src/common/unix.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <assert.h>
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/stat.h>
  26 #include <sys/types.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29
  30 #include <common/common.h>
  31 #include <common/sessiond-comm/sessiond-comm.h>
  32
  33 #include "unix.h"
  34
  35 /*
  36  * Connect to unix socket using the path name.
  37  */
  38 LTTNG_HIDDEN
  39 int lttcomm_connect_unix_sock(const char *pathname)
  40 {
  41         struct sockaddr_un s_un;
  42         int fd, ret, closeret;
  43
  44         if (strlen(pathname) >= sizeof(s_un.sun_path)) {
  45                 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
  46                                 pathname, strlen(pathname) + 1,
  47                                 sizeof(s_un.sun_path));
  48                 ret = -ENAMETOOLONG;
  49                 goto error;
  50         }
  51
  52         fd = socket(PF_UNIX, SOCK_STREAM, 0);
  53         if (fd < 0) {
  54                 PERROR("socket");
  55                 ret = fd;
  56                 goto error;
  57         }
  58
  59         memset(&s_un, 0, sizeof(s_un));
  60         s_un.sun_family = AF_UNIX;
  61         strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
  62         s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
  63
  64         ret = connect(fd, (struct sockaddr *) &s_un, sizeof(s_un));
  65         if (ret < 0) {
  66                 /*
  67                  * Don't print message on connect error, because connect is used in
  68                  * normal execution to detect if sessiond is alive.
  69                  */
  70                 goto error_connect;
  71         }
  72
  73         return fd;
  74
  75 error_connect:
  76         closeret = close(fd);
  77         if (closeret) {
  78                 PERROR("close");
  79         }
  80 error:
  81         return ret;
  82 }
  83
  84 /*
  85  * Do an accept(2) on the sock and return the new file descriptor. The socket
  86  * MUST be bind(2) before.
  87  */
  88 LTTNG_HIDDEN
  89 int lttcomm_accept_unix_sock(int sock)
  90 {
  91         int new_fd;
  92         struct sockaddr_un s_un;
  93         socklen_t len = sizeof(s_un);
  94
  95         /* Blocking call */
  96         new_fd = accept(sock, (struct sockaddr *) &s_un, &len);
  97         if (new_fd < 0) {
  98                 PERROR("accept");
  99         }
 100
 101         return new_fd;
 102 }
 103
 104 LTTNG_HIDDEN
 105 int lttcomm_create_anon_unix_socketpair(int *fds)
 106 {
 107         if (socketpair(PF_UNIX, SOCK_STREAM, 0, fds) < 0) {
 108                 PERROR("socketpair");
 109                 return -1;
 110         }
 111         return 0;
 112 }
 113
 114 /*
 115  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
 116  * and return the fd.
 117  */
 118 LTTNG_HIDDEN
 119 int lttcomm_create_unix_sock(const char *pathname)
 120 {
 121         struct sockaddr_un s_un;
 122         int fd = -1;
 123         int ret = -1;
 124
 125         if (strlen(pathname) >= sizeof(s_un.sun_path)) {
 126                 ERR("unix socket address (\"%s\") is longer than the platform's limit (%zu > %zu).",
 127                                 pathname, strlen(pathname) + 1,
 128                                 sizeof(s_un.sun_path));
 129                 ret = -ENAMETOOLONG;
 130                 goto error;
 131         }
 132
 133         /* Create server socket */
 134         if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
 135                 PERROR("socket");
 136                 goto error;
 137         }
 138
 139         memset(&s_un, 0, sizeof(s_un));
 140         s_un.sun_family = AF_UNIX;
 141         strncpy(s_un.sun_path, pathname, sizeof(s_un.sun_path));
 142         s_un.sun_path[sizeof(s_un.sun_path) - 1] = '\0';
 143
 144         /* Unlink the old file if present */
 145         (void) unlink(pathname);
 146         ret = bind(fd, (struct sockaddr *) &s_un, sizeof(s_un));
 147         if (ret < 0) {
 148                 PERROR("bind");
 149                 goto error;
 150         }
 151
 152         return fd;
 153
 154 error:
 155         if (fd >= 0) {
 156                 if (close(fd) < 0) {
 157                         PERROR("close create unix sock");
 158                 }
 159         }
 160         return ret;
 161 }
 162
 163 /*
 164  * Make the socket listen using LTTNG_SESSIOND_COMM_MAX_LISTEN.
