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(
  73                 "Fifo "
  74                 "{"
  75                         " name = %s,"
  76                         " fd = %d,"
  77                         " width = %d,"
  78                         " last_read = %d,"
  79                         " ttl = %d,"
  80                         " pos = %d,"
  81                         " next = %p,"
  82                 " }\n",
  83                 f->name,
  84                 f->fd,
  85                 f->width,
  86                 f->last_read,
  87                 f->ttl,
  88                 f->pos,
  89                 f->next
  90         );
  91 }
  92
  93 void
  94 fifo_print_all(Fifo *head, Config *cfg)
  95 {
  96         for (Fifo *f = head; f; f = f->next) {
  97                 fifo_print_one(f, cfg);
  98         }
  99 }
 100
 101 void
 102 config_print(Config *cfg)
 103 {
 104         info(
 105                 "Config "
 106                 "{"
 107                         " interval = %d,"
 108                         " separator = %s,"
 109                         " fifo_count = %d,"
 110                         " total_width = %d,"
 111                         " log_level = %d,"
 112                         " fifos = ..."
 113                 " }\n",
 114                 cfg->interval,
 115                 cfg->separator,
 116                 cfg->fifo_count,
 117                 cfg->total_width,
 118                 cfg->log_level
 119         );
 120         fifo_print_all(cfg->fifos, cfg);
 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 void
 133 print_usage()
 134 {
 135         assert(argv0);
 136         fprintf(
 137                 stderr,
 138                 "\n"
 139                 "Usage: %s [OPTION ...] SPEC [SPEC ...]\n"
 140                 "\n"
 141                 "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
 142                 "  FILE_PATH  = string\n"
 143                 "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
 144                 "  DATA_TTL   = int  (* (positive) number of seconds *)\n"
 145                 "  OPTION     = -i INTERVAL\n"
 146                 "             | -s SEPARATOR\n"
 147                 "             | -x (* Output to X root window *)\n"
 148                 "             | -l LOG_LEVEL\n"
 149                 "  SEPARATOR  = string\n"
 150                 "  INTERVAL   = int  (* (positive) number of seconds *)\n"
 151                 "  LOG_LEVEL  = int  (* %d through %d *)\n"
 152                 "\n",
 153                 argv0,
 154                 Nothing,
 155                 Debug
 156         );
 157         fprintf(
 158                 stderr,
 159                 "Example: %s -i 1 /dev/shm/khatus/khatus_sensor_x 4 10\n"
 160                 "\n",
 161                 argv0
 162         );
 163 }
 164
 165 void opts_parse_any(Config *, int, char *[], int);  /* For mutually-recursive calls. */
 166
 167 void
 168 parse_opts_opt_i(Config *cfg, int argc, char *argv[], int i)
 169 {
 170         if (i < argc) {
 171                 char *param = argv[i++];
 172
 173                 if (is_pos_num(param)) {
 174                         cfg->interval = atoi(param);
 175                         opts_parse_any(cfg, argc, argv, i);
 176                 } else {
 177                         usage("Option -i parameter is invalid: \"%s\"\n", param);
 178                 }
 179         } else {
 180                 usage("Option -i parameter is missing.\n");
 181         }
 182 }
 183
 184 void
 185 parse_opts_opt_s(Config *cfg, int argc, char *argv[], int i)
 186 {
 187         if (i < argc) {
 188                 cfg->separator = calloc((strlen(argv[i]) + 1), sizeof(char));
 189                 strcpy(cfg->separator, argv[i]);
 190                 opts_parse_any(cfg, argc, argv, ++i);
 191         } else {
 192                 usage("Option -s parameter is missing.\n");
 193         }
 194 }
 195
 196 void
 197 parse_opts_opt_l(Config *cfg, int argc, char *argv[], int i)
 198 {
 199         int log_level;
 200
