x5/khatus.c

   1 #include <sys/select.h>
   2 #include <sys/stat.h>
   3
   4 #include <assert.h>
   5 #include <ctype.h>
   6 #include <errno.h>
   7 #include <fcntl.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <time.h>
  12 #include <unistd.h>
  13
  14 #include <X11/Xlib.h>
  15
  16 #include "bsdtimespec.h"
  17 #include "khlib_log.h"
  18 #include "khlib_time.h"
  19
  20 #define usage(...) { \
  21         print_usage(); \
  22         fprintf(stderr, "Error:\n    " __VA_ARGS__); \
  23         exit(EXIT_FAILURE); \
  24 }
  25 #define ERRMSG "ERROR"
  26
  27 static const char errmsg[] = ERRMSG;
  28 static const int  errlen   = sizeof(ERRMSG) - 1;
  29
  30 char *argv0;
  31
  32 /* TODO: Convert slot list to slot array. */
  33 typedef struct Slot Slot;
  34 struct Slot {
  35         char            *in_fifo;
  36         int              in_fd;
  37         struct timespec  in_last_read;
  38         struct timespec  out_ttl;
  39         int              out_width;
  40         int              out_pos_lo;   /* Lowest  position on the output buffer. */
  41         int              out_pos_cur;  /* Current position on the output buffer. */
  42         int              out_pos_hi;   /* Highest position on the output buffer. */
  43         Slot            *next;
  44 };
  45
  46 typedef struct Config Config;
  47 struct Config {
  48         double interval;
  49         char * separator;
  50         Slot * slots;
  51         int    slot_count;
  52         int    total_width;
  53         int    output_to_x_root_window;
  54 };
  55
  56 enum read_status {
  57         END_OF_FILE,
  58         END_OF_MESSAGE,
  59         RETRY,
  60         FAILURE
  61 };
  62
  63 void
  64 slot_print_one(Slot *s)
  65 {
  66         khlib_info("Slot "
  67             "{"
  68             " in_fifo = %s,"
  69             " in_fd = %d,"
  70             " out_width = %d,"
  71             " in_last_read = {tv_sec = %ld, tv_nsec = %ld}"
  72             " out_ttl = {tv_sec = %ld, tv_nsec = %ld},"
  73             " out_pos_lo = %d,"
  74             " out_pos_cur = %d,"
  75             " out_pos_hi = %d,"
  76             " next = %p,"
  77             " }\n",
  78             s->in_fifo,
  79             s->in_fd,
  80             s->out_width,
  81             s->in_last_read.tv_sec,
  82             s->in_last_read.tv_nsec,
  83             s->out_ttl.tv_sec,
  84             s->out_ttl.tv_nsec,
  85             s->out_pos_lo,
  86             s->out_pos_cur,
  87             s->out_pos_hi,
  88             s->next
  89         );
  90 }
  91
  92 void
  93 slot_print_all(Slot *head)
  94 {
  95         for (Slot *s = head; s; s = s->next) {
  96                 slot_print_one(s);
  97         }
  98 }
  99
 100 void
 101 config_print(Config *cfg)
 102 {
 103         khlib_info(
 104             "Config "
 105             "{"
 106             " interval = %f,"
 107             " separator = %s,"
 108             " slot_count = %d,"
 109             " total_width = %d,"
 110             " slots = ..."