 165  */
 166 LTTNG_HIDDEN
 167 int lttcomm_listen_unix_sock(int sock)
 168 {
 169         int ret;
 170
 171         ret = listen(sock, LTTNG_SESSIOND_COMM_MAX_LISTEN);
 172         if (ret < 0) {
 173                 PERROR("listen");
 174         }
 175
 176         return ret;
 177 }
 178
 179 /*
 180  * Receive data of size len in put that data into the buf param. Using recvmsg
 181  * API.
 182  *
 183  * Return the size of received data.
 184  */
 185 LTTNG_HIDDEN
 186 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 187 {
 188         struct msghdr msg;
 189         struct iovec iov[1];
 190         ssize_t ret = -1;
 191         size_t len_last;
 192
 193         memset(&msg, 0, sizeof(msg));
 194
 195         iov[0].iov_base = buf;
 196         iov[0].iov_len = len;
 197         msg.msg_iov = iov;
 198         msg.msg_iovlen = 1;
 199
 200         do {
 201                 len_last = iov[0].iov_len;
 202                 ret = lttng_recvmsg_nosigpipe(sock, &msg);
 203                 if (ret > 0) {
 204                         iov[0].iov_base += ret;
 205                         iov[0].iov_len -= ret;
 206                         assert(ret <= len_last);
 207                 }
 208         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 209         if (ret < 0) {
 210                 PERROR("recvmsg");
 211         } else if (ret > 0) {
 212                 ret = len;
 213         }
 214         /* Else ret = 0 meaning an orderly shutdown. */
 215
 216         return ret;
 217 }
 218
 219 /*
 220  * Receive data of size len in put that data into the buf param. Using recvmsg
 221  * API. Only use with sockets set in non-blocking mode.
 222  *
 223  * NOTE: EPIPE errors are NOT reported. This call expects the socket to be in a
 224  * poll set. The poll loop will handle the EPIPE original cause.
 225  *
 226  * Return the size of received data.
 227  */
 228 LTTNG_HIDDEN
 229 ssize_t lttcomm_recv_unix_sock_non_block(int sock, void *buf, size_t len)
 230 {
 231         struct msghdr msg;
 232         struct iovec iov[1];
 233         ssize_t ret;
 234
 235         memset(&msg, 0, sizeof(msg));
 236
 237         iov[0].iov_base = buf;
 238         iov[0].iov_len = len;
 239         msg.msg_iov = iov;
 240         msg.msg_iovlen = 1;
 241
 242 retry:
 243         ret = lttng_recvmsg_nosigpipe(sock, &msg);
 244         if (ret < 0) {
 245                 if (errno == EINTR) {
 246                         goto retry;
 247                 } else {
 248                         /*
 249                          * We consider EPIPE and EAGAIN/EWOULDBLOCK as expected.
 250                          */
 251                         if (errno == EAGAIN || errno == EWOULDBLOCK ||
 252                                         errno == EPIPE) {
 253                                 /*
 254                                  * Nothing was recv.
 255                                  */
 256                                 ret = 0;
 257                                 goto end;
 258                         }
 259
 260                         /* Unexpected error */
 261                         PERROR("recvmsg");
 262                         ret = -1;
 263                         goto end;
 264                 }
 265         }
 266
 267 end:
 268         return ret;
 269 }
 270
 271 /*
 272  * Send buf data of size len. Using sendmsg API.
 273  *
 274  * Return the size of sent data.
