src/backlight/backlight.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2013 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 <libudev.h>
  23
  24 #include "util.h"
  25 #include "mkdir.h"
  26 #include "fileio.h"
  27
  28 int main(int argc, char *argv[]) {
  29         struct udev *udev = NULL;
  30         struct udev_device *device = NULL;
  31         _cleanup_free_ char *saved = NULL;
  32         int r;
  33
  34         if (argc != 3) {
  35                 log_error("This program requires two arguments.");
  36                 return EXIT_FAILURE;
  37         }
  38
  39         log_set_target(LOG_TARGET_AUTO);
  40         log_parse_environment();
  41         log_open();
  42
  43         umask(0022);
  44
  45         r = mkdir_p("/var/lib/systemd/backlight", 0755);
  46         if (r < 0) {
  47                 log_error("Failed to create backlight directory: %s", strerror(-r));
  48                 goto finish;
  49         }
  50
  51         udev = udev_new();
  52         if (!udev) {
  53                 r = log_oom();
  54                 goto finish;
  55         }
  56
  57         errno = 0;
  58         device = udev_device_new_from_subsystem_sysname(udev, "backlight", argv[2]);
  59         if (!device)
  60                 device = udev_device_new_from_subsystem_sysname(udev, "leds", argv[2]);
  61         if (!device) {
  62                 if (errno != 0) {
  63                         log_error("Failed to get backlight device '%s': %m", argv[2]);
  64                         r = -errno;
  65                 } else
  66                         r = log_oom();
  67
  68                 goto finish;
  69         }
  70
  71         if (!streq_ptr(udev_device_get_subsystem(device), "backlight") &&
  72             !streq_ptr(udev_device_get_subsystem(device), "leds")) {
  73                 log_error("Not a backlight device: %s", argv[2]);
  74                 r = -ENODEV;
  75                 goto finish;
  76         }
  77
  78         saved = strappend("/var/lib/systemd/backlight/", udev_device_get_sysname(device));
  79         if (!saved) {
  80                 r = log_oom();
  81                 goto finish;
  82         }
  83
  84         if (streq(argv[1], "load")) {
  85                 _cleanup_free_ char *value = NULL;
  86
  87                 r = read_one_line_file(saved, &value);
  88                 if (r < 0) {
  89
  90                         if (r == -ENOENT) {
  91                                 r = 0;
  92                                 goto finish;
  93                         }
  94
  95                         log_error("Failed to read %s: %s", saved, strerror(-r));
  96                         goto finish;
  97                 }
  98
  99                 r = udev_device_set_sysattr_value(device, "brightness", value);
 100                 if (r < 0) {
 101                         log_error("Failed to write system attribute: %s", strerror(-r));
 102                         goto finish;
 103                 }
 104
 105         } else if (streq(argv[1], "save")) {
 106                 const char *value;
 107
 108                 value = udev_device_get_sysattr_value(device, "brightness");
 109                 if (!value) {
 110                         log_error("Failed to read system attribute: %s", strerror(-r));
 111                         goto finish;
 112                 }
 113
 114                 r = write_string_file(saved, value);
 115                 if (r < 0) {
 116                         log_error("Failed to write %s: %s", saved, strerror(-r));
 117                         goto finish;
 118                 }
 119
 120         } else {
 121                 log_error("Unknown verb %s.", argv[1]);
 122                 r = -EINVAL;
 123                 goto finish;
 124         }
 125
 126 finish:
 127         if (device)
 128                 udev_device_unref(device);
 129
 130         if (udev)
 131                 udev_unref(udev);
 132
 133         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 134
 135 }