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
set_device_name(const char * name)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
usage(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 *
backlight_type_to_string(enum backlight_info_type type)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
main(int argc,char * argv[])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 }
225