source3/rpc_server/mdssd.c

   1 /*
   2  *  Unix SMB/CIFS implementation.
   3  *
   4  *  mds service daemon
   5  *
   6  *  Copyright (c) 2014      Ralph Boehme <rb@sernet.de>
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 3 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "includes.h"
  23 #include "serverid.h"
  24 #include "messages.h"
  25 #include "ntdomain.h"
  26
  27 #include "lib/id_cache.h"
  28
  29 #include "../lib/tsocket/tsocket.h"
  30 #include "lib/server_prefork.h"
  31 #include "lib/server_prefork_util.h"
  32 #include "librpc/rpc/dcerpc_ep.h"
  33
  34 #include "rpc_server/rpc_server.h"
  35 #include "rpc_server/rpc_ep_register.h"
  36 #include "rpc_server/rpc_sock_helper.h"
  37 #include "rpc_server/rpc_modules.h"
  38
  39 #include "librpc/gen_ndr/srv_mdssvc.h"
  40 #include "rpc_server/mdssvc/srv_mdssvc_nt.h"
  41
  42 #undef DBGC_CLASS
  43 #define DBGC_CLASS DBGC_RPC_SRV
  44
  45 #define DAEMON_NAME "mdssd"
  46 #define MDSSD_MAX_SOCKETS 64
  47
  48 static struct server_id parent_id;
  49 static struct prefork_pool *mdssd_pool = NULL;
  50 static int mdssd_child_id = 0;
  51
  52 static struct pf_daemon_config default_pf_mdssd_cfg = {
  53         .prefork_status = PFH_INIT,
  54         .min_children = 5,
  55         .max_children = 25,
  56         .spawn_rate = 5,
  57         .max_allowed_clients = 1000,
  58         .child_min_life = 60 /* 1 minute minimum life time */
  59 };
  60 static struct pf_daemon_config pf_mdssd_cfg = { 0 };
  61
  62 void start_mdssd(struct tevent_context *ev_ctx,
  63                  struct messaging_context *msg_ctx);
  64
  65 static void mdssd_smb_conf_updated(struct messaging_context *msg,
  66                                    void *private_data,
  67                                    uint32_t msg_type,
  68                                    struct server_id server_id,
  69                                    DATA_BLOB *data)
  70 {
  71         struct tevent_context *ev_ctx;
  72
  73         DEBUG(10, ("Got message saying smb.conf was updated. Reloading.\n"));
  74         ev_ctx = talloc_get_type_abort(private_data, struct tevent_context);
  75
  76         change_to_root_user();
  77         lp_load_global(get_dyn_CONFIGFILE());
  78
  79         reopen_logs();
  80         if (mdssd_child_id == 0) {
  81                 pfh_daemon_config(DAEMON_NAME,
  82                                   &pf_mdssd_cfg,
  83                                   &default_pf_mdssd_cfg);
  84                 pfh_manage_pool(ev_ctx, msg, &pf_mdssd_cfg, mdssd_pool);
  85         }
  86 }
  87
  88 static void mdssd_sig_term_handler(struct tevent_context *ev,
  89                                    struct tevent_signal *se,
  90                                    int signum,
  91                                    int count,
  92                                    void *siginfo,
  93                                    void *private_data)
  94 {
  95         shutdown_rpc_module("mdssvc");
  96
  97         DEBUG(0, ("termination signal\n"));
  98         exit(0);
  99 }
 100
 101 static void mdssd_setup_sig_term_handler(struct tevent_context *ev_ctx)
 102 {
 103         struct tevent_signal *se;
 104
 105         se = tevent_add_signal(ev_ctx,
 106                                ev_ctx,
 107                                SIGTERM, 0,
 108                                mdssd_sig_term_handler,
 109                                NULL);
 110         if (!se) {
 111                 DEBUG(0, ("failed to setup SIGTERM handler\n"));
 112                 exit(1);
 113         }
 114 }
 115
 116 static void mdssd_sig_hup_handler(struct tevent_context *ev,
 117                                   struct tevent_signal *se,
 118                                   int signum,
 119                                   int count,
 120                                   void *siginfo,
 121                                   void *pvt)
 122 {
 123
 124         change_to_root_user();
 125         lp_load_global(get_dyn_CONFIGFILE());
 126
 127         reopen_logs();
 128         pfh_daemon_config(DAEMON_NAME,
 129                           &pf_mdssd_cfg,
 130                           &default_pf_mdssd_cfg);
 131
 132         /* relay to all children */
 133         prefork_send_signal_to_all(mdssd_pool, SIGHUP);
 134 }
 135
 136 static void mdssd_setup_sig_hup_handler(struct tevent_context *ev_ctx)
 137 {
 138         struct tevent_signal *se;
