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Alessandro Mauri 2020-10-07 21:06:41 +02:00
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**/*.o
sbl*
tests/**
!**/*.c
!**/*.1

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GLWT(Good Luck With That) Public License
Copyright (c) Everyone, except Author
Everyone is permitted to copy, distribute, modify, merge, sell, publish,
sublicense or whatever they want with this software but at their OWN RISK.
Preamble
The author has absolutely no clue what the code in this project does.
It might just work or not, there is no third option.
GOOD LUCK WITH THAT PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION, AND MODIFICATION
0. You just DO WHATEVER YOU WANT TO as long as you NEVER LEAVE A
TRACE TO TRACK THE AUTHOR of the original product to blame for or hold
responsible.
IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
Good luck and Godspeed.

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# Simple backlight
Simple utility to change the backlight
## Features
- Set the monitor to change
- Save and restore backlight
- Written in C99, that is a pro i guess...
## Getting
Clone this repository, then use `make` to compile, `make install` and `make
uninstall` to install and uninstall, finally `make clean` to remove all the
compiled junk from the folder.
## Usage
Here are some examples:
```sh
# Increase brightness by 10% and save the changed brightness to $HOME/.savefile
$ sbl -c $HOME/.savefile -S -i 10
# Set the brightness to 30%
$ sbl -s 30
# Restore the saved backlight value from example 1
$ sbl -c $HOME/.savefile -r
# Forgot what does what?
$ sbl -h
```
Read the man page for detailed instructions

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CC ?= gcc
CFLAGS = -Wall -pedantic --std=c99 -O2
PREFIX = /usr/local
MANPREFIX = ${PREFIX}/share/man
sbl: sbl.c
dbg:
gcc -O0 -g sbl.c -o sbl-dbg
install: sbl
mkdir -p ${DESTDIR}${PREFIX}/bin
cp -f sbl ${DESTDIR}${PREFIX}/bin/sbl
chown root:root ${DESTDIR}${PREFIX}/bin/sbl
chmod 4755 ${DESTDIR}${PREFIX}/bin/sbl
mkdir -p ${DESTDIR}${MANPREFIX}/man1
cp -f sbl.1 ${DESTDIR}${MANPREFIX}/man1/sbl.1
chmod 644 ${DESTDIR}${MANPREFIX}/man1/sbl.1
uninstall:
rm -f ${DESTDIR}${PREFIX}/bin/sbl\
${DESTDIR}${MANPREFIX}/man1/sbl.1
clean:
rm -f sbl sbl-dbg