 111             " }\n",
 112             cfg->interval,
 113             cfg->separator,
 114             cfg->slot_count,
 115             cfg->total_width
 116         );
 117         slot_print_all(cfg->slots);
 118 }
 119
 120 int
 121 is_pos_num(char *str)
 122 {
 123         while (*str != '\0')
 124                 if (!isdigit(*(str++)))
 125                         return 0;
 126         return 1;
 127 }
 128
 129 int
 130 is_decimal(char *str)
 131 {
 132         char c;
 133         int seen = 0;
 134
 135         while ((c = *(str++)) != '\0')
 136                 if (!isdigit(c)) {
 137                         if (c == '.' && !seen++)
 138                                 continue;
 139                         else
 140                                 return 0;
 141                 }
 142         return 1;
 143 }
 144
 145 void
 146 print_usage()
 147 {
 148         assert(argv0);
 149         fprintf(
 150             stderr,
 151             "\n"
 152             "Usage: %s [OPTION ...] SPEC [SPEC ...]\n"
 153             "\n"
 154             "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
 155             "  FILE_PATH  = string\n"
 156             "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
 157             "  DATA_TTL   = float  (* (positive) number of seconds *)\n"
 158             "  OPTION     = -i INTERVAL\n"
 159             "             | -s SEPARATOR\n"
 160             "             | -x (* Output to X root window *)\n"
 161             "             | -l LOG_LEVEL\n"
 162             "  SEPARATOR  = string\n"
 163             "  INTERVAL   = float  (* (positive) number of seconds *)\n"
 164             "  LOG_LEVEL  = int  (* %d through %d *)\n"
 165             "\n",
 166             argv0,
 167             Nothing,
 168             Debug
 169         );
 170         fprintf(
 171             stderr,
 172             "Example: %s -i 1 /dev/shm/khatus/khatus_sensor_x 4 10\n"
 173             "\n",
 174             argv0
 175         );
 176 }
 177
 178 /* For mutually-recursive calls. */
 179 void opts_parse_any(Config *, int, char *[], int);
 180
 181 void
 182 parse_opts_opt_i(Config *cfg, int argc, char *argv[], int i)
 183 {
 184         char *param;
 185
 186         if (i >= argc)
 187                 usage("Option -i parameter is missing.\n");
 188         param = argv[i++];
 189         if (!is_decimal(param))
 190                 usage("Option -i parameter is invalid: \"%s\"\n", param);
 191         cfg->interval = atof(param);
 192         opts_parse_any(cfg, argc, argv, i);
 193 }
 194
 195 void
 196 parse_opts_opt_s(Config *cfg, int argc, char *argv[], int i)
 197 {
 198         if (i >= argc)
 199                 usage("Option -s parameter is missing.\n");
 200         cfg->separator = calloc((strlen(argv[i]) + 1), sizeof(char));
 201         strcpy(cfg->separator, argv[i]);
 202         opts_parse_any(cfg, argc, argv, ++i);
 203 }
 204
 205 void
 206 parse_opts_opt_l(Config *cfg, int argc, char *argv[], int i)
 207 {
 208         char *param;
 209         int log_level;
 210
 211         if (i >= argc)
 212                 usage("Option -l parameter is missing.\n");
 213         param = argv[i++];
 214         if (!is_pos_num(param))
 215                 usage("Option -l parameter is invalid: \"%s\"\n", param);
 216         log_level = atoi(param);
 217         if (log_level > Debug)
 218                 usage(
 219                     "Option -l value (%d) exceeds maximum (%d)\n",
 220                     log_level,
 221                     Debug
 222                 );
 223         _khlib_log_level = log_level;
 224         opts_parse_any(cfg, argc, argv, i);
 225 }
 226
 227 void
 228 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 229 {
 230         switch (argv[i][1]) {
 231         case 'i':
 232                 /* TODO: Generic set_int */
 233                 parse_opts_opt_i(cfg, argc, argv, ++i);
 234                 break;
 235         case 's':
 236                 /* TODO: Generic set_str */
 237                 parse_opts_opt_s(cfg, argc, argv, ++i);
 238                 break;
 239         case 'x':
 240                 cfg->output_to_x_root_window = 1;
 241                 opts_parse_any(cfg, argc, argv, ++i);
 242                 break;
 243         case 'l':
 244                 /* TODO: Generic set_int */
 245                 parse_opts_opt_l(cfg, argc, argv, ++i);
 246                 break;
 247         default :
 248                 usage("Option \"%s\" is invalid\n", argv[i]);
 249         }
 250 }
 251
 252 void
 253 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 254 {
 255         if ((i + 3) > argc)
 256                 usage(
 257                     "[spec] Parameter(s) missing for fifo \"%s\".\n",
 258                     argv[i]
 259                 );
 260
 261         char *n = argv[i++];
 262         char *w = argv[i++];
 263         char *t = argv[i++];
 264
 265         struct timespec in_last_read;
 266
 267         if (!is_pos_num(w))
 268                 usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 269         if (!is_decimal(t))
