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                 if (errno != 0) {
  61                         log_error("Failed to get backlight device: %m");
  62                         r = -errno;
  63                 } else
  64                         r = log_oom();
  65
  66                 goto finish;
  67         }
  68
  69         if (!streq_ptr(udev_device_get_subsystem(device), "backlight")) {
  70                 log_error("Not a backlight device: %s", argv[2]);
  71                 r = -ENODEV;
  72                 goto finish;
  73         }
  74
  75         saved = strappend("/var/lib/systemd/backlight/", udev_device_get_sysname(device));
  76         if (!saved) {
  77                 r = log_oom();
  78                 goto finish;
  79         }
  80
  81         if (streq(argv[1], "load")) {
  82                 _cleanup_free_ char *value = NULL;
  83
  84                 r = read_one_line_file(saved, &value);
  85                 if (r < 0) {
  86
  87                         if (r == -ENOENT) {
  88                                 r = 0;
  89                                 goto finish;
  90                         }
  91
  92                         log_error("Failed to read %s: %s", saved, strerror(-r));
  93                         goto finish;
  94                 }
  95
  96                 r = udev_device_set_sysattr_value(device, "brightness", value);
  97                 if (r < 0) {
  98                         log_error("Failed to write system attribute: %s", strerror(-r));
  99                         goto finish;
 100                 }
 101
 102         } else if (streq(argv[1], "save")) {
 103                 const char *value;
 104
 105                 value = udev_device_get_sysattr_value(device, "brightness");
 106                 if (!value) {
 107                         log_error("Failed to read system attribute: %s", strerror(-r));
 108                         goto finish;
 109                 }
 110
 111                 r = write_string_file(saved, value);
 112                 if (r < 0) {
 113                         log_error("Failed to write %s: %s", saved, strerror(-r));
 114                         goto finish;
 115                 }
 116
 117         } else {
 118                 log_error("Unknown verb %s.", argv[1]);
 119                 r = -EINVAL;
 120                 goto finish;
 121         }
 122
 123 finish:
 124         if (device)
 125                 udev_device_unref(device);
 126
 127         if (udev)
 128                 udev_unref(udev);
 129
 130         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 131
 132 }