ltt-control/lttd/lttd.c

   1 /* lttd
   2  *
   3  * Linux Trace Toolkit Daemon
   4  *
   5  * This is a simple daemon that reads a few relay+debugfs channels and save
   6  * them in a trace.
   7  *
   8  *
   9  * Copyright 2005 -
  10  *      Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  11  */
  12
  13 #ifdef HAVE_CONFIG_H
  14 #include <config.h>
  15 #endif
  16
  17 #define _REENTRANT
  18 #define _GNU_SOURCE
  19 #include <features.h>
  20 #include <stdio.h>
  21 #include <unistd.h>
  22 #include <errno.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <stdlib.h>
  26 #include <dirent.h>
  27 #include <string.h>
  28 #include <fcntl.h>
  29 #include <sys/poll.h>
  30 #include <sys/mman.h>
  31 #include <signal.h>
  32 #include <pthread.h>
  33 #include <sys/syscall.h>
  34 #include <unistd.h>
  35 #include <asm/ioctls.h>
  36
  37 #include <linux/version.h>
  38
  39 /* Relayfs IOCTL */
  40 #include <asm/ioctl.h>
  41 #include <asm/types.h>
  42
  43 /* Get the next sub buffer that can be read. */
  44 #define RELAY_GET_SUBBUF        _IOR(0xF5, 0x00,__u32)
  45 /* Release the oldest reserved (by "get") sub buffer. */
  46 #define RELAY_PUT_SUBBUF        _IOW(0xF5, 0x01,__u32)
  47 /* returns the number of sub buffers in the per cpu channel. */
  48 #define RELAY_GET_N_SUBBUFS     _IOR(0xF5, 0x02,__u32)
  49 /* returns the size of the sub buffers. */
  50 #define RELAY_GET_SUBBUF_SIZE   _IOR(0xF5, 0x03,__u32)
  51
  52 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,14)
  53 #include <linux/inotify.h>
  54 /* From the inotify-tools 2.6 package */
  55 static inline int inotify_init (void)
  56 {
  57         return syscall (__NR_inotify_init);
  58 }
  59
  60 static inline int inotify_add_watch (int fd, const char *name, __u32 mask)
  61 {
  62         return syscall (__NR_inotify_add_watch, fd, name, mask);
  63 }
  64
  65 static inline int inotify_rm_watch (int fd, __u32 wd)
  66 {
  67         return syscall (__NR_inotify_rm_watch, fd, wd);
  68 }
  69 #define HAS_INOTIFY
  70 #else
  71 static inline int inotify_init (void)
  72 {
  73         return -1;
  74 }
  75
  76 static inline int inotify_add_watch (int fd, const char *name, __u32 mask)
  77 {
  78         return 0;
  79 }
  80
  81 static inline int inotify_rm_watch (int fd, __u32 wd)
  82 {
  83         return 0;
  84 }
  85 #undef HAS_INOTIFY
  86 #endif
  87
  88 enum {
  89         GET_SUBBUF,
  90         PUT_SUBBUF,
  91         GET_N_BUBBUFS,
  92         GET_SUBBUF_SIZE
  93 };
  94
  95 struct fd_pair {
  96         int channel;
  97         int trace;
  98         unsigned int n_subbufs;
  99         unsigned int subbuf_size;
 100         void *mmap;
 101         pthread_mutex_t mutex;
 102 };
 103
 104 struct channel_trace_fd {
 105         struct fd_pair *pair;
 106         int num_pairs;
 107 };
 108
 109 struct inotify_watch {
 110         int wd;
 111         char path_channel[PATH_MAX];
 112         char path_trace[PATH_MAX];
 113 };
 114
 115 struct inotify_watch_array {
 116         struct inotify_watch *elem;
 117         int num;
 118 };
 119
 120 static char             *trace_name = NULL;
 121 static char             *channel_name = NULL;
 122 static int              daemon_mode = 0;
 123 static int              append_mode = 0;
 124 static unsigned long    num_threads = 1;
 125 volatile static int     quit_program = 0;       /* For signal handler */
 126 static int              dump_flight_only = 0;
 127 static int              dump_normal_only = 0;
 128
 129 /* Args :
 130  *
 131  * -t directory         Directory name of the trace to write to. Will be created.
