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  * Returns the size of received data, or negative error value.
 442  *
 443  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 444  * actually received in nb_fd.
 445  * Returns -EPIPE on orderly shutdown.
 446  */
 447 ssize_t ustcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 448 {
 449         struct iovec iov[1];
 450         ssize_t ret = 0;
 451         struct cmsghdr *cmsg;
 452         size_t sizeof_fds = nb_fd * sizeof(int);
 453         char recv_fd[CMSG_SPACE(sizeof_fds)];
 454         struct msghdr msg;
 455         char dummy;
 456
 457         memset(&msg, 0, sizeof(msg));
 458
 459         /* Prepare to receive the structures */
 460         iov[0].iov_base = &dummy;
 461         iov[0].iov_len = 1;
 462         msg.msg_iov = iov;
 463         msg.msg_iovlen = 1;
 464         msg.msg_control = recv_fd;
 465         msg.msg_controllen = sizeof(recv_fd);
 466
 467         do {
 468                 ret = recvmsg(sock, &msg, 0);
 469         } while (ret < 0 && errno == EINTR);
 470         if (ret < 0) {
 471                 if (errno != EPIPE && errno != ECONNRESET) {
 472                         PERROR("recvmsg fds");
 473                 }
 474                 ret = -errno;
 475                 if (ret == -ECONNRESET)
 476                         ret = -EPIPE;
 477                 goto end;
 478         }
 479         if (ret == 0) {
 480                 /* orderly shutdown */
 481                 ret = -EPIPE;
 482                 goto end;
 483         }
 484         if (ret != 1) {
 485                 ERR("Error: Received %zd bytes, expected %d\n",
 486                                 ret, 1);
 487                 goto end;
 488         }
 489         if (msg.msg_flags & MSG_CTRUNC) {
 490                 ERR("Error: Control message truncated.\n");
 491                 ret = -1;
 492                 goto end;
 493         }
 494         cmsg = CMSG_FIRSTHDR(&msg);
 495         if (!cmsg) {
 496                 ERR("Error: Invalid control message header\n");
 497                 ret = -1;
 498                 goto end;
 499         }
 500         if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
 501                 ERR("Didn't received any fd\n");
 502                 ret = -1;
 503                 goto end;
 504         }
 505         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 506                 ERR("Error: Received %zu bytes of ancillary data, expected %zu\n",
 507                                 (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
 508                 ret = -1;
 509                 goto end;
 510         }
 511         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 512         ret = sizeof_fds;
 513 end:
 514         return ret;
 515 }
 516
 517 int ustcomm_send_app_msg(int sock, struct ustcomm_ust_msg *lum)
 518 {
 519         ssize_t len;
 520
 521         len = ustcomm_send_unix_sock(sock, lum, sizeof(*lum));
 522         switch (len) {
 523         case sizeof(*lum):
 524                 break;
 525         default:
 526                 if (len < 0) {
 527                         return len;
 528                 } else {
 529                         ERR("incorrect message size: %zd\n", len);
 530                         return -EINVAL;
 531                 }
 532         }
 533         return 0;
 534 }
 535
 536 int ustcomm_recv_app_reply(int sock, struct ustcomm_ust_reply *lur,
 537                           uint32_t expected_handle, uint32_t expected_cmd)
 538 {
 539         ssize_t len;
 540
 541         memset(lur, 0, sizeof(*lur));
 542         len = ustcomm_recv_unix_sock(sock, lur, sizeof(*lur));
 543         switch (len) {
 544         case 0: /* orderly shutdown */
 545                 return -EPIPE;
 546         case sizeof(*lur):
 547         {
 548                 int err = 0;
 549
 550                 if (lur->handle != expected_handle) {
 551                         ERR("Unexpected result message handle: "
 552                                 "expected: %u vs received: %u\n",
 553                                 expected_handle, lur->handle);
 554                         err = 1;
 555                 }
 556                 if (lur->cmd != expected_cmd) {
 557                         ERR("Unexpected result message command "
 558                                 "expected: %u vs received: %u\n",
 559                                 expected_cmd, lur->cmd);
 560                         err = 1;
 561                 }
 562                 if (err) {
 563                         return -EINVAL;
 564                 } else {
 565                         return lur->ret_code;
 566                 }
 567         }
 568         default:
 569                 if (len >= 0) {
 570                         ERR("incorrect message size: %zd\n", len);
 571                 }
 572                 return len;
 573         }
 574 }
 575
 576 int ustcomm_send_app_cmd(int sock,
 577                         struct ustcomm_ust_msg *lum,
 578                         struct ustcomm_ust_reply *lur)
 579 {
 580         int ret;
 581
 582         ret = ustcomm_send_app_msg(sock, lum);
 583         if (ret)
 584                 return ret;
 585         ret = ustcomm_recv_app_reply(sock, lur, lum->handle, lum->cmd);
 586         if (ret > 0)
 587                 return -EIO;
 588         return ret;
 589 }
 590
 591 /*
 592  * chan_data is allocated internally if this function returns the
 593  * expected var_len.
