ustd/ustd.c

   1 /* Copyright (C) 2009  Pierre-Marc Fournier
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  16  */
  17
  18 #define _GNU_SOURCE
  19
  20 #include <sys/types.h>
  21 #include <sys/stat.h>
  22 #include <sys/shm.h>
  23 #include <fcntl.h>
  24 #include <unistd.h>
  25 #include <pthread.h>
  26 #include <signal.h>
  27
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30 #include <string.h>
  31 #include <errno.h>
  32 #include <assert.h>
  33 #include <getopt.h>
  34
  35 #include "ustd.h"
  36 #include "usterr.h"
  37 #include "ustcomm.h"
  38
  39 /* return value: 0 = subbuffer is finished, it won't produce data anymore
  40  *               1 = got subbuffer successfully
  41  *               <0 = error
  42  */
  43
  44 #define GET_SUBBUF_OK 1
  45 #define GET_SUBBUF_DONE 0
  46 #define GET_SUBBUF_DIED 2
  47
  48 #define PUT_SUBBUF_OK 1
  49 #define PUT_SUBBUF_DIED 0
  50 #define PUT_SUBBUF_PUSHED 2
  51 #define PUT_SUBBUF_DONE 3
  52
  53 char *sock_path=NULL;
  54 char *trace_path=NULL;
  55 int daemon_mode = 0;
  56 char *pidfile = NULL;
  57
  58 /* Number of active buffers and the mutex to protect it. */
  59 int active_buffers = 0;
  60 pthread_mutex_t active_buffers_mutex = PTHREAD_MUTEX_INITIALIZER;
  61 /* Whether a request to end the program was received. */
  62 sig_atomic_t terminate_req = 0;
  63
  64 int get_subbuffer(struct buffer_info *buf)
  65 {
  66         char *send_msg=NULL;
  67         char *received_msg=NULL;
  68         char *rep_code=NULL;
  69         int retval;
  70         int result;
  71
  72         asprintf(&send_msg, "get_subbuffer %s", buf->name);
  73         result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
  74         if((result == -1 && errno == EPIPE) || result == 0) {
  75                 DBG("app died while being traced");
  76                 retval = GET_SUBBUF_DIED;
  77                 goto end;
  78         }
  79         else if(result < 0) {
  80                 ERR("get_subbuffer: ustcomm_send_request failed");
  81                 retval = -1;
  82                 goto end;
  83         }
  84
  85         result = sscanf(received_msg, "%as %ld", &rep_code, &buf->consumed_old);
  86         if(result != 2 && result != 1) {
  87                 ERR("unable to parse response to get_subbuffer");
  88                 retval = -1;
  89                 goto end_rep;
  90         }
  91
  92         DBG("received msg is %s", received_msg);
  93
  94         if(!strcmp(rep_code, "OK")) {
  95                 DBG("got subbuffer %s", buf->name);
  96                 retval = GET_SUBBUF_OK;
  97         }
  98         else if(nth_token_is(received_msg, "END", 0) == 1) {
  99                 retval = GET_SUBBUF_DONE;
 100                 goto end_rep;
 101         }
 102         else if(!strcmp(received_msg, "NOTFOUND")) {
 103                 WARN("For buffer %s, the trace was not found. This likely means it was destroyed by the user.", buf->name);
 104                 retval = GET_SUBBUF_DONE;
 105                 goto end_rep;
 106         }
 107         else {
 108                 DBG("error getting subbuffer %s", buf->name);
 109                 retval = -1;
 110         }
 111
 112         /* FIMXE: free correctly the stuff */
 113 end_rep:
 114         if(rep_code)
 115                 free(rep_code);
 116 end:
 117         if(send_msg)
 118                 free(send_msg);
 119         if(received_msg)
 120                 free(received_msg);
 121
 122         return retval;
 123 }
 124
 125 int put_subbuffer(struct buffer_info *buf)
 126 {
 127         char *send_msg=NULL;
 128         char *received_msg=NULL;
 129         char *rep_code=NULL;
 130         int retval;
 131         int result;
 132
 133         asprintf(&send_msg, "put_subbuffer %s %ld", buf->name, buf->consumed_old);
 134         result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 135         if(result < 0 && errno == ECONNRESET) {
 136                 retval = PUT_SUBBUF_DIED;
 137                 goto end;
 138         }
 139         else if(result < 0) {
 140                 ERR("put_subbuffer: send_message failed");
 141                 retval = -1;
 142                 goto end;
 143         }
 144         else if(result == 0) {
 145                 /* Program seems finished. However this might not be
 146                  * the last subbuffer that has to be collected.
