_ERR;
  91         return ustcomm_readable_code[USTCOMM_CODE_OFFSET(code)];
  92 }
  93
  94 /*
  95  * ustcomm_connect_unix_sock
  96  *
  97  * Connect to unix socket using the path name.
  98  *
  99  * Caller handles FD tracker.
 100  */
 101 int ustcomm_connect_unix_sock(const char *pathname, long timeout)
 102 {
 103         struct sockaddr_un sun;
 104         int fd, ret;
 105
 106         /*
 107          * libust threads require the close-on-exec flag for all
 108          * resources so it does not leak file descriptors upon exec.
 109          */
 110         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 111         if (fd < 0) {
 112                 PERROR("socket");
 113                 ret = -errno;
 114                 goto error;
 115         }
 116         if (timeout >= 0) {
 117                 /* Give at least 10ms. */
 118                 if (timeout < 10)
 119                         timeout = 10;
 120                 ret = ustcomm_setsockopt_snd_timeout(fd, timeout);
 121                 if (ret < 0) {
 122                         WARN("Error setting connect socket send timeout");
 123                 }
 124         }
 125         ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
 126         if (ret < 0) {
 127                 PERROR("fcntl");
 128                 ret = -errno;
 129                 goto error_fcntl;
 130         }
 131
 132         memset(&sun, 0, sizeof(sun));
 133         sun.sun_family = AF_UNIX;
 134         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 135         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 136
 137         ret = connect(fd, (struct sockaddr *) &sun, sizeof(sun));
 138         if (ret < 0) {
 139                 /*
 140                  * Don't print message on connect ENOENT error, because
 141                  * connect is used in normal execution to detect if
 142                  * sessiond is alive. ENOENT is when the unix socket
 143                  * file does not exist, and ECONNREFUSED is when the
 144                  * file exists but no sessiond is listening.
 145                  */
 146                 if (errno != ECONNREFUSED && errno != ECONNRESET
 147                                 && errno != ENOENT && errno != EACCES)
 148                         PERROR("connect");
 149                 ret = -errno;
 150                 if (ret == -ECONNREFUSED || ret == -ECONNRESET)
 151                         ret = -EPIPE;
 152                 goto error_connect;
 153         }
 154
 155         return fd;
 156
 157 error_connect:
 158 error_fcntl:
 159         {
 160                 int closeret;
 161
 162                 closeret = close(fd);
 163                 if (closeret)
 164                         PERROR("close");
 165         }
 166 error:
 167         return ret;
 168 }
 169
 170 /*
 171  * ustcomm_accept_unix_sock
 172  *
 173  * Do an accept(2) on the sock and return the
 174  * new file descriptor. The socket MUST be bind(2) before.
 175  */
 176 int ustcomm_accept_unix_sock(int sock)
 177 {
 178         int new_fd;
 179         struct sockaddr_un sun;
 180         socklen_t len = 0;
 181
 182         /* Blocking call */
 183         new_fd = accept(sock, (struct sockaddr *) &sun, &len);
 184         if (new_fd < 0) {
 185                 if (errno != ECONNABORTED)
 186                         PERROR("accept");
 187                 new_fd = -errno;
 188                 if (new_fd == -ECONNABORTED)
 189                         new_fd = -EPIPE;
 190         }
 191         return new_fd;
 192 }
 193
 194 /*
 195  * ustcomm_create_unix_sock
 196  *
 197  * Creates a AF_UNIX local socket using pathname
 198  * bind the socket upon creation and return the fd.
 199  */
 200 int ustcomm_create_unix_sock(const char *pathname)
 201 {
 202         struct sockaddr_un sun;
 203         int fd, ret;
 204
 205         /* Create server socket */
 206         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 207                 PERROR("socket");
 208                 ret = -errno;
 209                 goto error;
 210         }
 211
 212         memset(&sun, 0, sizeof(sun));
 213         sun.sun_family = AF_UNIX;
 214         strncpy(sun.sun_path, pathname, sizeof(sun.sun_path));
 215         sun.sun_path[sizeof(sun.sun_path) - 1] = '\0';
 216
 217         /* Unlink the old file if present */
 218         (void) unlink(pathname);
 219         ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
 220         if (ret < 0) {
 221                 PERROR("bind");
 222                 ret = -errno;
 223                 goto error_close;
 224         }
 225
 226         return fd;
 227
 228 error_close:
 229         {
 230                 int closeret;
 231
 232                 closeret = close(fd);
 233                 if (closeret) {
 234                         PERROR("close");
 235                 }
 236         }
 237 error:
 238         return ret;
 239 }
 240
 241 /*
 242  * ustcomm_listen_unix_sock
 243  *
 244  * Make the socket listen using LTTNG_UST_COMM_MAX_LISTEN.
 245  */
 246 int ustcomm_listen_unix_sock(int sock)
 247 {
 248         int ret;
 249
 250         ret = listen(sock, LTTNG_UST_COMM_MAX_LISTEN);
 251         if (ret < 0) {
 252                 ret = -errno;
 253                 PERROR("listen");
 254         }
 255
 256         return ret;
 257 }
 258
 259 /*
 260  * ustcomm_close_unix_sock
 261  *
 262  * Shutdown cleanly a unix socket.
 263  *
 264  * Handles fd tracker internally.
 265  */
 266 int ustcomm_close_unix_sock(int sock)
 267 {
 268         int ret;
 269
 270         lttng_ust_lock_fd_tracker();
 271         ret = close(sock);
 272         if (!ret) {
 273                 lttng_ust_delete_fd_from_tracker(sock);
 274         } else {
 275                 PERROR("close");
 276                 ret = -errno;
 277         }
 278         lttng_ust_unlock_fd_tracker();
 279
 280         return ret;
 281 }
 282
 283 /*
 284  * ustcomm_recv_unix_sock
 285  *
 286  * Receive data of size len in put that data into
 287  * the buf param. Using recvmsg API.
 288  * Return the size of received data.
 289  * Return 0 on orderly shutdown.