 594  */
 595 ssize_t ustcomm_recv_channel_from_sessiond(int sock,
 596                 void **_chan_data, uint64_t var_len,
 597                 int *_wakeup_fd)
 598 {
 599         void *chan_data;
 600         ssize_t len, nr_fd;
 601         int wakeup_fd, ret;
 602
 603         if (var_len > LTTNG_UST_CHANNEL_DATA_MAX_LEN) {
 604                 len = -EINVAL;
 605                 goto error_check;
 606         }
 607         /* Receive variable length data */
 608         chan_data = zmalloc(var_len);
 609         if (!chan_data) {
 610                 len = -ENOMEM;
 611                 goto error_alloc;
 612         }
 613         len = ustcomm_recv_unix_sock(sock, chan_data, var_len);
 614         if (len != var_len) {
 615                 goto error_recv;
 616         }
 617         /* recv wakeup fd */
 618         lttng_ust_lock_fd_tracker();
 619         nr_fd = ustcomm_recv_fds_unix_sock(sock, &wakeup_fd, 1);
 620         if (nr_fd <= 0) {
 621                 lttng_ust_unlock_fd_tracker();
 622                 if (nr_fd < 0) {
 623                         len = nr_fd;
 624                         goto error_recv;
 625                 } else {
 626                         len = -EIO;
 627                         goto error_recv;
 628                 }
 629         }
 630
 631         ret = lttng_ust_add_fd_to_tracker(wakeup_fd);
 632         if (ret < 0) {
 633                 lttng_ust_unlock_fd_tracker();
 634                 ret = close(wakeup_fd);
 635                 if (ret) {
 636                         PERROR("close on wakeup_fd");
 637                 }
 638                 len = -EIO;
 639                 goto error_recv;
 640         }
 641
 642         *_wakeup_fd = ret;
 643         lttng_ust_unlock_fd_tracker();
 644
 645         *_chan_data = chan_data;
 646         return len;
 647
 648 error_recv:
 649         free(chan_data);
 650 error_alloc:
 651 error_check:
 652         return len;
 653 }
 654
 655 int ustcomm_recv_stream_from_sessiond(int sock,
 656                 uint64_t *memory_map_size,
 657                 int *shm_fd, int *wakeup_fd)
 658 {
 659         ssize_t len;
 660         int ret;
 661         int fds[2];
 662
 663         /* recv shm fd and wakeup fd */
 664         lttng_ust_lock_fd_tracker();
 665         len = ustcomm_recv_fds_unix_sock(sock, fds, 2);
 666         if (len <= 0) {
 667                 lttng_ust_unlock_fd_tracker();
 668                 if (len < 0) {
 669                         ret = len;
 670                         goto error;
 671                 } else {
 672                         ret = -EIO;
 673                         goto error;
 674                 }
 675         }
 676
 677         ret = lttng_ust_add_fd_to_tracker(fds[0]);
 678         if (ret < 0) {
 679                 lttng_ust_unlock_fd_tracker();
 680                 ret = close(fds[0]);
 681                 if (ret) {
 682                         PERROR("close on received shm_fd");
 683                 }
 684                 ret = -EIO;
 685                 goto error;
 686         }
 687         *shm_fd = ret;
 688
 689         ret = lttng_ust_add_fd_to_tracker(fds[1]);
 690         if (ret < 0) {
 691                 lttng_ust_unlock_fd_tracker();
 692                 ret = close(*shm_fd);
 693                 if (ret) {
 694                         PERROR("close on shm_fd");
 695                 }
 696                 *shm_fd = -1;
 697                 ret = close(fds[1]);
 698                 if (ret) {
 699                         PERROR("close on received wakeup_fd");
 700                 }
 701                 ret = -EIO;
 702                 goto error;
 703         }
 704         *wakeup_fd = ret;
 705         lttng_ust_unlock_fd_tracker();
 706         return 0;
 707
 708 error:
 709         return ret;
 710 }
 711
 712 /*
 713  * Returns 0 on success, negative error value on error.
 714  */
 715 int ustcomm_send_reg_msg(int sock,
 716                 enum ustctl_socket_type type,
 717                 uint32_t bits_per_long,
 718                 uint32_t uint8_t_alignment,
 719                 uint32_t uint16_t_alignment,
 720                 uint32_t uint32_t_alignment,
 721                 uint32_t uint64_t_alignment,
 722                 uint32_t long_alignment)
 723 {
 724         ssize_t len;
 725         struct ustctl_reg_msg reg_msg;
 726
 727         reg_msg.magic = LTTNG_UST_COMM_MAGIC;
 728         reg_msg.major = LTTNG_UST_ABI_MAJOR_VERSION;
 729         reg_msg.minor = LTTNG_UST_ABI_MINOR_VERSION;
 730         reg_msg.pid = getpid();
 731         reg_msg.ppid = getppid();
 732         reg_msg.uid = getuid();
 733         reg_msg.gid = getgid();
 734         reg_msg.bits_per_long = bits_per_long;
 735         reg_msg.uint8_t_alignment = uint8_t_alignment;
 736         reg_msg.uint16_t_alignment = uint16_t_alignment;
 737         reg_msg.uint32_t_alignment = uint32_t_alignment;
 738         reg_msg.uint64_t_alignment = uint64_t_alignment;
 739         reg_msg.long_alignment = long_alignment;
 740         reg_msg.socket_type = type;
 741         lttng_ust_getprocname(reg_msg.name);
 742         memset(reg_msg.padding, 0, sizeof(reg_msg.padding));
 743
 744         len = ustcomm_send_unix_sock(sock, &reg_msg, sizeof(reg_msg));
 745         if (len > 0 && len != sizeof(reg_msg))
 746                 return -EIO;
 747         if (len < 0)
 748                 return len;
 749         return 0;
 750 }
 751
 752 static
 753 ssize_t count_one_type(const struct lttng_type *lt)
 754 {
 755         switch (lt->atype) {
 756         case atype_integer:
 757         case atype_float:
 758         case atype_string:
 759         case atype_enum:
 760         case atype_array:
 761         case atype_sequence:
 762                 return 1;
 763         case atype_struct:
 764                 //TODO: implement non-empty struct.
