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 <unistd.h>
  12
  13 #include <X11/Xlib.h>
  14
  15 #define debug(args...) {fprintf(stderr, "[debug] " args);}
  16 #define info( args...) {fprintf(stderr, "[info] "  args);}
  17 #define error(args...) {fprintf(stderr, "[error] " args);}
  18 #define fatal(args...) {fprintf(stderr, "[fatal] " args); exit(EXIT_FAILURE);}
  19 #define usage(args...) {print_usage(); fatal("[usage] " args);}
  20
  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         int     last_read;
  35         int     ttl;
  36         int     pos;  /* Position on the output buffer. */
  37         Fifo   *next;
  38 };
  39
  40 typedef struct Config Config;
  41 struct Config {
  42         int    interval;
  43         char * separator;
  44         Fifo * fifos;
  45         int    fifo_count;
  46         int    total_width;
  47         int    output_to_x_root_window;
  48 } defaults = {
  49         .interval    = 1,
  50         .separator   = "|",
  51         .fifos       = NULL,
  52         .fifo_count  = 0,
  53         .total_width = 0,
  54         .output_to_x_root_window = 0,
  55 };
  56
  57 void
  58 fifo_print_one(Fifo *f)
  59 {
  60         debug(
  61                 "Fifo "
  62                 "{"
  63                         " name = %s,"
  64                         " fd = %d,"
  65                         " width = %d,"
  66                         " last_read = %d,"
  67                         " ttl = %d,"
  68                         " pos = %d,"
  69                         " next = %p,"
  70                 " }\n",
  71                 f->name,
  72                 f->fd,
  73                 f->width,
  74                 f->last_read,
  75                 f->ttl,
  76                 f->pos,
  77                 f->next
  78         );
  79 }
  80
  81 void
  82 fifo_print_all(Fifo *head)
  83 {
  84         for (Fifo *f = head; f; f = f->next) {
  85                 fifo_print_one(f);
  86         }
  87 }
  88
  89 void
  90 config_print(Config *c)
  91 {
  92         debug(
  93                 "Config "
  94                 "{"
  95                         " interval = %d,"
  96                         " separator = %s,"
  97                         " fifo_count = %d,"
  98                         " total_width = %d,"
  99                         " fifos = ..."
 100                 " }\n",
 101                 c->interval,
 102                 c->separator,
 103                 c->fifo_count,
 104                 c->total_width
 105         );
 106         fifo_print_all(c->fifos);
 107 }
 108
 109 int
 110 is_pos_num(char *s)
 111 {
 112         while (*s != '\0')
 113                 if (!isdigit(*(s++)))
 114                         return 0;
 115         return 1;
 116 }
 117
 118 void
 119 print_usage()
 120 {
 121         assert(argv0);
 122         fprintf(
 123                 stderr,
 124                 "\n"
 125                 "Usage: %s [OPTION ...] SPEC [SPEC ...]\n"
 126                 "\n"
 127                 "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
 128                 "  FILE_PATH  = string\n"
 129                 "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
 130                 "  DATA_TTL   = int  (* (positive) number of seconds *)\n"
 131                 "  OPTION     = -i INTERVAL\n"
 132                 "             | -s SEPARATOR\n"
 133                 "  SEPARATOR  = string\n"
 134                 "  INTERVAL   = int  (* (positive) number of seconds *)\n"
 135                 "\n",
 136                 argv0
 137         );
 138         fprintf(
 139                 stderr,
 140                 "Example: %s -i 1 /dev/shm/khatus/khatus_sensor_x 4 10\n"
 141                 "\n",
 142                 argv0
 143         );
 144 }
 145
 146 void opts_parse_any(Config *, int, char *[], int);  /* For mutually-recursive calls. */
 147
 148 void
 149 parse_opts_opt_i(Config *cfg, int argc, char *argv[], int i)
 150 {
 151         if (i < argc) {
 152                 char *param = argv[i++];
 153
 154                 if (is_pos_num(param)) {
 155                         cfg->interval = atoi(param);
 156                         opts_parse_any(cfg, argc, argv, i);
 157                 } else {
 158                         usage("Option -i parameter is invalid: \"%s\"\n", param);
 159                 }
 160         } else {
 161                 usage("Option -i parameter is missing.\n");
 162         }
 163 }
 164
 165 void
 166 parse_opts_opt_s(Config *cfg, int argc, char *argv[], int i)
 167 {
 168         if (i < argc) {
 169                 cfg->separator = calloc((strlen(argv[i]) + 1), sizeof(char));
 170                 strcpy(cfg->separator, argv[i]);
