usr.bin/backlight/backlight.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   3  *
   4  * Copyright (c) 2020 Emmanuel Vadot <manu@FreeBSD.org>
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/types.h>
  29 #include <sys/ioctl.h>
  30 #include <stdbool.h>
  31 #include <sys/capsicum.h>
  32 #include <sys/backlight.h>
  33
  34 #include <err.h>
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <limits.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #include <capsicum_helpers.h>
  43
  44 #define BACKLIGHT_QUERY                 0x0001
  45 #define BACKLIGHT_SET_BRIGHTNESS        0x0002
  46 #define BACKLIGHT_INCR                  0x0004
  47 #define BACKLIGHT_DECR                  0x0008
  48 #define BACKLIGHT_INFO                  0x0010
  49
  50 static char device_name[PATH_MAX] = "/dev/backlight/backlight0";
  51
  52 static void
  53 set_device_name(const char *name)
  54 {
  55
  56         if (name[0] == '/')
  57                 strlcpy(device_name, name, sizeof(device_name));
  58         else
  59                 snprintf(device_name, sizeof(device_name), "/dev/backlight/%s", name);
  60 }
  61
  62 static void
  63 usage(void)
  64 {
  65         fprintf(stderr, "Usage:\n");
  66         fprintf(stderr, "\tbacklight [-q] [-f device]\n");
  67         fprintf(stderr, "\tbacklight [-q] [-f device] -i\n");
  68         fprintf(stderr, "\tbacklight [-f device] value\n");
  69         fprintf(stderr, "\tbacklight [-f device] incr|+ value\n");
  70         fprintf(stderr, "\tbacklight [-f device] decr|- value\n");
  71         exit(1);
  72 }
  73
  74 static const char *
  75 backlight_type_to_string(enum backlight_info_type type)
  76 {
  77         switch (type) {
  78         case BACKLIGHT_TYPE_PANEL:
  79                 return ("Panel");
  80         case BACKLIGHT_TYPE_KEYBOARD:
  81                 return ("Keyboard");
  82         }
  83
  84         return ("Unknown");
  85 }
  86
  87 int
  88 main(int argc, char *argv[])
  89 {
  90         struct backlight_props props;
  91         struct backlight_info info;
  92         int fd;
  93         int action, ch;
  94         cap_rights_t right_ioctl;
  95         const unsigned long backlight_ioctls[] = {
  96                 BACKLIGHTGETSTATUS,
  97                 BACKLIGHTUPDATESTATUS,
  98                 BACKLIGHTGETINFO};
  99         long percent = -1;
 100         const char *percent_error;
 101         uint32_t i;
 102         bool quiet = false;
 103
 104         action = BACKLIGHT_QUERY;
 105         fd = -1;
 106
 107         while ((ch = getopt(argc, argv, "f:qhi")) != -1) {
 108                 switch (ch) {
 109                 case 'q':
 110                         quiet = true;
 111                         break;
 112                 case 'f':
 113                         set_device_name(optarg);
 114                         break;
 115                 case 'i':
 116                         action = BACKLIGHT_INFO;
 117                         break;
 118                 case 'h':
 119                         usage();
 120                         break;
 121                 }
 122         }
 123
 124         argc -= optind;
 125         argv += optind;
 126         if (argc != 0) {
 127                 if (strcmp("incr", argv[0]) == 0 ||
 128                     strcmp("+", argv[0]) == 0) {
 129                         action = BACKLIGHT_INCR;
 130                         argc -= 1;
 131                         argv += 1;
 132                 }
 133                 else if (strcmp("decr", argv[0]) == 0 ||
 134                     strcmp("-", argv[0]) == 0) {
 135                         action = BACKLIGHT_DECR;
 136                         argc -= 1;
 137                         argv += 1;
 138                 } else
 139                         action = BACKLIGHT_SET_BRIGHTNESS;
 140
 141                 if (argc == 1) {
 142                         /* ignore a trailing % for user friendlyness */
 143                         if (strlen(argv[0]) > 0 &&
 144                             argv[0][strlen(argv[0]) - 1] == '%')
 145                                 argv[0][strlen(argv[0]) - 1] = '\0';
 146                         percent = strtonum(argv[0], 0, 100, &percent_error);
 147                         if (percent_error)
 148                                 errx(1, "Cannot parse brightness level %s: %s",
 149                                     argv[0],
 150                                     percent_error);
 151                 }
 152         }
 153
 154         if ((fd = open(device_name, O_RDWR)) == -1)
 155                 errx(1, "cannot open %s: %s",
 156                     device_name, strerror(errno));
 157
 158         if (caph_limit_stdio() < 0)
 159                 errx(1, "can't limit stdio rights");
 160         caph_cache_catpages();
 161         cap_rights_init(&right_ioctl, CAP_IOCTL);
 162         if (caph_rights_limit(fd, &right_ioctl) < 0)
 163                 errx(1, "cap_right_limit() failed");
 164         if (caph_ioctls_limit(fd, backlight_ioctls, nitems(backlight_ioctls)) < 0)
 165                 errx(1, "caph_ioctls_limit() failed");
 166         if (caph_enter() < 0)
 167                 errx(1, "failed to enter capability mode");
 168
 169         switch (action) {
 170         case BACKLIGHT_QUERY:
 171                 if (ioctl(fd, BACKLIGHTGETSTATUS, &props) == -1)
 172                         errx(1, "Cannot query the backlight device");
 173                 if (quiet)
 174                         printf("%u\n", props.brightness);
 175                 else {
 176                         printf("brightness: %d\n", props.brightness);
 177                         if (props.nlevels != 0) {
 178                                 printf("levels:");
 179                                 for (i = 0; i < props.nlevels; i++)
 180                                         printf(" %d", props.levels[i]);
 181                                 printf("\n");
 182                         }
 183                 }
 184                 break;
 185         case BACKLIGHT_SET_BRIGHTNESS:
 186                 if (percent == -1)
 187                         usage();
 188                 props.brightness = percent;
 189                 if (ioctl(fd, BACKLIGHTUPDATESTATUS, &props) == -1)
 190                         errx(1, "Cannot update the backlight device");
 191                 break;
 192         case BACKLIGHT_INCR:
 193         case BACKLIGHT_DECR:
 194                 if (percent == 0)
 195                         /* Avoid any ioctl if we don't have anything to do */
 196                         break;
 197                 if (ioctl(fd, BACKLIGHTGETSTATUS, &props) == -1)
 198                         errx(1, "Cannot query the backlight device");
 199                 percent = percent == -1 ? 10 : percent;
 200                 percent = action == BACKLIGHT_INCR ? percent : -percent;
 201                 props.brightness += percent;
 202                 if ((int)props.brightness < 0)
 203                         props.brightness = 0;
 204                 if (props.brightness > 100)
 205                         props.brightness = 100;
 206                 if (ioctl(fd, BACKLIGHTUPDATESTATUS, &props) == -1)
 207                         errx(1, "Cannot update the backlight device");
 208                 break;
 209         case BACKLIGHT_INFO:
 210                 if (ioctl(fd, BACKLIGHTGETINFO, &info) == -1)
 211                         errx(1, "Cannot query the backlight device");
 212                 if (quiet == false) {
 213                         printf("Backlight name: %s\n", info.name);
 214                         printf("Backlight hardware type: %s\n", backlight_type_to_string(info.type));
 215                 } else {
 216                         printf("%s\n", info.name);
 217                         printf("%s\n", backlight_type_to_string(info.type));
 218                 }
 219                 break;
 220         }
 221
 222         close(fd);
 223         return (0);
 224 }