 765                 return 1;
 766         case atype_dynamic:
 767         {
 768                 const struct lttng_event_field *choices;
 769                 size_t nr_choices;
 770                 int ret;
 771
 772                 ret = lttng_ust_dynamic_type_choices(&nr_choices,
 773                         &choices);
 774                 if (ret)
 775                         return ret;
 776                 /*
 777                  * One field for enum, one field for variant, and
 778                  * one field per choice.
 779                  */
 780                 return count_fields_recursive(nr_choices, choices) + 2;
 781         }
 782         default:
 783                 return -EINVAL;
 784         }
 785         return 0;
 786 }
 787
 788 static
 789 ssize_t count_fields_recursive(size_t nr_fields,
 790                 const struct lttng_event_field *lttng_fields)
 791 {
 792         int i;
 793         ssize_t ret, count = 0;
 794
 795         for (i = 0; i < nr_fields; i++) {
 796                 const struct lttng_event_field *lf;
 797
 798                 lf = &lttng_fields[i];
 799                 /* skip 'nowrite' fields */
 800                 if (lf->nowrite)
 801                         continue;
 802                 ret = count_one_type(&lf->type);
 803                 if (ret < 0)
 804                         return ret;     /* error */
 805                 count += ret;
 806         }
 807         return count;
 808 }
 809
 810 static
 811 ssize_t count_ctx_fields_recursive(size_t nr_fields,
 812                 const struct lttng_ctx_field *lttng_fields)
 813 {
 814         int i;
 815         ssize_t ret, count = 0;
 816
 817         for (i = 0; i < nr_fields; i++) {
 818                 const struct lttng_event_field *lf;
 819
 820                 lf = &lttng_fields[i].event_field;
 821                 /* skip 'nowrite' fields */
 822                 if (lf->nowrite)
 823                         continue;
 824                 ret = count_one_type(&lf->type);
 825                 if (ret < 0)
 826                         return ret;     /* error */
 827                 count += ret;
 828         }
 829         return count;
 830 }
 831
 832 static
 833 int serialize_string_encoding(int32_t *ue,
 834                 enum lttng_string_encodings le)
 835 {
 836         switch (le) {
 837         case lttng_encode_none:
 838                 *ue = ustctl_encode_none;
 839                 break;
 840         case lttng_encode_UTF8:
 841                 *ue = ustctl_encode_UTF8;
 842                 break;
 843         case lttng_encode_ASCII:
 844                 *ue = ustctl_encode_ASCII;
 845                 break;
 846         default:
 847                 return -EINVAL;
 848         }
 849         return 0;
 850 }
 851
 852 static
 853 int serialize_integer_type(struct ustctl_integer_type *uit,
 854                 const struct lttng_integer_type *lit)
 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(&uit->encoding, lit->encoding))
 861                 return -EINVAL;
 862         uit->alignment = lit->alignment;
 863         return 0;
 864 }
 865
 866 static
 867 int serialize_basic_type(struct lttng_session *session,
 868                 enum ustctl_abstract_types *uatype,
 869                 enum lttng_abstract_types atype,
 870                 union _ustctl_basic_type *ubt,
 871                 const union _lttng_basic_type *lbt)
 872 {
 873         switch (atype) {
 874         case atype_integer:
 875         {
 876                 if (serialize_integer_type(&ubt->integer, &lbt->integer))
 877                         return -EINVAL;
 878                 *uatype = ustctl_atype_integer;
 879                 break;
 880         }
 881         case atype_string:
 882         {
 883                 if (serialize_string_encoding(&ubt->string.encoding,
 884                                 lbt->string.encoding))
 885                         return -EINVAL;
 886                 *uatype = ustctl_atype_string;
 887                 break;
 888         }
 889         case atype_float:
 890         {
 891                 struct ustctl_float_type *uft;
 892                 const struct lttng_float_type *lft;
 893
 894                 uft = &ubt->_float;
 895                 lft = &lbt->_float;
 896                 uft->exp_dig = lft->exp_dig;
 897                 uft->mant_dig = lft->mant_dig;
 898                 uft->alignment = lft->alignment;
 899                 uft->reverse_byte_order = lft->reverse_byte_order;
 900                 *uatype = ustctl_atype_float;
 901                 break;
 902         }
 903         case atype_enum:
 904         {
 905                 strncpy(ubt->enumeration.name, lbt->enumeration.desc->name,
 906                                 LTTNG_UST_SYM_NAME_LEN);
 907                 ubt->enumeration.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 908                 if (serialize_integer_type(&ubt->enumeration.container_type,
 909                                 &lbt->enumeration.container_type))
 910                         return -EINVAL;
 911                 if (session) {
 912                         const struct lttng_enum *_enum;
 913
 914                         _enum = lttng_ust_enum_get(session,
 915                                         lbt->enumeration.desc->name);
 916                         if (!_enum)
 917                                 return -EINVAL;
 918                         ubt->enumeration.id = _enum->id;
 919                 } else {
 920                         ubt->enumeration.id = -1ULL;
 921                 }
