x5/khatus.c

   1 /*
   2
   3 - [ ] Switch from regular files to named pipes
   4         - [ ] poll with select
   5
   6 */
   7
   8 #include <assert.h>
   9 #include <ctype.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13
  14 #include <fcntl.h>
  15 #include <unistd.h>
  16
  17 #define debug(args...) {fprintf(stderr, "[debug] " args);}
  18 #define info( args...) {fprintf(stderr, "[info] "  args);}
  19 #define error(args...) {fprintf(stderr, "[error] " args);}
  20 #define fatal(args...) {fprintf(stderr, "[fatal] " args); exit(EXIT_FAILURE);}
  21 #define usage(args...) {print_usage(); fatal("[usage] " args);}
  22
  23 char *argv0;
  24
  25 typedef struct File File;
  26 struct File {
  27         char   *name;
  28         int     fd;
  29         int     width;
  30         int     last_read;
  31         int     ttl;
  32         int     pos;  /* Position on the output buffer. */
  33         File   *next;
  34 };
  35
  36 typedef struct Config Config;
  37 struct Config {
  38         int    interval;
  39         char * separator;
  40         char * timefmt;
  41         File * files;
  42         int    file_count;
  43         int    total_width;
  44 } defaults = {
  45         .interval    = 1,
  46         .separator   = "|",
  47         .timefmt     = "%Y-%m-%d %H:%M:%S",
  48         .files       = NULL,
  49         .file_count  = 0,
  50         .total_width = 0,
  51 };
  52
  53
  54 int
  55 is_pos_num(char *s)
  56 {
  57         while (*s != '\0')
  58                 if (!isdigit(*(s++)))
  59                         return 0;
  60         return 1;
  61 }
  62
  63 void
  64 print_usage()
  65 {
  66         assert(argv0);
  67         fprintf(
  68                 stderr,
  69                 "\n"
  70                 "Usage: %s [OPTION ...] SPEC [SPEC ...]\n"
  71                 "\n"
  72                 "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
  73                 "  FILE_PATH  = string\n"
  74                 "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
  75                 "  DATA_TTL   = int  (* (positive) number of seconds *)\n"
  76                 "  OPTION     = -i INTERVAL\n"
  77                 "             | -s SEPARATOR\n"
  78                 "  SEPARATOR  = string\n"
  79                 "  INTERVAL   = int  (* (positive) number of seconds *)\n"
  80                 "\n",
  81                 argv0
  82         );
  83         fprintf(
  84                 stderr,
  85                 "Example: %s -i 1 /dev/shm/khatus/khatus_sensor_x 4 10\n"
  86                 "\n",
  87                 argv0
  88         );
  89 }
  90
  91 void opts_parse_any(Config *, int, char *[], int);  /* For mutually-recursive calls. */
  92
  93 void
  94 parse_opts_opt_i(Config *cfg, int argc, char *argv[], int i)
  95 {
  96         if (i < argc) {
  97                 char *param = argv[i++];
  98
  99                 if (is_pos_num(param)) {
 100                         cfg->interval = atoi(param);
 101                         opts_parse_any(cfg, argc, argv, i);
 102                 } else {
 103                         usage("Option -i parameter is invalid: \"%s\"\n", param);
 104                 }
 105         } else {
 106                 usage("Option -i parameter is missing.\n");
 107         }
 108 }
 109
 110 void
 111 parse_opts_opt_s(Config *cfg, int argc, char *argv[], int i)
 112 {
 113         if (i < argc) {
 114                 cfg->separator = calloc((strlen(argv[i]) + 1), sizeof(char));
 115                 strcpy(cfg->separator, argv[i]);
 116                 opts_parse_any(cfg, argc, argv, ++i);
 117         } else {
 118                 usage("Option -s parameter is missing.\n");
 119         }
 120 }
 121
 122 void
 123 parse_opts_opt_t(Config *cfg, int argc, char *argv[], int i)
 124 {
 125         if (i < argc) {
 126                 cfg->timefmt = calloc((strlen(argv[i]) + 1), sizeof(char));
 127                 strcpy(cfg->timefmt, argv[i]);
 128                 opts_parse_any(cfg, argc, argv, ++i);
 129         } else {
 130                 usage("Option -t parameter is missing.\n");
 131         }
 132 }
 133
 134 void
 135 parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 136 {
 137         switch (argv[i][1]) {
 138                 case 'i': parse_opts_opt_i(cfg, argc, argv, ++i); break;  /* TODO: Generic set_int */
 139                 case 's': parse_opts_opt_s(cfg, argc, argv, ++i); break;  /* TODO: Generic set_str */
 140                 case 't': parse_opts_opt_t(cfg, argc, argv, ++i); break;  /* TODO: Generic set_str */
 141                 default : usage("Option \"%s\" is invalid\n", argv[i]);
 142         }
 143 }
 144
 145 void
 146 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 147 {
 148         if ((i + 3) > argc)
 149                 usage("[spec] Parameter(s) missing for file \"%s\".\n", argv[i]);
 150
 151         char *n = argv[i++];
 152         char *w = argv[i++];
 153         char *t = argv[i++];
 154
 155         if (!is_pos_num(w))