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#define _DEFAULT_SOURCE
#define _POSIX_C_SOURCE 200809L
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <stdarg.h>
#include <errno.h>
#include <string.h>
#include <wordexp.h>
#include <limits.h>
#include <getopt.h>
#include <unistd.h>
#define BACKLIGHT_ROOT_PATH "/sys/class/backlight/"
#define BL_MIN 5
#define const_arr_size(val) ((int)(sizeof(val)/sizeof(val[0])))
const char *savefile_paths[] = {
NULL, /* reserved for external savefile path */
"/etc/sbl/savefile"
};
enum action {
DISPLAY, INCREASE, DECREASE, SET, RESTORE
};
static uid_t ruid;
int device_index = 0;
static void die (const char *, ...);
static void usage (void);
static void list_cards (void);
static void set_brightness (float);
static void change_permissions (const char *);
static void restore_permissions (void);
static int save_value (float);
static int get_max_brightness (void);
static float get_saved_value (void);
static float get_current_brightness (void);
static const char * backlight_path (int);
static const char * get_savefile (void);
int main (int argc, char *argv[])
{
int opc = 0, store = 0;
enum action act = DISPLAY;
float value = BL_MIN;
char *extfile = NULL;
/* Parse command line arguments */
while ((opc = getopt(argc, argv, "c:hI:li:d:s:Sr")) != -1) {
switch (opc) {
case 'l':
list_cards();
break;
case 'h':
usage();
break;
case 'c':
extfile = malloc(strlen(optarg) + 1);
if (!extfile)
die("malloc in main():");
strcpy(extfile, optarg);
savefile_paths[0] = extfile;
break;
case 'I':
device_index = atoi(optarg);
break;
case 'i':
act = INCREASE;
value = atof(optarg);
break;
case 'd':
act = DECREASE;
value = atof(optarg);
break;
case 's':
act = SET;
value = atof(optarg);
break;
case 'r':
act = RESTORE;
break;
case 'S':
store = 1;
break;
default:
exit(EXIT_FAILURE);
break;
}
}
ruid = getuid ();
switch (act) {
case DISPLAY:
printf("%.2f\n", get_current_brightness());
break;
case SET:
set_brightness(value);
break;
case INCREASE:
value += get_current_brightness();
set_brightness(value);
break;
case DECREASE:
value = get_current_brightness() - value;
set_brightness(value);
break;
case RESTORE:
set_brightness(get_saved_value());
break;
default:
break;
}
if (store)
save_value(get_current_brightness());
if (extfile)
free(extfile);
return 0;
}
int save_value (float value)
{
FILE *fd;
fd = fopen(get_savefile(), "w");
if (!fd)
die("could not open savefile");
fprintf(fd, "%f\n", value);
fclose(fd);
return 1;
}
float get_saved_value (void)
{
FILE *fd;
float rtf = -1;
fd = fopen(get_savefile(), "r");
if (!fd)
die("could not open savefile");
fscanf(fd, "%f", &rtf);
fclose(fd);
return rtf;
}
float get_current_brightness (void)
{
FILE *fd;
char buf[PATH_MAX] = {0};
int cb = -1;
const char *path = backlight_path(device_index);
if (!path)
die("invalid device index");
strcpy(buf, path);
strcat(buf, "/brightness");
fd = fopen(buf, "r");
if (!fd)
die("could not open %s", buf);
fscanf(fd, "%d", &cb);
fclose(fd);
return ((float)cb / (float)get_max_brightness()) * 100.0;;
}
int get_max_brightness (void)
{
FILE *fd;
char buf[PATH_MAX] = {0};
int rti = -1;
const char *path = backlight_path(device_index);
if (!path)
die("invalid device index");
strcpy(buf, path);
strcat(buf, "/max_brightness");
fd = fopen(buf, "r");
if (!fd)
die("could not open %s", buf);
fscanf(fd, "%d", &rti);
fclose(fd);
return rti;
}
/* Return the correct savefile path, creating it if it does not exist */
const char * get_savefile (void)
{
static char buf[PATH_MAX];
wordexp_t result = {0};
FILE *fd;
for (int i = 0; i < const_arr_size(savefile_paths); i++) {
if (!savefile_paths[i])
continue;
switch (wordexp(savefile_paths[i], &result, 0)) {
case 0:
break;
case WRDE_NOSPACE:
wordfree (&result);
die("Not enough space");
default:
die("Path not valid");
}
strcpy(buf, result.we_wordv[0]);
if ((fd = fopen(result.we_wordv[0], "r")))
break;
}
/* Create a savefile */
if (!fd) {
wordfree(&result);
for (int i = 0; i < const_arr_size(savefile_paths); i++) {
if (!savefile_paths[i])
continue;
switch (wordexp(savefile_paths[i], &result, 0)) {
case 0:
break;
case WRDE_NOSPACE:
wordfree (&result);
die("Not enough space");
default:
die("Path not valid");
}
strcpy(buf, result.we_wordv[0]);
if ((fd = fopen(result.we_wordv[0], "w")))
break;
}
}
wordfree(&result);
if (!fd)
die("could not open or create a savefile");
fclose(fd);
return buf;
}
const char * backlight_path (int index)
{
DIR *dp;
struct dirent *de;
static char buf[PATH_MAX];
memset(buf, 0, PATH_MAX);
if (index < 0)
die("%d is not a valid index", index);
if (!(dp = opendir(BACKLIGHT_ROOT_PATH)))
die("error opening " BACKLIGHT_ROOT_PATH);
errno = 0;
while ((de = readdir(dp))) {
if (!(de->d_type & DT_LNK))
continue;
if (index) {
index--;
continue;
} else {
strcpy(buf, BACKLIGHT_ROOT_PATH);
strcat(buf, de->d_name);
break;
}
}
closedir(dp);
if (errno)
die("error reading " BACKLIGHT_ROOT_PATH);
// FIXME: actually check return value of this
if (!buf[0])
return NULL;
return buf;
}
void list_cards (void)
{
int i = 0;
const char *s;
for (; (s = backlight_path(i)); i++)
printf("%d: %s\n", i, s);
exit(EXIT_SUCCESS);
}
void set_brightness (float value)
{
int set;
char buf[PATH_MAX] = {0};
const char *path = backlight_path(device_index);
FILE *fd;
if (value > 100)
value = 100;
if (value < BL_MIN)
value = BL_MIN;
set = (value/100.0) * get_max_brightness();
if (set < 0)
return;
if (!path)
die("invalid device index");
strcpy(buf, path);
strcat(buf, "/brightness");
change_permissions(buf);
fd = fopen(buf, "w");
if (!fd)
die("could not open %s", buf);
fprintf(fd, "%d", set);
fclose(fd);
restore_permissions();
}
/* Change the process permissions matching the ones pointed by path */
void change_permissions (const char *path)
{
int status;
struct stat st;
stat(path, &st);
status = seteuid(st.st_uid);
if (status < 0)
die("could not setuid");
}
static void restore_permissions (void)
{
int status;
status = seteuid(ruid);
if (status < 0)
die("could not setuid");
}
void die(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
if (fmt[0] && fmt[strlen(fmt) - 1] == ':') {
fputc(' ', stderr);
perror(NULL);
} else {
fputc('\n', stderr);
}
va_end(ap);
exit(errno ? errno : 1);
}
static void usage (void)
{
puts("Usage: sbl [-hlrS] [-c savefile] [-I index] [-i/d/s percent]\n"
"-h print this message\n"
"-l list devices by index\n"
"-r restore saved value\n"
"-S save value\n"
"-c savefile specify savefile\n"
"-I index specify device by index\n"
"-i percent increase backlight by percent\n"
"-d percent decrease backlight by percent\n"
"-s percent set backlight to percent\n");
exit(EXIT_SUCCESS);
}