 132  * -c directory         Root directory of the debugfs trace channels.
 133  * -d                   Run in background (daemon).
 134  * -a                                                   Trace append mode.
 135  * -s                                                   Send SIGUSR1 to parent when ready for IO.
 136  */
 137 void show_arguments(void)
 138 {
 139         printf("Please use the following arguments :\n");
 140         printf("\n");
 141         printf("-t directory  Directory name of the trace to write to.\n"
 142                                  "              It will be created.\n");
 143         printf("-c directory  Root directory of the debugfs trace channels.\n");
 144         printf("-d            Run in background (daemon).\n");
 145         printf("-a            Append to an possibly existing trace.\n");
 146         printf("-N            Number of threads to start.\n");
 147         printf("-f            Dump only flight recorder channels.\n");
 148         printf("-n            Dump only normal channels.\n");
 149         printf("\n");
 150 }
 151
 152
 153 /* parse_arguments
 154  *
 155  * Parses the command line arguments.
 156  *
 157  * Returns 1 if the arguments were correct, but doesn't ask for program
 158  * continuation. Returns -1 if the arguments are incorrect, or 0 if OK.
 159  */
 160 int parse_arguments(int argc, char **argv)
 161 {
 162         int ret = 0;
 163         int argn = 1;
 164
 165         if(argc == 2) {
 166                 if(strcmp(argv[1], "-h") == 0) {
 167                         return 1;
 168                 }
 169         }
 170
 171         while(argn < argc) {
 172
 173                 switch(argv[argn][0]) {
 174                         case '-':
 175                                 switch(argv[argn][1]) {
 176                                         case 't':
 177                                                 if(argn+1 < argc) {
 178                                                         trace_name = argv[argn+1];
 179                                                         argn++;
 180                                                 }
 181                                                 break;
 182                                         case 'c':
 183                                                 if(argn+1 < argc) {
 184                                                         channel_name = argv[argn+1];
 185                                                         argn++;
 186                                                 }
 187                                                 break;
 188                                         case 'd':
 189                                                 daemon_mode = 1;
 190                                                 break;
 191                                         case 'a':
 192                                                 append_mode = 1;
 193                                                 break;
 194                                         case 'N':
 195                                                 if(argn+1 < argc) {
 196                                                         num_threads = strtoul(argv[argn+1], NULL, 0);
 197                                                         argn++;
 198                                                 }
 199                                                 break;
 200                                         case 'f':
 201                                                 dump_flight_only = 1;
 202                                                 break;
 203                                         case 'n':
 204                                                 dump_normal_only = 1;
 205                                                 break;
 206                                         default:
 207                                                 printf("Invalid argument '%s'.\n", argv[argn]);
 208                                                 printf("\n");
 209                                                 ret = -1;
 210                                 }
 211                                 break;
 212                         default:
 213                                 printf("Invalid argument '%s'.\n", argv[argn]);
 214                                 printf("\n");
 215                                 ret = -1;
