src/ac-power/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 Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 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   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser 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 }