x5/khatus_sensor_battery.c

   1 #include <signal.h>
   2 #include <assert.h>
   3 #include <ctype.h>
   4 #include <errno.h>
   5 #include <limits.h>
   6 #include <signal.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <time.h>
  11 #include <unistd.h>
  12
  13 #include "khatus_lib_log.h"
  14 #include "khatus_lib_time.h"
  15
  16 #define usage(...) {print_usage(); fprintf(stderr, "Error:\n    " __VA_ARGS__); exit(EXIT_FAILURE);}
  17
  18 #define MAX_LEN 20
  19
  20 char *argv0;
  21
  22 double  opt_interval = 1.0;
  23 char   *opt_battery  = "BAT0";
  24
  25 void
  26 print_usage()
  27 {
  28         printf(
  29             "%s: [OPT ...]\n"
  30             "\n"
  31             "OPT = -i int     # interval\n"
  32             "    | -b string  # battery file name from /sys/class/power_supply/\n"
  33             "    | -h         # help message (i.e. what you're reading now :) )\n",
  34             argv0);
  35 }
  36
  37 void
  38 opt_parse(int argc, char **argv)
  39 {
  40         char c;
  41
  42         while ((c = getopt(argc, argv, "b:i:h")) != -1)
  43                 switch (c) {
  44                 case 'b':
  45                         opt_battery = calloc(strlen(optarg), sizeof(char));
  46                         strcpy(opt_battery, optarg);
  47                         break;
  48                 case 'i':
  49                         opt_interval = atof(optarg);
  50                         break;
  51                 case 'h':
  52                         print_usage();
  53                         exit(EXIT_SUCCESS);
  54                 case '?':
  55                         if (optopt == 'b' || optopt == 'i')
  56                                 fprintf(stderr,
  57                                         "Option -%c requires an argument.\n",
  58                                         optopt);
  59                         else if (isprint(optopt))
  60                                 fprintf (stderr,
  61                                         "Unknown option `-%c'.\n",
  62                                         optopt);
  63                         else
  64                                 fprintf(stderr,
  65                                         "Unknown option character `\\x%x'.\n",
  66                                         optopt);
  67                         exit(EXIT_FAILURE);
  68                 default:
  69                         assert(0);
  70                 }
  71 }
  72
  73 int
  74 get_capacity(char *buf, char *path)
  75 {
  76         FILE *fp;
  77         int cap;
  78
  79         if (!(fp = fopen(path, "r")))
  80                 fatal("Failed to open %s. errno: %d, msg: %s\n",
  81                     path, errno, strerror(errno));
  82
  83         switch (fscanf(fp, "%d", &cap)) {
  84         case -1: fatal("EOF\n");
  85         case  0: fatal("Read 0\n");
  86         case  1: break;
  87         default: assert(0);
  88         }
  89         fclose(fp);
  90         return snprintf(buf, 6, "%3d%%", cap);
  91 }
  92
  93 int
  94 main(int argc, char **argv)
  95 {
  96         argv0 = argv[0];
  97
  98         char  buf[10];
  99         char path[PATH_MAX];
 100         char *path_fmt = "/sys/class/power_supply/%s/capacity";
 101         struct timespec ti;
 102
 103         opt_parse(argc, argv);
 104         ti = timespec_of_float(opt_interval);
 105         debug("opt_battery: \"%s\"\n", opt_battery);
 106         debug("opt_interval: %f\n", opt_interval);
 107         debug("ti: {tv_sec = %ld, tv_nsec = %ld}\n", ti.tv_sec, ti.tv_nsec);
 108         memset(path, '\0', PATH_MAX);
 109         snprintf(path, PATH_MAX, path_fmt, opt_battery);
 110         signal(SIGPIPE, SIG_IGN);
 111
 112         for (;;) {
 113                 get_capacity(buf, path);
 114                 puts(buf);
 115                 fflush(stdout);
 116                 snooze(&ti);
 117         }
 118         return EXIT_SUCCESS;
 119 }