 270                 usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
 271         in_last_read.tv_sec  = 0;
 272         in_last_read.tv_nsec = 0;
 273         Slot *s = calloc(1, sizeof(struct Slot));
 274         if (s) {
 275                 s->in_fifo      = n;
 276                 s->in_fd        = -1;
 277                 s->out_width     = atoi(w);
 278                 s->out_ttl       = khlib_timespec_of_float(atof(t));
 279                 s->in_last_read = in_last_read;
 280                 s->out_pos_lo  = cfg->total_width;
 281                 s->out_pos_cur  = s->out_pos_lo;
 282                 s->out_pos_hi = s->out_pos_lo + s->out_width - 1;
 283                 s->next      = cfg->slots;
 284
 285                 cfg->slots        = s;
 286                 cfg->total_width += s->out_width;
 287                 cfg->slot_count++;
 288         } else {
 289                 khlib_fatal("[memory] Allocation failure.");
 290         }
 291         opts_parse_any(cfg, argc, argv, i);
 292 }
 293
 294 void
 295 opts_parse_any(Config *cfg, int argc, char *argv[], int i)
 296 {
 297         if (i < argc) {
 298                 switch (argv[i][0]) {
 299                 case '-':
 300                         parse_opts_opt(cfg, argc, argv, i);
 301                         break;
 302                 default :
 303                         parse_opts_spec(cfg, argc, argv, i);
 304                 }
 305         }
 306 }
 307
 308 void
 309 opts_parse(Config *cfg, int argc, char *argv[])
 310 {
 311         opts_parse_any(cfg, argc, argv, 1);
 312
 313         Slot *last = cfg->slots;
 314         cfg->slots = NULL;
 315         for (Slot *s = last; s; ) {
 316                 Slot *next = s->next;
 317                 s->next = cfg->slots;
 318                 cfg->slots = s;
 319                 s = next;
 320         }
 321 }
 322
 323 void
 324 slot_expire(Slot *s, struct timespec t, char *buf)
 325 {
 326         struct timespec td;
 327
 328         timespecsub(&t, &(s->in_last_read), &td);
 329         if (timespeccmp(&td, &(s->out_ttl), >=)) {
 330                 /* TODO: Maybe configurable expiry character. */
 331                 memset(buf + s->out_pos_lo, '_', s->out_pos_hi - s->out_pos_lo);
 332                 khlib_warn("Slot expired: \"%s\"\n", s->in_fifo);
 333         }
 334 }
 335
 336 void
 337 slot_read_error(Slot *s, char *buf)
 338 {
 339         char *b;
 340         int i;
 341
 342         b = buf + s->out_pos_lo;
 343         /* Copy as much of the error message as possible.
 344          * EXCLUDING the terminating \0. */
 345         for (i = 0; i < errlen && i < s->out_width; i++)
 346                 b[i] = errmsg[i];
 347         /* Any remaining slots: */
 348         for (; i < s->out_width; i++)
 349                 b[i] = '_';
 350 }
 351
 352 enum read_status
 353 slot_read_one(Slot *s, struct timespec t, char *buf)
 354 {
 355         char c;  /* Character read. */
 356         int  r;  /* Remaining unused slots in buffer range. */
 357
 358         for (;;) {
 359                 switch (read(s->in_fd, &c, 1)) {
 360                 case -1:
 361                         khlib_error(
 362                             "Failed to read: \"%s\". errno: %d, msg: %s\n",
 363                             s->in_fifo,
 364                             errno,
 365                             strerror(errno)
 366                         );
 367                         switch (errno) {
 368                         case EINTR:
 369                         case EAGAIN:
 370                                 return RETRY;
 371                         default:
 372                                 return FAILURE;
 373                         }
 374                 case  0:
 375                         khlib_debug("%s: End of FILE\n", s->in_fifo);
 376                         s->out_pos_cur = s->out_pos_lo;
 377                         return END_OF_FILE;
 378                 case  1:
 379                         /* TODO: Consider making msg term char a CLI option */
 380                         if (c == '\n' || c == '\0') {
 381                                 r = s->out_pos_hi - s->out_pos_cur;
 382                                 if (r > 0)
 383                                         memset(buf + s->out_pos_cur, ' ', r);
 384                                 s->out_pos_cur = s->out_pos_lo;
 385                                 s->in_last_read = t;
 386                                 return END_OF_MESSAGE;
 387                         } else {
 388                                 if (s->out_pos_cur <= s->out_pos_hi)
 389                                         buf[s->out_pos_cur++] = c;
 390                                 /* Drop beyond available range. */
 391                                 /*
 392                                  * TODO Define max after which we stop reading.
 393                                  *      To ensure that a rogue large message
 394                                  *      doesn't trap us here.
