|
|
@@ -0,0 +1,77 @@ |
|
|
|
#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); |
|
|
|
} |