 290  */
 291 ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
 292 {
 293         struct msghdr msg;
 294         struct iovec iov[1];
 295         ssize_t ret = -1;
 296         size_t len_last;
 297
 298         memset(&msg, 0, sizeof(msg));
 299
 300         iov[0].iov_base = buf;
 301         iov[0].iov_len = len;
 302         msg.msg_iov = iov;
 303         msg.msg_iovlen = 1;
 304
 305         do {
 306                 len_last = iov[0].iov_len;
 307                 ret = recvmsg(sock, &msg, 0);
 308                 if (ret > 0) {
 309                         iov[0].iov_base += ret;
 310                         iov[0].iov_len -= ret;
 311                         assert(ret <= len_last);
 312                 }
 313         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 314
 315         if (ret < 0) {
 316                 int shutret;
 317
 318                 if (errno != EPIPE && errno != ECONNRESET && errno != ECONNREFUSED)
 319                         PERROR("recvmsg");
 320                 ret = -errno;
 321                 if (ret == -ECONNRESET || ret == -ECONNREFUSED)
 322                         ret = -EPIPE;
 323
 324                 shutret = shutdown(sock, SHUT_RDWR);
 325                 if (shutret)
 326                         ERR("Socket shutdown error");
 327         } else if (ret > 0) {
 328                 ret = len;
 329         }
 330         /* ret = 0 means an orderly shutdown. */
 331
 332         return ret;
 333 }
 334
 335 /*
 336  * ustcomm_send_unix_sock
 337  *
 338  * Send buf data of size len. Using sendmsg API.
 339  * Return the size of sent data.
 340  */
 341 ssize_t ustcomm_send_unix_sock(int sock, const void *buf, size_t len)
 342 {
 343         struct msghdr msg;
 344         struct iovec iov[1];
 345         ssize_t ret;
 346
 347         memset(&msg, 0, sizeof(msg));
 348
 349         iov[0].iov_base = (void *) buf;
 350         iov[0].iov_len = len;
 351         msg.msg_iov = iov;
 352         msg.msg_iovlen = 1;
 353
 354         /*
 355          * Using the MSG_NOSIGNAL when sending data from sessiond to
 356          * libust, so libust does not receive an unhandled SIGPIPE or
 357          * SIGURG. The sessiond receiver side can be made more resilient
 358          * by ignoring SIGPIPE, but we don't have this luxury on the
 359          * libust side.
 360          */
 361         do {
 362                 ret = sendmsg(sock, &msg, MSG_NOSIGNAL);
 363         } while (ret < 0 && errno == EINTR);
 364
 365         if (ret < 0) {
 366                 int shutret;
 367
 368                 if (errno != EPIPE && errno != ECONNRESET)
 369                         PERROR("sendmsg");
 370                 ret = -errno;
 371                 if (ret == -ECONNRESET)
 372                         ret = -EPIPE;
 373
 374                 shutret = shutdown(sock, SHUT_RDWR);
 375                 if (shutret)
 376                         ERR("Socket shutdown error");
 377         }
 378
 379         return ret;
 380 }
 381
 382 /*
 383  * Send a message accompanied by fd(s) over a unix socket.
 384  *
 385  * Returns the size of data sent, or negative error value.
 386  */
 387 ssize_t ustcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 388 {
 389         struct msghdr msg;
 390         struct cmsghdr *cmptr;
 391         struct iovec iov[1];
 392         ssize_t ret = -1;
 393         unsigned int sizeof_fds = nb_fd * sizeof(int);
 394         char tmp[CMSG_SPACE(sizeof_fds)];
 395         char dummy = 0;
 396
 397         memset(&msg, 0, sizeof(msg));
 398         memset(tmp, 0, CMSG_SPACE(sizeof_fds) * sizeof(char));
 399
 400         if (nb_fd > USTCOMM_MAX_SEND_FDS)
 401                 return -EINVAL;
 402
 403         msg.msg_control = (caddr_t)tmp;
 404         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 405
 406         cmptr = CMSG_FIRSTHDR(&msg);
 407         if (!cmptr)
 408                 return -EINVAL;
 409         cmptr->cmsg_level = SOL_SOCKET;
 410         cmptr->cmsg_type = SCM_RIGHTS;
 411         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 412         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 413         /* Sum of the length of all control messages in the buffer: */
 414         msg.msg_controllen = cmptr->cmsg_len;
 415
 416         iov[0].iov_base = &dummy;
 417         iov[0].iov_len = 1;
 418         msg.msg_iov = iov;
 419         msg.msg_iovlen = 1;
 420
 421         do {
 422                 ret = sendmsg(sock, &msg, MSG_NOSIGNAL);
 423         } while (ret < 0 && errno == EINTR);
 424         if (ret < 0) {
 425                 /*
 426                  * We consider EPIPE and ECONNRESET as expected.
 427                  */
 428                 if (errno != EPIPE && errno != ECONNRESET) {
 429                         PERROR("sendmsg");
 430                 }
 431                 ret = -errno;
 432                 if (ret == -ECONNRESET)
 433                         ret = -EPIPE;
 434         }
 435         return ret;
 436 }
 437
 438 /*
 439  * Recv a message accompanied by fd(s) from a unix socket.
 440  *
 441  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 442  * actually received in nb_fd.
 443  * Returns -EPIPE on orderly shutdown.