 147                  */
 148                 retval = PUT_SUBBUF_DIED;
 149                 goto end;
 150         }
 151
 152         result = sscanf(received_msg, "%as", &rep_code);
 153         if(result != 1) {
 154                 ERR("unable to parse response to put_subbuffer");
 155                 retval = -1;
 156                 goto end_rep;
 157         }
 158
 159         if(!strcmp(rep_code, "OK")) {
 160                 DBG("subbuffer put %s", buf->name);
 161                 retval = PUT_SUBBUF_OK;
 162         }
 163         else if(!strcmp(received_msg, "NOTFOUND")) {
 164                 WARN("For buffer %s, the trace was not found. This likely means it was destroyed by the user.", buf->name);
 165                 /* However, maybe this was not the last subbuffer. So
 166                  * we return the program died.
 167                  */
 168                 retval = PUT_SUBBUF_DIED;
 169                 goto end_rep;
 170         }
 171         else {
 172                 DBG("put_subbuffer: received error, we were pushed");
 173                 retval = PUT_SUBBUF_PUSHED;
 174                 goto end_rep;
 175         }
 176
 177 end_rep:
 178         if(rep_code)
 179                 free(rep_code);
 180
 181 end:
 182         if(send_msg)
 183                 free(send_msg);
 184         if(received_msg)
 185                 free(received_msg);
 186
 187         return retval;
 188 }
 189
 190 void decrement_active_buffers(void *arg)
 191 {
 192         pthread_mutex_lock(&active_buffers_mutex);
 193         active_buffers--;
 194         pthread_mutex_unlock(&active_buffers_mutex);
 195 }
 196
 197 int create_dir_if_needed(char *dir)
 198 {
 199         int result;
 200         result = mkdir(dir, 0777);
 201         if(result == -1) {
 202                 if(errno != EEXIST) {
 203                         PERROR("mkdir");
 204                         return -1;
 205                 }
 206         }
 207
 208         return 0;
 209 }
 210
 211 int is_directory(const char *dir)
 212 {
 213         int result;
 214         struct stat st;
 215
 216         result = stat(dir, &st);
 217         if(result == -1) {
 218                 PERROR("stat");
 219                 return 0;
 220         }
 221
 222         if(!S_ISDIR(st.st_mode)) {
 223                 return 0;
 224         }
 225
 226         return 1;
 227 }
 228
 229 struct buffer_info *connect_buffer(pid_t pid, const char *bufname)
 230 {
 231         struct buffer_info *buf;
 232         char *send_msg;
 233         char *received_msg;
 234         int result;
 235         char *tmp;
 236         int fd;
 237         struct shmid_ds shmds;
 238
 239         buf = (struct buffer_info *) malloc(sizeof(struct buffer_info));
 240         if(buf == NULL) {
 241                 ERR("add_buffer: insufficient memory");
 242                 return NULL;
 243         }
 244
 245         buf->name = bufname;
 246         buf->pid = pid;
 247
 248         /* connect to app */
 249         result = ustcomm_connect_app(buf->pid, &buf->conn);
 250         if(result) {
 251                 WARN("unable to connect to process, it probably died before we were able to connect");
 252                 return NULL;
 253         }
 254
 255         /* get pidunique */
 256         asprintf(&send_msg, "get_pidunique");
 257         result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 258         free(send_msg);
 259         if(result == -1) {
 260                 ERR("problem in ustcomm_send_request(get_pidunique)");
 261                 return NULL;
 262         }
 263         if(result == 0) {
 264                 goto error;
 265         }
 266
 267         result = sscanf(received_msg, "%lld", &buf->pidunique);
