use va_arg instead of vsnprintf for calculate build string len

src/ccode/string.c

@@ -221,7 +221,14 @@ char* build_string(char* format, ...) {
     va_start(args, format);
 
     /* Determine the size needed for the string */
-    int size = vsnprintf(NULL, 0, format, args) + 1;
+    int size = strlen(format);
+    const char *arg;
+
+    /* Count the number of arguments until we hit a NULL */
+    while ((arg = va_arg(args, const char *)) != NULL) {
+        size+= strlen(arg);
+    }
+
     va_end(args);
 
     /* Allocate memory for the string */
@@ -232,7 +239,7 @@ char* build_string(char* format, ...) {
 
     /* Format the string */
     va_start(args, format);
-    vsnprintf(result, size, format, args);
+    sprintf(result, format, args);
     va_end(args);
 
     return result;