 156                 usage("[spec] Invalid width: \"%s\", for file \"%s\"\n", w, n);
 157         if (!is_pos_num(t))
 158                 usage("[spec] Invalid TTL: \"%s\", for file \"%s\"\n", t, n);
 159         File *f = calloc(1, sizeof(struct File));
 160         if (f) {
 161                 f->name      = n;
 162                 f->fd        = -1;
 163                 f->width     = atoi(w);
 164                 f->ttl       = atoi(t);
 165                 f->last_read = 0;
 166                 f->pos       = cfg->total_width;
 167                 f->next      = cfg->files;
 168
 169                 cfg->files        = f;
 170                 cfg->total_width += f->width;
 171                 cfg->file_count++;
 172         } else {
 173                 fatal("[memory] Allocation failure.");
 174         }
 175         opts_parse_any(cfg, argc, argv, i);
 176 }
 177
 178 void
 179 opts_parse_any(Config *cfg, int argc, char *argv[], int i)
 180 {
 181         if (i < argc) {
 182                 switch (argv[i][0]) {
 183                         case '-': parse_opts_opt(cfg, argc, argv, i); break;
 184                         default : parse_opts_spec(cfg, argc, argv, i);
 185                 }
 186         }
 187 }
 188
 189 void
 190 opts_parse(Config *cfg, int argc, char *argv[], int i)
 191 {
 192         opts_parse_any(cfg, argc, argv, 1);
 193
 194         File *last = cfg->files;
 195         cfg->files = NULL;
 196         for (File *f = last; f; ) {
 197                 File *next = f->next;
 198                 f->next = cfg->files;
 199                 cfg->files = f;
 200                 f = next;
 201         }
 202 }
 203
 204 void
 205 read_all(Config *cfg, char *buf)
 206 {
 207         /* TODO: stat then check TTL */
 208         for (File *f = cfg->files; f; f = f->next) {
 209                 if (f->fd < 0)
 210                         f->fd = open(f->name, O_RDONLY);
 211                 if (f->fd == -1) {
 212                         /* TODO: Consider backing off retries for failed files. */
 213                         fatal("Failed to open \"%s\"\n", f->name);
 214                 } else {
 215                         lseek(f->fd, 0, 0);
 216                         ssize_t n = read(f->fd, buf + f->pos, f->width);
 217                         int lasti = n + f->pos - 1;
 218                         char lastc = buf[lasti];
 219                         if (lastc == '\n')
 220                                 buf[lasti] = ' ';
 221                 }
 222         }
 223 }
 224
 225 int
 226 main(int argc, char *argv[])
 227 {
 228         int width;
 229         int nfiles = 0;
 230         int seplen;
 231         int prefix = 0;
 232         char *buf;
 233         Config *cfg = &defaults;
 234
 235         argv0 = argv[0];
 236
 237         opts_parse(cfg, argc, argv, 1);
 238         debug("argv0 = %s\n", argv0);
 239         debug("[config] interval    = %d\n", cfg->interval);
 240         debug("[config] separator   = %s\n", cfg->separator);
 241         debug("[config] file_count  = %d\n", cfg->file_count);
 242         debug("[config] total_width = %d\n", cfg->total_width);
 243         if (cfg->files == NULL)
 244                 usage("No file specs were given!\n");
 245         for (File *f = cfg->files; f; f = f->next) {
 246                 debug(
 247                         "[config] file = "
 248                         "{"
 249                                 " name = %s,"
 250                                 " pos = %d,"
 251                                 " width = %d,"
 252                                 " ttl = %d,"
 253                                 " last_read = %d,"
 254                         " }\n",
 255                         f->name,
 256                         f->pos,
 257                         f->width,
 258                         f->ttl,
 259                         f->last_read
 260                 );
 261         }
 262
 263         width  = cfg->total_width;
 264         seplen = strlen(cfg->separator);
 265
 266         /* 1st pass to make space for separators */
 267         for (File *f = cfg->files; f; f = f->next) {
 268                 f->pos += prefix;
 269                 prefix += seplen;
 270                 nfiles++;
 271         }
 272         width += (seplen * (nfiles - 1));
 273         buf = calloc(1, width + 1);
 274         if (buf == NULL)
 275                 fatal("[memory] Failed to allocate buffer of %d bytes", width);
 276         memset(buf, ' ', width);
 277         buf[width] = '\0';
 278         /* 2nd pass to set the separators */
 279         for (File *f = cfg->files; f; f = f->next) {
 280                 if (f->pos) {  /* Skip the first, left-most */
 281                         strcpy(buf + (f->pos - seplen), cfg->separator);
 282                 }
 283         }
 284
 285         /* TODO: nanosleep and nano time diff */
 286         for (;;) {
 287                 read_all(cfg, buf);
 288                 printf("%s\n", buf);
 289                 sleep(cfg->interval);
 290         }
 291 }