134 lines
3.1 KiB
C
134 lines
3.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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void usage(void){
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fprintf(stderr, "TODO: usage\n");
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exit(-1);
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}
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int check_valid_files(const char* f1, const char* f2){
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struct stat file1, file2;
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if(stat(f1, &file1)){
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printf("failed to open '%s'\n", f1);
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return -1;
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}
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if(stat(f2, &file2)){
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printf("failed to open '%s'\n", f2);
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return -1;
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}
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//Same device and same inode means same file
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//device id
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if(file1.st_dev != file2.st_dev)
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return -2;
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//inode number
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if(file1.st_ino != file2.st_ino)
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return -2;
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return 0;
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}
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int get_brightness(const char* file){
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FILE* bright = fopen(file, "r");
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char buff[127];
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if(!bright){
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fprintf(stderr, "Unable to open brightness file \"%s\"!\n", file);
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return 0;
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}
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if(!fgets(buff, sizeof(buff), bright)){
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fprintf(stderr, "Unable to read file \"%s\"!\n", file);
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fclose(bright);
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return 0;
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}
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fclose(bright);
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return atof(buff);
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}
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//argv[1] shall be [+-=]<percentage>|min|max|off
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int main(int argc, char** argv){
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const char* backlight_file = "/sys/class/backlight/intel_backlight/brightness";
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const char* max_backlight_file = "/sys/class/backlight/intel_backlight/max_brightness";
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//Make sure we have an argument and it is at least 2 characters long
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if(argc < 2 || strlen(argv[1]) < 2)
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usage();
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if(setuid(0)){
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fprintf(stderr, "Unable to setuid to 0!\n");
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return -3;
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}
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if(check_valid_files("/", "/proc/1/root")){
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fprintf(stderr, "No chroot today\n");
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return -4;
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}
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//Min brightness is just 0, so set it up front
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float min_brightness = 0;
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float max_brightness = get_brightness(max_backlight_file);
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float current_brightness = get_brightness(backlight_file);
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//Amount to inc/dec
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int delta;
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if(strlen(argv[1]) > 0)
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delta = max_brightness * atof(argv[1] + 1) / 100.0;
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else
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delta = 0;
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//Open brightness file for writing
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FILE* bright = fopen(backlight_file, "w+");
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if(!bright){
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fprintf(stderr, "Unable to open brightness file \"%s\" for writing!\n", backlight_file);
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return 1;
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}
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//Increment
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if(argv[1][0] == '+'){
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delta = delta + current_brightness;
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if(delta >= max_brightness)
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fprintf(bright, "%d", (int)max_brightness);
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else{
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fprintf(bright, "%d", delta);
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}
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//Decrement
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}else if(argv[1][0] == '-'){
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delta = current_brightness - delta;
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if(delta <= min_brightness)
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fprintf(bright, "%d", (int)min_brightness);
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else
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fprintf(bright, "%d", delta);
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//Directly set
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}else if(argv[1][0] == '='){
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if(delta >= max_brightness)
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fprintf(bright, "%d", (int)max_brightness);
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else if(delta <= min_brightness)
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fprintf(bright, "%d", (int)min_brightness);
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else
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fprintf(bright, "%d", delta);
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//Set to minimum plus one (so backlight is actually on!)
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}else if(!strcmp("min", argv[1])){
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fprintf(bright, "%d", (int)(min_brightness + 1));
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//Turn off backlight
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}else if(!strcmp("off", argv[1])){
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fprintf(bright, "%d", (int)min_brightness);
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//Set to maximum
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}else if(!strcmp("max", argv[1])){
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fprintf(bright, "%d", (int)max_brightness);
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//Unknown option
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}else{
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fclose(bright);
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usage();
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}
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fclose(bright);
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return 0;
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}
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