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