 171                 opts_parse_any(cfg, argc, argv, ++i);
 172         } else {
 173                 usage("Option -s parameter is missing.\n");
 174         }
 175 }
 176
 177 void
 178 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 179 {
 180         switch (argv[i][1]) {
 181                 case 'i': parse_opts_opt_i(cfg, argc, argv, ++i); break;  /* TODO: Generic set_int */
 182                 case 's': parse_opts_opt_s(cfg, argc, argv, ++i); break;  /* TODO: Generic set_str */
 183                 case 'x': {
 184                         cfg->output_to_x_root_window = 1;
 185                         opts_parse_any(cfg, argc, argv, ++i);
 186                         break;
 187                 }
 188                 default : usage("Option \"%s\" is invalid\n", argv[i]);
 189         }
 190 }
 191
 192 void
 193 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 194 {
 195         if ((i + 3) > argc)
 196                 usage("[spec] Parameter(s) missing for fifo \"%s\".\n", argv[i]);
 197
 198         char *n = argv[i++];
 199         char *w = argv[i++];
 200         char *t = argv[i++];
 201
 202         if (!is_pos_num(w))
 203                 usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 204         if (!is_pos_num(t))
 205                 usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
 206         Fifo *f = calloc(1, sizeof(struct Fifo));
 207         if (f) {
 208                 f->name      = n;
 209                 f->fd        = -1;
 210                 f->width     = atoi(w);
 211                 f->ttl       = atoi(t);
 212                 f->last_read = 0;
 213                 f->pos       = cfg->total_width;
 214                 f->next      = cfg->fifos;
 215
 216                 cfg->fifos        = f;
 217                 cfg->total_width += f->width;
 218                 cfg->fifo_count++;
 219         } else {
 220                 fatal("[memory] Allocation failure.");
 221         }
 222         opts_parse_any(cfg, argc, argv, i);
 223 }
 224
 225 void
 226 opts_parse_any(Config *cfg, int argc, char *argv[], int i)
 227 {
 228         if (i < argc) {
 229                 switch (argv[i][0]) {
 230                         case '-': parse_opts_opt(cfg, argc, argv, i); break;
 231                         default : parse_opts_spec(cfg, argc, argv, i);
 232                 }
 233         }
 234 }
 235
 236 void
 237 opts_parse(Config *cfg, int argc, char *argv[])
 238 {
 239         opts_parse_any(cfg, argc, argv, 1);
 240
 241         Fifo *last = cfg->fifos;
 242         cfg->fifos = NULL;
 243         for (Fifo *f = last; f; ) {
 244                 Fifo *next = f->next;
 245                 f->next = cfg->fifos;
 246                 cfg->fifos = f;
 247                 f = next;
 248         }
 249 }
 250
 251 void
 252 read_error(Fifo *f, char *buf)
 253 {
 254         char *b;
 255         int i;
 256
 257         b = buf + f->pos;
 258         /* Copy as much of the error message as possible.
 259          * EXCLUDING the reminating \0. */
 260         for (i = 0; i < errlen && i < f->width; i++)
 261                 b[i] = errmsg[i];
 262         /* Any remaining slots: */
 263         for (; i < f->width; i++)
 264                 b[i] = '_';
 265 }
 266
 267 void
 268 read_one(Fifo *f, char *buf)
 269 {
 270         ssize_t current;
 271         ssize_t total;
 272         char *b;
 273         char c;
 274
 275         current = 0;
 276         total = 0;
 277         c = '\0';
 278         b = buf + f->pos;
 279         /* TODO: Could optimize here and only blank-out the remaining slots. */
 280         memset(b, ' ', f->width);
 281         while ((current = read(f->fd, &c, 1)) && c != '\n' && c != '\0' && total++ < f->width)
 282                 *b++ = c;
 283         if (current == -1) {
 284                 error("Failed to read: \"%s\". Error: %s\n", f->name, strerror(errno));
 285                 read_error(f, buf);
 286         }
 287         /* TODO Record timestamp read */
 288         close(f->fd);
 289         f->fd = -1;
 290 }
 291
 292 void
 293 read_all(Config *cfg, char *buf)
 294 {
 295         fd_set fds;
 296         int maxfd = -1;
 297         int ready;
 298         struct stat st;
 299
 300         FD_ZERO(&fds);
 301         /* TODO: Check TTL */
 302         for (Fifo *f = cfg->fifos; f; f = f->next) {
 303                 /* TODO: Create the FIFO if it doesn't already exist. */
 304                 if (lstat(f->name, &st) < 0) {
 305                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 306                         read_error(f, buf);
 307                         continue;
 308                 }
 309                 if (!(st.st_mode & S_IFIFO)) {
