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 "khatus_lib_log.h"
  18 #include "khatus_lib_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 fifo list to fifo array. */
  33 typedef struct Fifo Fifo;
  34 struct Fifo {
  35         char   *name;
  36         int     fd;
  37         int     width;
  38         struct timespec last_read;
  39         struct timespec ttl;
  40         int     pos_init;  /* Initial position on the output buffer. */
  41         int     pos_curr;  /* Current position on the output buffer. */
  42         int     pos_final; /* Final   position on the output buffer. */
  43         Fifo   *next;
  44 };
  45
  46 typedef struct Config Config;
  47 struct Config {
  48         double interval;
  49         char * separator;
  50         Fifo * fifos;
  51         int    fifo_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 fifo_print_one(Fifo *f)
  65 {
  66         info("Fifo "
  67             "{"
  68             " name = %s,"
  69             " fd = %d,"
  70             " width = %d,"
  71             " last_read = {tv_sec = %ld, tv_nsec = %ld}"
  72             " ttl = {tv_sec = %ld, tv_nsec = %ld},"
  73             " pos_init = %d,"
  74             " pos_curr = %d,"
  75             " pos_final = %d,"
  76             " next = %p,"
  77             " }\n",
  78             f->name,
  79             f->fd,
  80             f->width,
  81             f->last_read.tv_sec,
  82             f->last_read.tv_nsec,
  83             f->ttl.tv_sec,
  84             f->ttl.tv_nsec,
  85             f->pos_init,
  86             f->pos_curr,
  87             f->pos_final,
  88             f->next
  89         );
  90 }
  91
  92 void
  93 fifo_print_all(Fifo *head)
  94 {
  95         for (Fifo *f = head; f; f = f->next) {
  96                 fifo_print_one(f);
  97         }
  98 }
  99
 100 void
 101 config_print(Config *cfg)
 102 {
 103         info(
 104             "Config "
 105             "{"
 106             " interval = %f,"
 107             " separator = %s,"
 108             " fifo_count = %d,"
 109             " total_width = %d,"
 110             " fifos = ..."
 111             " }\n",
 112             cfg->interval,
 113             cfg->separator,
 114             cfg->fifo_count,
 115             cfg->total_width
 116         );
 117         fifo_print_all(cfg->fifos);
 118 }
 119
 120 int
 121 is_pos_num(char *s)
 122 {
 123         while (*s != '\0')
 124                 if (!isdigit(*(s++)))
 125                         return 0;
 126         return 1;
 127 }
 128
 129 int
 130 is_decimal(char *s)
 131 {
 132         char c;
 133         int seen = 0;
 134
 135         while ((c = *(s++)) != '\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         _khatus_lib_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 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         last_read.tv_sec  = 0;
 272         last_read.tv_nsec = 0;
 273         Fifo *f = calloc(1, sizeof(struct Fifo));
 274         if (f) {
 275                 f->name      = n;
 276                 f->fd        = -1;
 277                 f->width     = atoi(w);
 278                 f->ttl       = timespec_of_float(atof(t));
 279                 f->last_read = last_read;
 280                 f->pos_init  = cfg->total_width;
 281                 f->pos_curr  = f->pos_init;
 282                 f->pos_final = f->pos_init + f->width - 1;
 283                 f->next      = cfg->fifos;
 284
 285                 cfg->fifos        = f;
 286                 cfg->total_width += f->width;
 287                 cfg->fifo_count++;
 288         } else {
 289                 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         Fifo *last = cfg->fifos;
 314         cfg->fifos = NULL;
 315         for (Fifo *f = last; f; ) {
 316                 Fifo *next = f->next;
 317                 f->next = cfg->fifos;
 318                 cfg->fifos = f;
 319                 f = next;
 320         }
 321 }
 322
 323 void
 324 fifo_expire(Fifo *f, struct timespec t, char *buf)
 325 {
 326         struct timespec td;
 327
 328         timespecsub(&t, &(f->last_read), &td);
 329         if (timespeccmp(&td, &(f->ttl), >=)) {
 330                 /* TODO: Maybe configurable expiry character. */
 331                 memset(buf + f->pos_init, '_', f->pos_final - f->pos_init);
 332                 warn("Data source expired: \"%s\"\n", f->name);
 333         }
 334 }
 335
 336 void
 337 fifo_read_error(Fifo *f, char *buf)
 338 {
 339         char *b;
 340         int i;
 341
 342         b = buf + f->pos_init;
 343         /* Copy as much of the error message as possible.
