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