 216                 }
 217                 argn++;
 218         }
 219
 220         if(trace_name == NULL) {
 221                 printf("Please specify a trace name.\n");
 222                 printf("\n");
 223                 ret = -1;
 224         }
 225
 226         if(channel_name == NULL) {
 227                 printf("Please specify a channel name.\n");
 228                 printf("\n");
 229                 ret = -1;
 230         }
 231
 232         return ret;
 233 }
 234
 235 void show_info(void)
 236 {
 237         printf("Linux Trace Toolkit Trace Daemon " VERSION "\n");
 238         printf("\n");
 239         printf("Reading from debugfs directory : %s\n", channel_name);
 240         printf("Writing to trace directory : %s\n", trace_name);
 241         printf("\n");
 242 }
 243
 244
 245 /* signal handling */
 246
 247 static void handler(int signo)
 248 {
 249         printf("Signal %d received : exiting cleanly\n", signo);
 250         quit_program = 1;
 251 }
 252
 253
 254 int open_buffer_file(char *filename, char *path_channel, char *path_trace,
 255         struct channel_trace_fd *fd_pairs)
 256 {
 257         int open_ret = 0;
 258         int ret = 0;
 259         struct stat stat_buf;
 260
 261         if(strncmp(filename, "flight-", sizeof("flight-")-1) != 0) {
 262                 if(dump_flight_only) {
 263                         printf("Skipping normal channel %s\n", path_channel);
 264                         return 0;
 265                 }
 266         } else {
 267                 if(dump_normal_only) {
 268                         printf("Skipping flight channel %s\n", path_channel);
 269                         return 0;
 270                 }
 271         }
 272         printf("Opening file.\n");
 273
 274         fd_pairs->pair = realloc(fd_pairs->pair,
 275                         ++fd_pairs->num_pairs * sizeof(struct fd_pair));
 276
 277         /* Open the channel in read mode */
 278         fd_pairs->pair[fd_pairs->num_pairs-1].channel =
 279                 open(path_channel, O_RDONLY | O_NONBLOCK);
 280         if(fd_pairs->pair[fd_pairs->num_pairs-1].channel == -1) {
 281                 perror(path_channel);
 282                 fd_pairs->num_pairs--;
 283                 return 0;       /* continue */
 284         }
 285         /* Open the trace in write mode, only append if append_mode */
 286         ret = stat(path_trace, &stat_buf);
 287         if(ret == 0) {
 288                 if(append_mode) {
 289                         printf("Appending to file %s as requested\n", path_trace);
 290
 291                         fd_pairs->pair[fd_pairs->num_pairs-1].trace =
 292                                 open(path_trace, O_WRONLY|O_APPEND,
 293                                                 S_IRWXU|S_IRWXG|S_IRWXO);
 294
 295                         if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
 296                                 perror(path_trace);
 297                         }
 298                 } else {
 299                         printf("File %s exists, cannot open. Try append mode.\n", path_trace);
 300                         open_ret = -1;
 301                         goto end;
 302                 }
 303         } else {
 304                 if(errno == ENOENT) {
 305                         fd_pairs->pair[fd_pairs->num_pairs-1].trace =
 306                                 open(path_trace, O_WRONLY|O_CREAT|O_EXCL,
 307                                                 S_IRWXU|S_IRWXG|S_IRWXO);
 308                         if(fd_pairs->pair[fd_pairs->num_pairs-1].trace == -1) {
 309                                 perror(path_trace);
 310                         }
 311                 }
 312         }
 313 end:
 314         return open_ret;
 315 }
 316
 317 int open_channel_trace_pairs(char *subchannel_name, char *subtrace_name,
 318                 struct channel_trace_fd *fd_pairs, int *inotify_fd,
 319                 struct inotify_watch_array *iwatch_array)
 320 {
 321         DIR *channel_dir = opendir(subchannel_name);
 322         struct dirent *entry;
 323         struct stat stat_buf;
 324         int ret;
 325         char path_channel[PATH_MAX];
 326         int path_channel_len;
 327         char *path_channel_ptr;
 328         char path_trace[PATH_MAX];
