xref: /freebsd/usr.bin/backlight/backlight.c (revision fe6060f10f634930ff71b7c50291ddc610da2475)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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  * $FreeBSD$
28  */
29 
30 #include <sys/types.h>
31 #include <sys/ioctl.h>
32 #include <stdbool.h>
33 #include <sys/capsicum.h>
34 #include <sys/backlight.h>
35 
36 #include <err.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <limits.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44 #include <capsicum_helpers.h>
45 
46 #define	BACKLIGHT_QUERY			0x0001
47 #define	BACKLIGHT_SET_BRIGHTNESS	0x0002
48 #define	BACKLIGHT_INCR			0x0004
49 #define	BACKLIGHT_DECR			0x0008
50 #define	BACKLIGHT_INFO			0x0010
51 
52 static char device_name[PATH_MAX] = "/dev/backlight/backlight0";
53 
54 static void
55 set_device_name(const char *name)
56 {
57 
58 	if (name[0] == '/')
59 		strlcpy(device_name, name, sizeof(device_name));
60 	else
61 		snprintf(device_name, sizeof(device_name), "/dev/backlight/%s", name);
62 }
63 
64 static void
65 usage(void)
66 {
67 	fprintf(stderr, "Usage:\n");
68 	fprintf(stderr, "\tbacklight [-f dev]\n");
69 	fprintf(stderr, "\tbacklight [-f dev] -i\n");
70 	fprintf(stderr, "\tbacklight [-f dev] <percent>\n");
71 	fprintf(stderr, "\tbacklight [-f dev] incr|+ <percent>\n");
72 	fprintf(stderr, "\tbacklight [-f dev] decr|- <percent>\n");
73 	exit(1);
74 }
75 
76 static const char *
77 backlight_type_to_string(enum backlight_info_type type)
78 {
79 	switch (type) {
80 	case BACKLIGHT_TYPE_PANEL:
81 		return ("Panel");
82 	case BACKLIGHT_TYPE_KEYBOARD:
83 		return ("Keyboard");
84 	}
85 
86 	return ("Unknown");
87 }
88 
89 int
90 main(int argc, char *argv[])
91 {
92 	struct backlight_props props;
93 	struct backlight_info info;
94 	int fd;
95 	int action, ch;
96 	cap_rights_t right_ioctl;
97 	const unsigned long backlight_ioctls[] = {
98 		BACKLIGHTGETSTATUS,
99 		BACKLIGHTUPDATESTATUS,
100 		BACKLIGHTGETINFO};
101 	long percent = -1;
102 	const char *percent_error;
103 	uint32_t i;
104 	bool setname;
105 	bool quiet = false;
106 
107 	action = BACKLIGHT_QUERY;
108 	setname = false;
109 	fd = -1;
110 
111 	while ((ch = getopt(argc, argv, "f:qhi")) != -1) {
112 		switch (ch) {
113 		case 'q':
114 			quiet = true;
115 			break;
116 		case 'f':
117 			setname = true;
118 			set_device_name(optarg);
119 			break;
120 		case 'i':
121 			action = BACKLIGHT_INFO;
122 			break;
123 		case 'h':
124 			usage();
125 			break;
126 		}
127 	}
128 
129 	argc -= optind;
130 	argv += optind;
131 	if (argc != 0) {
132 		if (strcmp("incr", argv[0]) == 0 ||
133 		    strcmp("+", argv[0]) == 0) {
134 			action = BACKLIGHT_INCR;
135 			argc -= 1;
136 			argv += 1;
137 		}
138 		else if (strcmp("decr", argv[0]) == 0 ||
139 		    strcmp("-", argv[0]) == 0) {
140 			action = BACKLIGHT_DECR;
141 			argc -= 1;
142 			argv += 1;
143 		} else
144 			action = BACKLIGHT_SET_BRIGHTNESS;
145 
146 		if (argc == 1) {
147 			/* ignore a trailing % for user friendlyness */
148 			if (strlen(argv[0]) > 0 &&
149 			    argv[0][strlen(argv[0]) - 1] == '%')
150 				argv[0][strlen(argv[0]) - 1] = '\0';
151 			percent = strtonum(argv[0], 0, 100, &percent_error);
152 			if (percent_error)
153 				errx(1, "Cannot parse brightness level %s: %s",
154 				    argv[0],
155 				    percent_error);
156 		}
157 	}
158 
159 	if ((fd = open(device_name, O_RDWR)) == -1)
160 		errx(1, "cannot open %s: %s",
161 		    device_name, strerror(errno));
162 
163 	if (caph_limit_stdio() < 0)
164 		errx(1, "can't limit stdio rights");
165 	caph_cache_catpages();
166 	cap_rights_init(&right_ioctl, CAP_IOCTL);
167 	if (caph_rights_limit(fd, &right_ioctl) < 0)
168 		errx(1, "cap_right_limit() failed");
169 	if (caph_ioctls_limit(fd, backlight_ioctls, nitems(backlight_ioctls)) < 0)
170 		errx(1, "caph_ioctls_limit() failed");
171 	if (caph_enter() < 0)
172 		errx(1, "failed to enter capability mode");
173 
174 	switch (action) {
175 	case BACKLIGHT_QUERY:
176 		if (ioctl(fd, BACKLIGHTGETSTATUS, &props) == -1)
177 			errx(1, "Cannot query the backlight device");
178 		if (quiet)
179 			printf("%u\n", props.brightness);
180 		else {
181 			printf("brightness: %d\n", props.brightness);
182 			if (props.nlevels != 0) {
183 				printf("levels:");
184 				for (i = 0; i < props.nlevels; i++)
185 					printf(" %d", props.levels[i]);
186 				printf("\n");
187 			}
188 		}
189 		break;
190 	case BACKLIGHT_SET_BRIGHTNESS:
191 		if (percent == -1)
192 			usage();
193 		props.brightness = percent;
194 		if (ioctl(fd, BACKLIGHTUPDATESTATUS, &props) == -1)
195 			errx(1, "Cannot update the backlight device");
196 		break;
197 	case BACKLIGHT_INCR:
198 	case BACKLIGHT_DECR:
199 		if (percent == 0)
200 			/* Avoid any ioctl if we don't have anything to do */
201 			break;
202 		if (ioctl(fd, BACKLIGHTGETSTATUS, &props) == -1)
203 			errx(1, "Cannot query the backlight device");
204 		percent = percent == -1 ? 10 : percent;
205 		percent = action == BACKLIGHT_INCR ? percent : -percent;
206 		props.brightness += percent;
207 		if ((int)props.brightness < 0)
208 			props.brightness = 0;
209 		if (props.brightness > 100)
210 			props.brightness = 100;
211 		if (ioctl(fd, BACKLIGHTUPDATESTATUS, &props) == -1)
212 			errx(1, "Cannot update the backlight device");
213 		break;
214 	case BACKLIGHT_INFO:
215 		if (ioctl(fd, BACKLIGHTGETINFO, &info) == -1)
216 			errx(1, "Cannot query the backlight device");
217 		if (quiet == false) {
218 			printf("Backlight name: %s\n", info.name);
219 			printf("Backlight hardware type: %s\n", backlight_type_to_string(info.type));
220 		} else {
221 			printf("%s\n", info.name);
222 			printf("%s\n", backlight_type_to_string(info.type));
223 		}
224 		break;
225 	}
226 
227 	close(fd);
228 	return (0);
229 }
230