fix: invalid const and declaration ordering and added smart pointer for get

main/io/nvs_handler.cpp

@@ -46,7 +46,7 @@ void NVSStorageHandler::put(const char* const& key, const char* const& value) {
   }
 }
 
-char* NVSStorageHandler::get(const char* const& key) const {
+std::unique_ptr<char[]> NVSStorageHandler::get(const char* const& key) const {
   if (this->nvsHandle == 0) {
     printf("NVS handle is not initialized.\n");
     return nullptr;
@@ -62,11 +62,10 @@ char* NVSStorageHandler::get(const char* const& key) const {
     return nullptr;
   }
 
-  char* value = (char*)malloc(required_size);
-  err = nvs_get_str(this->nvsHandle, key, value, &required_size);
+  std::unique_ptr<char[]> value(new char[required_size]);
+  err = nvs_get_str(this->nvsHandle, key, value.get(), &required_size);
   if (err != ESP_OK) {
     printf("Error (%s) getting value for key %s from NVS!\n", esp_err_to_name(err), key);
-    free(value);
     return nullptr;
   }
 
@@ -106,7 +105,7 @@ esp_err_t NVSStorageHandler::process_all(KeyValueProcessor processor, void* arg)
     }
 
     // call the processor with the key and value
-    processor(arg, info.key, this->get(info.key));
+    processor(arg, info.key, this->get(info.key).get());
   }
   return ESP_OK;
 }
@@ -133,7 +132,7 @@ esp_err_t NVSStorageHandler::process_filtered(const char* const& key_prefix, Key
         return err;
       }
       // call the processor with the key and value
-      processor(arg, info.key, this->get(info.key));
+      processor(arg, info.key, this->get(info.key).get());
     }
   }
   return ESP_OK;
@@ -162,7 +161,7 @@ esp_err_t NVSStorageHandler::process_filtered(FilterFunc filter_func, KeyValuePr
         return err;
       }
       // call the processor with the key and value
-      processor(arg, info.key, this->get(info.key));
+      processor(arg, info.key, this->get(info.key).get());
     }
   }
   return ESP_OK;