 329         int path_trace_len;
 330         char *path_trace_ptr;
 331         int open_ret = 0;
 332
 333         if(channel_dir == NULL) {
 334                 perror(subchannel_name);
 335                 open_ret = ENOENT;
 336                 goto end;
 337         }
 338
 339         printf("Creating trace subdirectory %s\n", subtrace_name);
 340         ret = mkdir(subtrace_name, S_IRWXU|S_IRWXG|S_IRWXO);
 341         if(ret == -1) {
 342                 if(errno != EEXIST) {
 343                         perror(subtrace_name);
 344                         open_ret = -1;
 345                         goto end;
 346                 }
 347         }
 348
 349         strncpy(path_channel, subchannel_name, PATH_MAX-1);
 350         path_channel_len = strlen(path_channel);
 351         path_channel[path_channel_len] = '/';
 352         path_channel_len++;
 353         path_channel_ptr = path_channel + path_channel_len;
 354
 355         strncpy(path_trace, subtrace_name, PATH_MAX-1);
 356         path_trace_len = strlen(path_trace);
 357         path_trace[path_trace_len] = '/';
 358         path_trace_len++;
 359         path_trace_ptr = path_trace + path_trace_len;
 360
 361 #ifdef HAS_INOTIFY
 362         iwatch_array->elem = realloc(iwatch_array->elem,
 363                 ++iwatch_array->num * sizeof(struct inotify_watch));
 364
 365         printf("Adding inotify for channel %s\n", path_channel);
 366         iwatch_array->elem[iwatch_array->num-1].wd = inotify_add_watch(*inotify_fd, path_channel, IN_CREATE);
 367         strcpy(iwatch_array->elem[iwatch_array->num-1].path_channel, path_channel);
 368         strcpy(iwatch_array->elem[iwatch_array->num-1].path_trace, path_trace);
 369         printf("Added inotify for channel %s, wd %u\n", iwatch_array->elem[iwatch_array->num-1].path_channel,
 370                 iwatch_array->elem[iwatch_array->num-1].wd);
 371 #endif
 372
 373         while((entry = readdir(channel_dir)) != NULL) {
 374
 375                 if(entry->d_name[0] == '.') continue;
 376
 377                 strncpy(path_channel_ptr, entry->d_name, PATH_MAX - path_channel_len);
 378                 strncpy(path_trace_ptr, entry->d_name, PATH_MAX - path_trace_len);
 379
 380                 ret = stat(path_channel, &stat_buf);
 381                 if(ret == -1) {
 382                         perror(path_channel);
 383                         continue;
 384                 }
 385
 386                 printf("Channel file : %s\n", path_channel);
 387
 388                 if(S_ISDIR(stat_buf.st_mode)) {
 389
 390                         printf("Entering channel subdirectory...\n");
 391                         ret = open_channel_trace_pairs(path_channel, path_trace, fd_pairs,
 392                                 inotify_fd, iwatch_array);
 393                         if(ret < 0) continue;
 394                 } else if(S_ISREG(stat_buf.st_mode)) {
 395                         open_ret = open_buffer_file(entry->d_name, path_channel, path_trace,
 396                                 fd_pairs);
 397                         if(open_ret)
 398                                 goto end;
 399                 }
 400         }
 401
 402 end:
 403         closedir(channel_dir);
 404
 405         return open_ret;
 406 }
 407
 408
 409 int read_subbuffer(struct fd_pair *pair)
 410 {
 411         unsigned int    consumed_old;
 412         int err, ret=0;
 413
 414
 415         err = ioctl(pair->channel, RELAY_GET_SUBBUF,
 416                                                                 &consumed_old);
 417         printf("cookie : %u\n", consumed_old);
 418         if(err != 0) {
 419                 ret = errno;
 420                 perror("Reserving sub buffer failed (everything is normal, it is due to concurrency)");
 421                 goto get_error;
 422         }
 423
 424         err = TEMP_FAILURE_RETRY(write(pair->trace,
 425                                 pair->mmap
 426                                         + (consumed_old & ((pair->n_subbufs * pair->subbuf_size)-1)),
 427                                 pair->subbuf_size));
 428
 429         if(err < 0) {
 430                 ret = errno;
 431                 perror("Error in writing to file");
 432                 goto write_error;
 433         }
 434 #if 0
 435         err = fsync(pair->trace);