 922                 *uatype = ustctl_atype_enum;
 923                 break;
 924         }
 925         case atype_array:
 926         case atype_sequence:
 927         default:
 928                 return -EINVAL;
 929         }
 930         return 0;
 931 }
 932
 933 static
 934 int serialize_dynamic_type(struct lttng_session *session,
 935                 struct ustctl_field *fields, size_t *iter_output,
 936                 const struct lttng_event_field *lf)
 937 {
 938         const struct lttng_event_field *choices;
 939         char tag_field_name[LTTNG_UST_SYM_NAME_LEN];
 940         const struct lttng_type *tag_type;
 941         const struct lttng_event_field *tag_field_generic;
 942         struct lttng_event_field tag_field = {
 943                 .name = tag_field_name,
 944                 .nowrite = 0,
 945         };
 946         struct ustctl_field *uf;
 947         size_t nr_choices, i;
 948         int ret;
 949
 950         tag_field_generic = lttng_ust_dynamic_type_tag_field();
 951         tag_type = &tag_field_generic->type;
 952
 953         /* Serialize enum field. */
 954         strncpy(tag_field_name, lf->name, LTTNG_UST_SYM_NAME_LEN);
 955         tag_field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 956         strncat(tag_field_name,
 957                 "_tag",
 958                 LTTNG_UST_SYM_NAME_LEN - strlen(tag_field_name) - 1);
 959         tag_field.type = *tag_type;
 960         ret = serialize_one_field(session, fields, iter_output,
 961                 &tag_field);
 962         if (ret)
 963                 return ret;
 964
 965         /* Serialize variant field. */
 966         uf = &fields[*iter_output];
 967         ret = lttng_ust_dynamic_type_choices(&nr_choices, &choices);
 968         if (ret)
 969                 return ret;
 970
 971         strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
 972         uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 973         uf->type.atype = ustctl_atype_variant;
 974         uf->type.u.variant.nr_choices = nr_choices;
 975         strncpy(uf->type.u.variant.tag_name,
 976                 tag_field_name,
 977                 LTTNG_UST_SYM_NAME_LEN);
 978         uf->type.u.variant.tag_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 979         (*iter_output)++;
 980
 981         /* Serialize choice fields after variant. */
 982         for (i = 0; i < nr_choices; i++) {
 983                 ret = serialize_one_field(session, fields,
 984                         iter_output, &choices[i]);
 985                 if (ret)
 986                         return ret;
 987         }
 988         return 0;
 989 }
 990
 991 static
 992 int serialize_one_field(struct lttng_session *session,
 993                 struct ustctl_field *fields, size_t *iter_output,
 994                 const struct lttng_event_field *lf)
 995 {
 996         const struct lttng_type *lt = &lf->type;
 997         int ret;
 998
 999         /* skip 'nowrite' fields */
1000         if (lf->nowrite)
1001                 return 0;
1002
1003         switch (lt->atype) {
1004         case atype_integer:
1005         case atype_float:
1006         case atype_string:
1007         case atype_enum:
1008         {
1009                 struct ustctl_field *uf = &fields[*iter_output];
1010                 struct ustctl_type *ut = &uf->type;
1011
1012                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1013                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1014                 ret = serialize_basic_type(session, &ut->atype, lt->atype,
1015                         &ut->u.basic, &lt->u.basic);
1016                 if (ret)
1017                         return ret;
1018                 (*iter_output)++;
1019                 break;
1020         }
1021         case atype_array:
1022         {
1023                 struct ustctl_field *uf = &fields[*iter_output];
1024                 struct ustctl_type *ut = &uf->type;
1025                 struct ustctl_basic_type *ubt;
1026                 const struct lttng_basic_type *lbt;
1027
1028                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1029                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1030                 uf->type.atype = ustctl_atype_array;
1031                 ubt = &ut->u.array.elem_type;
1032                 lbt = &lt->u.array.elem_type;
1033                 ut->u.array.length = lt->u.array.length;
1034                 ret = serialize_basic_type(session, &ubt->atype, lbt->atype,
1035                         &ubt->u.basic, &lbt->u.basic);
1036                 if (ret)
1037                         return -EINVAL;
1038                 ut->atype = ustctl_atype_array;
1039                 (*iter_output)++;
1040                 break;
1041         }
1042         case atype_sequence:
1043         {
1044                 struct ustctl_field *uf = &fields[*iter_output];
1045                 struct ustctl_type *ut = &uf->type;
1046                 struct ustctl_basic_type *ubt;
1047                 const struct lttng_basic_type *lbt;
1048                 int ret;
1049
1050                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1051                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1052                 uf->type.atype = ustctl_atype_sequence;
1053                 ubt = &ut->u.sequence.length_type;
1054                 lbt = &lt->u.sequence.length_type;
1055                 ret = serialize_basic_type(session, &ubt->atype, lbt->atype,
1056                         &ubt->u.basic, &lbt->u.basic);
1057                 if (ret)