 201         if (i < argc) {
 202                 char *param = argv[i++];
 203
 204                 if (is_pos_num(param)) {
 205                         log_level = atoi(param);
 206                         if (log_level <= Debug) {
 207                                 cfg->log_level = log_level;
 208                                 opts_parse_any(cfg, argc, argv, i);
 209                         } else {
 210                                 usage("Option -l value (%d) exceeds maximum (%d)\n", log_level, Debug);
 211                         }
 212                 } else {
 213                         usage("Option -l parameter is invalid: \"%s\"\n", param);
 214                 }
 215         } else {
 216                 usage("Option -l parameter is missing.\n");
 217         }
 218 }
 219
 220 void
 221 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 222 {
 223         switch (argv[i][1]) {
 224                 case 'i':
 225                         /* TODO: Generic set_int */
 226                         parse_opts_opt_i(cfg, argc, argv, ++i);
 227                         break;
 228                 case 's':
 229                         /* TODO: Generic set_str */
 230                         parse_opts_opt_s(cfg, argc, argv, ++i);
 231                         break;
 232                 case 'x':
 233                         cfg->output_to_x_root_window = 1;
 234                         opts_parse_any(cfg, argc, argv, ++i);
 235                         break;
 236                 case 'l':
 237                         /* TODO: Generic set_int */
 238                         parse_opts_opt_l(cfg, argc, argv, ++i);
 239                         break;
 240                 default :
 241                         usage("Option \"%s\" is invalid\n", argv[i]);
 242         }
 243 }
 244
 245 void
 246 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 247 {
 248         if ((i + 3) > argc)
 249                 usage("[spec] Parameter(s) missing for fifo \"%s\".\n", argv[i]);
 250
 251         char *n = argv[i++];
 252         char *w = argv[i++];
 253         char *t = argv[i++];
 254
 255         if (!is_pos_num(w))
 256                 usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 257         if (!is_pos_num(t))
 258                 usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
 259         Fifo *f = calloc(1, sizeof(struct Fifo));
 260         if (f) {
 261                 f->name      = n;
 262                 f->fd        = -1;
 263                 f->width     = atoi(w);
 264                 f->ttl       = atoi(t);
 265                 f->last_read = 0;
 266                 f->pos       = cfg->total_width;
 267                 f->next      = cfg->fifos;
 268
 269                 cfg->fifos        = f;
 270                 cfg->total_width += f->width;
 271                 cfg->fifo_count++;
 272         } else {
 273                 fatal("[memory] Allocation failure.");
 274         }
 275         opts_parse_any(cfg, argc, argv, i);
 276 }
 277
 278 void
 279 opts_parse_any(Config *cfg, int argc, char *argv[], int i)
 280 {
 281         if (i < argc) {
 282                 switch (argv[i][0]) {
 283                         case '-':
 284                                 parse_opts_opt(cfg, argc, argv, i);
 285                                 break;
 286                         default :
 287                                 parse_opts_spec(cfg, argc, argv, i);
 288                 }
 289         }
 290 }
 291
 292 void
 293 opts_parse(Config *cfg, int argc, char *argv[])
 294 {
 295         opts_parse_any(cfg, argc, argv, 1);
 296
 297         Fifo *last = cfg->fifos;
 298         cfg->fifos = NULL;
 299         for (Fifo *f = last; f; ) {
 300                 Fifo *next = f->next;
 301                 f->next = cfg->fifos;
 302                 cfg->fifos = f;
 303                 f = next;
 304         }
 305 }
 306
 307 void
 308 fifo_read_error(Fifo *f, char *buf)
 309 {
 310         char *b;
 311         int i;
 312
 313         b = buf + f->pos;
 314         /* Copy as much of the error message as possible.