 268         if(result != 1) {
 269                 ERR("unable to parse response to get_pidunique");
 270                 return NULL;
 271         }
 272         free(received_msg);
 273         DBG("got pidunique %lld", buf->pidunique);
 274
 275         /* get shmid */
 276         asprintf(&send_msg, "get_shmid %s", buf->name);
 277         result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 278         free(send_msg);
 279         if(result == -1) {
 280                 ERR("problem in ustcomm_send_request(get_shmid)");
 281                 return NULL;
 282         }
 283         if(result == 0) {
 284                 goto error;
 285         }
 286
 287         result = sscanf(received_msg, "%d %d", &buf->shmid, &buf->bufstruct_shmid);
 288         if(result != 2) {
 289                 ERR("unable to parse response to get_shmid (\"%s\")", received_msg);
 290                 return NULL;
 291         }
 292         free(received_msg);
 293         DBG("got shmids %d %d", buf->shmid, buf->bufstruct_shmid);
 294
 295         /* get n_subbufs */
 296         asprintf(&send_msg, "get_n_subbufs %s", buf->name);
 297         result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 298         free(send_msg);
 299         if(result == -1) {
 300                 ERR("problem in ustcomm_send_request(g_n_subbufs)");
 301                 return NULL;
 302         }
 303         if(result == 0) {
 304                 goto error;
 305         }
 306
 307         result = sscanf(received_msg, "%d", &buf->n_subbufs);
 308         if(result != 1) {
 309                 ERR("unable to parse response to get_n_subbufs");
 310                 return NULL;
 311         }
 312         free(received_msg);
 313         DBG("got n_subbufs %d", buf->n_subbufs);
 314
 315         /* get subbuf size */
 316         asprintf(&send_msg, "get_subbuf_size %s", buf->name);
 317         result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 318         free(send_msg);
 319         if(result == -1) {
 320                 ERR("problem in ustcomm_send_request(get_subbuf_size)");
 321                 return NULL;
 322         }
 323         if(result == 0) {
 324                 goto error;
 325         }
 326
 327         result = sscanf(received_msg, "%d", &buf->subbuf_size);
 328         if(result != 1) {
 329                 ERR("unable to parse response to get_subbuf_size");
 330                 return NULL;
 331         }
 332         free(received_msg);
 333         DBG("got subbuf_size %d", buf->subbuf_size);
 334
 335         /* attach memory */
 336         buf->mem = shmat(buf->shmid, NULL, 0);
 337         if(buf->mem == (void *) 0) {
 338                 PERROR("shmat");
 339                 return NULL;
 340         }
 341         DBG("successfully attached buffer memory");
 342
 343         buf->bufstruct_mem = shmat(buf->bufstruct_shmid, NULL, 0);
 344         if(buf->bufstruct_mem == (void *) 0) {
 345                 PERROR("shmat");
 346                 return NULL;
 347         }
 348         DBG("successfully attached buffer bufstruct memory");
 349
 350         /* obtain info on the memory segment */
 351         result = shmctl(buf->shmid, IPC_STAT, &shmds);
 352         if(result == -1) {
 353                 PERROR("shmctl");
 354                 return NULL;
 355         }
 356         buf->memlen = shmds.shm_segsz;
 357
 358         /* open file for output */
 359         if(!trace_path) {
 360                 /* Only create the directory if using the default path, because
 361                  * of the risk of typo when using trace path override. We don't
 362                  * want to risk creating plenty of useless directories in that case.
