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@@ -2,17 +2,24 @@ |
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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 <stdbool.h> |
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static char *argv0 = "./backlight"; |
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static char *backlight_file = "/sys/devices/platform/backlight/backlight/backlight/brightness"; |
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static char *max_backlight_file = "/sys/devices/platform/backlight/backlight/backlight/max_brightness"; |
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int max_brightness = 10; |
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void print_usage() |
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{ |
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printf("usage: %s COMMAND [VALUE]\n", argv0); |
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printf(" COMMAND = {get, set}\n"); |
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printf(" get ... prints current backlight level\n"); |
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printf(" set ... sets backlight level to VALUE\n"); |
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printf(" VALUE = [0..10] ... backlight amount\n"); |
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printf(" get ... prints current raw backlight level\n"); |
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printf(" get_percent ... prints current percentage backlight level\n"); |
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printf(" set ... sets backlight level to raw VALUE_RAW\n"); |
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printf(" set_percent ... sets backlight level to percentage VALUE_PCT\n"); |
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printf(" VALUE_RAW = [0..%d]\n", max_brightness); |
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printf(" VALUE_PCT = [0..100]\n"); |
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} |
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void print_usage_and_fail() |
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@@ -21,7 +28,19 @@ void print_usage_and_fail() |
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exit(EXIT_FAILURE); |
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} |
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void command_get() |
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void read_max_brightness() |
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{ |
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FILE *fp = fopen(max_backlight_file, "r"); |
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if (fp == NULL) { |
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fprintf(stderr, "Cannot open file '%s' for reading. Using the default max brightness '%d'.\n", |
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max_backlight_file, max_brightness); |
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return; |
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} |
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fscanf(fp, "%d", &max_brightness); |
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fclose(fp); |
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} |
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void command_get(bool percent) |
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{ |
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FILE *fp = fopen(backlight_file, "r"); |
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if (fp == NULL) { |
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@@ -30,13 +49,17 @@ void command_get() |
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} |
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int buffer_length = 255; |
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char buffer[buffer_length]; |
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while (fgets(buffer, buffer_length, fp)) { |
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fgets(buffer, buffer_length, fp); |
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if (percent) { |
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int value = atoi(buffer); |
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printf("%d\n", value * 100 / max_brightness); |
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} else { |
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printf("%s", buffer); |
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} |
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fclose(fp); |
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} |
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void command_set(int value) |
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void command_set(int value, bool percent) |
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{ |
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if (setuid(0)) { |
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fprintf(stderr, "Cannot set root permissions via setuid(0).\n"); |
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@@ -48,12 +71,14 @@ void command_set(int value) |
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fprintf(stderr, "Cannot open file '%s' for writing.\n", backlight_file); |
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exit(EXIT_FAILURE); |
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} |
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fprintf(fp, "%d\n", value); |
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int raw = percent ? (value * max_brightness / 100) : value; |
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fprintf(fp, "%d\n", raw); |
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fclose(fp); |
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} |
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int main(int argc, char *argv[]) |
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{ |
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read_max_brightness(); |
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if (argc < 1) { |
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print_usage_and_fail(); |
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} |
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@@ -63,15 +88,24 @@ int main(int argc, char *argv[]) |
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} |
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char *command = argv[1]; |
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if ((strcmp(command, "get") == 0) && (argc == 2)) { |
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command_get(); |
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command_get(false); |
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} else if ((strcmp(command, "get_percent") == 0) && (argc == 2)) { |
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command_get(true); |
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} else if ((strcmp(command, "set") == 0) && (argc == 3)) { |
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int value = atoi(argv[2]); |
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if (value < 0 || value > 10) { |
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if (value < 0 || value > max_brightness) { |
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print_usage_and_fail(); |
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} |
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command_set(value, false); |
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} else if ((strcmp(command, "set_percent") == 0) && (argc == 3)) { |
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int value = atoi(argv[2]); |
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if (value < 0 || value > 100) { |
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print_usage_and_fail(); |
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} |
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command_set(value); |
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command_set(value, true); |
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} else { |
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print_usage_and_fail(); |
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} |
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exit(EXIT_SUCCESS); |
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} |
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