 315          * EXCLUDING the reminating \0. */
 316         for (i = 0; i < errlen && i < f->width; i++)
 317                 b[i] = errmsg[i];
 318         /* Any remaining slots: */
 319         for (; i < f->width; i++)
 320                 b[i] = '_';
 321 }
 322
 323 void
 324 fifo_read_one(Fifo *f, char *buf, Config *cfg)
 325 {
 326         ssize_t current;
 327         ssize_t total;
 328         char *b;
 329         char c;
 330
 331         current = 0;
 332         total = 0;
 333         c = '\0';
 334         b = buf + f->pos;
 335         while ((current = read(f->fd, &c, 1)) && c != '\n' && c != '\0' && total++ < f->width)
 336                 *b++ = c;
 337         if (current == -1) {
 338                 error("Failed to read: \"%s\". Error: %s\n", f->name, strerror(errno));
 339                 fifo_read_error(f, buf);
 340         } else
 341                 while (total++ < f->width)
 342                         *b++ = ' ';
 343         /* TODO Record timestamp read */
 344         close(f->fd);
 345         f->fd = -1;
 346 }
 347
 348 void
 349 fifo_read_all(Config *cfg, char *buf)
 350 {
 351         fd_set fds;
 352         int maxfd = -1;
 353         int ready;
 354         struct stat st;
 355
 356         FD_ZERO(&fds);
 357         for (Fifo *f = cfg->fifos; f; f = f->next) {
 358                 /* TODO: Create the FIFO if it doesn't already exist. */
 359                 if (lstat(f->name, &st) < 0) {
 360                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 361                         fifo_read_error(f, buf);
 362                         continue;
 363                 }
 364                 if (!(st.st_mode & S_IFIFO)) {
 365                         error("\"%s\" is not a FIFO\n", f->name);
 366                         fifo_read_error(f, buf);
 367                         continue;
 368                 }
 369                 debug("opening: %s\n", f->name);
 370                 if (f->fd < 0)
 371                         f->fd = open(f->name, O_RDONLY | O_NONBLOCK);
 372                 if (f->fd == -1) {
 373                         /* TODO: Consider backing off retries for failed fifos. */
 374                         error("Failed to open \"%s\"\n", f->name);
 375                         fifo_read_error(f, buf);
 376                         continue;
 377                 }
 378                 if (f->fd > maxfd)
 379                         maxfd = f->fd;
 380                 FD_SET(f->fd, &fds);
 381         }
 382         debug("selecting...\n");
 383         ready = select(maxfd + 1, &fds, NULL, NULL, NULL);
 384         debug("ready: %d\n", ready);
 385         assert(ready != 0);
 386         if (ready < 0)
 387                 fatal("%s", strerror(errno));
 388         for (Fifo *f = cfg->fifos; f; f = f->next) {
 389                 if (FD_ISSET(f->fd, &fds)) {
 390                         debug("reading: %s\n", f->name);
 391                         fifo_read_one(f, buf, cfg);
 392                 }
 393         }
 394 }
 395
 396 void
 397 snooze(struct timespec *t, Config *cfg)
 398 {
 399         struct timespec remainder;
 400         int result;
 401
 402         result = nanosleep(t, &remainder);
 403
 404         if (result < 0) {
 405                 if (errno == EINTR) {
 406                         info(
 407                                 "nanosleep interrupted. Remainder: "
 408                                 "{ tv_sec = %ld, tv_nsec = %ld }",
 409                                 remainder.tv_sec, remainder.tv_nsec);
 410                         /* No big deal if we occasionally sleep less,
 411                          * so not attempting to correct after an interruption.