 444  */
 445 ssize_t ustcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 446 {
 447         struct iovec iov[1];
 448         ssize_t ret = 0;
 449         struct cmsghdr *cmsg;
 450         size_t sizeof_fds = nb_fd * sizeof(int);
 451         char recv_fd[CMSG_SPACE(sizeof_fds)];
 452         struct msghdr msg;
 453         char dummy;
 454
 455         memset(&msg, 0, sizeof(msg));
 456
 457         /* Prepare to receive the structures */
 458         iov[0].iov_base = &dummy;
 459         iov[0].iov_len = 1;
 460         msg.msg_iov = iov;
 461         msg.msg_iovlen = 1;
 462         msg.msg_control = recv_fd;
 463         msg.msg_controllen = sizeof(recv_fd);
 464
 465         do {
 466                 ret = recvmsg(sock, &msg, 0);
 467         } while (ret < 0 && errno == EINTR);
 468         if (ret < 0) {
 469                 if (errno != EPIPE && errno != ECONNRESET) {
 470                         PERROR("recvmsg fds");
 471                 }
 472                 ret = -errno;
 473                 if (ret == -ECONNRESET)
 474                         ret = -EPIPE;
 475                 goto end;
 476         }
 477         if (ret == 0) {
 478                 /* orderly shutdown */
 479                 ret = -EPIPE;
 480                 goto end;
 481         }
 482         if (ret != 1) {
 483                 ERR("Error: Received %zd bytes, expected %d\n",
 484                                 ret, 1);
 485                 goto end;
 486         }
 487         if (msg.msg_flags & MSG_CTRUNC) {
 488                 ERR("Error: Control message truncated.\n");
 489                 ret = -1;
 490                 goto end;
 491         }
 492         cmsg = CMSG_FIRSTHDR(&msg);
 493         if (!cmsg) {
 494                 ERR("Error: Invalid control message header\n");
 495                 ret = -1;
 496                 goto end;
 497         }
 498         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 499                 ERR("Didn't received any fd\n");
 500                 ret = -1;
 501                 goto end;
 502         }
 503         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 504                 ERR("Error: Received %zu bytes of ancillary data, expected %zu\n",
 505                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 506                 ret = -1;
 507                 goto end;
 508         }
 509         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 510         ret = nb_fd;
 511 end:
 512         return ret;
 513 }
 514
 515 int ustcomm_send_app_msg(int sock, struct ustcomm_ust_msg *lum)
 516 {
 517         ssize_t len;
 518
 519         len = ustcomm_send_unix_sock(sock, lum, sizeof(*lum));
 520         switch (len) {
 521         case sizeof(*lum):
 522                 break;
 523         default:
 524                 if (len < 0) {
 525                         return len;
 526                 } else {
 527                         ERR("incorrect message size: %zd\n", len);
 528                         return -EINVAL;
 529                 }
 530         }
 531         return 0;
 532 }
 533
 534 int ustcomm_recv_app_reply(int sock, struct ustcomm_ust_reply *lur,
 535                           uint32_t expected_handle, uint32_t expected_cmd)
 536 {
 537         ssize_t len;
 538
 539         memset(lur, 0, sizeof(*lur));
 540         len = ustcomm_recv_unix_sock(sock, lur, sizeof(*lur));
 541         switch (len) {
 542         case 0: /* orderly shutdown */
 543                 return -EPIPE;
 544         case sizeof(*lur):
 545         {
 546                 int err = 0;
 547
 548                 if (lur->handle != expected_handle) {
 549                         ERR("Unexpected result message handle: "
 550                                 "expected: %u vs received: %u\n",
 551                                 expected_handle, lur->handle);
 552                         err = 1;
 553                 }
 554                 if (lur->cmd != expected_cmd) {
 555                         ERR("Unexpected result message command "
 556                                 "expected: %u vs received: %u\n",
 557                                 expected_cmd, lur->cmd);
 558                         err = 1;
 559                 }
 560                 if (err) {
 561                         return -EINVAL;
 562                 } else {
 563                         return lur->ret_code;
 564                 }
 565         }
 566         default:
 567                 if (len >= 0) {
 568                         ERR("incorrect message size: %zd\n", len);
 569                 }
 570                 return len;
 571         }
 572 }
 573
 574 int ustcomm_send_app_cmd(int sock,
 575                         struct ustcomm_ust_msg *lum,
 576                         struct ustcomm_ust_reply *lur)
 577 {
 578         int ret;
 579
 580         ret = ustcomm_send_app_msg(sock, lum);
 581         if (ret)
 582                 return ret;
 583         ret = ustcomm_recv_app_reply(sock, lur, lum->handle, lum->cmd);
 584         if (ret > 0)
 585                 return -EIO;
 586         return ret;
 587 }
 588
 589 /*
 590  * chan_data is allocated internally if this function returns the
 591  * expected var_len.
 592  */
 593 ssize_t ustcomm_recv_channel_from_sessiond(int sock,
 594                 void **_chan_data, uint64_t var_len,
 595                 int *_wakeup_fd)
 596 {
 597         void *chan_data;
 598         ssize_t len, nr_fd;
 599         int wakeup_fd, ret;
 600
 601         if (var_len > LTTNG_UST_CHANNEL_DATA_MAX_LEN) {
 602                 len = -EINVAL;
 603                 goto error_check;
 604         }
 605         /* Receive variable length data */
 606         chan_data = zmalloc(var_len);
 607         if (!chan_data) {
 608                 len = -ENOMEM;
 609                 goto error_alloc;
 610         }
 611         len = ustcomm_recv_unix_sock(sock, chan_data, var_len);
 612         if (len != var_len) {
 613                 goto error_recv;
 614         }
 615         /* recv wakeup fd */
 616         lttng_ust_lock_fd_tracker();
 617         nr_fd = ustcomm_recv_fds_unix_sock(sock, &wakeup_fd, 1);
 618         if (nr_fd <= 0) {
 619                 lttng_ust_unlock_fd_tracker();
 620                 if (nr_fd < 0) {
 621                         len = nr_fd;
 622                         goto error_recv;
 623                 } else {
 624                         len = -EIO;
 625                         goto error_recv;
 626                 }
 627         }
 628
 629         ret = lttng_ust_add_fd_to_tracker(wakeup_fd);
 630         if (ret < 0) {
 631                 lttng_ust_unlock_fd_tracker();
 632                 ret = close(wakeup_fd);
 633                 if (ret) {
 634                         PERROR("close on wakeup_fd");
 635                 }
 636                 len = -EIO;
 637                 goto error_recv;
 638         }
 639
 640         *_wakeup_fd = ret;
 641         lttng_ust_unlock_fd_tracker();
 642
 643         *_chan_data = chan_data;
 644         return len;
 645
 646 error_recv:
 647         free(chan_data);
 648 error_alloc:
 649 error_check:
 650         return len;
 651 }
 652
 653 int ustcomm_recv_stream_from_sessiond(int sock,
 654                 uint64_t *memory_map_size,
 655                 int *shm_fd, int *wakeup_fd)
 656 {
 657         ssize_t len;
 658         int ret;
 659         int fds[2];
 660
 661         /* recv shm fd and wakeup fd */
 662         lttng_ust_lock_fd_tracker();
 663         len = ustcomm_recv_fds_unix_sock(sock, fds, 2);
 664         if (len <= 0) {
 665                 lttng_ust_unlock_fd_tracker();
 666                 if (len < 0) {
 667                         ret = len;
 668                         goto error;
 669                 } else {
 670                         ret = -EIO;
 671                         goto error;
 672                 }
 673         }
 674
 675         ret = lttng_ust_add_fd_to_tracker(fds[0]);
 676         if (ret < 0) {
 677                 lttng_ust_unlock_fd_tracker();
 678                 ret = close(fds[0]);
 679                 if (ret) {
 680                         PERROR("close on received shm_fd");
 681                 }
 682                 ret = -EIO;
 683                 goto error;
 684         }
 685         *shm_fd = ret;
 686
 687         ret = lttng_ust_add_fd_to_tracker(fds[1]);
 688         if (ret < 0) {
 689                 lttng_ust_unlock_fd_tracker();
 690                 ret = close(*shm_fd);
 691                 if (ret) {
 692                         PERROR("close on shm_fd");
 693                 }
 694                 *shm_fd = -1;
 695                 ret = close(fds[1]);
 696                 if (ret) {
 697                         PERROR("close on received wakeup_fd");
 698                 }
 699                 ret = -EIO;
 700                 goto error;
 701         }
 702         *wakeup_fd = ret;
 703         lttng_ust_unlock_fd_tracker();
 704         return 0;
 705
 706 error:
 707         return ret;
 708 }
 709
 710 /*
 711  * Returns 0 on success, negative error value on error.