 395                                  */
 396                         }
 397                         break;
 398                 default:
 399                         assert(0);
 400                 }
 401         }
 402 }
 403
 404 void
 405 slot_read_all(Config *cfg, struct timespec *ti, char *buf)
 406 {
 407         fd_set fds;
 408         int maxfd = -1;
 409         int ready = 0;
 410         struct stat st;
 411         struct timespec t;
 412
 413         FD_ZERO(&fds);
 414         for (Slot *s = cfg->slots; s; s = s->next) {
 415                 /* TODO: Create the FIFO if it doesn't already exist. */
 416                 if (lstat(s->in_fifo, &st) < 0) {
 417                         khlib_error(
 418                             "Cannot stat \"%s\". Error: %s\n",
 419                             s->in_fifo,
 420                             strerror(errno)
 421                         );
 422                         slot_read_error(s, buf);
 423                         continue;
 424                 }
 425                 if (!(st.st_mode & S_IFIFO)) {
 426                         khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
 427                         slot_read_error(s, buf);
 428                         continue;
 429                 }
 430                 if (s->in_fd < 0) {
 431                         khlib_debug(
 432                             "%s: closed. opening. in_fd: %d\n",
 433                             s->in_fifo,
 434                             s->in_fd
 435                         );
 436                         s->in_fd = open(s->in_fifo, O_RDONLY | O_NONBLOCK);
 437                 } else {
 438                         khlib_debug(
 439                             "%s: already openned. in_fd: %d\n",
 440                             s->in_fifo,
 441                             s->in_fd
 442                         );
 443                 }
 444                 if (s->in_fd == -1) {
 445                         /* TODO Consider backing off retries for failed slots */
 446                         khlib_error("Failed to open \"%s\"\n", s->in_fifo);
 447                         slot_read_error(s, buf);
 448                         continue;
 449                 }
 450                 khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
 451                 if (s->in_fd > maxfd)
 452                         maxfd = s->in_fd;
 453                 FD_SET(s->in_fd, &fds);
 454         }
 455         khlib_debug("selecting...\n");
 456         ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
 457         khlib_debug("ready: %d\n", ready);
 458         clock_gettime(CLOCK_MONOTONIC, &t);
 459         if (ready == -1) {
 460                 switch (errno) {
 461                 case EINTR:
 462                         khlib_error(
 463                             "pselect temp failure: %d, errno: %d, msg: %s\n",
 464                             ready,
 465                             errno,
 466                             strerror(errno)
 467                         );
 468                         /* TODO: Reconsider what to do here. */
 469                         return;
 470                 default:
 471                         khlib_fatal(
 472                             "pselect failed: %d, errno: %d, msg: %s\n",
 473                             ready,
 474                             errno,
 475                             strerror(errno)
 476                         );
 477                 }
 478         }
 479         /* At-least-once ensures that expiries are still checked on timeouts. */
 480         do {
 481                 for (Slot *s = cfg->slots; s; s = s->next) {
 482                         if (FD_ISSET(s->in_fd, &fds)) {
 483                                 khlib_debug("reading: %s\n", s->in_fifo);
 484                                 switch (slot_read_one(s, t, buf)) {
 485                                 /*
 486                                  * ### MESSAGE LOSS ###
 487                                  * is introduced by closing at EOM in addition
 488                                  * to EOF, since there may be unread messages
 489                                  * remaining in the pipe. However,
 490                                  *
 491                                  * ### INTER-MESSAGE PUSHBACK ###
 492                                  * is also gained, since pipes block at the
 493                                  * "open" call.
 494                                  *
 495                                  * This is an acceptable trade-off because we
 496                                  * are a stateless reporter of a _most-recent_
 497                                  * status, not a stateful accumulator.
