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(...) {print_usage(); fprintf(stderr, "Error:\n    " __VA_ARGS__); exit(EXIT_FAILURE);}
  21 #define ERRMSG "ERROR"
  22
  23 static const char errmsg[] = ERRMSG;
  24 static const int  errlen   = sizeof(ERRMSG) - 1;
  25
  26 char *argv0;
  27
  28 /* TODO: Convert fifo list to fifo array. */
  29 typedef struct Fifo Fifo;
  30 struct Fifo {
  31         char   *name;
  32         int     fd;
  33         int     width;
  34         struct timespec last_read;
  35         struct timespec ttl;
  36         int     pos_init;  /* Initial position on the output buffer. */
  37         int     pos_curr;  /* Current position on the output buffer. */
  38         int     pos_final; /* Final   position on the output buffer. */
  39         Fifo   *next;
  40 };
  41
  42 typedef struct Config Config;
  43 struct Config {
  44         double interval;
  45         char * separator;
  46         Fifo * fifos;
  47         int    fifo_count;
  48         int    total_width;
  49         int    output_to_x_root_window;
  50 } defaults = {
  51         .interval    = 1.0,
  52         .separator   = "|",
  53         .fifos       = NULL,
  54         .fifo_count  = 0,
  55         .total_width = 0,
  56         .output_to_x_root_window = 0,
  57 };
  58
  59 enum read_status {
  60         END_OF_FILE,
  61         END_OF_MESSAGE,
  62         RETRY,
  63         FAILURE
  64 };
  65
  66 void
  67 fifo_print_one(Fifo *f)
  68 {
  69         info("Fifo "
  70             "{"
  71             " name = %s,"
  72             " fd = %d,"
  73             " width = %d,"
  74             " last_read = {tv_sec = %ld, tv_nsec = %ld}"
  75             " ttl = {tv_sec = %ld, tv_nsec = %ld},"
  76             " pos_init = %d,"
  77             " pos_curr = %d,"
  78             " pos_final = %d,"
  79             " next = %p,"
  80             " }\n",
  81             f->name,
  82             f->fd,
  83             f->width,
  84             f->last_read.tv_sec,
  85             f->last_read.tv_nsec,
  86             f->ttl.tv_sec,
  87             f->ttl.tv_nsec,
  88             f->pos_init,
  89             f->pos_curr,
  90             f->pos_final,
  91             f->next
  92         );
  93 }
  94
  95 void
  96 fifo_print_all(Fifo *head)
  97 {
  98         for (Fifo *f = head; f; f = f->next) {
  99                 fifo_print_one(f);
 100         }
 101 }
 102
 103 void
 104 config_print(Config *cfg)
 105 {
 106         info(
 107             "Config "
 108             "{"
 109             " interval = %f,"
 110             " separator = %s,"
 111             " fifo_count = %d,"
 112             " total_width = %d,"
 113             " fifos = ..."