 712  */
 713 int ustcomm_send_reg_msg(int sock,
 714                 enum ustctl_socket_type type,
 715                 uint32_t bits_per_long,
 716                 uint32_t uint8_t_alignment,
 717                 uint32_t uint16_t_alignment,
 718                 uint32_t uint32_t_alignment,
 719                 uint32_t uint64_t_alignment,
 720                 uint32_t long_alignment)
 721 {
 722         ssize_t len;
 723         struct ustctl_reg_msg reg_msg;
 724
 725         reg_msg.magic = LTTNG_UST_COMM_MAGIC;
 726         reg_msg.major = LTTNG_UST_ABI_MAJOR_VERSION;
 727         reg_msg.minor = LTTNG_UST_ABI_MINOR_VERSION;
 728         reg_msg.pid = getpid();
 729         reg_msg.ppid = getppid();
 730         reg_msg.uid = getuid();
 731         reg_msg.gid = getgid();
 732         reg_msg.bits_per_long = bits_per_long;
 733         reg_msg.uint8_t_alignment = uint8_t_alignment;
 734         reg_msg.uint16_t_alignment = uint16_t_alignment;
 735         reg_msg.uint32_t_alignment = uint32_t_alignment;
 736         reg_msg.uint64_t_alignment = uint64_t_alignment;
 737         reg_msg.long_alignment = long_alignment;
 738         reg_msg.socket_type = type;
 739         lttng_ust_getprocname(reg_msg.name);
 740         memset(reg_msg.padding, 0, sizeof(reg_msg.padding));
 741
 742         len = ustcomm_send_unix_sock(sock, &reg_msg, sizeof(reg_msg));
 743         if (len > 0 && len != sizeof(reg_msg))
 744                 return -EIO;
 745         if (len < 0)
 746                 return len;
 747         return 0;
 748 }
 749
 750 static
 751 ssize_t count_one_type(const struct lttng_type *lt)
 752 {
 753         switch (lt->atype) {
 754         case atype_integer:
 755         case atype_float:
 756         case atype_string:
 757         case atype_enum:
 758         case atype_array:
 759         case atype_sequence:
 760                 return 1;
 761         case atype_struct:
 762                 //TODO: implement non-empty struct.
 763                 return 1;
 764         case atype_dynamic:
 765         {
 766                 const struct lttng_event_field *choices;
 767                 size_t nr_choices;
 768                 int ret;
 769
 770                 ret = lttng_ust_dynamic_type_choices(&nr_choices,
 771                         &choices);
 772                 if (ret)
 773                         return ret;
 774                 /*
 775                  * One field for enum, one field for variant, and
 776                  * one field per choice.
 777                  */
 778                 return count_fields_recursive(nr_choices, choices) + 2;
 779         }
 780         default:
 781                 return -EINVAL;
 782         }
 783         return 0;
 784 }
 785
 786 static
 787 ssize_t count_fields_recursive(size_t nr_fields,
 788                 const struct lttng_event_field *lttng_fields)
 789 {
 790         int i;
 791         ssize_t ret, count = 0;
 792
 793         for (i = 0; i < nr_fields; i++) {
 794                 const struct lttng_event_field *lf;
 795
 796                 lf = &lttng_fields[i];
 797                 /* skip 'nowrite' fields */
 798                 if (lf->nowrite)
 799                         continue;
 800                 ret = count_one_type(&lf->type);
 801                 if (ret < 0)
 802                         return ret;     /* error */
 803                 count += ret;
 804         }
 805         return count;
 806 }
 807
 808 static
 809 ssize_t count_ctx_fields_recursive(size_t nr_fields,
 810                 const struct lttng_ctx_field *lttng_fields)
 811 {
 812         int i;
 813         ssize_t ret, count = 0;
 814
 815         for (i = 0; i < nr_fields; i++) {
 816                 const struct lttng_event_field *lf;
 817
 818                 lf = &lttng_fields[i].event_field;
 819                 /* skip 'nowrite' fields */
 820                 if (lf->nowrite)
 821                         continue;
 822                 ret = count_one_type(&lf->type);
 823                 if (ret < 0)
 824                         return ret;     /* error */
 825                 count += ret;
 826         }
 827         return count;
 828 }
 829
 830 static
 831 int serialize_string_encoding(int32_t *ue,
 832                 enum lttng_string_encodings le)
 833 {
 834         switch (le) {
 835         case lttng_encode_none:
 836                 *ue = ustctl_encode_none;
 837                 break;
 838         case lttng_encode_UTF8:
 839                 *ue = ustctl_encode_UTF8;
 840                 break;
 841         case lttng_encode_ASCII:
 842                 *ue = ustctl_encode_ASCII;
 843                 break;
 844         default:
 845                 return -EINVAL;
 846         }
 847         return 0;
 848 }
 849
 850 static
 851 int serialize_integer_type(struct ustctl_integer_type *uit,
 852                 const struct lttng_integer_type *lit)
 853 {
 854         int32_t encoding;
 855
 856         uit->size = lit->size;
 857         uit->signedness = lit->signedness;
 858         uit->reverse_byte_order = lit->reverse_byte_order;
 859         uit->base = lit->base;
 860         if (serialize_string_encoding(&encoding, lit->encoding))
 861                 return -EINVAL;
 862         uit->encoding = encoding;
 863         uit->alignment = lit->alignment;
 864         return 0;
 865 }
 866
 867 static
 868 int serialize_basic_type(struct lttng_session *session,
 869                 enum ustctl_abstract_types *uatype,
 870                 enum lttng_abstract_types atype,
 871                 union _ustctl_basic_type *ubt,
 872                 const union _lttng_basic_type *lbt)
 873 {
 874         switch (atype) {
 875         case atype_integer:
 876         {
 877                 if (serialize_integer_type(&ubt->integer, &lbt->integer))
 878                         return -EINVAL;
 879                 *uatype = ustctl_atype_integer;
 880                 break;
 881         }
 882         case atype_string:
 883         {
 884                 int32_t encoding;
 885
 886                 if (serialize_string_encoding(&encoding, lbt->string.encoding))
 887                         return -EINVAL;
 888                 ubt->string.encoding = encoding;
 889                 *uatype = ustctl_atype_string;
 890                 break;
 891         }
 892         case atype_float:
 893         {
 894                 struct ustctl_float_type *uft;
 895                 const struct lttng_float_type *lft;
 896
 897                 uft = &ubt->_float;
 898                 lft = &lbt->_float;
 899                 uft->exp_dig = lft->exp_dig;
 900                 uft->mant_dig = lft->mant_dig;
 901                 uft->alignment = lft->alignment;
 902                 uft->reverse_byte_order = lft->reverse_byte_order;
 903                 *uatype = ustctl_atype_float;
 904                 break;
 905         }
 906         case atype_enum:
 907         {
 908                 strncpy(ubt->enumeration.name, lbt->enumeration.desc->name,
 909                                 LTTNG_UST_SYM_NAME_LEN);
 910                 ubt->enumeration.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 911                 if (serialize_integer_type(&ubt->enumeration.container_type,
 912                                 &lbt->enumeration.container_type))
 913                         return -EINVAL;