 412                          */
 413                 } else {
 414                         fatal("nanosleep: %s\n", strerror(errno));
 415                 }
 416         }
 417 }
 418
 419 int
 420 main(int argc, char *argv[])
 421 {
 422         int width  = 0;
 423         int nfifos = 0;
 424         int seplen = 0;
 425         int prefix = 0;
 426         int errors = 0;
 427         char *buf;
 428         Config cfg0 = defaults;
 429         Config *cfg = &cfg0;
 430         Display *display = NULL;
 431         struct stat st;
 432         struct timespec
 433                 t0,  /* time stamp. before reading fifos */
 434                 t1,  /* time stamp. after  reading fifos */
 435                 ti,  /* time interval desired    (t1 - t0) */
 436                 td,  /* time interval measured   (t1 - t0) */
 437                 tc;  /* time interval correction (ti - td) when td < ti */
 438
 439         argv0 = argv[0];
 440
 441         opts_parse(cfg, argc, argv);
 442         debug("argv0 = %s\n", argv0);
 443         config_print(cfg);
 444
 445         /* TODO: Support interval < 1. i.e. implement timespec_of_float */
 446         ti.tv_sec  = cfg->interval;
 447         ti.tv_nsec = 0;
 448
 449         if (cfg->fifos == NULL)
 450                 usage("No fifo specs were given!\n");
 451
 452         /* 1st pass to check file existence and type */
 453         for (Fifo *f = cfg->fifos; f; f = f->next) {
 454                 if (lstat(f->name, &st) < 0) {
 455                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 456                         errors++;
 457                         continue;
 458                 }
 459                 if (!(st.st_mode & S_IFIFO)) {
 460                         error("\"%s\" is not a FIFO\n", f->name);
 461                         errors++;
 462                         continue;
 463                 }
 464         }
 465         if (errors)
 466                 fatal("Encountered errors with the given file paths. See log.\n");
 467
 468         width  = cfg->total_width;
 469         seplen = strlen(cfg->separator);
 470
 471         /* 2nd pass to make space for separators */
 472         for (Fifo *f = cfg->fifos; f; f = f->next) {
 473                 f->pos += prefix;
 474                 prefix += seplen;
 475                 nfifos++;
 476         }
 477         width += (seplen * (nfifos - 1));
 478         buf = calloc(1, width + 1);
 479         if (buf == NULL)
 480                 fatal("[memory] Failed to allocate buffer of %d bytes", width);
 481         memset(buf, ' ', width);
 482         buf[width] = '\0';
 483         /* 3rd pass to set the separators */
 484         for (Fifo *f = cfg->fifos; f; f = f->next) {
 485                 if (f->pos) {  /* Skip the first, left-most */
 486                         /* Copying only seplen ensures we omit the '\0' byte. */
 487                         strncpy(buf + (f->pos - seplen), cfg->separator, seplen);
 488                 }
 489         }
 490
 491         if (cfg->output_to_x_root_window && !(display = XOpenDisplay(NULL)))
 492                 fatal("XOpenDisplay failed with: %p\n", display);
 493         /* TODO: Handle signals */
 494         for (;;) {
 495                 clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
 496                 /* TODO: Cache expiration. i.e. use the TTL */
 497                 /* TODO: How to trigger TTL check? On select? Alarm signal? */
 498                 /* TODO: Set timeout on fifo_read_all based on diff of last time of
 499                  *       fifo_read_all and desired time of next TTL check.
 500                  */
 501                 /* TODO: How long to wait on IO? Max TTL? */
 502                 fifo_read_all(cfg, buf);
 503                 if (cfg->output_to_x_root_window) {
 504                         if (XStoreName(display, DefaultRootWindow(display), buf) < 0)
 505                                 fatal("XStoreName failed.\n");
 506                         XFlush(display);
 507                 } else {
 508                         puts(buf);
 509                         fflush(stdout);
 510                 }
 511                 clock_gettime(CLOCK_MONOTONIC, &t1); // FIXME: check errors
 512                 timespecsub(&t1, &t0, &td);
 513                 debug("td {tv_sec = %ld, tv_nsec = %ld}\n", td.tv_sec, td.tv_nsec);
 514                 if (timespeccmp(&td, &ti, <)) {
 515                         /* Pushback on data producers by refusing to read the
 516                          * pipe more frequently than the interval.
 517                          */
 518                         timespecsub(&ti, &td, &tc);
 519                         debug("snooze YES\n");
 520                         snooze(&tc, cfg);
 521                 } else
 522                         debug("snooze NO\n");
 523         }
 524
 525         return EXIT_SUCCESS;
 526 }