 344          * EXCLUDING the terminating \0. */
 345         for (i = 0; i < errlen && i < f->width; i++)
 346                 b[i] = errmsg[i];
 347         /* Any remaining slots: */
 348         for (; i < f->width; i++)
 349                 b[i] = '_';
 350 }
 351
 352 enum read_status
 353 fifo_read_one(Fifo *f, 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(f->fd, &c, 1)) {
 360                 case -1:
 361                         error("Failed to read: \"%s\". errno: %d, msg: %s\n",
 362                             f->name, errno, strerror(errno));
 363                         switch (errno) {
 364                         case EINTR:
 365                         case EAGAIN:
 366                                 return RETRY;
 367                         default:
 368                                 return FAILURE;
 369                         }
 370                 case  0:
 371                         debug("%s: End of FILE\n", f->name);
 372                         f->pos_curr = f->pos_init;
 373                         return END_OF_FILE;
 374                 case  1:
 375                         /* TODO: Consider making msg term char a CLI option */
 376                         if (c == '\n' || c == '\0') {
 377                                 r = f->pos_final - f->pos_curr;
 378                                 if (r > 0)
 379                                         memset(buf + f->pos_curr, ' ', r);
 380                                 f->pos_curr = f->pos_init;
 381                                 f->last_read = t;
 382                                 return END_OF_MESSAGE;
 383                         } else {
 384                                 if (f->pos_curr <= f->pos_final)
 385                                         buf[f->pos_curr++] = c;
 386                                 /* Drop beyond available range. */
 387                                 /*
 388                                  * TODO Define max after which we stop reading.
 389                                  *      To ensure that a rogue large message
 390                                  *      doesn't trap us here.
 391                                  */
 392                         }
 393                         break;
 394                 default:
 395                         assert(0);
 396                 }
 397         }
 398 }
 399
 400 void
 401 fifo_read_all(Config *cfg, struct timespec *ti, char *buf)
 402 {
 403         fd_set fds;
 404         int maxfd = -1;
 405         int ready = 0;
 406         struct stat st;
 407         struct timespec t;
 408
 409         FD_ZERO(&fds);
 410         for (Fifo *f = cfg->fifos; f; f = f->next) {
 411                 /* TODO: Create the FIFO if it doesn't already exist. */
 412                 if (lstat(f->name, &st) < 0) {
 413                         error(
 414                             "Cannot stat \"%s\". Error: %s\n",
 415                             f->name,
 416                             strerror(errno)
 417                         );
 418                         fifo_read_error(f, buf);
 419                         continue;
 420                 }
 421                 if (!(st.st_mode & S_IFIFO)) {
 422                         error("\"%s\" is not a FIFO\n", f->name);
 423                         fifo_read_error(f, buf);
 424                         continue;
 425                 }
 426                 if (f->fd < 0) {
 427                         debug("%s: closed. opening. fd: %d\n", f->name, f->fd);
 428                         f->fd = open(f->name, O_RDONLY | O_NONBLOCK);
 429                 } else {
 430                         debug("%s: already openned. fd: %d\n", f->name, f->fd);
 431                 }
 432                 if (f->fd == -1) {
 433                         /* TODO Consider backing off retries for failed fifos */
 434                         error("Failed to open \"%s\"\n", f->name);
 435                         fifo_read_error(f, buf);
 436                         continue;
 437                 }
 438                 debug("%s: open. fd: %d\n", f->name, f->fd);
 439                 if (f->fd > maxfd)
 440                         maxfd = f->fd;
 441                 FD_SET(f->fd, &fds);
 442         }
 443         debug("selecting...\n");
 444         ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
 445         debug("ready: %d\n", ready);
 446         clock_gettime(CLOCK_MONOTONIC, &t);
 447         if (ready == -1) {
 448                 switch (errno) {
 449                 case EINTR:
 450                         error("pselect temp failure: %d, errno: %d, msg: %s\n",
 451                             ready, errno, strerror(errno));
 452                         /* TODO: Reconsider what to do here. */
 453                         return;
 454                 default:
 455                         fatal("pselect failed: %d, errno: %d, msg: %s\n",
 456                             ready, errno, strerror(errno));
 457                 }
 458         }
 459         /* At-least-once ensures that expiries are still checked on timeouts. */
 460         do {
 461                 for (Fifo *f = cfg->fifos; f; f = f->next) {
 462                         if (FD_ISSET(f->fd, &fds)) {
 463                                 debug("reading: %s\n", f->name);
 464                                 switch (fifo_read_one(f, t, buf)) {
 465                                 /*
 466                                  * ### MESSAGE LOSS ###
 467                                  * is introduced by closing at EOM in addition
 468                                  * to EOF, since there may be unread messages
 469                                  * remaining in the pipe. However,
 470                                  *
 471                                  * ### INTER-MESSAGE PUSHBACK ###
 472                                  * is also gained, since pipes block at the
 473                                  * "open" call.
 474                                  *
 475                                  * This is an acceptable trade-off because we
 476                                  * are a stateless reporter of a _most-recent_
 477                                  * status, not a stateful accumulator.