 275  */
 276 LTTNG_HIDDEN
 277 ssize_t lttcomm_send_unix_sock(int sock, const void *buf, size_t len)
 278 {
 279         struct msghdr msg;
 280         struct iovec iov[1];
 281         ssize_t ret;
 282
 283         memset(&msg, 0, sizeof(msg));
 284
 285         iov[0].iov_base = (void *) buf;
 286         iov[0].iov_len = len;
 287         msg.msg_iov = iov;
 288         msg.msg_iovlen = 1;
 289
 290         while (iov[0].iov_len) {
 291                 ret = sendmsg(sock, &msg, 0);
 292                 if (ret < 0) {
 293                         if (errno == EINTR) {
 294                                 continue;
 295                         } else {
 296                                 /*
 297                                  * Only warn about EPIPE when quiet mode is
 298                                  * deactivated.
 299                                  * We consider EPIPE as expected.
 300                                  */
 301                                 if (errno != EPIPE || !lttng_opt_quiet) {
 302                                         PERROR("sendmsg");
 303                                 }
 304                                 goto end;
 305                         }
 306                 }
 307                 iov[0].iov_len -= ret;
 308                 iov[0].iov_base += ret;
 309         }
 310         ret = len;
 311 end:
 312         return ret;
 313 }
 314
 315 /*
 316  * Send buf data of size len. Using sendmsg API.
 317  * Only use with non-blocking sockets. The difference with the blocking version
 318  * of the function is that this one does not retry to send on partial sends,
 319  * except if the interruption was caused by a signal (EINTR).
 320  *
 321  * NOTE: EPIPE errors are NOT reported. This call expects the socket to be in a
 322  * poll set. The poll loop will handle the EPIPE original cause.
 323  *
 324  * Return the size of sent data.
 325  */
 326 LTTNG_HIDDEN
 327 ssize_t lttcomm_send_unix_sock_non_block(int sock, const void *buf, size_t len)
 328 {
 329         struct msghdr msg;
 330         struct iovec iov[1];
 331         ssize_t ret;
 332
 333         memset(&msg, 0, sizeof(msg));
 334
 335         iov[0].iov_base = (void *) buf;
 336         iov[0].iov_len = len;
 337         msg.msg_iov = iov;
 338         msg.msg_iovlen = 1;
 339
 340 retry:
 341         ret = sendmsg(sock, &msg, 0);
 342         if (ret < 0) {
 343                 if (errno == EINTR) {
 344                         goto retry;
 345                 } else {
 346                         /*
 347                          * We consider EPIPE and EAGAIN/EWOULDBLOCK as expected.
 348                          */
 349                         if (errno == EAGAIN || errno == EWOULDBLOCK ||
 350                                         errno == EPIPE) {
 351                                 /*
 352                                  * This can happen in non blocking mode.
 353                                  * Nothing was sent.
 354                                  */
 355                                 ret = 0;
 356                                 goto end;
 357                         }
 358
 359                         /* Unexpected error */
 360                         PERROR("sendmsg");
 361                         ret = -1;
 362                         goto end;
 363                 }
 364         }
 365 end:
 366         return ret;
 367 }
 368
 369 /*
 370  * Shutdown cleanly a unix socket.
 371  */
 372 LTTNG_HIDDEN
 373 int lttcomm_close_unix_sock(int sock)
 374 {
 375         int ret, closeret;
 376
 377         /* Shutdown receptions and transmissions */
 378         ret = shutdown(sock, SHUT_RDWR);
 379         if (ret < 0) {
 380                 PERROR("shutdown");
 381         }
 382
 383         closeret = close(sock);
 384         if (closeret) {
 385                 PERROR("close");
 386         }
 387
 388         return ret;
 389 }
 390
 391 /*
 392  * Send a message accompanied by fd(s) over a unix socket.
 393  *
 394  * Returns the size of data sent, or negative error value.