 436         if(err < 0) {
 437                 ret = errno;
 438                 perror("Error in writing to file");
 439                 goto write_error;
 440         }
 441 #endif //0
 442 write_error:
 443         err = ioctl(pair->channel, RELAY_PUT_SUBBUF, &consumed_old);
 444         if(err != 0) {
 445                 ret = errno;
 446                 if(errno == EFAULT) {
 447                         perror("Error in unreserving sub buffer\n");
 448                 } else if(errno == EIO) {
 449                         perror("Reader has been pushed by the writer, last subbuffer corrupted.");
 450                         /* FIXME : we may delete the last written buffer if we wish. */
 451                 }
 452                 goto get_error;
 453         }
 454
 455 get_error:
 456         return ret;
 457 }
 458
 459
 460
 461 int map_channels(struct channel_trace_fd *fd_pairs,
 462         int idx_begin, int idx_end)
 463 {
 464         int i,j;
 465         int ret=0;
 466
 467         if(fd_pairs->num_pairs <= 0) {
 468                 printf("No channel to read\n");
 469                 goto end;
 470         }
 471
 472         /* Get the subbuf sizes and number */
 473
 474         for(i=idx_begin;i<idx_end;i++) {
 475                 struct fd_pair *pair = &fd_pairs->pair[i];
 476
 477                 ret = ioctl(pair->channel, RELAY_GET_N_SUBBUFS,
 478                                                         &pair->n_subbufs);
 479                 if(ret != 0) {
 480                         perror("Error in getting the number of subbuffers");
 481                         goto end;
 482                 }
 483                 ret = ioctl(pair->channel, RELAY_GET_SUBBUF_SIZE,
 484                                                         &pair->subbuf_size);
 485                 if(ret != 0) {
 486                         perror("Error in getting the size of the subbuffers");
 487                         goto end;
 488                 }
 489                 ret = pthread_mutex_init(&pair->mutex, NULL);   /* Fast mutex */
 490                 if(ret != 0) {
 491                         perror("Error in mutex init");
 492                         goto end;
 493                 }
 494         }
 495
 496         /* Mmap each FD */
 497         for(i=idx_begin;i<idx_end;i++) {
 498                 struct fd_pair *pair = &fd_pairs->pair[i];
 499
 500                 pair->mmap = mmap(0, pair->subbuf_size * pair->n_subbufs, PROT_READ,
 501                                 MAP_SHARED, pair->channel, 0);
 502                 if(pair->mmap == MAP_FAILED) {
 503                         perror("Mmap error");
 504                         goto munmap;
 505                 }
 506         }
 507
 508         goto end; /* success */
 509
 510         /* Error handling */
 511         /* munmap only the successfully mmapped indexes */
 512 munmap:
 513                 /* Munmap each FD */
 514         for(j=idx_begin;j<i;j++) {
 515                 struct fd_pair *pair = &fd_pairs->pair[j];
 516                 int err_ret;
 517
 518                 err_ret = munmap(pair->mmap, pair->subbuf_size * pair->n_subbufs);
 519                 if(err_ret != 0) {
 520                         perror("Error in munmap");
 521                 }
 522                 ret |= err_ret;
 523         }
 524
 525 end:
 526         return ret;
 527
 528
 529 }
 530
 531
 532 int unmap_channels(struct channel_trace_fd *fd_pairs)
 533 {
 534         int j;
 535         int ret=0;
 536
 537         /* Munmap each FD */
 538         for(j=0;j<fd_pairs->num_pairs;j++) {
 539                 struct fd_pair *pair = &fd_pairs->pair[j];
 540                 int err_ret;
 541
 542                 err_ret = munmap(pair->mmap, pair->subbuf_size * pair->n_subbufs);
 543                 if(err_ret != 0) {
 544                         perror("Error in munmap");
 545                 }
 546                 ret |= err_ret;
 547                 err_ret = pthread_mutex_destroy(&pair->mutex);
 548                 if(err_ret != 0) {
 549                         perror("Error in mutex destroy");
 550                 }
 551                 ret |= err_ret;
 552         }
 553
 554         return ret;
 555 }
 556
 557 #ifdef HAS_INOTIFY
 558 /* Inotify event arrived.
 559  *
 560  * Only support add file for now.