 114             " }\n",
 115             cfg->interval,
 116             cfg->separator,
 117             cfg->fifo_count,
 118             cfg->total_width
 119         );
 120         fifo_print_all(cfg->fifos);
 121 }
 122
 123 int
 124 is_pos_num(char *s)
 125 {
 126         while (*s != '\0')
 127                 if (!isdigit(*(s++)))
 128                         return 0;
 129         return 1;
 130 }
 131
 132 int
 133 is_decimal(char *s)
 134 {
 135         char c;
 136         int seen = 0;
 137
 138         while ((c = *(s++)) != '\0')
 139                 if (!isdigit(c)) {
 140                         if (c == '.' && !seen++)
 141                                 continue;
 142                         else
 143                                 return 0;
 144                 }
 145         return 1;
 146 }
 147
 148 void
 149 print_usage()
 150 {
 151         assert(argv0);
 152         fprintf(
 153             stderr,
 154             "\n"
 155             "Usage: %s [OPTION ...] SPEC [SPEC ...]\n"
 156             "\n"
 157             "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
 158             "  FILE_PATH  = string\n"
 159             "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
 160             "  DATA_TTL   = float  (* (positive) number of seconds *)\n"
 161             "  OPTION     = -i INTERVAL\n"
 162             "             | -s SEPARATOR\n"
 163             "             | -x (* Output to X root window *)\n"
 164             "             | -l LOG_LEVEL\n"
 165             "  SEPARATOR  = string\n"
 166             "  INTERVAL   = float  (* (positive) number of seconds *)\n"
 167             "  LOG_LEVEL  = int  (* %d through %d *)\n"
 168             "\n",
 169             argv0,
 170             Nothing,
 171             Debug
 172         );
 173         fprintf(
 174             stderr,
 175             "Example: %s -i 1 /dev/shm/khatus/khatus_sensor_x 4 10\n"
 176             "\n",
 177             argv0
 178         );
 179 }
 180
 181 void opts_parse_any(Config *, int, char *[], int);  /* For mutually-recursive calls. */
 182
 183 void
 184 parse_opts_opt_i(Config *cfg, int argc, char *argv[], int i)
 185 {
 186         char *param;
 187
 188         if (i >= argc)
 189                 usage("Option -i parameter is missing.\n");
 190         param = argv[i++];
 191         if (!is_decimal(param))
 192                 usage("Option -i parameter is invalid: \"%s\"\n", param);
 193         cfg->interval = atof(param);
 194         opts_parse_any(cfg, argc, argv, i);
 195 }
 196
 197 void
 198 parse_opts_opt_s(Config *cfg, int argc, char *argv[], int i)
 199 {
 200         if (i >= argc)
 201                 usage("Option -s parameter is missing.\n");
 202         cfg->separator = calloc((strlen(argv[i]) + 1), sizeof(char));
 203         strcpy(cfg->separator, argv[i]);
 204         opts_parse_any(cfg, argc, argv, ++i);
 205 }
 206
 207 void
 208 parse_opts_opt_l(Config *cfg, int argc, char *argv[], int i)
 209 {
 210         char *param;
 211         int log_level;
 212
 213         if (i >= argc)
 214                 usage("Option -l parameter is missing.\n");
 215         param = argv[i++];
 216         if (!is_pos_num(param))
 217                 usage("Option -l parameter is invalid: \"%s\"\n", param);
 218         log_level = atoi(param);
 219         if (log_level > Debug)
 220                 usage("Option -l value (%d) exceeds maximum (%d)\n", log_level, Debug);
 221         _khatus_lib_log_level = log_level;
 222         opts_parse_any(cfg, argc, argv, i);
 223 }
 224
 225 void
 226 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 227 {
 228         switch (argv[i][1]) {
 229         case 'i':
 230                 /* TODO: Generic set_int */
 231                 parse_opts_opt_i(cfg, argc, argv, ++i);
 232                 break;
 233         case 's':
 234                 /* TODO: Generic set_str */
 235                 parse_opts_opt_s(cfg, argc, argv, ++i);
 236                 break;
 237         case 'x':
 238                 cfg->output_to_x_root_window = 1;
 239                 opts_parse_any(cfg, argc, argv, ++i);
 240                 break;
 241         case 'l':
 242                 /* TODO: Generic set_int */
