src/ac-power.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdlib.h>
  23 #include <stdbool.h>
  24 #include <errno.h>
  25 #include <string.h>
  26 #include <libudev.h>
  27
  28 #include "util.h"
  29
  30 static int on_ac_power(void) {
  31         int r;
  32
  33         struct udev *udev;
  34         struct udev_enumerate *e = NULL;
  35         struct udev_list_entry *item = NULL, *first = NULL;
  36         bool found_offline = false, found_online = false;
  37
  38         if (!(udev = udev_new())) {
  39                 r = -ENOMEM;
  40                 goto finish;
  41         }
  42
  43         if (!(e = udev_enumerate_new(udev))) {
  44                 r = -ENOMEM;
  45                 goto finish;
  46         }
  47
  48         if (udev_enumerate_add_match_subsystem(e, "power_supply") < 0) {
  49                 r = -EIO;
  50                 goto finish;
  51         }
  52
  53         if (udev_enumerate_scan_devices(e) < 0) {
  54                 r = -EIO;
  55                 goto finish;
  56         }
  57
  58         first = udev_enumerate_get_list_entry(e);
  59         udev_list_entry_foreach(item, first) {
  60                 struct udev_device *d;
  61                 const char *type, *online;
  62
  63                 if (!(d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)))) {
  64                         r = -ENOMEM;
  65                         goto finish;
  66                 }
  67
  68                 if (!(type = udev_device_get_sysattr_value(d, "type")))
  69                         goto next;
  70
  71                 if (!streq(type, "Mains"))
  72                         goto next;
  73
  74                 if (!(online = udev_device_get_sysattr_value(d, "online")))
  75                         goto next;
  76
  77                 if (streq(online, "1")) {
  78                         found_online = true;
  79                         break;
  80                 } else if (streq(online, "0"))
  81                         found_offline = true;
  82
  83         next:
  84                 udev_device_unref(d);
  85         }
  86
  87         r = found_online || !found_offline;
  88
  89 finish:
  90         if (e)
  91                 udev_enumerate_unref(e);
  92
  93         if (udev)
  94                 udev_unref(udev);
  95
  96         return r;
  97 }
  98
  99 int main(int argc, char *argv[]) {
 100         int r;
 101
 102         /* This is mostly intended to be used for scripts which want
 103          * to detect whether AC power is plugged in or not. */
 104
 105         if ((r = on_ac_power()) < 0) {
 106                 log_error("Failed to read AC status: %s", strerror(-r));
 107                 return EXIT_FAILURE;
 108         }
 109
 110         return r == 0;
 111 }