1 files changed, 76 insertions, 0 deletions
diff --git a/.bin/bri.c b/.bin/bri.c
new file mode 100755
index 00000000..88a11994
--- /dev/null
+++ b/.bin/bri.c
@@ -0,0 +1,76 @@
+#if 0
+sudo rm $(dirname $0)/bri && \
+cc -Wall -Wextra -pedantic $@ -o $(dirname $0)/bri $0 && \
+sudo chown root:root $(dirname $0)/bri && \
+exec sudo chmod u+s $(dirname $0)/bri
+#endif
+
+// Backlight brightness control.
+
+#include <dirent.h>
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) {
+    int error;
+
+    if (argc < 2) errx(EX_USAGE, "usage: bri N | +... | -...");
+
+    error = chdir("/sys/class/backlight");
+    if (error) err(EX_IOERR, "/sys/class/backlight");
+
+    DIR *dir = opendir(".");
+    if (!dir) err(EX_IOERR, "opendir");
+
+    struct dirent *entry;
+    while (NULL != (errno = 0, entry = readdir(dir))) {
+        if (entry->d_name[0] == '.') continue;
+
+        error = chdir(entry->d_name);
+        if (error) err(EX_IOERR, entry->d_name);
+        break;
+    }
+    if (!entry) {
+        if (errno) err(EX_IOERR, "readdir");
+        errx(EX_CONFIG, "empty /sys/class/backlight");
+    }
+
+    char *bright = argv[1];
+
+    if (bright[0] == '+' || bright[0] == '-') {
+        FILE *actual = fopen("actual_brightness", "r");
+        if (!actual) err(EX_IOERR, "actual_brightness");
+
+        unsigned int current;
+        int match = fscanf(actual, "%u", &current);
+        if (match == EOF) err(EX_IOERR, "fscanf");
+        if (match < 1) err(EX_DATAERR, "fscanf");
+
+        size_t count = strnlen(bright, 15);
+        if (bright[0] == '+') {
+            current += 16 * count;
+        } else {
+            current -= 16 * count;
+        }
+
+        char buf[15];
+        snprintf(buf, sizeof(buf), "%u", current);
+
+        bright = buf;
+    }
+
+    error = setuid(0);
+    if (error) err(EX_NOPERM, "setuid");
+
+    FILE *brightness = fopen("brightness", "w");
+    if (!brightness) err(EX_IOERR, "brightness");
+
+    int count = fprintf(brightness, "%s", bright);
+    if (count < 0) err(EX_IOERR, "fprintf");
+
+    return EX_OK;
+}