 139
 140         se = tevent_add_signal(ev_ctx,
 141                                ev_ctx,
 142                                SIGHUP, 0,
 143                                mdssd_sig_hup_handler,
 144                                NULL);
 145         if (!se) {
 146                 DEBUG(0, ("failed to setup SIGHUP handler\n"));
 147                 exit(1);
 148         }
 149 }
 150
 151 /**********************************************************
 152  * Children
 153  **********************************************************/
 154
 155 static void mdssd_chld_sig_hup_handler(struct tevent_context *ev,
 156                                        struct tevent_signal *se,
 157                                        int signum,
 158                                        int count,
 159                                        void *siginfo,
 160                                        void *pvt)
 161 {
 162         change_to_root_user();
 163         reopen_logs();
 164 }
 165
 166 static bool mdssd_setup_chld_hup_handler(struct tevent_context *ev_ctx)
 167 {
 168         struct tevent_signal *se;
 169
 170         se = tevent_add_signal(ev_ctx,
 171                                ev_ctx,
 172                                SIGHUP, 0,
 173                                mdssd_chld_sig_hup_handler,
 174                                NULL);
 175         if (!se) {
 176                 DEBUG(1, ("failed to setup SIGHUP handler"));
 177                 return false;
 178         }
 179
 180         return true;
 181 }
 182
 183 static void parent_ping(struct messaging_context *msg_ctx,
 184                         void *private_data,
 185                         uint32_t msg_type,
 186                         struct server_id server_id,
 187                         DATA_BLOB *data)
 188 {
 189         /*
 190          * The fact we received this message is enough to let make the
 191          * event loop if it was idle. mdssd_children_main will cycle
 192          * through mdssd_next_client at least once. That function will
 193          * take whatever action is necessary
 194          */
 195         DEBUG(10, ("Got message that the parent changed status.\n"));
 196         return;
 197 }
 198
 199 static bool mdssd_child_init(struct tevent_context *ev_ctx,
 200                              int child_id,
 201                              struct pf_worker_data *pf)
 202 {
 203         NTSTATUS status;
 204         struct messaging_context *msg_ctx = server_messaging_context();
 205         bool ok;
 206
 207         status = reinit_after_fork(msg_ctx, ev_ctx,
 208                                    true, "mdssd-child");
 209         if (!NT_STATUS_IS_OK(status)) {
 210                 DEBUG(0,("reinit_after_fork() failed\n"));
 211                 smb_panic("reinit_after_fork() failed");
 212         }
 213
 214         mdssd_child_id = child_id;
 215         reopen_logs();
 216
 217         ok = mdssd_setup_chld_hup_handler(ev_ctx);
 218         if (!ok) {
 219                 return false;
 220         }
 221
 222         if (!serverid_register(messaging_server_id(msg_ctx),
 223                                FLAG_MSG_GENERAL)) {
 224                 return false;
 225         }
 226
 227         messaging_register(msg_ctx, ev_ctx,
 228                            MSG_SMB_CONF_UPDATED, mdssd_smb_conf_updated);
 229         messaging_register(msg_ctx, ev_ctx,
 230                            MSG_PREFORK_PARENT_EVENT, parent_ping);
 231
 232         ok = init_rpc_module("mdssvc", NULL);
 233         if (!ok) {
 234                 DBG_ERR("Failed to de-intialize RPC\n");
 235                 return false;
 236         }
 237
 238         return true;
 239 }
 240
 241 struct mdssd_children_data {
 242         struct tevent_context *ev_ctx;
 243         struct messaging_context *msg_ctx;
 244         struct pf_worker_data *pf;
 245         int listen_fd_size;
 246         int *listen_fds;
 247 };
 248
 249 static void mdssd_next_client(void *pvt);
 250
 251 static int mdssd_children_main(struct tevent_context *ev_ctx,
 252                                struct messaging_context *msg_ctx,
 253                                struct pf_worker_data *pf,
 254                                int child_id,
 255                                int listen_fd_size,
 256                                int *listen_fds,
 257                                void *private_data)
