1 files changed, 129 insertions, 0 deletions
diff --git a/kbd.c b/kbd.c
new file mode 100644
index 0000000..30f0fcc
--- /dev/null
+++ b/kbd.c
@@ -0,0 +1,129 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+
+#define BUF_SIZE 100
+#define KBD_MAX_PATH        "/sys/class/leds/tpacpi::kbd_backlight/max_brightness"
+#define KBD_BRIGHTNESS_PATH "/sys/class/leds/tpacpi::kbd_backlight/brightness"
+
+#define KBD_ERROR_ARGS -1
+#define KBD_ERROR_MEM  -2
+#define KBD_SUCCESS    1
+
+typedef enum direction { BL_DOWN, BL_UP, BL_OFF, BL_MAX } direction_t;
+
+int read_int(const char *path, int *value);
+int write_int(const char *path, int value);
+int bl_new(int current, int max, direction_t direction);
+void usage(const char *name);
+int get_direction(const char *str, direction_t *dir);
+
+int main(int argc, char *argv[]) {
+    int bl_max = -1, bl_current = -1, bl;
+    direction_t direction;
+
+    if (argc < 2) {
+        usage(argv[0]);
+        return -1;
+    }
+
+    if (get_direction(argv[1], &direction) != KBD_SUCCESS) {
+        fprintf(stderr, "E: Unexpected argument \"%s\"\n", argv[1]);
+        usage(argv[0]);
+        return 1;
+    }
+
+    if (read_int(KBD_MAX_PATH, &bl_max) != KBD_SUCCESS) {
+        fprintf(stderr, "E: Failed to read maximum brightness from \"%s\"\n", KBD_MAX_PATH);
+        usage(argv[0]);
+        return 1;
+    }
+
+    if (read_int(KBD_BRIGHTNESS_PATH, &bl_current) != KBD_SUCCESS) {
+        fprintf(stderr, "E: Failed to read current brightness from \"%s\"\n", KBD_BRIGHTNESS_PATH);
+        usage(argv[0]);
+        return 1;
+    }
+
+    bl = bl_new(bl_current, bl_max, direction);
+
+    if (write_int(KBD_BRIGHTNESS_PATH, bl) != KBD_SUCCESS) {
+        fprintf(stderr, "E: Failed to writing to \"%s\"\n", KBD_BRIGHTNESS_PATH);
+        usage(argv[0]);
+        return 1;
+    }
+
+    return 0;
+}
+
+int read_int(const char *path, int *value) {
+    FILE *fp = fopen(path, "r");
+    int pos;
+
+    if (fp == NULL)
+      return KBD_ERROR_MEM;
+
+    char buf[BUF_SIZE];
+    if (fread(buf, sizeof(char), BUF_SIZE, fp) == 0)
+      return KBD_ERROR_MEM;
+
+    int status = sscanf(buf, "%d%n", value, &pos);
+    if (status == EOF || pos != 1) {
+      return KBD_ERROR_MEM;
+    }
+
+    fclose(fp);
+    return KBD_SUCCESS;
+}
+
+int write_int(const char *path, int value) {
+    FILE *fp = fopen(path, "w");
+
+    if (fp == NULL)
+      return KBD_ERROR_MEM;
+
+    int status = fprintf(fp, "%d", value);
+    if (status < 0)
+      return KBD_ERROR_MEM;
+
+    fclose(fp);
+    return KBD_SUCCESS;
+}
+
+int bl_new(int current, int max, direction_t direction) {
+    switch(direction) {
+        case BL_DOWN:
+            return (current == 0 ? 0 : current - 1);
+            break;
+        case BL_UP:
+            return (current == max ? max : current + 1);
+            break;
+        case BL_OFF:
+            return 0;
+            break;
+        case BL_MAX:
+            return max;
+            break;
+    }
+    return 0;
+}
+
+void usage(const char *name) {
+    fprintf(stderr, "Usage: %s [up|down|off|max]\n", name);
+}
+
+int get_direction(const char *str, direction_t *dir) {
+    if (strcmp(str, "up") == 0) {
+        *dir = BL_UP;
+    } else if (strcmp(str, "down") == 0) {
+        *dir = BL_DOWN;
+    } else if (strcmp(str, "off") == 0) {
+        *dir = BL_OFF;
+    } else if (strcmp(str, "max") == 0) {
+        *dir = BL_MAX;
+    } else {
+      return KBD_ERROR_ARGS;
+    }
+    return KBD_SUCCESS;
+}