 478                                  */
 479                                 case END_OF_MESSAGE:
 480                                 case END_OF_FILE:
 481                                 case FAILURE:
 482                                         close(f->fd);
 483                                         f->fd = -1;
 484                                         ready--;
 485                                         break;
 486                                 case RETRY:
 487                                         break;
 488                                 default:
 489                                         assert(0);
 490                                 }
 491                         } else {
 492                                 fifo_expire(f, t, buf);
 493                         }
 494                 }
 495         } while (ready);
 496         assert(ready == 0);
 497 }
 498
 499 int
 500 main(int argc, char *argv[])
 501 {
 502         Config cfg = {
 503                 .interval    = 1.0,
 504                 .separator   = "|",
 505                 .fifos       = NULL,
 506                 .fifo_count  = 0,
 507                 .total_width = 0,
 508                 .output_to_x_root_window = 0,
 509         };
 510
 511         int width  = 0;
 512         int nfifos = 0;
 513         int seplen = 0;
 514         int prefix = 0;
 515         int errors = 0;
 516         char *buf;
 517         Display *d = NULL;
 518         struct stat st;
 519         struct timespec
 520                 t0,  /* time stamp. before reading fifos */
 521                 t1,  /* time stamp. after  reading fifos */
 522                 ti,  /* time interval desired    (t1 - t0) */
 523                 td,  /* time interval measured   (t1 - t0) */
 524                 tc;  /* time interval correction (ti - td) when td < ti */
 525
 526         argv0 = argv[0];
 527
 528         opts_parse(&cfg, argc, argv);
 529         debug("argv0 = %s\n", argv0);
 530         config_print(&cfg);
 531
 532         ti = timespec_of_float(cfg.interval);
 533
 534         if (cfg.fifos == NULL)
 535                 usage("No fifo specs were given!\n");
 536
 537         /* 1st pass to check file existence and type */
 538         for (Fifo *f = cfg.fifos; f; f = f->next) {
 539                 if (lstat(f->name, &st) < 0) {
 540                         error(
 541                             "Cannot stat \"%s\". Error: %s\n",
 542                             f->name,
 543                             strerror(errno)
 544                         );
 545                         errors++;
 546                         continue;
 547                 }
 548                 if (!(st.st_mode & S_IFIFO)) {
 549                         error("\"%s\" is not a FIFO\n", f->name);
 550                         errors++;
 551                         continue;
 552                 }
 553         }
 554         if (errors)
 555                 fatal("Encountered errors with given file paths. See log.\n");
 556
 557         width  = cfg.total_width;
 558         seplen = strlen(cfg.separator);
 559
 560         /* 2nd pass to make space for separators */
 561         for (Fifo *f = cfg.fifos; f; f = f->next) {
 562                 f->pos_init  += prefix;
 563                 f->pos_final += prefix;
 564                 f->pos_curr = f->pos_init;
 565                 prefix += seplen;
 566                 nfifos++;
 567         }
 568         width += (seplen * (nfifos - 1));
 569         buf = calloc(1, width + 1);
 570         if (buf == NULL)
 571                 fatal("[memory] Failed to allocate buffer of %d bytes", width);
 572         memset(buf, ' ', width);
 573         buf[width] = '\0';
 574         /* 3rd pass to set the separators */
 575         for (Fifo *f = cfg.fifos; f; f = f->next) {
 576                 if (f->pos_init) {  /* Skip the first, left-most */
 577                         /* Copying only seplen ensures we omit the '\0' byte. */
 578                         strncpy(
 579                             buf + (f->pos_init - seplen),
 580                             cfg.separator,
 581                             seplen
 582                         );
 583                 }
 584         }
 585
 586         if (cfg.output_to_x_root_window && !(d = XOpenDisplay(NULL)))
 587                 fatal("XOpenDisplay failed with: %p\n", d);
 588         /* TODO: Handle signals */
 589         for (;;) {
 590                 clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
 591                 fifo_read_all(&cfg, &ti, buf);
 592                 if (cfg.output_to_x_root_window) {
 593                         if (XStoreName(d, DefaultRootWindow(d), buf) < 0)
 594                                 fatal("XStoreName failed.\n");
 595                         XFlush(d);
 596                 } else {
 597                         puts(buf);
 598                         fflush(stdout);
 599                 }
 600                 clock_gettime(CLOCK_MONOTONIC, &t1); // FIXME: check errors
 601                 timespecsub(&t1, &t0, &td);
 602                 debug(
 603                     "td {tv_sec = %ld, tv_nsec = %ld}\n",
 604                     td.tv_sec,
 605                     td.tv_nsec
 606                 );
 607                 if (timespeccmp(&td, &ti, <)) {
 608                         /* Pushback on data producers by refusing to read the
 609                          * pipe more frequently than the interval.
 610                          */
 611                         timespecsub(&ti, &td, &tc);
 612                         debug("snooze YES\n");
 613                         snooze(&tc);
 614                 } else {
 615                         debug("snooze NO\n");
 616                 }
 617         }
 618
 619         return EXIT_SUCCESS;
 620 }