 561  */
 562
 563 int read_inotify(int inotify_fd,
 564         struct channel_trace_fd *fd_pairs,
 565         struct inotify_watch_array *iwatch_array)
 566 {
 567         char buf[sizeof(struct inotify_event) + PATH_MAX];
 568         char path_channel[PATH_MAX];
 569         char path_trace[PATH_MAX];
 570         ssize_t len;
 571         struct inotify_event *ievent;
 572         size_t offset;
 573         unsigned int i;
 574         int ret;
 575         int old_num;
 576
 577         offset = 0;
 578         len = read(inotify_fd, buf, sizeof(struct inotify_event) + PATH_MAX);
 579         if(len < 0) {
 580                 printf("Error in read from inotify FD %s.\n", strerror(len));
 581                 return -1;
 582         }
 583         while(offset < len) {
 584                 ievent = (struct inotify_event *)&(buf[offset]);
 585                 for(i=0; i<iwatch_array->num; i++) {
 586                         if(iwatch_array->elem[i].wd == ievent->wd &&
 587                                 ievent->mask == IN_CREATE) {
 588                                 printf("inotify wd %u event mask : %u for %s%s\n",
 589                                         ievent->wd, ievent->mask,
 590                                         iwatch_array->elem[i].path_channel, ievent->name);
 591                                 old_num = fd_pairs->num_pairs;
 592                                 strcpy(path_channel, iwatch_array->elem[i].path_channel);
 593                                 strcat(path_channel, ievent->name);
 594                                 strcpy(path_trace, iwatch_array->elem[i].path_trace);
 595                                 strcat(path_trace, ievent->name);
 596                                 if(ret = open_buffer_file(ievent->name, path_channel,
 597                                         path_trace, fd_pairs)) {
 598                                         printf("Error opening buffer file\n");
 599                                         return -1;
 600                                 }
 601                                 if(ret = map_channels(fd_pairs, old_num, fd_pairs->num_pairs)) {
 602                                         printf("Error mapping channel\n");
 603                                         return -1;
 604                                 }
 605
 606                         }
 607                 }
 608                 offset += sizeof(*ievent) + ievent->len;
 609         }
 610 }
 611 #endif //HAS_INOTIFY
 612
 613 /* read_channels
 614  *
 615  * Thread worker.
 616  *
 617  * Read the debugfs channels and write them in the paired tracefiles.
 618  *
 619  * @fd_pairs : paired channels and trace files.
 620  *
 621  * returns 0 on success, -1 on error.
 622  *
 623  * Note that the high priority polled channels are consumed first. We then poll
 624  * again to see if these channels are still in priority. Only when no
 625  * high priority channel is left, we start reading low priority channels.
 626  *
 627  * Note that a channel is considered high priority when the buffer is almost
 628  * full.
 629  */
 630
 631 int read_channels(unsigned int thread_num, struct channel_trace_fd *fd_pairs,
 632         int inotify_fd, struct inotify_watch_array *iwatch_array)
 633 {
 634         struct pollfd *pollfd = NULL;
 635         int i,j;
 636         int num_rdy, num_hup;
 637         int high_prio;
 638         int ret = 0;
 639         int inotify_fds;
 640         unsigned int old_num;
 641
 642 #ifdef HAS_INOTIFY
 643         inotify_fds = 1;
 644 #else
 645         inotify_fds = 0;
 646 #endif
 647
 648         /* Start polling the FD. Keep one fd for inotify */
 649         pollfd = malloc((inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
 650
 651 #ifdef HAS_INOTIFY
 652         pollfd[0].fd = inotify_fd;
 653         pollfd[0].events = POLLIN|POLLPRI;
 654 #endif
 655
 656         for(i=0;i<fd_pairs->num_pairs;i++) {
 657                 pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
 658                 pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
 659         }
 660
 661         while(1) {
 662                 high_prio = 0;
 663                 num_hup = 0;
 664 #ifdef DEBUG
 665                 printf("Press a key for next poll...\n");
 666                 char buf[1];
 667                 read(STDIN_FILENO, &buf, 1);
 668                 printf("Next poll (polling %d fd) :\n", 1+fd_pairs->num_pairs);
 669 #endif //DEBUG
 670
 671                 /* Have we received a signal ? */
 672                 if(quit_program) break;
 673