 498                                  */
 499                                 case END_OF_MESSAGE:
 500                                 case END_OF_FILE:
 501                                 case FAILURE:
 502                                         close(s->in_fd);
 503                                         s->in_fd = -1;
 504                                         ready--;
 505                                         break;
 506                                 case RETRY:
 507                                         break;
 508                                 default:
 509                                         assert(0);
 510                                 }
 511                         } else {
 512                                 slot_expire(s, t, buf);
 513                         }
 514                 }
 515         } while (ready);
 516         assert(ready == 0);
 517 }
 518
 519 int
 520 main(int argc, char *argv[])
 521 {
 522         Config cfg = {
 523                 .interval    = 1.0,
 524                 .separator   = "|",
 525                 .slots       = NULL,
 526                 .slot_count  = 0,
 527                 .total_width = 0,
 528                 .output_to_x_root_window = 0,
 529         };
 530
 531         int width  = 0;
 532         int nslots = 0;
 533         int seplen = 0;
 534         int prefix = 0;
 535         int errors = 0;
 536         char *buf;
 537         Display *d = NULL;
 538         struct stat st;
 539         struct timespec
 540                 t0,  /* time stamp. before reading slots */
 541                 t1,  /* time stamp. after  reading slots */
 542                 ti,  /* time interval desired    (t1 - t0) */
 543                 td,  /* time interval measured   (t1 - t0) */
 544                 tc;  /* time interval correction (ti - td) when td < ti */
 545
 546         argv0 = argv[0];
 547
 548         opts_parse(&cfg, argc, argv);
 549         khlib_debug("argv0 = %s\n", argv0);
 550         config_print(&cfg);
 551
 552         ti = khlib_timespec_of_float(cfg.interval);
 553
 554         if (cfg.slots == NULL)
 555                 usage("No slot specs were given!\n");
 556
 557         /* 1st pass to check file existence and type */
 558         for (Slot *s = cfg.slots; s; s = s->next) {
 559                 if (lstat(s->in_fifo, &st) < 0) {
 560                         khlib_error(
 561                             "Cannot stat \"%s\". Error: %s\n",
 562                             s->in_fifo,
 563                             strerror(errno)
 564                         );
 565                         errors++;
 566                         continue;
 567                 }
 568                 if (!(st.st_mode & S_IFIFO)) {
 569                         khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
 570                         errors++;
 571                         continue;
 572                 }
 573         }
 574         if (errors)
 575                 khlib_fatal(
 576                     "Encountered errors with given file paths. See log.\n"
 577                 );
 578
 579         width  = cfg.total_width;
 580         seplen = strlen(cfg.separator);
 581
 582         /* 2nd pass to make space for separators */
 583         for (Slot *s = cfg.slots; s; s = s->next) {
 584                 s->out_pos_lo  += prefix;
 585                 s->out_pos_hi += prefix;
 586                 s->out_pos_cur = s->out_pos_lo;
 587                 prefix += seplen;
 588                 nslots++;
 589         }
 590         width += (seplen * (nslots - 1));
 591         buf = calloc(1, width + 1);
 592         if (buf == NULL)
 593                 khlib_fatal(
 594                     "[memory] Failed to allocate buffer of %d bytes",
 595                     width
 596                 );
 597         memset(buf, ' ', width);
 598         buf[width] = '\0';
 599         /* 3rd pass to set the separators */
 600         for (Slot *s = cfg.slots; s; s = s->next) {
 601                 if (s->out_pos_lo) {  /* Skip the first, left-most */
 602                         /* Copying only seplen ensures we omit the '\0' byte. */
 603                         strncpy(
 604                             buf + (s->out_pos_lo - seplen),
 605                             cfg.separator,
 606                             seplen
 607                         );
 608                 }
 609         }
 610
 611         if (cfg.output_to_x_root_window && !(d = XOpenDisplay(NULL)))
 612                 khlib_fatal("XOpenDisplay failed with: %p\n", d);
 613         /* TODO: Handle signals */
 614         for (;;) {
 615                 clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
 616                 slot_read_all(&cfg, &ti, buf);
 617                 if (cfg.output_to_x_root_window) {
 618                         if (XStoreName(d, DefaultRootWindow(d), buf) < 0)
 619                                 khlib_fatal("XStoreName failed.\n");
 620                         XFlush(d);
 621                 } else {
 622                         puts(buf);
 623                         fflush(stdout);
 624                 }
 625                 clock_gettime(CLOCK_MONOTONIC, &t1); // FIXME: check errors
 626                 timespecsub(&t1, &t0, &td);
 627                 khlib_debug(
 628                     "td {tv_sec = %ld, tv_nsec = %ld}\n",
 629                     td.tv_sec,
 630                     td.tv_nsec
 631                 );
 632                 if (timespeccmp(&td, &ti, <)) {
 633                         /* Pushback on data producers by refusing to read the
 634                          * pipe more frequently than the interval.
 635                          */
 636                         timespecsub(&ti, &td, &tc);
 637                         khlib_debug("khlib_sleep YES\n");
 638                         khlib_sleep(&tc);
 639                 } else {
 640                         khlib_debug("khlib_sleep NO\n");
 641                 }
 642         }
 643
 644         return EXIT_SUCCESS;
 645 }