 914                 if (session) {
 915                         const struct lttng_enum *_enum;
 916
 917                         _enum = lttng_ust_enum_get_from_desc(session, lbt->enumeration.desc);
 918                         if (!_enum)
 919                                 return -EINVAL;
 920                         ubt->enumeration.id = _enum->id;
 921                 } else {
 922                         ubt->enumeration.id = -1ULL;
 923                 }
 924                 *uatype = ustctl_atype_enum;
 925                 break;
 926         }
 927         case atype_array:
 928         case atype_sequence:
 929         default:
 930                 return -EINVAL;
 931         }
 932         return 0;
 933 }
 934
 935 static
 936 int serialize_dynamic_type(struct lttng_session *session,
 937                 struct ustctl_field *fields, size_t *iter_output,
 938                 const struct lttng_event_field *lf)
 939 {
 940         const struct lttng_event_field *choices;
 941         char tag_field_name[LTTNG_UST_SYM_NAME_LEN];
 942         const struct lttng_type *tag_type;
 943         const struct lttng_event_field *tag_field_generic;
 944         struct lttng_event_field tag_field = {
 945                 .name = tag_field_name,
 946                 .nowrite = 0,
 947         };
 948         struct ustctl_field *uf;
 949         size_t nr_choices, i;
 950         int ret;
 951
 952         tag_field_generic = lttng_ust_dynamic_type_tag_field();
 953         tag_type = &tag_field_generic->type;
 954
 955         /* Serialize enum field. */
 956         strncpy(tag_field_name, lf->name, LTTNG_UST_SYM_NAME_LEN);
 957         tag_field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 958         strncat(tag_field_name,
 959                 "_tag",
 960                 LTTNG_UST_SYM_NAME_LEN - strlen(tag_field_name) - 1);
 961         tag_field.type = *tag_type;
 962         ret = serialize_one_field(session, fields, iter_output,
 963                 &tag_field);
 964         if (ret)
 965                 return ret;
 966
 967         /* Serialize variant field. */
 968         uf = &fields[*iter_output];
 969         ret = lttng_ust_dynamic_type_choices(&nr_choices, &choices);
 970         if (ret)
 971                 return ret;
 972
 973         strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
 974         uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 975         uf->type.atype = ustctl_atype_variant;
 976         uf->type.u.variant.nr_choices = nr_choices;
 977         strncpy(uf->type.u.variant.tag_name,
 978                 tag_field_name,
 979                 LTTNG_UST_SYM_NAME_LEN);
 980         uf->type.u.variant.tag_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 981         (*iter_output)++;
 982
 983         /* Serialize choice fields after variant. */
 984         for (i = 0; i < nr_choices; i++) {
 985                 ret = serialize_one_field(session, fields,
 986                         iter_output, &choices[i]);
 987                 if (ret)
 988                         return ret;
 989         }
 990         return 0;
 991 }
 992
 993 static
 994 int serialize_one_field(struct lttng_session *session,
 995                 struct ustctl_field *fields, size_t *iter_output,
 996                 const struct lttng_event_field *lf)
 997 {
 998         const struct lttng_type *lt = &lf->type;
 999         int ret;
1000
1001         /* skip 'nowrite' fields */
1002         if (lf->nowrite)
1003                 return 0;
1004
1005         switch (lt->atype) {
1006         case atype_integer:
1007         case atype_float:
1008         case atype_string:
1009         case atype_enum:
1010         {
1011                 struct ustctl_field *uf = &fields[*iter_output];
1012                 struct ustctl_type *ut = &uf->type;
1013                 enum ustctl_abstract_types atype;
1014
1015                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1016                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1017                 ret = serialize_basic_type(session, &atype, lt->atype,
1018                         &ut->u.basic, &lt->u.basic);
1019                 if (ret)
1020                         return ret;
1021                 ut->atype = atype;
1022                 (*iter_output)++;
1023                 break;
1024         }
1025         case atype_array:
1026         {
1027                 struct ustctl_field *uf = &fields[*iter_output];
1028                 struct ustctl_type *ut = &uf->type;
1029                 struct ustctl_basic_type *ubt;
1030                 const struct lttng_basic_type *lbt;
1031                 enum ustctl_abstract_types atype;
1032
1033                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1034                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1035                 uf->type.atype = ustctl_atype_array;
1036                 ubt = &ut->u.array.elem_type;
1037                 lbt = &lt->u.array.elem_type;
1038                 ut->u.array.length = lt->u.array.length;
1039                 ret = serialize_basic_type(session, &atype, lbt->atype,
1040                         &ubt->u.basic, &lbt->u.basic);
1041                 if (ret)
1042                         return -EINVAL;
1043                 ubt->atype = atype;
1044                 ut->atype = ustctl_atype_array;
1045                 (*iter_output)++;
1046                 break;
1047         }
1048         case atype_sequence:
1049         {
1050                 struct ustctl_field *uf = &fields[*iter_output];
1051                 struct ustctl_type *ut = &uf->type;
1052                 struct ustctl_basic_type *ubt;
1053                 const struct lttng_basic_type *lbt;
1054                 enum ustctl_abstract_types atype;
1055                 int ret;
1056
1057                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1058                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1059                 uf->type.atype = ustctl_atype_sequence;
1060                 ubt = &ut->u.sequence.length_type;
1061                 lbt = &lt->u.sequence.length_type;
1062                 ret = serialize_basic_type(session, &atype, lbt->atype,
1063                         &ubt->u.basic, &lbt->u.basic);
1064                 if (ret)
1065                         return -EINVAL;
1066                 ubt->atype = atype;
1067                 ubt = &ut->u.sequence.elem_type;
1068                 lbt = &lt->u.sequence.elem_type;
1069                 ret = serialize_basic_type(session, &atype, lbt->atype,
1070                         &ubt->u.basic, &lbt->u.basic);
1071                 if (ret)
1072                         return -EINVAL;
1073                 ubt->atype = atype;
1074                 ut->atype = ustctl_atype_sequence;
1075                 (*iter_output)++;
1076                 break;
1077         }
1078         case atype_dynamic:
1079         {
1080                 ret = serialize_dynamic_type(session, fields, iter_output, lf);
1081                 if (ret)
1082                         return -EINVAL;
1083                 break;
1084         }
1085         case atype_struct:
1086         {
1087                 struct ustctl_field *uf = &fields[*iter_output];
1088
1089                 /*
1090                  * TODO: add support for non-empty struct.