 395  */
 396 LTTNG_HIDDEN
 397 ssize_t lttcomm_send_fds_unix_sock(int sock, const int *fds, size_t nb_fd)
 398 {
 399         struct msghdr msg;
 400         struct cmsghdr *cmptr;
 401         struct iovec iov[1];
 402         ssize_t ret = -1;
 403         unsigned int sizeof_fds = nb_fd * sizeof(int);
 404         char tmp[CMSG_SPACE(sizeof_fds)];
 405         char dummy = 0;
 406
 407         memset(&msg, 0, sizeof(msg));
 408         memset(tmp, 0, sizeof(tmp));
 409
 410         if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 411                 return -EINVAL;
 412
 413         msg.msg_control = (caddr_t)tmp;
 414         msg.msg_controllen = CMSG_LEN(sizeof_fds);
 415
 416         cmptr = CMSG_FIRSTHDR(&msg);
 417         if (!cmptr) {
 418                 return -1;
 419         }
 420
 421         cmptr->cmsg_level = SOL_SOCKET;
 422         cmptr->cmsg_type = SCM_RIGHTS;
 423         cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
 424         memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
 425         /* Sum of the length of all control messages in the buffer: */
 426         msg.msg_controllen = cmptr->cmsg_len;
 427
 428         iov[0].iov_base = &dummy;
 429         iov[0].iov_len = 1;
 430         msg.msg_iov = iov;
 431         msg.msg_iovlen = 1;
 432
 433         do {
 434                 ret = sendmsg(sock, &msg, 0);
 435         } while (ret < 0 && errno == EINTR);
 436         if (ret < 0) {
 437                 /*
 438                  * Only warn about EPIPE when quiet mode is deactivated.
 439                  * We consider EPIPE as expected.
 440                  */
 441                 if (errno != EPIPE || !lttng_opt_quiet) {
 442                         PERROR("sendmsg");
 443                 }
 444         }
 445         return ret;
 446 }
 447
 448 /*
 449  * Recv a message accompanied by fd(s) from a unix socket.
 450  *
 451  * Returns the size of received data, or negative error value.
 452  *
 453  * Expect at most "nb_fd" file descriptors. Returns the number of fd
 454  * actually received in nb_fd.
 455  */
 456 LTTNG_HIDDEN
 457 ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 458 {
 459         struct iovec iov[1];
 460         ssize_t ret = 0;
 461         struct cmsghdr *cmsg;
 462         size_t sizeof_fds = nb_fd * sizeof(int);
 463
 464 #ifdef __linux__
 465 /* Account for the struct ucred cmsg in the buffer size */
 466 #define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds) + CMSG_SPACE(sizeof(struct ucred))
 467 #else
 468 #define LTTNG_SOCK_RECV_FDS_BUF_SIZE CMSG_SPACE(sizeof_fds)
 469 #endif /* __linux__ */
 470
 471         char recv_buf[LTTNG_SOCK_RECV_FDS_BUF_SIZE];
 472         struct msghdr msg;
 473         char dummy;
 474
 475         memset(&msg, 0, sizeof(msg));
 476
 477         /* Prepare to receive the structures */
 478         iov[0].iov_base = &dummy;
 479         iov[0].iov_len = 1;
 480         msg.msg_iov = iov;
 481         msg.msg_iovlen = 1;
 482
 483         cmsg = (struct cmsghdr *) recv_buf;
 484         cmsg->cmsg_len = CMSG_LEN(sizeof_fds);
 485         cmsg->cmsg_level = SOL_SOCKET;
 486         cmsg->cmsg_type = SCM_RIGHTS;
 487
 488         msg.msg_control = cmsg;
 489         msg.msg_controllen = CMSG_LEN(sizeof(recv_buf));
 490         msg.msg_flags = 0;
 491
 492         do {
 493                 ret = recvmsg(sock, &msg, 0);
 494         } while (ret < 0 && errno == EINTR);
 495         if (ret < 0) {
 496                 PERROR("recvmsg fds");
 497                 goto end;
 498         }
 499
 500         if (ret != 1) {
 501                 fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 502                                 ret, 1);
 503                 goto end;
 504         }
 505
 506         if (msg.msg_flags & MSG_CTRUNC) {
 507                 fprintf(stderr, "Error: Control message truncated.\n");
 508                 ret = -1;
 509                 goto end;
 510         }
 511
 512         /*
 513          * If the socket was configured with SO_PASSCRED, the kernel will add a
 514          * control message (cmsg) to the ancillary data of the unix socket. We
 515          * need to expect a cmsg of the SCM_CREDENTIALS as the first control
 516          * message.