 674                 num_rdy = poll(pollfd, inotify_fds+fd_pairs->num_pairs, -1);
 675                 if(num_rdy == -1) {
 676                         perror("Poll error");
 677                         goto free_fd;
 678                 }
 679
 680                 printf("Data received\n");
 681 #ifdef HAS_INOTIFY
 682                 switch(pollfd[0].revents) {
 683                         case POLLERR:
 684                                 printf("Error returned in polling inotify fd %d.\n", pollfd[0].fd);
 685                                 break;
 686                         case POLLHUP:
 687                                 printf("Polling inotify fd %d tells it has hung up.\n", pollfd[0].fd);
 688                                 break;
 689                         case POLLNVAL:
 690                                 printf("Polling inotify fd %d tells fd is not open.\n", pollfd[0].fd);
 691                                 break;
 692                         case POLLPRI:
 693                         case POLLIN:
 694                                 printf("Polling inotify fd %d : data ready.\n", pollfd[0].fd);
 695                                 old_num = fd_pairs->num_pairs;
 696                                 read_inotify(inotify_fd, fd_pairs, iwatch_array);
 697                                 pollfd = realloc(pollfd,
 698                                                 (inotify_fds + fd_pairs->num_pairs) * sizeof(struct pollfd));
 699                                 for(i=old_num;i<fd_pairs->num_pairs;i++) {
 700                                         pollfd[inotify_fds+i].fd = fd_pairs->pair[i].channel;
 701                                         pollfd[inotify_fds+i].events = POLLIN|POLLPRI;
 702                                 }
 703                         break;
 704                 }
 705 #endif
 706
 707                 for(i=inotify_fds;i<inotify_fds+fd_pairs->num_pairs;i++) {
 708                         switch(pollfd[i].revents) {
 709                                 case POLLERR:
 710                                         printf("Error returned in polling fd %d.\n", pollfd[i].fd);
 711                                         num_hup++;
 712                                         break;
 713                                 case POLLHUP:
 714                                         printf("Polling fd %d tells it has hung up.\n", pollfd[i].fd);
 715                                         num_hup++;
 716                                         break;
 717                                 case POLLNVAL:
 718                                         printf("Polling fd %d tells fd is not open.\n", pollfd[i].fd);
 719                                         num_hup++;
 720                                         break;
 721                                 case POLLPRI:
 722                                         if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
 723                                                 printf("Urgent read on fd %d\n", pollfd[i].fd);
 724                                                 /* Take care of high priority channels first. */
 725                                                 high_prio = 1;
 726                                                 /* it's ok to have an unavailable subbuffer */
 727                                                 ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
 728                                                 if(ret == EAGAIN) ret = 0;
 729
 730                                                 ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
 731                                                 if(ret)
 732                                                         printf("Error in mutex unlock : %s\n", strerror(ret));
 733                                         }
 734                                         break;
 735                         }
 736                 }
 737                 /* If every buffer FD has hung up, we end the read loop here */
 738                 if(num_hup == fd_pairs->num_pairs) break;
 739
 740                 if(!high_prio) {
 741                         for(i=inotify_fds;i<inotify_fds+fd_pairs->num_pairs;i++) {
 742                                 switch(pollfd[i].revents) {
 743                                         case POLLIN:
 744                                                 if(pthread_mutex_trylock(&fd_pairs->pair[i-inotify_fds].mutex) == 0) {
 745                                                         /* Take care of low priority channels. */
 746                                                         printf("Normal read on fd %d\n", pollfd[i].fd);