1091                  */
1092                 if (lf->type.u._struct.nr_fields != 0) {
1093                         return -EINVAL;
1094                 }
1095                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1096                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1097                 uf->type.atype = ustctl_atype_struct;
1098                 uf->type.u._struct.nr_fields = 0;
1099                 (*iter_output)++;
1100                 break;
1101         }
1102         default:
1103                 return -EINVAL;
1104         }
1105         return 0;
1106 }
1107
1108 static
1109 int serialize_fields(struct lttng_session *session,
1110                 size_t *_nr_write_fields,
1111                 struct ustctl_field **ustctl_fields,
1112                 size_t nr_fields,
1113                 const struct lttng_event_field *lttng_fields)
1114 {
1115         struct ustctl_field *fields;
1116         int ret;
1117         size_t i, iter_output = 0;
1118         ssize_t nr_write_fields;
1119
1120         nr_write_fields = count_fields_recursive(nr_fields, lttng_fields);
1121         if (nr_write_fields < 0) {
1122                 return (int) nr_write_fields;
1123         }
1124
1125         fields = zmalloc(nr_write_fields * sizeof(*fields));
1126         if (!fields)
1127                 return -ENOMEM;
1128
1129         for (i = 0; i < nr_fields; i++) {
1130                 ret = serialize_one_field(session, fields, &iter_output,
1131                                 &lttng_fields[i]);
1132                 if (ret)
1133                         goto error_type;
1134         }
1135
1136         *_nr_write_fields = nr_write_fields;
1137         *ustctl_fields = fields;
1138         return 0;
1139
1140 error_type:
1141         free(fields);
1142         return ret;
1143 }
1144
1145 static
1146 int serialize_entries(struct ustctl_enum_entry **_entries,
1147                 size_t nr_entries,
1148                 const struct lttng_enum_entry *lttng_entries)
1149 {
1150         struct ustctl_enum_entry *entries;
1151         int i;
1152
1153         /* Serialize the entries */
1154         entries = zmalloc(nr_entries * sizeof(*entries));
1155         if (!entries)
1156                 return -ENOMEM;
1157         for (i = 0; i < nr_entries; i++) {
1158                 struct ustctl_enum_entry *uentry;
1159                 const struct lttng_enum_entry *lentry;
1160
1161                 uentry = &entries[i];
1162                 lentry = &lttng_entries[i];
1163
1164                 uentry->start.value = lentry->start.value;
1165                 uentry->start.signedness = lentry->start.signedness;
1166                 uentry->end.value = lentry->end.value;
1167                 uentry->end.signedness = lentry->end.signedness;
1168                 strncpy(uentry->string, lentry->string, LTTNG_UST_SYM_NAME_LEN);
1169                 uentry->string[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1170
1171                 if (lentry->u.extra.options & LTTNG_ENUM_ENTRY_OPTION_IS_AUTO) {
1172                         uentry->u.extra.options |=
1173                                 USTCTL_UST_ENUM_ENTRY_OPTION_IS_AUTO;
1174                 }
1175         }
1176         *_entries = entries;
1177         return 0;
1178 }
1179
1180 static
1181 int serialize_ctx_fields(struct lttng_session *session,
1182                 size_t *_nr_write_fields,
1183                 struct ustctl_field **ustctl_fields,
1184                 size_t nr_fields,
1185                 const struct lttng_ctx_field *lttng_fields)
1186 {
1187         struct ustctl_field *fields;
1188         int ret;
1189         size_t i, iter_output = 0;
1190         ssize_t nr_write_fields;
1191
1192         nr_write_fields = count_ctx_fields_recursive(nr_fields,
1193                         lttng_fields);
1194         if (nr_write_fields < 0) {
1195                 return (int) nr_write_fields;
1196         }
1197
1198         fields = zmalloc(nr_write_fields * sizeof(*fields));
1199         if (!fields)
1200                 return -ENOMEM;
1201
1202         for (i = 0; i < nr_fields; i++) {
1203                 ret = serialize_one_field(session, fields, &iter_output,
1204                                 &lttng_fields[i].event_field);
1205                 if (ret)
1206                         goto error_type;
1207         }
1208
1209         *_nr_write_fields = nr_write_fields;
1210         *ustctl_fields = fields;
1211         return 0;
1212
1213 error_type:
1214         free(fields);
1215         return ret;
1216 }
1217
1218 /*
1219  * Returns 0 on success, negative error value on error.
