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 warn( args...) if (cfg->log_level >= Warn ) {fprintf(stderr, "[warn] "  args); fflush(stderr);}
  21 #define error(args...) if (cfg->log_level >= Error) {fprintf(stderr, "[error] " args); fflush(stderr);}
  22 #define fatal(args...) {fprintf(stderr, "[fatal] " args); exit(EXIT_FAILURE);}
  23 #define usage(args...) {print_usage(); fatal("[usage] " args);}
  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 typedef enum LogLevel {
  33         Nothing,
  34         Error,
  35         Warn,
  36         Info,
  37         Debug
  38 } LogLevel;
  39
  40 /* TODO: Convert fifo list to fifo array. */
  41 typedef struct Fifo Fifo;
  42 struct Fifo {
  43         char   *name;
  44         int     fd;
  45         int     width;
  46         int     last_read;
  47         int     ttl;
  48         int     pos;  /* Position on the output buffer. */
  49         Fifo   *next;
  50 };
  51
  52 typedef struct Config Config;
  53 struct Config {
  54         int    interval;
  55         char * separator;
  56         Fifo * fifos;
  57         int    fifo_count;
  58         int    total_width;
  59         int    output_to_x_root_window;
  60         LogLevel log_level;
  61 } defaults = {
  62         .interval    = 1,
  63         .separator   = "|",
  64         .fifos       = NULL,
  65         .fifo_count  = 0,
  66         .total_width = 0,
  67         .output_to_x_root_window = 0,
  68         .log_level   = Info,
  69 };
  70
  71 void
  72 fifo_print_one(Fifo *f, Config *cfg)
  73 {
  74         info("Fifo "
  75             "{"
  76             " name = %s,"
  77             " fd = %d,"
  78             " width = %d,"
  79             " last_read = %d,"
  80             " ttl = %d,"
  81             " pos = %d,"
  82             " next = %p,"
  83             " }\n",
  84             f->name,
  85             f->fd,
  86             f->width,
  87             f->last_read,
  88             f->ttl,
  89             f->pos,
  90             f->next
  91         );
  92 }
  93
  94 void
  95 fifo_print_all(Fifo *head, Config *cfg)
  96 {
  97         for (Fifo *f = head; f; f = f->next) {
  98                 fifo_print_one(f, cfg);
  99         }
 100 }
 101
 102 void
 103 config_print(Config *cfg)
 104 {
 105         info(
 106             "Config "
 107             "{"
 108             " interval = %d,"
 109             " separator = %s,"
 110             " fifo_count = %d,"
 111             " total_width = %d,"
 112             " log_level = %d,"
 113             " fifos = ..."
 114             " }\n",
 115             cfg->interval,
 116             cfg->separator,
 117             cfg->fifo_count,
 118             cfg->total_width,
 119             cfg->log_level
 120         );
 121         fifo_print_all(cfg->fifos, cfg);
 122 }
 123
 124 int
 125 is_pos_num(char *s)
 126 {
 127         while (*s != '\0')
 128                 if (!isdigit(*(s++)))
 129                         return 0;
 130         return 1;
 131 }
 132
 133 void
 134 print_usage()
 135 {
 136         assert(argv0);
 137         fprintf(
 138             stderr,
 139             "\n"
 140             "Usage: %s [OPTION ...] SPEC [SPEC ...]\n"
 141             "\n"
 142             "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
 143             "  FILE_PATH  = string\n"
 144             "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
 145             "  DATA_TTL   = int  (* (positive) number of seconds *)\n"
 146             "  OPTION     = -i INTERVAL\n"
 147             "             | -s SEPARATOR\n"
 148             "             | -x (* Output to X root window *)\n"
 149             "             | -l LOG_LEVEL\n"
 150             "  SEPARATOR  = string\n"
 151             "  INTERVAL   = int  (* (positive) number of seconds *)\n"
 152             "  LOG_LEVEL  = int  (* %d through %d *)\n"
 153             "\n",
 154             argv0,
 155             Nothing,
 156             Debug
 157         );
 158         fprintf(
 159             stderr,
 160             "Example: %s -i 1 /dev/shm/khatus/khatus_sensor_x 4 10\n"
 161             "\n",
 162             argv0
 163         );
 164 }
 165
 166 void opts_parse_any(Config *, int, char *[], int);  /* For mutually-recursive calls. */
 167
 168 void
 169 parse_opts_opt_i(Config *cfg, int argc, char *argv[], int i)
 170 {
 171         char *param;
 172
 173         if (i >= argc)