 517          */
 518         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 519                 if (cmsg->cmsg_level != SOL_SOCKET) {
 520                         fprintf(stderr, "Error: The socket needs to be of type SOL_SOCKET\n");
 521                         ret = -1;
 522                         goto end;
 523                 }
 524                 if (cmsg->cmsg_type == SCM_RIGHTS) {
 525                         /*
 526                          * We found the controle message for file descriptors,
 527                          * now copy the fds to the fds ptr and return success.
 528                          */
 529                         if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
 530                                 fprintf(stderr, "Error: Received %zu bytes of"
 531                                         "ancillary data for FDs, expected %zu\n",
 532                                         (size_t) cmsg->cmsg_len,
 533                                         (size_t) CMSG_LEN(sizeof_fds));
 534                                 ret = -1;
 535                                 goto end;
 536                         }
 537                         memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
 538                         ret = sizeof_fds;
 539                         goto end;
 540                 }
 541 #ifdef __linux__
 542                 if (cmsg->cmsg_type == SCM_CREDENTIALS) {
 543                         /*
 544                          * Expect credentials to be sent when expecting fds even
 545                          * if no credential were include in the send(). The
 546                          * kernel adds them...
 547                          */
 548                         ret = -1;
 549                 }
 550 #endif /* __linux__ */
 551         }
 552 end:
 553         return ret;
 554 }
 555
 556 /*
 557  * Send a message with credentials over a unix socket.
 558  *
 559  * Returns the size of data sent, or negative error value.
 560  */
 561 LTTNG_HIDDEN
 562 ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
 563 {
 564         struct msghdr msg;
 565         struct iovec iov[1];
 566         ssize_t ret = -1;
 567 #ifdef __linux__
 568         struct cmsghdr *cmptr;
 569         size_t sizeof_cred = sizeof(lttng_sock_cred);
 570         char anc_buf[CMSG_SPACE(sizeof_cred)];
 571         lttng_sock_cred *creds;
 572
 573         memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
 574 #endif /* __linux__ */
 575
 576         memset(&msg, 0, sizeof(msg));
 577
 578         iov[0].iov_base = buf;
 579         iov[0].iov_len = len;
 580         msg.msg_iov = iov;
 581         msg.msg_iovlen = 1;
 582
 583 #ifdef __linux__
 584         msg.msg_control = (caddr_t) anc_buf;
 585         msg.msg_controllen = CMSG_LEN(sizeof_cred);
 586
 587         cmptr = CMSG_FIRSTHDR(&msg);
 588         if (!cmptr) {
 589                 return -1;
 590         }
 591         cmptr->cmsg_level = SOL_SOCKET;
 592         cmptr->cmsg_type = LTTNG_SOCK_CREDS;
 593         cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
 594
 595         creds = (lttng_sock_cred*) CMSG_DATA(cmptr);
 596
 597         LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
 598         LTTNG_SOCK_SET_GID_CRED(creds, getegid());
 599         LTTNG_SOCK_SET_PID_CRED(creds, getpid());
 600 #endif /* __linux__ */
 601
 602         do {
 603                 ret = sendmsg(sock, &msg, 0);
 604         } while (ret < 0 && errno == EINTR);
 605         if (ret < 0) {
 606                 /*
 607                  * Only warn about EPIPE when quiet mode is deactivated.
 608                  * We consider EPIPE as expected.
 609                  */
 610                 if (errno != EPIPE || !lttng_opt_quiet) {
 611                         PERROR("sendmsg");
 612                 }
 613         }
 614         return ret;
 615 }
 616
 617 /*
 618  * Recv a message accompanied with credentials from a unix socket.