 747                                                         /* it's ok to have an unavailable subbuffer */
 748                                                         ret = read_subbuffer(&fd_pairs->pair[i-inotify_fds]);
 749                                                         if(ret == EAGAIN) ret = 0;
 750
 751                                                         ret = pthread_mutex_unlock(&fd_pairs->pair[i-inotify_fds].mutex);
 752                                                         if(ret)
 753                                                                 printf("Error in mutex unlock : %s\n", strerror(ret));
 754                                                 }
 755                                                 break;
 756                                 }
 757                         }
 758                 }
 759
 760         }
 761
 762 free_fd:
 763         free(pollfd);
 764
 765 end:
 766         return ret;
 767 }
 768
 769
 770 void close_channel_trace_pairs(struct channel_trace_fd *fd_pairs, int inotify_fd,
 771         struct inotify_watch_array *iwatch_array)
 772 {
 773         int i;
 774         int ret;
 775
 776         for(i=0;i<fd_pairs->num_pairs;i++) {
 777                 ret = close(fd_pairs->pair[i].channel);
 778                 if(ret == -1) perror("Close error on channel");
 779                 ret = close(fd_pairs->pair[i].trace);
 780                 if(ret == -1) perror("Close error on trace");
 781         }
 782         free(fd_pairs->pair);
 783         free(iwatch_array->elem);
 784 }
 785
 786 /* Thread worker */
 787 void * thread_main(void *arg)
 788 {
 789         struct channel_trace_fd fd_pairs = { NULL, 0 };
 790         int inotify_fd = -1;
 791         struct inotify_watch_array inotify_watch_array = { NULL, 0 };
 792         int ret = 0;
 793         unsigned int thread_num = (unsigned int)arg;
 794
 795         inotify_fd = inotify_init();
 796
 797         if(ret = open_channel_trace_pairs(channel_name, trace_name, &fd_pairs,
 798                         &inotify_fd, &inotify_watch_array))
 799                 goto close_channel;
 800
 801         if(ret = map_channels(&fd_pairs, 0, fd_pairs.num_pairs))
 802                 goto close_channel;
 803
 804         ret = read_channels(thread_num, &fd_pairs, inotify_fd, &inotify_watch_array);
 805
 806         ret |= unmap_channels(&fd_pairs);
 807
 808 close_channel:
 809         close_channel_trace_pairs(&fd_pairs, inotify_fd, &inotify_watch_array);
 810         if(inotify_fd >= 0)
 811                 close(inotify_fd);
 812
 813         return (void*)ret;
 814 }
 815
 816 int main(int argc, char ** argv)
 817 {
 818         int ret = 0;
 819         struct sigaction act;
 820         pthread_t *tids;
 821         unsigned int i;
 822         void *tret;
 823
 824         ret = parse_arguments(argc, argv);
 825
 826         if(ret != 0) show_arguments();
 827         if(ret < 0) return EINVAL;
 828         if(ret > 0) return 0;
 829
 830         show_info();
 831
 832         if(daemon_mode) {
 833                 ret = daemon(0, 0);
 834
 835                 if(ret == -1) {
 836                         perror("An error occured while daemonizing.");
 837                         exit(-1);
 838                 }
 839         }
 840
 841         /* Connect the signal handlers */
 842         act.sa_handler = handler;
 843         act.sa_flags = 0;
 844         sigemptyset(&(act.sa_mask));
 845         sigaddset(&(act.sa_mask), SIGTERM);
 846         sigaddset(&(act.sa_mask), SIGQUIT);
 847         sigaddset(&(act.sa_mask), SIGINT);
 848         sigaction(SIGTERM, &act, NULL);
 849         sigaction(SIGQUIT, &act, NULL);
 850         sigaction(SIGINT, &act, NULL);
 851
 852         tids = malloc(sizeof(pthread_t) * num_threads);
 853         for(i=0; i<num_threads; i++) {
 854
 855                 ret = pthread_create(&tids[i], NULL, thread_main, (void*)i);
 856                 if(ret) {
 857                         perror("Error creating thread");
 858                         break;
 859                 }
 860         }
 861
 862         for(i=0; i<num_threads; i++) {
 863                 ret = pthread_join(tids[i], &tret);
 864                 if(ret) {
 865                         perror("Error joining thread");
 866                         break;
 867                 }
 868                 if((int)tret != 0) {
 869                         printf("Error %s occured in thread %u\n", strerror((int)tret), i);
 870                 }
 871         }
 872
 873         free(tids);
 874
 875         return ret;
 876 }