1058                         return -EINVAL;
1059                 ubt = &ut->u.sequence.elem_type;
1060                 lbt = &lt->u.sequence.elem_type;
1061                 ret = serialize_basic_type(session, &ubt->atype, lbt->atype,
1062                         &ubt->u.basic, &lbt->u.basic);
1063                 if (ret)
1064                         return -EINVAL;
1065                 ut->atype = ustctl_atype_sequence;
1066                 (*iter_output)++;
1067                 break;
1068         }
1069         case atype_dynamic:
1070         {
1071                 ret = serialize_dynamic_type(session, fields, iter_output, lf);
1072                 if (ret)
1073                         return -EINVAL;
1074                 break;
1075         }
1076         case atype_struct:
1077         {
1078                 struct ustctl_field *uf = &fields[*iter_output];
1079
1080                 /*
1081                  * TODO: add support for non-empty struct.
1082                  */
1083                 if (lf->type.u._struct.nr_fields != 0) {
1084                         return -EINVAL;
1085                 }
1086                 strncpy(uf->name, lf->name, LTTNG_UST_SYM_NAME_LEN);
1087                 uf->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1088                 uf->type.atype = ustctl_atype_struct;
1089                 uf->type.u._struct.nr_fields = 0;
1090                 (*iter_output)++;
1091                 break;
1092         }
1093         default:
1094                 return -EINVAL;
1095         }
1096         return 0;
1097 }
1098
1099 static
1100 int serialize_fields(struct lttng_session *session,
1101                 size_t *_nr_write_fields,
1102                 struct ustctl_field **ustctl_fields,
1103                 size_t nr_fields,
1104                 const struct lttng_event_field *lttng_fields)
1105 {
1106         struct ustctl_field *fields;
1107         int ret;
1108         size_t i, iter_output = 0;
1109         ssize_t nr_write_fields;
1110
1111         nr_write_fields = count_fields_recursive(nr_fields, lttng_fields);
1112         if (nr_write_fields < 0) {
1113                 return (int) nr_write_fields;
1114         }
1115
1116         fields = zmalloc(nr_write_fields * sizeof(*fields));
1117         if (!fields)
1118                 return -ENOMEM;
1119
1120         for (i = 0; i < nr_fields; i++) {
1121                 ret = serialize_one_field(session, fields, &iter_output,
1122                                 &lttng_fields[i]);
1123                 if (ret)
1124                         goto error_type;
1125         }
1126
1127         *_nr_write_fields = nr_write_fields;
1128         *ustctl_fields = fields;
1129         return 0;
1130
1131 error_type:
1132         free(fields);
1133         return ret;
1134 }
1135
1136 static
1137 int serialize_entries(struct ustctl_enum_entry **_entries,
1138                 size_t nr_entries,
1139                 const struct lttng_enum_entry *lttng_entries)
1140 {
1141         struct ustctl_enum_entry *entries;
1142         int i;
1143
1144         /* Serialize the entries */
1145         entries = zmalloc(nr_entries * sizeof(*entries));
1146         if (!entries)
1147                 return -ENOMEM;
1148         for (i = 0; i < nr_entries; i++) {
1149                 struct ustctl_enum_entry *uentry;
1150                 const struct lttng_enum_entry *lentry;
1151
1152                 uentry = &entries[i];
1153                 lentry = &lttng_entries[i];
1154
1155                 uentry->start.value = lentry->start.value;
1156                 uentry->start.signedness = lentry->start.signedness;
1157                 uentry->end.value = lentry->end.value;
1158                 uentry->end.signedness = lentry->end.signedness;
1159                 strncpy(uentry->string, lentry->string, LTTNG_UST_SYM_NAME_LEN);
1160                 uentry->string[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1161
1162                 if (lentry->u.extra.options & LTTNG_ENUM_ENTRY_OPTION_IS_AUTO) {
1163                         uentry->u.extra.options |=
1164                                 USTCTL_UST_ENUM_ENTRY_OPTION_IS_AUTO;
1165                 }
1166         }
1167         *_entries = entries;
1168         return 0;
1169 }
1170
1171 static
1172 int serialize_ctx_fields(struct lttng_session *session,
1173                 size_t *_nr_write_fields,
1174                 struct ustctl_field **ustctl_fields,
1175                 size_t nr_fields,
1176                 const struct lttng_ctx_field *lttng_fields)
1177 {
1178         struct ustctl_field *fields;
1179         int ret;
1180         size_t i, iter_output = 0;
1181         ssize_t nr_write_fields;
1182
1183         nr_write_fields = count_ctx_fields_recursive(nr_fields,
1184                         lttng_fields);
1185         if (nr_write_fields < 0) {
1186                 return (int) nr_write_fields;
1187         }
1188
1189         fields = zmalloc(nr_write_fields * sizeof(*fields));
1190         if (!fields)
1191                 return -ENOMEM;
1192
1193         for (i = 0; i < nr_fields; i++) {
1194                 ret = serialize_one_field(session, fields, &iter_output,
1195                                 &lttng_fields[i].event_field);
1196                 if (ret)
1197                         goto error_type;
1198         }
1199
1200         *_nr_write_fields = nr_write_fields;
1201         *ustctl_fields = fields;
1202         return 0;
1203
1204 error_type:
1205         free(fields);
1206         return ret;
1207 }
1208
1209 /*
1210  * Returns 0 on success, negative error value on error.
