move some functionality to lib_commons from library

lib_commons.c

+/** @file libcommons.c */
+
+#include "lib_commons.h"
+
+size_t write_func(void *buffer, size_t size, size_t nmemb, void *data)
+{
+	struct string *str = (struct string *)data;
+	size_t len = size * nmemb;
+	size_t new_len = str->len + (len);
+	char *tmp_ptr = str->ptr;
+
+	str->ptr = realloc(str->ptr, new_len + 1);
+	if (!str->ptr)
+	{
+		//debug_print("not enough memory (realloc returned NULL)\n");
+		free(tmp_ptr);
+		return 0;
+	}
+
+	memcpy(str->ptr + str->len, buffer, len);
+	str->ptr[new_len] = '\0';
+	str->len = new_len;
+
+	return len;
+}
+
+struct json_object *get_json_string_object_by_key(struct json_object *json_obj, char *string, char *output_key) //"string" should be key?
+{
+	struct json_object_iter iterator;
+	struct json_object *string_object = NULL;
+	struct json_object *jstring = NULL;
+	enum json_type type;
+
+	type = json_object_get_type(json_obj);
+	if (type == json_type_object) // flow could be changed
+	{
+		//search the key from the json object
+		json_object_object_foreachC(json_obj, iterator)
+		{
+			printf("iteratorKey is :%s\n", iterator.key);
+			if (strcmp(string, (char *)iterator.key) == 0) // flow could be changed
+			{
+				//debug_print("Input string value: %s\n", (char *)json_object_get_string(iterator.val));
+				//debug_print("Input string key: %s\n", (char *)iterator.key);
+
+				string_object = json_object_new_object();
+				json_object_object_add(string_object, output_key, iterator.val);
+
+				//debug_print("The json object created: %sn", json_object_to_json_string(string_object));
+				break;
+			}
+		}
+	}
+	return string_object; // who is responsible for not leaking memory for scope of this function?
+}
\ No newline at end of file

lib_commons.h

+#ifndef LIB_COMMON_H
+#define LIB_COMMON_H
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <json-c/json.h>
+
+/**
+ * Struct used for parsing the curl response from the dongle.
+ */
+struct string {
+	char *ptr;  /*!< String for storage */
+	size_t len; /*!< Length of stored string */
+};
+
+/**
+ * The callback function from performing the curl command, response from server will be reconstructed here.
+ *
+ * @param[in] buffer: Contains chunk of response from server.
+ * @param[in] size: Size (byte) of type in buffer array.
+ * @param[in] nmemb: Number of members in buffer.
+ * @param[out] data: Pointer to area allocated for storing results from server.
+ *
+ * @return Number of bytes managed (size*nmemb).
+ */
+size_t write_func(void *buffer, size_t size, size_t nmemb, void *data);
+
+struct json_object *get_json_string_object_by_key(json_object *json_obj, char *string, char *output_key);
+#endif
\ No newline at end of file