 258 {
 259         struct mdssd_children_data *data;
 260         bool ok;
 261         int ret = 0;
 262
 263         ok = mdssd_child_init(ev_ctx, child_id, pf);
 264         if (!ok) {
 265                 return 1;
 266         }
 267
 268         data = talloc(ev_ctx, struct mdssd_children_data);
 269         if (!data) {
 270                 return 1;
 271         }
 272         data->pf = pf;
 273         data->ev_ctx = ev_ctx;
 274         data->msg_ctx = msg_ctx;
 275         data->listen_fd_size = listen_fd_size;
 276         data->listen_fds = listen_fds;
 277
 278         /* loop until it is time to exit */
 279         while (pf->status != PF_WORKER_EXITING) {
 280                 /* try to see if it is time to schedule the next client */
 281                 mdssd_next_client(data);
 282
 283                 ret = tevent_loop_once(ev_ctx);
 284                 if (ret != 0) {
 285                         DEBUG(0, ("tevent_loop_once() exited with %d: %s\n",
 286                                   ret, strerror(errno)));
 287                         pf->status = PF_WORKER_EXITING;
 288                 }
 289         }
 290
 291         return ret;
 292 }
 293
 294 static void mdssd_client_terminated(void *pvt)
 295 {
 296         struct mdssd_children_data *data;
 297
 298         data = talloc_get_type_abort(pvt, struct mdssd_children_data);
 299
 300         pfh_client_terminated(data->pf);
 301
 302         mdssd_next_client(pvt);
 303 }
 304
 305 struct mdssd_new_client {
 306         struct mdssd_children_data *data;
 307 };
 308
 309 static void mdssd_handle_client(struct tevent_req *req);
 310
 311 static void mdssd_next_client(void *pvt)
 312 {
 313         struct tevent_req *req;
 314         struct mdssd_children_data *data;
 315         struct mdssd_new_client *next;
 316
 317         data = talloc_get_type_abort(pvt, struct mdssd_children_data);
 318
 319         if (!pfh_child_allowed_to_accept(data->pf)) {
 320                 /* nothing to do for now we are already listening
 321                  * or we are not allowed to listen further */
 322                 return;
 323         }
 324
 325         next = talloc_zero(data, struct mdssd_new_client);
 326         if (!next) {
 327                 DEBUG(1, ("Out of memory!?\n"));
 328                 return;
 329         }
 330         next->data = data;
 331
 332         req = prefork_listen_send(next,
 333                                   data->ev_ctx,
 334                                   data->pf,
 335                                   data->listen_fd_size,
 336                                   data->listen_fds);
 337         if (!req) {
 338                 DEBUG(1, ("Failed to make listening request!?\n"));
 339                 talloc_free(next);
 340                 return;
 341         }
 342         tevent_req_set_callback(req, mdssd_handle_client, next);
 343 }
 344
 345 static void mdssd_handle_client(struct tevent_req *req)
 346 {
 347         struct mdssd_children_data *data;
 348         struct mdssd_new_client *client;
 349         const DATA_BLOB ping = data_blob_null;
 350         int rc;
 351         int sd;
 352         TALLOC_CTX *tmp_ctx;
 353         struct tsocket_address *srv_addr;
 354         struct tsocket_address *cli_addr;
 355
 356         client = tevent_req_callback_data(req, struct mdssd_new_client);
 357         data = client->data;
 358
 359         tmp_ctx = talloc_stackframe();
 360         if (tmp_ctx == NULL) {
 361                 DEBUG(1, ("Failed to allocate stackframe!\n"));
 362                 return;
 363         }
 364
 365         rc = prefork_listen_recv(req,
 366                                  tmp_ctx,
 367                                  &sd,
 368                                  &srv_addr,
 369                                  &cli_addr);
 370
 371         /* this will free the request too */
 372         talloc_free(client);
 373
 374         if (rc != 0) {
 375                 DEBUG(6, ("No client connection was available after all!\n"));
 376                 goto done;
 377         }
 378
 379         /* Warn parent that our status changed */
 380         messaging_send(data->msg_ctx, parent_id,
 381                         MSG_PREFORK_CHILD_EVENT, &ping);
 382
 383         DEBUG(2, ("mdssd preforked child %d got client connection!\n",
 384                   (int)(data->pf->pid)));
 385
 386         if (tsocket_address_is_inet(srv_addr, "ip")) {