 310                         error("\"%s\" is not a FIFO\n", f->name);
 311                         read_error(f, buf);
 312                         continue;
 313                 }
 314                 debug("opening: %s\n", f->name);
 315                 if (f->fd < 0)
 316                         f->fd = open(f->name, O_RDONLY | O_NONBLOCK);
 317                 if (f->fd == -1) {
 318                         /* TODO: Consider backing off retries for failed fifos. */
 319                         error("Failed to open \"%s\"\n", f->name);
 320                         read_error(f, buf);
 321                         continue;
 322                 }
 323                 if (f->fd > maxfd)
 324                         maxfd = f->fd;
 325                 FD_SET(f->fd, &fds);
 326         }
 327         debug("selecting...\n");
 328         ready = select(maxfd + 1, &fds, NULL, NULL, NULL);
 329         debug("ready: %d\n", ready);
 330         assert(ready != 0);
 331         if (ready < 0)
 332                 fatal("%s", strerror(errno));
 333         for (Fifo *f = cfg->fifos; f; f = f->next) {
 334                 if (FD_ISSET(f->fd, &fds)) {
 335                         debug("reading: %s\n", f->name);
 336                         read_one(f, buf);
 337                 }
 338         }
 339 }
 340
 341 int
 342 main(int argc, char *argv[])
 343 {
 344         int width  = 0;
 345         int nfifos = 0;
 346         int seplen = 0;
 347         int prefix = 0;
 348         int errors = 0;
 349         char *buf;
 350         Config cfg0 = defaults;
 351         Config *cfg = &cfg0;
 352         Display *display = NULL;
 353         struct stat st;
 354
 355         argv0 = argv[0];
 356
 357         opts_parse(cfg, argc, argv);
 358         debug("argv0 = %s\n", argv0);
 359         config_print(cfg);
 360         if (cfg->fifos == NULL)
 361                 usage("No fifo specs were given!\n");
 362
 363         /* 1st pass to check file existence and type */
 364         for (Fifo *f = cfg->fifos; f; f = f->next) {
 365                 if (lstat(f->name, &st) < 0) {
 366                         error("Cannot stat \"%s\". Error: %s\n", f->name, strerror(errno));
 367                         errors++;
 368                         continue;
 369                 }
 370                 if (!(st.st_mode & S_IFIFO)) {
 371                         error("\"%s\" is not a FIFO\n", f->name);
 372                         errors++;
 373                         continue;
 374                 }
 375         }
 376         if (errors)
 377                 fatal("Encountered errors with the given file paths. See log.\n");
 378
 379         width  = cfg->total_width;
 380         seplen = strlen(cfg->separator);
 381
 382         /* 2nd pass to make space for separators */
 383         for (Fifo *f = cfg->fifos; f; f = f->next) {
 384                 f->pos += prefix;
 385                 prefix += seplen;
 386                 nfifos++;
 387         }
 388         width += (seplen * (nfifos - 1));
 389         buf = calloc(1, width + 1);
 390         if (buf == NULL)
 391                 fatal("[memory] Failed to allocate buffer of %d bytes", width);
 392         memset(buf, ' ', width);
 393         buf[width] = '\0';
 394         /* 3rd pass to set the separators */
 395         for (Fifo *f = cfg->fifos; f; f = f->next) {
 396                 if (f->pos) {  /* Skip the first, left-most */
 397                         /* Copying only seplen ensures we omit the '\0' byte. */
 398                         strncpy(buf + (f->pos - seplen), cfg->separator, seplen);
 399                 }
 400         }
 401
 402         if (cfg->output_to_x_root_window && !(display = XOpenDisplay(NULL)))
 403                 fatal("XOpenDisplay failed with: %p\n", display);
 404         /* TODO: nanosleep and nano time diff */
 405         /* TODO: Handle signals */
 406         for (;;) {
 407                 /* TODO: Check TTL and maybe blank-out */
 408                 /* TODO: How to trigger TTL check? On select? Alarm signal? */
 409                 /* TODO: Set timeout on read_all based on diff of last time of
 410                  *       read_all and desired time of next TTL check.
 411                  * */
 412                 read_all(cfg, buf);
 413                 if (cfg->output_to_x_root_window) {
 414                         if (XStoreName(display, DefaultRootWindow(display), buf) < 0)
 415                                 fatal("XStoreName failed.\n");
 416                         XFlush(display);
 417                 } else {
 418                         puts(buf);
 419                         fflush(stdout);
 420                 }
 421         }
 422
 423         return EXIT_SUCCESS;
 424 }