 363                  */
 364                 result = create_dir_if_needed(USTD_DEFAULT_TRACE_PATH);
 365                 if(result == -1) {
 366                         ERR("could not create directory %s", USTD_DEFAULT_TRACE_PATH);
 367                         return NULL;
 368                 }
 369
 370                 trace_path = USTD_DEFAULT_TRACE_PATH;
 371         }
 372
 373         asprintf(&tmp, "%s/%u_%lld", trace_path, buf->pid, buf->pidunique);
 374         result = create_dir_if_needed(tmp);
 375         if(result == -1) {
 376                 ERR("could not create directory %s", tmp);
 377                 free(tmp);
 378                 return NULL;
 379         }
 380         free(tmp);
 381
 382         asprintf(&tmp, "%s/%u_%lld/%s", trace_path, buf->pid, buf->pidunique, buf->name);
 383         result = fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 00600);
 384         if(result == -1) {
 385                 PERROR("open");
 386                 ERR("failed opening trace file %s", tmp);
 387                 return NULL;
 388         }
 389         buf->file_fd = fd;
 390         free(tmp);
 391
 392         pthread_mutex_lock(&active_buffers_mutex);
 393         active_buffers++;
 394         pthread_mutex_unlock(&active_buffers_mutex);
 395
 396         return buf;
 397
 398 error:
 399         free(buf);
 400         return NULL;
 401 }
 402
 403 int write_current_subbuffer(struct buffer_info *buf)
 404 {
 405         int result;
 406
 407         void *subbuf_mem = buf->mem + (buf->consumed_old & (buf->n_subbufs * buf->subbuf_size-1));
 408
 409         size_t cur_sb_size = subbuffer_data_size(subbuf_mem);
 410
 411         result = patient_write(buf->file_fd, subbuf_mem, cur_sb_size);
 412         if(result == -1) {
 413                 PERROR("write");
 414                 /* FIXME: maybe drop this trace */
 415                 return 0;
 416         }
 417
 418         return 0;
 419 }
 420
 421 int consumer_loop(struct buffer_info *buf)
 422 {
 423         int result;
 424
 425         pthread_cleanup_push(decrement_active_buffers, NULL);
 426
 427         for(;;) {
 428                 /* get the subbuffer */
 429                 result = get_subbuffer(buf);
 430                 if(result == -1) {
 431                         ERR("error getting subbuffer");
 432                         continue;
 433                 }
 434                 else if(result == GET_SUBBUF_DONE) {
 435                         /* this is done */
 436                         break;
 437                 }
 438                 else if(result == GET_SUBBUF_DIED) {
 439                         finish_consuming_dead_subbuffer(buf);
 440                         break;
 441                 }
 442
 443                 /* write data to file */
 444                 write_current_subbuffer(buf);
 445                 /* FIXME: handle return value? */
 446
 447                 /* put the subbuffer */
 448                 /* FIXME: we actually should unput the buffer before consuming... */
 449                 result = put_subbuffer(buf);
 450                 if(result == -1) {
 451                         ERR("unknown error putting subbuffer (channel=%s)", buf->name);
 452                         break;
 453                 }
 454                 else if(result == PUT_SUBBUF_PUSHED) {
 455                         ERR("Buffer overflow (channel=%s), reader pushed. This channel will not be usable passed this point.", buf->name);
 456                         break;
 457                 }
 458                 else if(result == PUT_SUBBUF_DIED) {
 459                         WARN("application died while putting subbuffer");
 460                         /* FIXME: probably need to skip the first subbuffer in finish_consuming_dead_subbuffer */
 461                         finish_consuming_dead_subbuffer(buf);
 462                         break;
 463                 }
 464                 else if(result == PUT_SUBBUF_DONE) {
 465                         /* Done with this subbuffer */
 466                         /* FIXME: add a case where this branch is used? Upon
 467                          * normal trace termination, at put_subbuf time, a
 468                          * special last-subbuffer code could be returned by
 469                          * the listener.
 470                          */
 471                         break;
 472                 }
 473                 else if(result == PUT_SUBBUF_OK) {
 474                 }
 475         }
 476
 477         DBG("thread for buffer %s is stopping", buf->name);
 478
 479         /* FIXME: destroy, unalloc... */
 480
 481         pthread_cleanup_pop(1);
 482
 483         return 0;
 484 }
 485
 486 void free_buffer(struct buffer_info *buf)
 487 {
 488 }
 489
 490 struct consumer_thread_args {
 491         pid_t pid;
 492         const char *bufname;
 493 };
 494
 495 void *consumer_thread(void *arg)
 496 {
 497         struct buffer_info *buf = (struct buffer_info *) arg;
 498         struct consumer_thread_args *args = (struct consumer_thread_args *) arg;
 499
 500         DBG("GOT ARGS: pid %d bufname %s", args->pid, args->bufname);
 501
 502         buf = connect_buffer(args->pid, args->bufname);