1220  */
1221 int ustcomm_register_event(int sock,
1222         struct lttng_session *session,
1223         int session_objd,               /* session descriptor */
1224         int channel_objd,               /* channel descriptor */
1225         const char *event_name,         /* event name (input) */
1226         int loglevel,
1227         const char *signature,          /* event signature (input) */
1228         size_t nr_fields,               /* fields */
1229         const struct lttng_event_field *lttng_fields,
1230         const char *model_emf_uri,
1231         uint32_t *id)                   /* event id (output) */
1232 {
1233         ssize_t len;
1234         struct {
1235                 struct ustcomm_notify_hdr header;
1236                 struct ustcomm_notify_event_msg m;
1237         } msg;
1238         struct {
1239                 struct ustcomm_notify_hdr header;
1240                 struct ustcomm_notify_event_reply r;
1241         } reply;
1242         size_t signature_len, fields_len, model_emf_uri_len;
1243         struct ustctl_field *fields = NULL;
1244         size_t nr_write_fields = 0;
1245         int ret;
1246
1247         memset(&msg, 0, sizeof(msg));
1248         msg.header.notify_cmd = USTCTL_NOTIFY_CMD_EVENT;
1249         msg.m.session_objd = session_objd;
1250         msg.m.channel_objd = channel_objd;
1251         strncpy(msg.m.event_name, event_name, LTTNG_UST_SYM_NAME_LEN);
1252         msg.m.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1253         msg.m.loglevel = loglevel;
1254         signature_len = strlen(signature) + 1;
1255         msg.m.signature_len = signature_len;
1256
1257         /* Calculate fields len, serialize fields. */
1258         if (nr_fields > 0) {
1259                 ret = serialize_fields(session, &nr_write_fields, &fields,
1260                                 nr_fields, lttng_fields);
1261                 if (ret)
1262                         return ret;
1263         }
1264
1265         fields_len = sizeof(*fields) * nr_write_fields;
1266         msg.m.fields_len = fields_len;
1267         if (model_emf_uri) {
1268                 model_emf_uri_len = strlen(model_emf_uri) + 1;
1269         } else {
1270                 model_emf_uri_len = 0;
1271         }
1272         msg.m.model_emf_uri_len = model_emf_uri_len;
1273
1274         len = ustcomm_send_unix_sock(sock, &msg, sizeof(msg));
1275         if (len > 0 && len != sizeof(msg)) {
1276                 ret = -EIO;
1277                 goto error_fields;
1278         }
1279         if (len < 0) {
1280                 ret = len;
1281                 goto error_fields;
1282         }
1283
1284         /* send signature */
1285         len = ustcomm_send_unix_sock(sock, signature, signature_len);
1286         if (len > 0 && len != signature_len) {
1287                 ret = -EIO;
1288                 goto error_fields;
1289         }
1290         if (len < 0) {
1291                 ret = len;
1292                 goto error_fields;
1293         }
1294
1295         /* send fields */
1296         if (fields_len > 0) {
1297                 len = ustcomm_send_unix_sock(sock, fields, fields_len);
1298                 if (len > 0 && len != fields_len) {
1299                         ret = -EIO;
1300                         goto error_fields;
1301                 }
1302                 if (len < 0) {
1303                         ret = len;
1304                         goto error_fields;
1305                 }
1306         }
1307         free(fields);
1308
1309         if (model_emf_uri_len) {
1310                 /* send model_emf_uri */
1311                 len = ustcomm_send_unix_sock(sock, model_emf_uri,
1312                                 model_emf_uri_len);
1313                 if (len > 0 && len != model_emf_uri_len) {
1314                         return -EIO;
1315                 }
1316                 if (len < 0) {
1317                         return len;
1318                 }
1319         }
1320
1321         /* receive reply */
1322         len = ustcomm_recv_unix_sock(sock, &reply, sizeof(reply));
1323         switch (len) {
1324         case 0: /* orderly shutdown */
1325                 return -EPIPE;
1326         case sizeof(reply):
1327                 if (reply.header.notify_cmd != msg.header.notify_cmd) {
1328                         ERR("Unexpected result message command "
1329                                 "expected: %u vs received: %u\n",
1330                                 msg.header.notify_cmd, reply.header.notify_cmd);
1331                         return -EINVAL;
1332                 }
1333                 if (reply.r.ret_code > 0)
1334                         return -EINVAL;
1335                 if (reply.r.ret_code < 0)
1336                         return reply.r.ret_code;
1337                 *id = reply.r.event_id;
1338                 DBG("Sent register event notification for name \"%s\": ret_code %d, event_id %u\n",
1339                         event_name, reply.r.ret_code, reply.r.event_id);
1340                 return 0;
1341         default:
1342                 if (len < 0) {
1343                         /* Transport level error */
1344                         if (errno == EPIPE || errno == ECONNRESET)
1345                                 len = -errno;
1346                         return len;
1347                 } else {
1348                         ERR("incorrect message size: %zd\n", len);
1349                         return len;
1350                 }
1351         }
1352         /* Unreached. */
1353
1354         /* Error path only. */
1355 error_fields:
1356         free(fields);
1357         return ret;
1358 }
1359
1360 /*
1361  * Returns 0 on success, negative error value on error.
1362  * Returns -EPIPE or -ECONNRESET if other end has hung up.
1363  */
1364 int ustcomm_register_enum(int sock,
1365         int session_objd,               /* session descriptor */
1366         const char *enum_name,          /* enum name (input) */
1367         size_t nr_entries,              /* entries */
1368         const struct lttng_enum_entry *lttng_entries,
1369         uint64_t *id)
1370 {
1371         ssize_t len;
1372         struct {
1373                 struct ustcomm_notify_hdr header;
1374                 struct ustcomm_notify_enum_msg m;
1375         } msg;
1376         struct {
1377                 struct ustcomm_notify_hdr header;
1378                 struct ustcomm_notify_enum_reply r;
1379         } reply;
1380         size_t entries_len;
1381         struct ustctl_enum_entry *entries = NULL;
1382         int ret;
1383
1384         memset(&msg, 0, sizeof(msg));
1385         msg.header.notify_cmd = USTCTL_NOTIFY_CMD_ENUM;
1386         msg.m.session_objd = session_objd;
1387         strncpy(msg.m.enum_name, enum_name, LTTNG_UST_SYM_NAME_LEN);
1388         msg.m.enum_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1389
1390         /* Calculate entries len, serialize entries. */
1391         if (nr_entries > 0) {
1392                 ret = serialize_entries(&entries,
1393                                 nr_entries, lttng_entries);
1394                 if (ret)
1395                         return ret;
1396         }
1397
1398         entries_len = sizeof(*entries) * nr_entries;
1399         msg.m.entries_len = entries_len;
1400
1401         len = ustcomm_send_unix_sock(sock, &msg, sizeof(msg));
1402         if (len > 0 && len != sizeof(msg)) {
1403                 ret = -EIO;
1404                 goto error_entries;
1405         }
1406         if (len < 0) {
1407                 ret = len;
1408                 goto error_entries;
1409         }
1410
1411         /* send entries */
1412         if (entries_len > 0) {
1413                 len = ustcomm_send_unix_sock(sock, entries, entries_len);
1414                 if (len > 0 && len != entries_len) {
1415                         ret = -EIO;
1416                         goto error_entries;
1417                 }
1418                 if (len < 0) {
1419                         ret = len;
1420                         goto error_entries;
1421                 }
1422         }
1423         free(entries);
1424         entries = NULL;
1425
1426         /* receive reply */
1427         len = ustcomm_recv_unix_sock(sock, &reply, sizeof(reply));
1428         switch (len) {
1429         case 0: /* orderly shutdown */
1430                 return -EPIPE;
1431         case sizeof(reply):
1432                 if (reply.header.notify_cmd != msg.header.notify_cmd) {
1433                         ERR("Unexpected result message command "
1434                                 "expected: %u vs received: %u\n",
1435                                 msg.header.notify_cmd, reply.header.notify_cmd);
1436                         return -EINVAL;
1437                 }
1438                 if (reply.r.ret_code > 0)
1439                         return -EINVAL;
1440                 if (reply.r.ret_code < 0)
1441                         return reply.r.ret_code;
1442                 *id = reply.r.enum_id;
1443                 DBG("Sent register enum notification for name \"%s\": ret_code %d\n",
1444                         enum_name, reply.r.ret_code);
1445                 return 0;
1446         default:
1447                 if (len < 0) {
1448                         /* Transport level error */
1449                         if (errno == EPIPE || errno == ECONNRESET)
1450                                 len = -errno;
1451                         return len;
1452                 } else {
1453                         ERR("incorrect message size: %zd\n", len);
1454                         return len;
1455                 }
1456         }
1457         return ret;
1458
1459 error_entries:
1460         free(entries);
1461         return ret;
1462 }
1463
1464 /*
1465  * Returns 0 on success, negative error value on error.
