Setting up a JSON configuration file to change LED paths without recompiling

v1

- the change allows the paths to the LED folders to be changed without
  having to recompile the widget
- the JSON file itself is included in this commit with the name "hvac.json"
- the location which the parser expects the configuration
  file to be in is /etc

v2

- optimised code in terms of opening and closing paths for writing
- put afb header definitions together

v3

- removed all caps warning notifications

Change-Id: If075c6650d8802849cbd706be4adbca9f1996c9e
Signed-off-by: Yordan Dimitrov <y.dimitrov.14@gmail.com>

diff --git a/binding/hvac-demo-binding.c b/binding/hvac-demo-binding.c
index b4f922a..a8993a1 100644 (file)
--- a/binding/hvac-demo-binding.c
+++ b/binding/hvac-demo-binding.c
@@ -29,14 +29,14 @@
 #include <net/if.h>
 #include <linux/can.h>
 #include <math.h>
-
 #include <json-c/json.h>
 
 #define AFB_BINDING_VERSION 2
+#include <afb/afb-binding.h>
+
 #define RED "/sys/class/leds/blinkm-3-9-red/brightness"
-#define BLUE "/sys/class/leds/blinkm-3-9-blue/brightness"
 #define GREEN "/sys/class/leds/blinkm-3-9-green/brightness"
-#include <afb/afb-binding.h>
+#define BLUE "/sys/class/leds/blinkm-3-9-blue/brightness"
 
 #define CAN_DEV "vcan0"
 
@@ -134,6 +134,16 @@ struct can_handler {
        struct sockaddr_can txAddress;
 };
 
+struct led_paths {
+       char *red;
+       char *green;
+       char *blue;
+}led_paths_values = {
+       .red = RED,
+       .green = GREEN,
+       .blue = BLUE
+};
+
 static struct can_handler can_handler = { .socket = -1, .simulation = false, .send_msg = "SENDING CAN FRAME"};
 
 static int open_can_dev_helper()
@@ -233,40 +243,52 @@ static uint8_t read_fanspeed()
 }
 
 /* 
- * @brief Writing to LED for both temperature sliders
+ * @param: None
+ *
+ * @brief: Parse JSON configuration file for blinkm path
  */
-
-static int temp_write_led()
+static int parse_config()
 {
-       int rc = 0, red_flag, blue_flag, green_flag, red_value, green_value, blue_value;
-       int right_temp;
-       int left_temp;
+       struct json_object *ledtemp = NULL;
+       struct json_object *jobj = json_object_from_file("/etc/hvac.json");
 
-       // /sys/class/leds/blinkm-3-9-red/brightness
-       FILE* r = fopen(RED, "w");
-       if (r == NULL) {
-               AFB_ERROR("Unable to open RED path for writing");
-               red_flag = 1;
+       // Check if .json file has been parsed as a json_object
+       if (!jobj) {
+               AFB_ERROR("JSON file could not be opened!\n");
+               return 1;
        }
 
-       // /sys/class/leds/blinkm-3-9-green/brightness
-       FILE* g = fopen(GREEN, "w");
-       if (g == NULL) {
-               AFB_ERROR("Unable to open GREEN path for writing");
-               green_flag = 1;
+       // Check if json_object with key "ledtemp" has been found in .json file
+       if (!json_object_object_get_ex(jobj, "ledtemp", &ledtemp)){
+               AFB_ERROR("Key not found!\n");
+               return 1;
        }
 
-       // /sys/class/leds/blinkm-3-9-blue/brightness
-       FILE* b = fopen(BLUE, "w");
-       if (b == NULL) {
-               AFB_ERROR("Unable to open BLUE path for writing");
-               blue_flag = 1;
+       // Extract directory paths for each LED colour
+       json_object_object_foreach(ledtemp, key, value) {
+               if (strcmp(key, "red") == 0) {
+                       led_paths_values.red = json_object_get_string(value);
+               } else if (strcmp(key, "green") == 0) {
+                       led_paths_values.green = json_object_get_string(value);
+               } else if (strcmp(key, "blue") == 0) {
+                       led_paths_values.blue = json_object_get_string(value);
+               }
        }
 
-       if (red_flag || green_flag || blue_flag)
-       {
-               rc = 1;
-       }
+       // return 0 if all succeeded
+       return 0;
+
+}
+
+/* 
+ * @brief Writing to LED for both temperature sliders
+ */
+static int temp_write_led()
+{
+
+       int rc = -1, red_value, green_value, blue_value;
+       int right_temp;
+       int left_temp;
 
        left_temp = read_temp_left_led() - 15;
        right_temp = read_temp_right_led() - 15;
@@ -275,16 +297,38 @@ static int temp_write_led()
        red_value = (degree_colours[left_temp].rgb[0] + degree_colours[right_temp].rgb[0]) / 2;
        green_value = (degree_colours[left_temp].rgb[1] + degree_colours[right_temp].rgb[1]) / 2;
        blue_value = (degree_colours[left_temp].rgb[2] + degree_colours[right_temp].rgb[2]) / 2;
+       
+       // default path: /sys/class/leds/blinkm-3-9-red/brightness
+       FILE* r = fopen(led_paths_values.red, "w");
+       if(r){
+               fprintf(r, "%d", red_value);
+               fclose(r);
+       } else {
+               AFB_ERROR("Unable to open red LED path!\n");
+               return -1;
+       }
 
-       // Writes to LED file the specific colour
-       fprintf(r, "%d", red_value);
-       fprintf(g, "%d", green_value);
-       fprintf(b, "%d", blue_value);
-       fclose(r);
-       fclose(g);
-       fclose(b);
-       return rc;
+       // default path: /sys/class/leds/blinkm-3-9-green/brightness
+       FILE* g = fopen(led_paths_values.green, "w");
+       if(g){
+               fprintf(g, "%d", green_value);
+               fclose(g);
+       } else {
+               AFB_ERROR("Unable to open green LED path!\n");
+               return -1;
+       }
+
+       // default path: /sys/class/leds/blinkm-3-9-blue/brightness
+       FILE* b = fopen(led_paths_values.blue, "w");
+       if(b){
+               fprintf(b, "%d", blue_value);
+               fclose(b);
+       } else {
+               AFB_ERROR("Unable to open blue LED path!\n");
+               return -1;
+       }
 
+       return 0;
 }
 
 /*
@@ -655,6 +699,8 @@ int bindingServicePreInit(struct afb_service service)
 int bindingServiceInit(struct afb_service service)
 {
        event = afb_daemon_make_event("language");
+       if(parse_config() != 0)
+               AFB_WARNING("Default values are being used!\n");
        if(afb_daemon_require_api("identity", 1))
                return -1;
        return afb_service_call_sync("identity", "subscribe", NULL, NULL);

diff --git a/hvac.json b/hvac.json
new file mode 100644 (file)
index 0000000..6e7d0db
--- /dev/null
+++ b/hvac.json
@@ -0,0 +1,7 @@
+{
+       "ledtemp": {
+               "red": "/sys/class/leds/blinkm-3-9-red/brightness",
+               "green": "/sys/class/leds/blinkm-3-9-green/brightness",
+               "blue": "/sys/class/leds/blinkm-3-9-blue/brightness"
+       }
+}
\ No newline at end of file