 243                 parse_opts_opt_l(cfg, argc, argv, ++i);
 244                 break;
 245         default :
 246                 usage("Option \"%s\" is invalid\n", argv[i]);
 247         }
 248 }
 249
 250 void
 251 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 252 {
 253         if ((i + 3) > argc)
 254                 usage("[spec] Parameter(s) missing for fifo \"%s\".\n", argv[i]);
 255
 256         char *n = argv[i++];
 257         char *w = argv[i++];
 258         char *t = argv[i++];
 259
 260         struct timespec last_read;
 261
 262         if (!is_pos_num(w))
 263                 usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 264         if (!is_decimal(t))
 265                 usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
 266         last_read.tv_sec  = 0;
 267         last_read.tv_nsec = 0;
 268         Fifo *f = calloc(1, sizeof(struct Fifo));
 269         if (f) {
 270                 f->name      = n;
 271                 f->fd        = -1;
 272                 f->width     = atoi(w);
 273                 f->ttl       = timespec_of_float(atof(t));
 274                 f->last_read = last_read;
 275                 f->pos_init  = cfg->total_width;
 276                 f->pos_curr  = f->pos_init;
 277                 f->pos_final = f->pos_init + f->width - 1;
 278                 f->next      = cfg->fifos;
 279
 280                 cfg->fifos        = f;
 281                 cfg->total_width += f->width;
 282                 cfg->fifo_count++;
 283         } else {
 284                 fatal("[memory] Allocation failure.");
 285         }
 286         opts_parse_any(cfg, argc, argv, i);
 287 }
 288
 289 void
 290 opts_parse_any(Config *cfg, int argc, char *argv[], int i)
 291 {
 292         if (i < argc) {
 293                 switch (argv[i][0]) {
 294                 case '-':
 295                         parse_opts_opt(cfg, argc, argv, i);
 296                         break;
 297                 default :
 298                         parse_opts_spec(cfg, argc, argv, i);
 299                 }
 300         }
 301 }
 302
 303 void
 304 opts_parse(Config *cfg, int argc, char *argv[])
 305 {
 306         opts_parse_any(cfg, argc, argv, 1);
 307
 308         Fifo *last = cfg->fifos;
 309         cfg->fifos = NULL;
 310         for (Fifo *f = last; f; ) {
 311                 Fifo *next = f->next;
 312                 f->next = cfg->fifos;
 313                 cfg->fifos = f;
 314                 f = next;
 315         }
 316 }
 317
 318 void
 319 fifo_expire(Fifo *f, struct timespec t, char *buf)
 320 {
 321         struct timespec td;
 322
 323         timespecsub(&t, &(f->last_read), &td);
 324         if (timespeccmp(&td, &(f->ttl), >=)) {
 325                 /* TODO: Maybe configurable expiry character. */
 326                 memset(buf + f->pos_init, '_', f->pos_final - f->pos_init);
 327                 warn("Data source expired: \"%s\"\n", f->name);
 328         }
 329 }
 330
 331 void
 332 fifo_read_error(Fifo *f, char *buf)
 333 {
 334         char *b;
 335         int i;
 336
 337         b = buf + f->pos_init;
 338         /* Copy as much of the error message as possible.
 339          * EXCLUDING the terminating \0. */
 340         for (i = 0; i < errlen && i < f->width; i++)
 341                 b[i] = errmsg[i];
 342         /* Any remaining slots: */
 343         for (; i < f->width; i++)
 344                 b[i] = '_';
 345 }
 346
 347 enum read_status
 348 fifo_read_one(Fifo *f, struct timespec t, char *buf)
 349 {
 350         char c;  /* Character read. */
 351         int  r;  /* Remaining unused slots in buffer range. */
 352
 353         for (;;) {
 354                 switch (read(f->fd, &c, 1)) {
 355                 case -1:
 356                         error("Failed to read: \"%s\". errno: %d, msg: %s\n",
 357                             f->name, errno, strerror(errno));
 358                         switch (errno) {
 359                         case EINTR:
 360                         case EAGAIN:
 361                                 return RETRY;
 362                         default:
 363                                 return FAILURE;
 364                         }
 365                 case  0:
 366                         debug("%s: End of FILE\n", f->name);