1466  * Returns -EPIPE or -ECONNRESET if other end has hung up.
1467  */
1468 int ustcomm_register_channel(int sock,
1469         struct lttng_session *session,
1470         int session_objd,               /* session descriptor */
1471         int channel_objd,               /* channel descriptor */
1472         size_t nr_ctx_fields,
1473         const struct lttng_ctx_field *ctx_fields,
1474         uint32_t *chan_id,              /* channel id (output) */
1475         int *header_type)               /* header type (output) */
1476 {
1477         ssize_t len;
1478         struct {
1479                 struct ustcomm_notify_hdr header;
1480                 struct ustcomm_notify_channel_msg m;
1481         } msg;
1482         struct {
1483                 struct ustcomm_notify_hdr header;
1484                 struct ustcomm_notify_channel_reply r;
1485         } reply;
1486         size_t fields_len;
1487         struct ustctl_field *fields = NULL;
1488         int ret;
1489         size_t nr_write_fields = 0;
1490
1491         memset(&msg, 0, sizeof(msg));
1492         msg.header.notify_cmd = USTCTL_NOTIFY_CMD_CHANNEL;
1493         msg.m.session_objd = session_objd;
1494         msg.m.channel_objd = channel_objd;
1495
1496         /* Calculate fields len, serialize fields. */
1497         if (nr_ctx_fields > 0) {
1498                 ret = serialize_ctx_fields(session, &nr_write_fields, &fields,
1499                                 nr_ctx_fields, ctx_fields);
1500                 if (ret)
1501                         return ret;
1502         }
1503
1504         fields_len = sizeof(*fields) * nr_write_fields;
1505         msg.m.ctx_fields_len = fields_len;
1506         len = ustcomm_send_unix_sock(sock, &msg, sizeof(msg));
1507         if (len > 0 && len != sizeof(msg)) {
1508                 free(fields);
1509                 return -EIO;
1510         }
1511         if (len < 0) {
1512                 free(fields);
1513                 return len;
1514         }
1515
1516         /* send fields */
1517         if (fields_len > 0) {
1518                 len = ustcomm_send_unix_sock(sock, fields, fields_len);
1519                 free(fields);
1520                 if (len > 0 && len != fields_len) {
1521                         return -EIO;
1522                 }
1523                 if (len < 0) {
1524                         return len;
1525                 }
1526         } else {
1527                 free(fields);
1528         }
1529
1530         len = ustcomm_recv_unix_sock(sock, &reply, sizeof(reply));
1531         switch (len) {
1532         case 0: /* orderly shutdown */
1533                 return -EPIPE;
1534         case sizeof(reply):
1535                 if (reply.header.notify_cmd != msg.header.notify_cmd) {
1536                         ERR("Unexpected result message command "
1537                                 "expected: %u vs received: %u\n",
1538                                 msg.header.notify_cmd, reply.header.notify_cmd);
1539                         return -EINVAL;
1540                 }
1541                 if (reply.r.ret_code > 0)
1542                         return -EINVAL;
1543                 if (reply.r.ret_code < 0)
1544                         return reply.r.ret_code;
1545                 *chan_id = reply.r.chan_id;
1546                 switch (reply.r.header_type) {
1547                 case 1:
1548                 case 2:
1549                         *header_type = reply.r.header_type;
1550                         break;
1551                 default:
1552                         ERR("Unexpected channel header type %u\n",
1553                                 reply.r.header_type);
1554                         return -EINVAL;
1555                 }
1556                 DBG("Sent register channel notification: chan_id %d, header_type %d\n",
1557                         reply.r.chan_id, reply.r.header_type);
1558                 return 0;
1559         default:
1560                 if (len < 0) {
1561                         /* Transport level error */
1562                         if (errno == EPIPE || errno == ECONNRESET)
1563                                 len = -errno;
1564                         return len;
1565                 } else {
1566                         ERR("incorrect message size: %zd\n", len);
1567                         return len;
1568                 }
1569         }
1570 }
1571
1572 /*
1573  * Set socket reciving timeout.
1574  */
1575 int ustcomm_setsockopt_rcv_timeout(int sock, unsigned int msec)
1576 {
1577         int ret;
1578         struct timeval tv;
1579
1580         tv.tv_sec = msec / 1000;
1581         tv.tv_usec = (msec * 1000 % 1000000);
1582
1583         ret = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
1584         if (ret < 0) {
1585                 PERROR("setsockopt SO_RCVTIMEO");
1586                 ret = -errno;
1587         }
1588
1589         return ret;
1590 }
1591
1592 /*
1593  * Set socket sending timeout.
1594  */
1595 int ustcomm_setsockopt_snd_timeout(int sock, unsigned int msec)
1596 {
1597         int ret;
1598         struct timeval tv;
1599
1600         tv.tv_sec = msec / 1000;
1601         tv.tv_usec = (msec * 1000) % 1000000;
1602
1603         ret = setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
1604         if (ret < 0) {
1605                 PERROR("setsockopt SO_SNDTIMEO");
1606                 ret = -errno;
1607         }
1608
1609         return ret;
1610 }