Changed to mutable char* for reading config

Author: ed7coyne

src/thing/Config.cpp

@@ -26,7 +26,7 @@ void Config::SerializeToJson(Stream* output, std::function<void(int size)> handl
   root.printTo(*output);
 }
 
-void Config::ReadFromJson(const char* string) {
+void Config::ReadFromJson(char* string) {
   DynamicJsonBuffer jsonBuffer;
   JsonObject& root = jsonBuffer.parseObject(string);
   host = root["host"].asString();

src/thing/Config.h

@@ -31,7 +31,9 @@ struct Config {
   Pins pins;
 
   void SerializeToJson(Stream* output, std::function<void(int size)> handle_size) const;
-  void ReadFromJson(const char* string);
+
+  // We need a mutable char array here, otherwise a copy will be made.
+  void ReadFromJson(char* string);
 };
 
 }  // namespace thing

src/thing/FireThing.cpp

@@ -91,7 +91,9 @@ bool FireThing::ReadConfigFromStorage(Config* config) {
       SPIFFS.end();
       return false;
     }
-    config->ReadFromJson(cfg.readString().c_str());
+    char buffer[cfg.size()];
+    cfg.readBytes(buffer, cfg.size());
+    config->ReadFromJson(buffer);
     debug_("Config read from disk.");
   }
 

src/thing/Portal.cpp

@@ -125,8 +125,16 @@ void Portal::Start(const Config& config) {
         debug_("Config updated called without param.");
         return;
       }
-      String config = server_.arg("config");
-      config_.ReadFromJson(config.c_str());
+
+      char* buffer;
+      { // Scoped to free String memory.
+        String config = server_.arg("config");
+        buffer = (char*)malloc(config.length+1());
+        memcpy(buffer, config.c_str(), config.length()+1);
+      }
+      config_.ReadFromJson(buffer);
+      free(buffer);
+
       callback_(config_);
       server_.send(200, "text/plain", "");
       debug_("config updated.");