 367                         f->pos_curr = f->pos_init;
 368                         return END_OF_FILE;
 369                 case  1:
 370                         /* TODO: Consider making msg term char a CLI option */
 371                         if (c == '\n' || c == '\0') {
 372                                 r = f->pos_final - f->pos_curr;
 373                                 if (r > 0)
 374                                         memset(buf + f->pos_curr, ' ', r);
 375                                 f->pos_curr = f->pos_init;
 376                                 f->last_read = t;
 377                                 return END_OF_MESSAGE;
 378                         } else {
 379                                 if (f->pos_curr <= f->pos_final)
 380                                         buf[f->pos_curr++] = c;
 381                                 /* Drop beyond available range. */
 382                         }
 383                         break;
 384                 default:
 385                         assert(0);
 386                 }
 387         }
 388 }
 389
 390 void
 391 fifo_read_all(Config *cfg, struct timespec *ti, char *buf)
 392 {
 393         fd_set fds;
 394         int maxfd = -1;
 395         int ready = 0;
 396         struct stat st;
 397         struct timespec t;
 398
 399         FD_ZERO(&fds);
 400         for (Fifo *f = cfg->fifos; f; f = f->next) {
 401                 /* TODO: Create the FIFO if it doesn't already exist. */
 402                 if (lstat(f->name, &st) < 0) {
 403                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 404                         fifo_read_error(f, buf);
 405                         continue;
 406                 }
 407                 if (!(st.st_mode & S_IFIFO)) {
 408                         error("\"%s\" is not a FIFO\n", f->name);
 409                         fifo_read_error(f, buf);
 410                         continue;
 411                 }
 412                 if (f->fd < 0) {
 413                         debug("%s: closed. opening. fd: %d\n", f->name, f->fd);
 414                         f->fd = open(f->name, O_RDONLY | O_NONBLOCK);
 415                 } else {
 416                         debug("%s: already openned. fd: %d\n", f->name, f->fd);
 417                 }
 418                 if (f->fd == -1) {
 419                         /* TODO: Consider backing off retries for failed fifos. */
 420                         error("Failed to open \"%s\"\n", f->name);
 421                         fifo_read_error(f, buf);
 422                         continue;
 423                 }
 424                 debug("%s: open. fd: %d\n", f->name, f->fd);
 425                 if (f->fd > maxfd)
 426                         maxfd = f->fd;
 427                 FD_SET(f->fd, &fds);
 428         }
 429         debug("selecting...\n");
 430         ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
 431         debug("ready: %d\n", ready);
 432         assert(ready >= 0);
 433         clock_gettime(CLOCK_MONOTONIC, &t);
 434         /* At-least-once ensures that expiries are still checked on timeouts. */
 435         do {
 436                 for (Fifo *f = cfg->fifos; f; f = f->next) {
 437                         if (FD_ISSET(f->fd, &fds)) {
 438                                 debug("reading: %s\n", f->name);
 439                                 switch (fifo_read_one(f, t, buf)) {
 440                                 /*
 441                                  * ### MESSAGE LOSS ###
 442                                  * is introduced by closing at EOM in addition
 443                                  * to EOF, since there may be unread messages
 444                                  * remaining in the pipe. However,
 445                                  *
 446                                  * ### INTER-MESSAGE PUSHBACK ###
 447                                  * is also gained, since pipes block at the
 448                                  * "open" call.
 449                                  *
 450                                  * This is an acceptable trade-off because we
 451                                  * are a stateless reporter of a _most-recent_
 452                                  * status, not a stateful accumulator.