 387                 DEBUG(3, ("Got a tcpip client connection from %s on inteface %s\n",
 388                            tsocket_address_string(cli_addr, tmp_ctx),
 389                            tsocket_address_string(srv_addr, tmp_ctx)));
 390
 391                 dcerpc_ncacn_accept(data->ev_ctx,
 392                                     data->msg_ctx,
 393                                     NCACN_IP_TCP,
 394                                     "IP",
 395                                     cli_addr,
 396                                     srv_addr,
 397                                     sd,
 398                                     NULL);
 399         } else if (tsocket_address_is_unix(srv_addr)) {
 400                 const char *p;
 401                 const char *b;
 402
 403                 p = tsocket_address_unix_path(srv_addr, tmp_ctx);
 404                 if (p == NULL) {
 405                         talloc_free(tmp_ctx);
 406                         return;
 407                 }
 408
 409                 b = strrchr(p, '/');
 410                 if (b != NULL) {
 411                         b++;
 412                 } else {
 413                         b = p;
 414                 }
 415
 416                 if (strstr(p, "/np/")) {
 417                         named_pipe_accept_function(data->ev_ctx,
 418                                                    data->msg_ctx,
 419                                                    b,
 420                                                    sd,
 421                                                    mdssd_client_terminated,
 422                                                    data);
 423                 } else {
 424                         dcerpc_ncacn_accept(data->ev_ctx,
 425                                             data->msg_ctx,
 426                                             NCALRPC,
 427                                             b,
 428                                             cli_addr,
 429                                             srv_addr,
 430                                             sd,
 431                                             NULL);
 432                 }
 433         } else {
 434                 DEBUG(0, ("ERROR: Unsupported socket!\n"));
 435         }
 436
 437 done:
 438         talloc_free(tmp_ctx);
 439 }
 440
 441 /*
 442  * MAIN
 443  */
 444
 445 static void child_ping(struct messaging_context *msg_ctx,
 446                         void *private_data,
 447                         uint32_t msg_type,
 448                         struct server_id server_id,
 449                         DATA_BLOB *data)
 450 {
 451         struct tevent_context *ev_ctx;
 452
 453         ev_ctx = talloc_get_type_abort(private_data, struct tevent_context);
 454
 455         DEBUG(10, ("Got message that a child changed status.\n"));
 456         pfh_manage_pool(ev_ctx, msg_ctx, &pf_mdssd_cfg, mdssd_pool);
 457 }
 458
 459 static bool mdssd_schedule_check(struct tevent_context *ev_ctx,
 460                                  struct messaging_context *msg_ctx,
 461                                  struct timeval current_time);
 462
 463 static void mdssd_check_children(struct tevent_context *ev_ctx,
 464                                     struct tevent_timer *te,
 465                                     struct timeval current_time,
 466                                     void *pvt);
 467
 468 static void mdssd_sigchld_handler(struct tevent_context *ev_ctx,
 469                                   struct prefork_pool *pfp,
 470                                   void *pvt)
 471 {
 472         struct messaging_context *msg_ctx;
 473
 474         msg_ctx = talloc_get_type_abort(pvt, struct messaging_context);
 475
 476         /* run pool management so we can fork/retire or increase
 477          * the allowed connections per child based on load */
 478         pfh_manage_pool(ev_ctx, msg_ctx, &pf_mdssd_cfg, mdssd_pool);
 479 }
 480
 481 static bool mdssd_setup_children_monitor(struct tevent_context *ev_ctx,
 482                                          struct messaging_context *msg_ctx)
 483 {
 484         bool ok;
 485
 486         /* add our oun sigchld callback */
 487         prefork_set_sigchld_callback(mdssd_pool, mdssd_sigchld_handler, msg_ctx);
 488
 489         ok = mdssd_schedule_check(ev_ctx, msg_ctx, tevent_timeval_current());
 490
 491         return ok;
 492 }
 493