 174                 usage("Option -i parameter is missing.\n");
 175         param = argv[i++];
 176         if (!is_pos_num(param))
 177                 usage("Option -i parameter is invalid: \"%s\"\n", param);
 178         cfg->interval = atoi(param);
 179         opts_parse_any(cfg, argc, argv, i);
 180 }
 181
 182 void
 183 parse_opts_opt_s(Config *cfg, int argc, char *argv[], int i)
 184 {
 185         if (i >= argc)
 186                 usage("Option -s parameter is missing.\n");
 187         cfg->separator = calloc((strlen(argv[i]) + 1), sizeof(char));
 188         strcpy(cfg->separator, argv[i]);
 189         opts_parse_any(cfg, argc, argv, ++i);
 190 }
 191
 192 void
 193 parse_opts_opt_l(Config *cfg, int argc, char *argv[], int i)
 194 {
 195         char *param;
 196         int log_level;
 197
 198         if (i >= argc)
 199                 usage("Option -l parameter is missing.\n");
 200         param = argv[i++];
 201         if (!is_pos_num(param))
 202                 usage("Option -l parameter is invalid: \"%s\"\n", param);
 203         log_level = atoi(param);
 204         if (log_level > Debug)
 205                 usage("Option -l value (%d) exceeds maximum (%d)\n", log_level, Debug);
 206         cfg->log_level = log_level;
 207         opts_parse_any(cfg, argc, argv, i);
 208 }
 209
 210 void
 211 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 212 {
 213         switch (argv[i][1]) {
 214         case 'i':
 215                 /* TODO: Generic set_int */
 216                 parse_opts_opt_i(cfg, argc, argv, ++i);
 217                 break;
 218         case 's':
 219                 /* TODO: Generic set_str */
 220                 parse_opts_opt_s(cfg, argc, argv, ++i);
 221                 break;
 222         case 'x':
 223                 cfg->output_to_x_root_window = 1;
 224                 opts_parse_any(cfg, argc, argv, ++i);
 225                 break;
 226         case 'l':
 227                 /* TODO: Generic set_int */
 228                 parse_opts_opt_l(cfg, argc, argv, ++i);
 229                 break;
 230         default :
 231                 usage("Option \"%s\" is invalid\n", argv[i]);
 232         }
 233 }
 234
 235 void
 236 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 237 {
 238         if ((i + 3) > argc)
 239                 usage("[spec] Parameter(s) missing for fifo \"%s\".\n", argv[i]);
 240
 241         char *n = argv[i++];
 242         char *w = argv[i++];
 243         char *t = argv[i++];
 244
 245         if (!is_pos_num(w))
 246                 usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 247         if (!is_pos_num(t))
 248                 usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
 249         Fifo *f = calloc(1, sizeof(struct Fifo));
 250         if (f) {
 251                 f->name      = n;
 252                 f->fd        = -1;
 253                 f->width     = atoi(w);
 254                 f->ttl       = atoi(t);
 255                 f->last_read = 0;
 256                 f->pos       = cfg->total_width;
 257                 f->next      = cfg->fifos;
 258
 259                 cfg->fifos        = f;
 260                 cfg->total_width += f->width;
 261                 cfg->fifo_count++;
 262         } else {
 263                 fatal("[memory] Allocation failure.");
 264         }
 265         opts_parse_any(cfg, argc, argv, i);
 266 }
 267
 268 void
 269 opts_parse_any(Config *cfg, int argc, char *argv[], int i)
 270 {
 271         if (i < argc) {
 272                 switch (argv[i][0]) {
 273                 case '-':
 274                         parse_opts_opt(cfg, argc, argv, i);
 275                         break;
 276                 default :
 277                         parse_opts_spec(cfg, argc, argv, i);
 278                 }
 279         }
 280 }
 281
 282 void
 283 opts_parse(Config *cfg, int argc, char *argv[])
 284 {
 285         opts_parse_any(cfg, argc, argv, 1);
 286
 287         Fifo *last = cfg->fifos;
 288         cfg->fifos = NULL;
 289         for (Fifo *f = last; f; ) {
 290                 Fifo *next = f->next;
 291                 f->next = cfg->fifos;
 292                 cfg->fifos = f;
 293                 f = next;
 294         }
 295 }
 296
 297 void
 298 fifo_read_error(Fifo *f, char *buf)
 299 {
 300         char *b;
 301         int i;
 302
 303         b = buf + f->pos;
 304         /* Copy as much of the error message as possible.