 453                                  */
 454                                 case END_OF_MESSAGE:
 455                                 case END_OF_FILE:
 456                                 case FAILURE:
 457                                         close(f->fd);
 458                                         f->fd = -1;
 459                                         ready--;
 460                                         break;
 461                                 case RETRY:
 462                                         break;
 463                                 default:
 464                                         assert(0);
 465                                 }
 466                         } else {
 467                                 fifo_expire(f, t, buf);
 468                         }
 469                 }
 470         } while (ready);
 471         assert(ready == 0);
 472 }
 473
 474 int
 475 main(int argc, char *argv[])
 476 {
 477         int width  = 0;
 478         int nfifos = 0;
 479         int seplen = 0;
 480         int prefix = 0;
 481         int errors = 0;
 482         char *buf;
 483         Config cfg0 = defaults;
 484         Config *cfg = &cfg0;
 485         Display *display = NULL;
 486         struct stat st;
 487         struct timespec
 488                 t0,  /* time stamp. before reading fifos */
 489                 t1,  /* time stamp. after  reading fifos */
 490                 ti,  /* time interval desired    (t1 - t0) */
 491                 td,  /* time interval measured   (t1 - t0) */
 492                 tc;  /* time interval correction (ti - td) when td < ti */
 493
 494         argv0 = argv[0];
 495
 496         opts_parse(cfg, argc, argv);
 497         debug("argv0 = %s\n", argv0);
 498         config_print(cfg);
 499
 500         ti = timespec_of_float(cfg->interval);
 501
 502         if (cfg->fifos == NULL)
 503                 usage("No fifo specs were given!\n");
 504
 505         /* 1st pass to check file existence and type */
 506         for (Fifo *f = cfg->fifos; f; f = f->next) {
 507                 if (lstat(f->name, &st) < 0) {
 508                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 509                         errors++;
 510                         continue;
 511                 }
 512                 if (!(st.st_mode & S_IFIFO)) {
 513                         error("\"%s\" is not a FIFO\n", f->name);
 514                         errors++;
 515                         continue;
 516                 }
 517         }
 518         if (errors)
 519                 fatal("Encountered errors with the given file paths. See log.\n");
 520
 521         width  = cfg->total_width;
 522         seplen = strlen(cfg->separator);
 523
 524         /* 2nd pass to make space for separators */
 525         for (Fifo *f = cfg->fifos; f; f = f->next) {
 526                 f->pos_init  += prefix;
 527                 f->pos_final += prefix;
 528                 f->pos_curr = f->pos_init;
 529                 prefix += seplen;
 530                 nfifos++;
 531         }
 532         width += (seplen * (nfifos - 1));
 533         buf = calloc(1, width + 1);
 534         if (buf == NULL)
 535                 fatal("[memory] Failed to allocate buffer of %d bytes", width);
 536         memset(buf, ' ', width);
 537         buf[width] = '\0';
 538         /* 3rd pass to set the separators */
 539         for (Fifo *f = cfg->fifos; f; f = f->next) {
 540                 if (f->pos_init) {  /* Skip the first, left-most */
 541                         /* Copying only seplen ensures we omit the '\0' byte. */
 542                         strncpy(buf + (f->pos_init - seplen), cfg->separator, seplen);
 543                 }
 544         }
 545
 546         if (cfg->output_to_x_root_window && !(display = XOpenDisplay(NULL)))
 547                 fatal("XOpenDisplay failed with: %p\n", display);
 548         /* TODO: Handle signals */
 549         for (;;) {
 550                 clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
 551                 fifo_read_all(cfg, &ti, buf);
 552                 if (cfg->output_to_x_root_window) {
 553                         if (XStoreName(display, DefaultRootWindow(display), buf) < 0)
 554                                 fatal("XStoreName failed.\n");
 555                         XFlush(display);
 556                 } else {
 557                         puts(buf);
 558                         fflush(stdout);
 559                 }
 560                 clock_gettime(CLOCK_MONOTONIC, &t1); // FIXME: check errors
 561                 timespecsub(&t1, &t0, &td);
 562                 debug("td {tv_sec = %ld, tv_nsec = %ld}\n", td.tv_sec, td.tv_nsec);
 563                 if (timespeccmp(&td, &ti, <)) {
 564                         /* Pushback on data producers by refusing to read the
 565                          * pipe more frequently than the interval.
 566                          */
 567                         timespecsub(&ti, &td, &tc);
 568                         debug("snooze YES\n");
 569                         snooze(&tc);
 570                 } else {
 571                         debug("snooze NO\n");
 572                 }
 573         }
 574
 575         return EXIT_SUCCESS;
 576 }