 503         if(buf == NULL) {
 504                 ERR("failed to connect to buffer");
 505                 goto end;
 506         }
 507
 508         consumer_loop(buf);
 509
 510         free_buffer(buf);
 511
 512         end:
 513         /* bufname is free'd in free_buffer() */
 514         free(args);
 515         return NULL;
 516 }
 517
 518 int start_consuming_buffer(pid_t pid, const char *bufname)
 519 {
 520         pthread_t thr;
 521         struct consumer_thread_args *args;
 522
 523         DBG("beginning of start_consuming_buffer: args: pid %d bufname %s", pid, bufname);
 524
 525         args = (struct consumer_thread_args *) malloc(sizeof(struct consumer_thread_args));
 526
 527         args->pid = pid;
 528         args->bufname = strdup(bufname);
 529         DBG("beginning2 of start_consuming_buffer: args: pid %d bufname %s", args->pid, args->bufname);
 530
 531         pthread_create(&thr, NULL, consumer_thread, args);
 532         DBG("end of start_consuming_buffer: args: pid %d bufname %s", args->pid, args->bufname);
 533
 534         return 0;
 535 }
 536
 537 void usage(void)
 538 {
 539         fprintf(stderr, "Usage:\nustd OPTIONS\n\nOptions:\n"
 540                         "\t-h\t\tDisplay this usage.\n"
 541                         "\t-o DIR\t\tSpecify the directory where to output the traces.\n"
 542                         "\t-s PATH\t\tSpecify the path to use for the daemon socket.\n"
 543                         "\t-d\t\tStart as a daemon.\n"
 544                         "\t--pidfile FILE\tWrite the PID in this file (when using -d).\n");
 545 }
 546
 547 int parse_args(int argc, char **argv)
 548 {
 549         int c;
 550
 551         while (1) {
 552                 int option_index = 0;
 553                 static struct option long_options[] = {
 554                         {"pidfile", 1, 0, 'p'},
 555                         {"help", 0, 0, 'h'},
 556                         {"version", 0, 0, 'V'},
 557                         {0, 0, 0, 0}
 558                 };
 559
 560                 c = getopt_long(argc, argv, "hs:o:d", long_options, &option_index);
 561                 if (c == -1)
 562                         break;
 563
 564                 switch (c) {
 565                 case 0:
 566                         printf("option %s", long_options[option_index].name);
 567                         if (optarg)
 568                                 printf(" with arg %s", optarg);
 569                         printf("\n");
 570                         break;
 571                 case 's':
 572                         sock_path = optarg;
 573                         break;
 574                 case 'o':
 575                         trace_path = optarg;
 576                         if(!is_directory(trace_path)) {
 577                                 ERR("Not a valid directory. (%s)", trace_path);
 578                                 return -1;
 579                         }
 580                         break;
 581                 case 'd':
 582                         daemon_mode = 1;
 583                         break;
 584                 case 'p':
 585                         pidfile = strdup(optarg);
 586                         break;
 587                 case 'h':
 588                         usage();
 589                         exit(0);
 590                 case 'V':
 591                         printf("Version 0.0\n");
 592                         break;
 593
 594                 default:
 595                         /* unknown option or other error; error is
 596                         printed by getopt, just return */
 597                         return -1;
 598                 }
 599         }
 600
 601         return 0;
 602 }
 603
 604 void sigterm_handler(int sig)
 605 {
 606         terminate_req = 1;
 607 }
 608
 609 static int write_pidfile(const char *file_name, pid_t pid)
 610 {
 611         FILE *pidfp;
 612
 613         pidfp = fopen(file_name, "w");
 614         if(!pidfp) {
 615                 PERROR("fopen (%s)", pidfile);
 616                 WARN("killing child process");
 617                 return -1;
 618         }
 619
 620         fprintf(pidfp, "%d\n", pid);
 621
 622         fclose(pidfp);
 623
 624         return 0;
 625 }
 626
 627 int start_ustd(int fd)
 628 {
 629         struct ustcomm_ustd ustd;
 630         int result;
 631         sigset_t sigset;
 632         struct sigaction sa;
 633
 634         result = sigemptyset(&sigset);
 635         if(result == -1) {
 636                 PERROR("sigemptyset");
 637                 return 1;
 638         }
 639         sa.sa_handler = sigterm_handler;
 640         sa.sa_mask = sigset;
 641         sa.sa_flags = SA_RESTART;
 642         result = sigaction(SIGTERM, &sa, NULL);
 643         if(result == -1) {
 644                 PERROR("sigaction");
 645                 return 1;
 646         }
 647
 648         result = ustcomm_init_ustd(&ustd, sock_path);
 649         if(result == -1) {
 650                 ERR("failed to initialize socket");
 651                 return 1;
 652         }
 653
 654         /* setup handler for SIGPIPE */
 655         result = sigemptyset(&sigset);