1211  */
1212 int ustcomm_register_event(int sock,
1213         struct lttng_session *session,
1214         int session_objd,               /* session descriptor */
1215         int channel_objd,               /* channel descriptor */
1216         const char *event_name,         /* event name (input) */
1217         int loglevel,
1218         const char *signature,          /* event signature (input) */
1219         size_t nr_fields,               /* fields */
1220         const struct lttng_event_field *lttng_fields,
1221         const char *model_emf_uri,
1222         uint32_t *id)                   /* event id (output) */
1223 {
1224         ssize_t len;
1225         struct {
1226                 struct ustcomm_notify_hdr header;
1227                 struct ustcomm_notify_event_msg m;
1228         } msg;
1229         struct {
1230                 struct ustcomm_notify_hdr header;
1231                 struct ustcomm_notify_event_reply r;
1232         } reply;
1233         size_t signature_len, fields_len, model_emf_uri_len;
1234         struct ustctl_field *fields = NULL;
1235         size_t nr_write_fields = 0;
1236         int ret;
1237
1238         memset(&msg, 0, sizeof(msg));
1239         msg.header.notify_cmd = USTCTL_NOTIFY_CMD_EVENT;
1240         msg.m.session_objd = session_objd;
1241         msg.m.channel_objd = channel_objd;
1242         strncpy(msg.m.event_name, event_name, LTTNG_UST_SYM_NAME_LEN);
1243         msg.m.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1244         msg.m.loglevel = loglevel;
1245         signature_len = strlen(signature) + 1;
1246         msg.m.signature_len = signature_len;
1247
1248         /* Calculate fields len, serialize fields. */
1249         if (nr_fields > 0) {
1250                 ret = serialize_fields(session, &nr_write_fields, &fields,
1251                                 nr_fields, lttng_fields);
1252                 if (ret)
1253                         return ret;
1254         }
1255
1256         fields_len = sizeof(*fields) * nr_write_fields;
1257         msg.m.fields_len = fields_len;
1258         if (model_emf_uri) {
1259                 model_emf_uri_len = strlen(model_emf_uri) + 1;
1260         } else {
1261                 model_emf_uri_len = 0;
1262         }
1263         msg.m.model_emf_uri_len = model_emf_uri_len;
1264
1265         len = ustcomm_send_unix_sock(sock, &msg, sizeof(msg));
1266         if (len > 0 && len != sizeof(msg)) {
1267                 ret = -EIO;
1268                 goto error_fields;
1269         }
1270         if (len < 0) {
1271                 ret = len;
1272                 goto error_fields;
1273         }
1274
1275         /* send signature */
1276         len = ustcomm_send_unix_sock(sock, signature, signature_len);
1277         if (len > 0 && len != signature_len) {
1278                 ret = -EIO;
1279                 goto error_fields;
1280         }
1281         if (len < 0) {
1282                 ret = len;
1283                 goto error_fields;
1284         }
1285
1286         /* send fields */
1287         if (fields_len > 0) {
1288                 len = ustcomm_send_unix_sock(sock, fields, fields_len);
1289                 if (len > 0 && len != fields_len) {
1290                         ret = -EIO;
1291                         goto error_fields;
1292                 }
1293                 if (len < 0) {
1294                         ret = len;
1295                         goto error_fields;
1296                 }
1297         }
1298         free(fields);
1299
1300         if (model_emf_uri_len) {
1301                 /* send model_emf_uri */
1302                 len = ustcomm_send_unix_sock(sock, model_emf_uri,
1303                                 model_emf_uri_len);
1304                 if (len > 0 && len != model_emf_uri_len) {
1305                         return -EIO;
1306                 }
1307                 if (len < 0) {
1308                         return len;
1309                 }
1310         }
1311
1312         /* receive reply */
1313         len = ustcomm_recv_unix_sock(sock, &reply, sizeof(reply));
1314         switch (len) {
1315         case 0: /* orderly shutdown */
1316                 return -EPIPE;
1317         case sizeof(reply):
1318                 if (reply.header.notify_cmd != msg.header.notify_cmd) {
1319                         ERR("Unexpected result message command "
1320                                 "expected: %u vs received: %u\n",
1321                                 msg.header.notify_cmd, reply.header.notify_cmd);
1322                         return -EINVAL;
1323                 }
1324                 if (reply.r.ret_code > 0)
1325                         return -EINVAL;
1326                 if (reply.r.ret_code < 0)
1327                         return reply.r.ret_code;
1328                 *id = reply.r.event_id;
1329                 DBG("Sent register event notification for name \"%s\": ret_code %d, event_id %u\n",
1330                         event_name, reply.r.ret_code, reply.r.event_id);
1331                 return 0;
1332         default:
1333                 if (len < 0) {
1334                         /* Transport level error */
1335                         if (errno == EPIPE || errno == ECONNRESET)
1336                                 len = -errno;
1337                         return len;
1338                 } else {
1339                         ERR("incorrect message size: %zd\n", len);
1340                         return len;
1341                 }
1342         }
1343         /* Unreached. */
1344
1345         /* Error path only. */
1346 error_fields:
1347         free(fields);
1348         return ret;
1349 }
1350
1351 /*
1352  * Returns 0 on success, negative error value on error.