 494 static bool mdssd_schedule_check(struct tevent_context *ev_ctx,
 495                                  struct messaging_context *msg_ctx,
 496                                  struct timeval current_time)
 497 {
 498         struct tevent_timer *te;
 499         struct timeval next_event;
 500
 501         /* check situation again in 10 seconds */
 502         next_event = tevent_timeval_current_ofs(10, 0);
 503
 504         /* TODO: check when the socket becomes readable, so that children
 505          * are checked only when there is some activity ? */
 506         te = tevent_add_timer(ev_ctx, mdssd_pool, next_event,
 507                               mdssd_check_children, msg_ctx);
 508         if (!te) {
 509                 DEBUG(2, ("Failed to set up children monitoring!\n"));
 510                 return false;
 511         }
 512
 513         return true;
 514 }
 515
 516 static void mdssd_check_children(struct tevent_context *ev_ctx,
 517                                  struct tevent_timer *te,
 518                                  struct timeval current_time,
 519                                  void *pvt)
 520 {
 521         struct messaging_context *msg_ctx;
 522
 523         msg_ctx = talloc_get_type_abort(pvt, struct messaging_context);
 524
 525         pfh_manage_pool(ev_ctx, msg_ctx, &pf_mdssd_cfg, mdssd_pool);
 526
 527         mdssd_schedule_check(ev_ctx, msg_ctx, current_time);
 528 }
 529
 530 /*
 531  * start it up
 532  */
 533
 534 static bool mdssd_create_sockets(struct tevent_context *ev_ctx,
 535                                  struct messaging_context *msg_ctx,
 536                                  int *listen_fd,
 537                                  int *listen_fd_size)
 538 {
 539         struct dcerpc_binding_vector *v, *v_orig;
 540         TALLOC_CTX *tmp_ctx;
 541         NTSTATUS status;
 542         int fd = -1;
 543         int rc;
 544         bool ok = false;
 545
 546         tmp_ctx = talloc_stackframe();
 547         if (tmp_ctx == NULL) {
 548                 return false;
 549         }
 550
 551         status = dcerpc_binding_vector_new(tmp_ctx, &v_orig);
 552         if (!NT_STATUS_IS_OK(status)) {
 553                 goto done;
 554         }
 555
 556         /* mdssvc */
 557         fd = create_named_pipe_socket("mdssvc");
 558         if (fd < 0) {
 559                 goto done;
 560         }
 561
 562         rc = listen(fd, pf_mdssd_cfg.max_allowed_clients);
 563         if (rc == -1) {
 564                 goto done;
 565         }
 566         listen_fd[*listen_fd_size] = fd;
 567         (*listen_fd_size)++;
 568
 569         fd = create_dcerpc_ncalrpc_socket("mdssvc");
 570         if (fd < 0) {
 571                 goto done;
 572         }
 573
 574         rc = listen(fd, pf_mdssd_cfg.max_allowed_clients);
 575         if (rc == -1) {
 576                 goto done;
 577         }
 578         listen_fd[*listen_fd_size] = fd;
 579         (*listen_fd_size)++;
 580         fd = -1;
 581
 582         v = dcerpc_binding_vector_dup(tmp_ctx, v_orig);
 583         if (v == NULL) {
 584                 goto done;
 585         }
 586
 587         status = dcerpc_binding_vector_replace_iface(&ndr_table_mdssvc, v);
 588         if (!NT_STATUS_IS_OK(status)) {
 589                 goto done;
 590         }
 591
 592         status = dcerpc_binding_vector_add_np_default(&ndr_table_mdssvc, v);
 593         if (!NT_STATUS_IS_OK(status)) {
 594                 goto done;
 595         }
 596
 597         status = dcerpc_binding_vector_add_unix(&ndr_table_mdssvc, v, "mdssvc");
 598         if (!NT_STATUS_IS_OK(status)) {
 599                 goto done;
 600         }
 601
 602         ok = true;
 603 done:
 604         if (fd != -1) {
 605                 close(fd);
 606         }
 607         talloc_free(tmp_ctx);
 608         return ok;
 609 }
 610
 611 void start_mdssd(struct tevent_context *ev_ctx,
 612                  struct messaging_context *msg_ctx)
 613 {
 614         NTSTATUS status;
 615         int listen_fd[MDSSD_MAX_SOCKETS];
 616         int listen_fd_size = 0;
 617         pid_t pid;
 618         int rc;
 619         bool ok;
 620
 621         DEBUG(1, ("Forking Metadata Service Daemon\n"));
 622
 623         /*
 624          * Block signals before forking child as it will have to
 625          * set its own handlers. Child will re-enable SIGHUP as
 626          * soon as the handlers are set up.
