From a60d3738495218b0bc10cdd6f79d0e823f08fd3e Mon Sep 17 00:00:00 2001
From: Siyuan Miao <i@xswan.net>
Date: Mon, 3 Mar 2025 13:31:08 +0100
Subject: [PATCH] fix(usb_config): check if usb_config is defined in
 kvm_config.json

---
 config.go  | 9 +++++++--
 jsonrpc.go | 4 ++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/config.go b/config.go
index f12ab45..ecb0909 100644
--- a/config.go
+++ b/config.go
@@ -37,7 +37,7 @@ type Config struct {
 	DisplayMaxBrightness int               `json:"display_max_brightness"`
 	DisplayDimAfterSec   int               `json:"display_dim_after_sec"`
 	DisplayOffAfterSec   int               `json:"display_off_after_sec"`
-	UsbConfig            UsbConfig         `json:"usb_config"`
+	UsbConfig            *UsbConfig        `json:"usb_config"`
 }
 
 const configPath = "/userdata/kvm_config.json"
@@ -50,7 +50,7 @@ var defaultConfig = &Config{
 	DisplayMaxBrightness: 64,
 	DisplayDimAfterSec:   120,  // 2 minutes
 	DisplayOffAfterSec:   1800, // 30 minutes
-	UsbConfig: UsbConfig{
+	UsbConfig: &UsbConfig{
 		VendorId:     "0x1d6b", //The Linux Foundation
 		ProductId:    "0x0104", //Multifunction Composite Gadget
 		SerialNumber: "",
@@ -90,6 +90,11 @@ func LoadConfig() {
 		return
 	}
 
+	// merge the user config with the default config
+	if loadedConfig.UsbConfig == nil {
+		loadedConfig.UsbConfig = defaultConfig.UsbConfig
+	}
+
 	config = &loadedConfig
 }
 
diff --git a/jsonrpc.go b/jsonrpc.go
index 1b87465..b1b36c5 100644
--- a/jsonrpc.go
+++ b/jsonrpc.go
@@ -540,12 +540,12 @@ func rpcSetUsbEmulationState(enabled bool) error {
 
 func rpcGetUsbConfig() (UsbConfig, error) {
 	LoadConfig()
-	return config.UsbConfig, nil
+	return *config.UsbConfig, nil
 }
 
 func rpcSetUsbConfig(usbConfig UsbConfig) error {
 	LoadConfig()
-	config.UsbConfig = usbConfig
+	config.UsbConfig = &usbConfig
 
 	err := UpdateGadgetConfig()
 	if err != nil {