1353  * Returns -EPIPE or -ECONNRESET if other end has hung up.
1354  */
1355 int ustcomm_register_enum(int sock,
1356         int session_objd,               /* session descriptor */
1357         const char *enum_name,          /* enum name (input) */
1358         size_t nr_entries,              /* entries */
1359         const struct lttng_enum_entry *lttng_entries,
1360         uint64_t *id)
1361 {
1362         ssize_t len;
1363         struct {
1364                 struct ustcomm_notify_hdr header;
1365                 struct ustcomm_notify_enum_msg m;
1366         } msg;
1367         struct {
1368                 struct ustcomm_notify_hdr header;
1369                 struct ustcomm_notify_enum_reply r;
1370         } reply;
1371         size_t entries_len;
1372         struct ustctl_enum_entry *entries = NULL;
1373         int ret;
1374
1375         memset(&msg, 0, sizeof(msg));
1376         msg.header.notify_cmd = USTCTL_NOTIFY_CMD_ENUM;
1377         msg.m.session_objd = session_objd;
1378         strncpy(msg.m.enum_name, enum_name, LTTNG_UST_SYM_NAME_LEN);
1379         msg.m.enum_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
1380
1381         /* Calculate entries len, serialize entries. */
1382         if (nr_entries > 0) {
1383                 ret = serialize_entries(&entries,
1384                                 nr_entries, lttng_entries);
1385                 if (ret)
1386                         return ret;
1387         }
1388
1389         entries_len = sizeof(*entries) * nr_entries;
1390         msg.m.entries_len = entries_len;
1391
1392         len = ustcomm_send_unix_sock(sock, &msg, sizeof(msg));
1393         if (len > 0 && len != sizeof(msg)) {
1394                 ret = -EIO;
1395                 goto error_entries;
1396         }
1397         if (len < 0) {
1398                 ret = len;
1399                 goto error_entries;
1400         }
1401
1402         /* send entries */
1403         if (entries_len > 0) {
1404                 len = ustcomm_send_unix_sock(sock, entries, entries_len);
1405                 if (len > 0 && len != entries_len) {
1406                         ret = -EIO;
1407                         goto error_entries;
1408                 }
1409                 if (len < 0) {
1410                         ret = len;
1411                         goto error_entries;
1412                 }
1413         }
1414         free(entries);
1415         entries = NULL;
1416
1417         /* receive reply */
1418         len = ustcomm_recv_unix_sock(sock, &reply, sizeof(reply));
1419         switch (len) {
1420         case 0: /* orderly shutdown */
1421                 return -EPIPE;
1422         case sizeof(reply):
1423                 if (reply.header.notify_cmd != msg.header.notify_cmd) {
1424                         ERR("Unexpected result message command "
1425                                 "expected: %u vs received: %u\n",
1426                                 msg.header.notify_cmd, reply.header.notify_cmd);
1427                         return -EINVAL;
1428                 }
1429                 if (reply.r.ret_code > 0)
1430                         return -EINVAL;
1431                 if (reply.r.ret_code < 0)
1432                         return reply.r.ret_code;
1433                 *id = reply.r.enum_id;
1434                 DBG("Sent register enum notification for name \"%s\": ret_code %d\n",
1435                         enum_name, reply.r.ret_code);
1436                 return 0;
1437         default:
1438                 if (len < 0) {
1439                         /* Transport level error */
1440                         if (errno == EPIPE || errno == ECONNRESET)
1441                                 len = -errno;
1442                         return len;
1443                 } else {
1444                         ERR("incorrect message size: %zd\n", len);
1445                         return len;
1446                 }
1447         }
1448         return ret;
1449
1450 error_entries:
1451         free(entries);
1452         return ret;
1453 }
1454
1455 /*
1456  * Returns 0 on success, negative error value on error.