 656         if(result == -1) {
 657                 PERROR("sigemptyset");
 658                 return 1;
 659         }
 660         result = sigaddset(&sigset, SIGPIPE);
 661         if(result == -1) {
 662                 PERROR("sigaddset");
 663                 return 1;
 664         }
 665         result = sigprocmask(SIG_BLOCK, &sigset, NULL);
 666         if(result == -1) {
 667                 PERROR("sigprocmask");
 668                 return 1;
 669         }
 670
 671         /* Write pidfile */
 672         if(pidfile) {
 673                 result = write_pidfile(pidfile, getpid());
 674                 if(result == -1) {
 675                         ERR("failed to write pidfile");
 676                         return 1;
 677                 }
 678         }
 679
 680         /* Notify parent that we are successfully started. */
 681         if(fd != -1) {
 682                 /* write any one character */
 683                 result = write(fd, "!", 1);
 684                 if(result == -1) {
 685                         PERROR("write");
 686                         return -1;
 687                 }
 688                 if(result != 1) {
 689                         ERR("Problem sending confirmation of daemon start to parent");
 690                         return -1;
 691                 }
 692                 result = close(fd);
 693                 if(result == -1) {
 694                         PERROR("close");
 695                 }
 696         }
 697
 698         /* app loop */
 699         for(;;) {
 700                 char *recvbuf;
 701
 702                 /* check for requests on our public socket */
 703                 result = ustcomm_ustd_recv_message(&ustd, &recvbuf, NULL, 100);
 704                 if(result == -1) {
 705                         ERR("error in ustcomm_ustd_recv_message");
 706                         goto loop_end;
 707                 }
 708                 if(result > 0) {
 709                         if(!strncmp(recvbuf, "collect", 7)) {
 710                                 pid_t pid;
 711                                 char *bufname;
 712                                 int result;
 713
 714                                 result = sscanf(recvbuf, "%*s %d %50as", &pid, &bufname);
 715                                 if(result != 2) {
 716                                         ERR("parsing error: %s", recvbuf);
 717                                         goto free_bufname;
 718                                 }
 719
 720                                 result = start_consuming_buffer(pid, bufname);
 721                                 if(result < 0) {
 722                                         ERR("error in add_buffer");
 723                                         goto free_bufname;
 724                                 }
 725
 726                                 free_bufname:
 727                                 free(bufname);
 728                         }
 729
 730                         free(recvbuf);
 731                 }
 732
 733                 loop_end:
 734
 735                 if(terminate_req) {
 736                         pthread_mutex_lock(&active_buffers_mutex);
 737                         if(active_buffers == 0) {
 738                                 pthread_mutex_unlock(&active_buffers_mutex);
 739                                 break;
 740                         }
 741                         pthread_mutex_unlock(&active_buffers_mutex);
 742                 }
 743         }
 744
 745         return 0;
 746 }
 747
 748 int start_ustd_daemon()
 749 {
 750         int result;
 751         int fd[2];
 752         pid_t child_pid;
 753
 754         result = pipe(fd);
 755
 756         result = child_pid = fork();
 757         if(result == -1) {
 758                 PERROR("fork");
 759                 return -1;
 760         }
 761         else if(result == 0) {
 762                 return start_ustd(fd[1]);
 763         }
 764         else {
 765                 char buf;
 766
 767                 result = read(fd[0], &buf, 1);
 768                 if(result == -1) {
 769                         PERROR("read");
 770                         return -1;
 771                 }
 772                 if(result != 1) {
 773                         ERR("did not receive valid confirmation that the daemon is started");
 774                         return -1;
 775                 }
 776
 777                 result = close(fd[0]);
 778                 if(result == -1) {
 779                         PERROR("close");
 780                 }
 781
 782                 DBG("The daemon is now successfully started");
 783         }
 784
 785         /* Wait for confirmation that the server is ready. */
 786
 787
 788         return 0;
 789 }
 790
 791 int main(int argc, char **argv)
 792 {
 793         int result;
 794
 795         result = parse_args(argc, argv);
 796         if(result == -1) {
 797                 exit(1);
 798         }
 799
 800         if(daemon_mode) {
 801                 result = start_ustd_daemon();
 802         }
 803         else {
 804                 result = start_ustd(-1);
 805         }
 806
 807         return result;
 808 }