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mirror of https://github.com/Dejvino/pinephone-toolkit.git synced 2024-11-14 11:33:28 +00:00

Add backlight

This commit is contained in:
Dejvino 2020-05-30 17:23:08 +02:00
parent 6838ca091b
commit c7140f898b
3 changed files with 92 additions and 0 deletions

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README.md Normal file
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# PinePhone Toolkit
A collection of tools and utility apps for the PINE64 PinePhone.
## Components
### backlight
Get / Set backlight brightness.
## Building
```
$ meson build
$ cd build
$ ninja
```

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meson.build Normal file
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project('PinePhone Toolkit', 'c')
executable('pptk-backlight', ['src/backlight.c'])

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src/backlight.c Normal file
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static char *argv0 = "./backlight";
static char *backlight_file = "/sys/devices/platform/backlight/backlight/backlight/brightness";
void print_usage()
{
printf("usage: %s COMMAND [VALUE]\n", argv0);
printf(" COMMAND = {get, set}\n");
printf(" get ... prints current backlight level\n");
printf(" set ... sets backlight level to VALUE\n");
printf(" VALUE = [0..10] ... backlight amount\n");
}
void print_usage_and_fail()
{
print_usage();
exit(EXIT_FAILURE);
}
void command_get()
{
FILE *fp = fopen(backlight_file, "r");
if (fp == NULL) {
fprintf(stderr, "Cannot open file '%s' for reading.\n", backlight_file);
exit(EXIT_FAILURE);
}
int buffer_length = 255;
char buffer[buffer_length];
while (fgets(buffer, buffer_length, fp)) {
printf("%s", buffer);
}
fclose(fp);
}
void command_set(int value)
{
if (setuid(0)) {
fprintf(stderr, "Cannot set root permissions via setuid(0).\n");
exit(EXIT_FAILURE);
}
FILE *fp = fopen(backlight_file, "w+");
if (fp == NULL) {
fprintf(stderr, "Cannot open file '%s' for writing.\n", backlight_file);
exit(EXIT_FAILURE);
}
fprintf(fp, "%d\n", value);
fclose(fp);
}
int main(int argc, char *argv[])
{
if (argc < 1) {
print_usage_and_fail();
}
argv0 = argv[0];
if (argc < 2) {
print_usage_and_fail();
}
char *command = argv[1];
if ((strcmp(command, "get") == 0) && (argc == 2)) {
command_get();
} else if ((strcmp(command, "set") == 0) && (argc == 3)) {
int value = atoi(argv[2]);
if (value < 0 || value > 10) {
print_usage_and_fail();
}
command_set(value);
} else {
print_usage_and_fail();
}
exit(EXIT_SUCCESS);
}