1457  * Returns -EPIPE or -ECONNRESET if other end has hung up.
1458  */
1459 int ustcomm_register_channel(int sock,
1460         struct lttng_session *session,
1461         int session_objd,               /* session descriptor */
1462         int channel_objd,               /* channel descriptor */
1463         size_t nr_ctx_fields,
1464         const struct lttng_ctx_field *ctx_fields,
1465         uint32_t *chan_id,              /* channel id (output) */
1466         int *header_type)               /* header type (output) */
1467 {
1468         ssize_t len;
1469         struct {
1470                 struct ustcomm_notify_hdr header;
1471                 struct ustcomm_notify_channel_msg m;
1472         } msg;
1473         struct {
1474                 struct ustcomm_notify_hdr header;
1475                 struct ustcomm_notify_channel_reply r;
1476         } reply;
1477         size_t fields_len;
1478         struct ustctl_field *fields = NULL;
1479         int ret;
1480         size_t nr_write_fields = 0;
1481
1482         memset(&msg, 0, sizeof(msg));
1483         msg.header.notify_cmd = USTCTL_NOTIFY_CMD_CHANNEL;
1484         msg.m.session_objd = session_objd;
1485         msg.m.channel_objd = channel_objd;
1486
1487         /* Calculate fields len, serialize fields. */
1488         if (nr_ctx_fields > 0) {
1489                 ret = serialize_ctx_fields(session, &nr_write_fields, &fields,
1490                                 nr_ctx_fields, ctx_fields);
1491                 if (ret)
1492                         return ret;
1493         }
1494
1495         fields_len = sizeof(*fields) * nr_write_fields;
1496         msg.m.ctx_fields_len = fields_len;
1497         len = ustcomm_send_unix_sock(sock, &msg, sizeof(msg));
1498         if (len > 0 && len != sizeof(msg)) {
1499                 free(fields);
1500                 return -EIO;
1501         }
1502         if (len < 0) {
1503                 free(fields);
1504                 return len;
1505         }
1506
1507         /* send fields */
1508         if (fields_len > 0) {
1509                 len = ustcomm_send_unix_sock(sock, fields, fields_len);
1510                 free(fields);
1511                 if (len > 0 && len != fields_len) {
1512                         return -EIO;
1513                 }
1514                 if (len < 0) {
1515                         return len;
1516                 }
1517         } else {
1518                 free(fields);
1519         }
1520
1521         len = ustcomm_recv_unix_sock(sock, &reply, sizeof(reply));
1522         switch (len) {
1523         case 0: /* orderly shutdown */
1524                 return -EPIPE;
1525         case sizeof(reply):
1526                 if (reply.header.notify_cmd != msg.header.notify_cmd) {
1527                         ERR("Unexpected result message command "
1528                                 "expected: %u vs received: %u\n",
1529                                 msg.header.notify_cmd, reply.header.notify_cmd);
1530                         return -EINVAL;
1531                 }
1532                 if (reply.r.ret_code > 0)
1533                         return -EINVAL;
1534                 if (reply.r.ret_code < 0)
1535                         return reply.r.ret_code;
1536                 *chan_id = reply.r.chan_id;
1537                 switch (reply.r.header_type) {
1538                 case 1:
1539                 case 2:
1540                         *header_type = reply.r.header_type;
1541                         break;
1542                 default:
1543                         ERR("Unexpected channel header type %u\n",
1544                                 reply.r.header_type);
1545                         return -EINVAL;
1546                 }
1547                 DBG("Sent register channel notification: chan_id %d, header_type %d\n",
1548                         reply.r.chan_id, reply.r.header_type);
1549                 return 0;
1550         default:
1551                 if (len < 0) {
1552                         /* Transport level error */
1553                         if (errno == EPIPE || errno == ECONNRESET)
1554                                 len = -errno;
1555                         return len;
1556                 } else {
1557                         ERR("incorrect message size: %zd\n", len);
1558                         return len;
1559                 }
1560         }
1561 }
1562
1563 /*
1564  * Set socket reciving timeout.
1565  */
1566 int ustcomm_setsockopt_rcv_timeout(int sock, unsigned int msec)
1567 {
1568         int ret;
1569         struct timeval tv;
1570
1571         tv.tv_sec = msec / 1000;
1572         tv.tv_usec = (msec * 1000 % 1000000);
1573
1574         ret = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
1575         if (ret < 0) {
1576                 PERROR("setsockopt SO_RCVTIMEO");
1577                 ret = -errno;
1578         }
1579
1580         return ret;
1581 }
1582
1583 /*
1584  * Set socket sending timeout.
1585  */
1586 int ustcomm_setsockopt_snd_timeout(int sock, unsigned int msec)
1587 {
1588         int ret;
1589         struct timeval tv;
1590
1591         tv.tv_sec = msec / 1000;
1592         tv.tv_usec = (msec * 1000) % 1000000;
1593
1594         ret = setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
1595         if (ret < 0) {
1596                 PERROR("setsockopt SO_SNDTIMEO");
1597                 ret = -errno;
1598         }
1599
1600         return ret;
1601 }