C: Json comments: added an obi_read_comment function to read one value

from comments

src/libjson/json_utils.c

@@ -238,7 +238,45 @@ char* obi_add_comment(char* comments, const char* key, const char* value)
 
 	// Free structure
 	cJSON_Delete(comments_struct);
+
 	return new_comments;
 }
 
 
+char* obi_read_comment(char* comments, const char* key)
+{
+	cJSON* comments_struct = NULL;
+	cJSON* value_json      = NULL;
+	char*  value           = NULL;
+
+	comments_struct = cJSON_Parse(comments);
+	if (comments_struct == NULL)
+	{
+		obi_set_errno(OBI_JSON_ERROR);
+		obidebug(1, "\nError parsing the comments when reading comments, key: %s", key);
+		return NULL;
+	}
+
+	value_json = cJSON_GetObjectItem(comments_struct, key);
+	if (value_json == NULL)
+	{
+		obi_set_errno(OBI_JSON_ERROR);
+		obidebug(1, "\nError getting a value when reading a comment, key: %s", key);
+		return NULL;
+	}
+
+	value = cJSON_Print(value_json);
+	if (value == NULL)
+	{
+		obi_set_errno(OBI_JSON_ERROR);
+		obidebug(1, "\nError formatting a value when reading a comment, key: %s", key);
+		return NULL;
+	}
+
+	// Free structure
+	cJSON_Delete(comments_struct);
+
+	return value;
+}
+
+

src/libjson/json_utils.h

@@ -21,6 +21,9 @@
 /**
  * @brief Add a comment (in the key/value form) to a (JSON formatted) comments character string.
  *
+ * Note: The usual way to use this function is to call obi_add_comment() with a view or a column's comments,
+ *       then obi_view_write_comments() with the result, then free said result.
+ *
  * @warning If the key is already in the structure, its associated value is turned
  *          into an array if needed and the new value is added to that array.
  *             // TODO discuss replace boolean
@@ -40,4 +43,23 @@
 char* obi_add_comment(char* comments, const char* key, const char* value);
 
 
+/**
+ * @brief Read a comment (returns its value) from a (JSON formatted) comments character string.
+ *
+ * @warning The returned character string is framed with "". // TODO which sucks
+ *
+ * @warning The returned pointer has to be freed by the caller.
+ *
+ * @param comments The initial comments, in the form of a JSON formatted character string.
+ * @param key The key referring to the wanted value.
+ *
+ * @returns A pointer on the character string containing the formatted value, framed with "".
+ * @retval NULL if an error occurred.
+ *
+ * @since August 2019
+ * @author Celine Mercier (celine.mercier@metabarcoding.org)
+ */
+char* obi_read_comment(char* comments, const char* key);
+
+
 #endif /* JSON_UTILS_H_ */