 305          * EXCLUDING the reminating \0. */
 306         for (i = 0; i < errlen && i < f->width; i++)
 307                 b[i] = errmsg[i];
 308         /* Any remaining slots: */
 309         for (; i < f->width; i++)
 310                 b[i] = '_';
 311 }
 312
 313 void
 314 fifo_read_one(Fifo *f, char *buf, Config *cfg)
 315 {
 316         ssize_t current;
 317         ssize_t total;
 318         char *b;
 319         char c;
 320
 321         current = 0;
 322         total = 0;
 323         c = '\0';
 324         b = buf + f->pos;
 325         while ((current = read(f->fd, &c, 1)) && c != '\n' && c != '\0' && total++ < f->width)
 326                 *b++ = c;
 327         if (current == -1) {
 328                 error("Failed to read: \"%s\". Error: %s\n", f->name, strerror(errno));
 329                 fifo_read_error(f, buf);
 330         } else {
 331                 while (total++ < f->width)
 332                         *b++ = ' ';
 333         }
 334         /* TODO Record timestamp read */
 335         close(f->fd);
 336         f->fd = -1;
 337 }
 338
 339 void
 340 fifo_read_all(Config *cfg, char *buf)
 341 {
 342         fd_set fds;
 343         int maxfd = -1;
 344         int ready;
 345         struct stat st;
 346
 347         FD_ZERO(&fds);
 348         for (Fifo *f = cfg->fifos; f; f = f->next) {
 349                 /* TODO: Create the FIFO if it doesn't already exist. */
 350                 if (lstat(f->name, &st) < 0) {
 351                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 352                         fifo_read_error(f, buf);
 353                         continue;
 354                 }
 355                 if (!(st.st_mode & S_IFIFO)) {
 356                         error("\"%s\" is not a FIFO\n", f->name);
 357                         fifo_read_error(f, buf);
 358                         continue;
 359                 }
 360                 debug("opening: %s\n", f->name);
 361                 if (f->fd < 0)
 362                         f->fd = open(f->name, O_RDONLY | O_NONBLOCK);
 363                 if (f->fd == -1) {
 364                         /* TODO: Consider backing off retries for failed fifos. */
 365                         error("Failed to open \"%s\"\n", f->name);
 366                         fifo_read_error(f, buf);
 367                         continue;
 368                 }
 369                 if (f->fd > maxfd)
 370                         maxfd = f->fd;
 371                 FD_SET(f->fd, &fds);
 372         }
 373         debug("selecting...\n");
 374         ready = select(maxfd + 1, &fds, NULL, NULL, NULL);
 375         debug("ready: %d\n", ready);
 376         assert(ready != 0);
 377         if (ready < 0)
 378                 fatal("%s", strerror(errno));
 379         for (Fifo *f = cfg->fifos; f; f = f->next) {
 380                 if (FD_ISSET(f->fd, &fds)) {
 381                         debug("reading: %s\n", f->name);
 382                         fifo_read_one(f, buf, cfg);
 383                 }
 384         }
 385 }
 386
 387 void
 388 snooze(struct timespec *t, Config *cfg)
 389 {
 390         struct timespec remainder;
 391         int result;
 392
 393         result = nanosleep(t, &remainder);
 394
 395         if (result < 0) {
 396                 if (errno == EINTR) {
 397                         warn(
 398                             "nanosleep interrupted. Remainder: "
 399                             "{ tv_sec = %ld, tv_nsec = %ld }",
 400                             remainder.tv_sec, remainder.tv_nsec);
 401                         /* No big deal if we occasionally sleep less,
 402                          * so not attempting to correct after an interruption.