 619  *
 620  * Returns the size of received data, or negative error value.
 621  */
 622 LTTNG_HIDDEN
 623 ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 624                 lttng_sock_cred *creds)
 625 {
 626         struct msghdr msg;
 627         struct iovec iov[1];
 628         ssize_t ret;
 629         size_t len_last;
 630 #ifdef __linux__
 631         struct cmsghdr *cmptr;
 632         size_t sizeof_cred = sizeof(lttng_sock_cred);
 633         char anc_buf[CMSG_SPACE(sizeof_cred)];
 634 #endif  /* __linux__ */
 635
 636         memset(&msg, 0, sizeof(msg));
 637
 638         /* Not allowed */
 639         if (creds == NULL) {
 640                 ret = -1;
 641                 goto end;
 642         }
 643
 644         /* Prepare to receive the structures */
 645         iov[0].iov_base = buf;
 646         iov[0].iov_len = len;
 647         msg.msg_iov = iov;
 648         msg.msg_iovlen = 1;
 649
 650 #ifdef __linux__
 651         msg.msg_control = anc_buf;
 652         msg.msg_controllen = sizeof(anc_buf);
 653 #endif /* __linux__ */
 654
 655         do {
 656                 len_last = iov[0].iov_len;
 657                 ret = recvmsg(sock, &msg, 0);
 658                 if (ret > 0) {
 659                         iov[0].iov_base += ret;
 660                         iov[0].iov_len -= ret;
 661                         assert(ret <= len_last);
 662                 }
 663         } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
 664         if (ret < 0) {
 665                 PERROR("recvmsg fds");
 666                 goto end;
 667         } else if (ret > 0) {
 668                 ret = len;
 669         }
 670         /* Else ret = 0 meaning an orderly shutdown. */
 671
 672 #ifdef __linux__
 673         if (msg.msg_flags & MSG_CTRUNC) {
 674                 fprintf(stderr, "Error: Control message truncated.\n");
 675                 ret = -1;
 676                 goto end;
 677         }
 678
 679         cmptr = CMSG_FIRSTHDR(&msg);
 680         if (cmptr == NULL) {
 681                 fprintf(stderr, "Error: Invalid control message header\n");
 682                 ret = -1;
 683                 goto end;
 684         }
 685
 686         if (cmptr->cmsg_level != SOL_SOCKET ||
 687                         cmptr->cmsg_type != LTTNG_SOCK_CREDS) {
 688                 fprintf(stderr, "Didn't received any credentials\n");
 689                 ret = -1;
 690                 goto end;
 691         }
 692
 693         if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
 694                 fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
 695                                 (size_t) cmptr->cmsg_len, (size_t) CMSG_LEN(sizeof_cred));
 696                 ret = -1;
 697                 goto end;
 698         }
 699
 700         memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
 701 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 702         {
 703                 int peer_ret;
 704
 705                 peer_ret = getpeereid(sock, &creds->uid, &creds->gid);
 706                 if (peer_ret != 0) {
 707                         return peer_ret;
 708                 }
 709         }
 710 #else
 711 #error "Please implement credential support for your OS."
 712 #endif  /* __linux__ */
 713
 714 end:
 715         return ret;
 716 }
 717
 718 /*
 719  * Set socket option to use credentials passing.
 720  */
 721 #ifdef __linux__
 722 LTTNG_HIDDEN
 723 int lttcomm_setsockopt_creds_unix_sock(int sock)
 724 {
 725         int ret, on = 1;
 726
 727         /* Set socket for credentials retrieval */
 728         ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
 729         if (ret < 0) {
 730                 PERROR("setsockopt creds unix sock");
 731         }
 732         return ret;
 733 }
 734 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 735 LTTNG_HIDDEN
 736 int lttcomm_setsockopt_creds_unix_sock(int sock)
 737 {
 738         return 0;
 739 }
 740 #else
 741 #error "Please implement credential support for your OS."
 742 #endif /* __linux__ */