 627          */
 628         BlockSignals(true, SIGTERM);
 629         BlockSignals(true, SIGHUP);
 630
 631         pid = fork();
 632         if (pid == -1) {
 633                 DEBUG(0, ("Failed to fork mdssd [%s], aborting ...\n",
 634                            strerror(errno)));
 635                 exit(1);
 636         }
 637
 638         /* parent or error */
 639         if (pid != 0) {
 640
 641                 /* Re-enable SIGHUP before returnig */
 642                 BlockSignals(false, SIGTERM);
 643                 BlockSignals(false, SIGHUP);
 644
 645                 return;
 646         }
 647
 648         status = reinit_after_fork(msg_ctx, ev_ctx, true, "mdssd-master");
 649         if (!NT_STATUS_IS_OK(status)) {
 650                 DEBUG(0,("reinit_after_fork() failed\n"));
 651                 smb_panic("reinit_after_fork() failed");
 652         }
 653
 654         reopen_logs();
 655
 656         /* save the parent process id so the children can use it later */
 657         parent_id = messaging_server_id(msg_ctx);
 658
 659         pfh_daemon_config(DAEMON_NAME,
 660                           &pf_mdssd_cfg,
 661                           &default_pf_mdssd_cfg);
 662
 663         mdssd_setup_sig_term_handler(ev_ctx);
 664         mdssd_setup_sig_hup_handler(ev_ctx);
 665
 666         BlockSignals(false, SIGTERM);
 667         BlockSignals(false, SIGHUP);
 668
 669         ok = mdssd_create_sockets(ev_ctx, msg_ctx, listen_fd, &listen_fd_size);
 670         if (!ok) {
 671                 exit(1);
 672         }
 673
 674         /* start children before any more initialization is done */
 675         ok = prefork_create_pool(ev_ctx, /* mem_ctx */
 676                                  ev_ctx,
 677                                  msg_ctx,
 678                                  listen_fd_size,
 679                                  listen_fd,
 680                                  pf_mdssd_cfg.min_children,
 681                                  pf_mdssd_cfg.max_children,
 682                                  &mdssd_children_main,
 683                                  NULL,
 684                                  &mdssd_pool);
 685         if (!ok) {
 686                 exit(1);
 687         }
 688
 689         if (!serverid_register(messaging_server_id(msg_ctx),
 690                                FLAG_MSG_GENERAL)) {
 691                 exit(1);
 692         }
 693
 694         messaging_register(msg_ctx,
 695                            ev_ctx,
 696                            MSG_SMB_CONF_UPDATED,
 697                            mdssd_smb_conf_updated);
 698         messaging_register(msg_ctx, ev_ctx,
 699                            MSG_PREFORK_CHILD_EVENT, child_ping);
 700
 701         ok = setup_rpc_module(ev_ctx, msg_ctx, "mdssvc");
 702         if (!ok) {
 703                 exit(1);
 704         }
 705
 706         ok = mdssd_setup_children_monitor(ev_ctx, msg_ctx);
 707         if (!ok) {
 708                 exit(1);
 709         }
 710
 711         DEBUG(1, ("mdssd Daemon Started (%u)\n", (unsigned int)getpid()));
 712
 713         /* loop forever */
 714         rc = tevent_loop_wait(ev_ctx);
 715
 716         /* should not be reached */
 717         DEBUG(0,("mdssd: tevent_loop_wait() exited with %d - %s\n",
 718                  rc, (rc == 0) ? "out of events" : strerror(errno)));
 719         exit(1);
 720 }