 403                          */
 404                 } else {
 405                         fatal("nanosleep: %s\n", strerror(errno));
 406                 }
 407         }
 408 }
 409
 410 int
 411 main(int argc, char *argv[])
 412 {
 413         int width  = 0;
 414         int nfifos = 0;
 415         int seplen = 0;
 416         int prefix = 0;
 417         int errors = 0;
 418         char *buf;
 419         Config cfg0 = defaults;
 420         Config *cfg = &cfg0;
 421         Display *display = NULL;
 422         struct stat st;
 423         struct timespec
 424                 t0,  /* time stamp. before reading fifos */
 425                 t1,  /* time stamp. after  reading fifos */
 426                 ti,  /* time interval desired    (t1 - t0) */
 427                 td,  /* time interval measured   (t1 - t0) */
 428                 tc;  /* time interval correction (ti - td) when td < ti */
 429
 430         argv0 = argv[0];
 431
 432         opts_parse(cfg, argc, argv);
 433         debug("argv0 = %s\n", argv0);
 434         config_print(cfg);
 435
 436         /* TODO: Support interval < 1. i.e. implement timespec_of_float */
 437         ti.tv_sec  = cfg->interval;
 438         ti.tv_nsec = 0;
 439
 440         if (cfg->fifos == NULL)
 441                 usage("No fifo specs were given!\n");
 442
 443         /* 1st pass to check file existence and type */
 444         for (Fifo *f = cfg->fifos; f; f = f->next) {
 445                 if (lstat(f->name, &st) < 0) {
 446                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 447                         errors++;
 448                         continue;
 449                 }
 450                 if (!(st.st_mode & S_IFIFO)) {
 451                         error("\"%s\" is not a FIFO\n", f->name);
 452                         errors++;
 453                         continue;
 454                 }
 455         }
 456         if (errors)
 457                 fatal("Encountered errors with the given file paths. See log.\n");
 458
 459         width  = cfg->total_width;
 460         seplen = strlen(cfg->separator);
 461
 462         /* 2nd pass to make space for separators */
 463         for (Fifo *f = cfg->fifos; f; f = f->next) {
 464                 f->pos += prefix;
 465                 prefix += seplen;
 466                 nfifos++;
 467         }
 468         width += (seplen * (nfifos - 1));
 469         buf = calloc(1, width + 1);
 470         if (buf == NULL)
 471                 fatal("[memory] Failed to allocate buffer of %d bytes", width);
 472         memset(buf, ' ', width);
 473         buf[width] = '\0';
 474         /* 3rd pass to set the separators */
 475         for (Fifo *f = cfg->fifos; f; f = f->next) {
 476                 if (f->pos) {  /* Skip the first, left-most */
 477                         /* Copying only seplen ensures we omit the '\0' byte. */
 478                         strncpy(buf + (f->pos - seplen), cfg->separator, seplen);
 479                 }
 480         }
 481
 482         if (cfg->output_to_x_root_window && !(display = XOpenDisplay(NULL)))
 483                 fatal("XOpenDisplay failed with: %p\n", display);
 484         /* TODO: Handle signals */
 485         for (;;) {
 486                 clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
 487                 /* TODO: Cache expiration. i.e. use the TTL */
 488                 /* TODO: How to trigger TTL check? On select? Alarm signal? */
 489                 /* TODO: Set timeout on fifo_read_all based on diff of last time of
 490                  *       fifo_read_all and desired time of next TTL check.
 491                  */
 492                 /* TODO: How long to wait on IO? Max TTL? */
 493                 fifo_read_all(cfg, buf);
 494                 if (cfg->output_to_x_root_window) {
 495                         if (XStoreName(display, DefaultRootWindow(display), buf) < 0)
 496                                 fatal("XStoreName failed.\n");
 497                         XFlush(display);
 498                 } else {
 499                         puts(buf);
 500                         fflush(stdout);
 501                 }
 502                 clock_gettime(CLOCK_MONOTONIC, &t1); // FIXME: check errors
 503                 timespecsub(&t1, &t0, &td);
 504                 debug("td {tv_sec = %ld, tv_nsec = %ld}\n", td.tv_sec, td.tv_nsec);
 505                 if (timespeccmp(&td, &ti, <)) {
 506                         /* Pushback on data producers by refusing to read the
 507                          * pipe more frequently than the interval.
 508                          */
 509                         timespecsub(&ti, &td, &tc);
 510                         debug("snooze YES\n");
 511                         snooze(&tc, cfg);
 512                 } else {
 513                         debug("snooze NO\n");
 514                 }
 515         }
 516
 517         return EXIT_SUCCESS;
 518 }