Fix ESP32 network:stop/0

Removes all of the registered event handlers when the driver is stopped.

No longer deletes default_event_loop when the driver is stopped. Deleting this loop was a mistake
since other processes may use the default loop and it is normally created at boot up, not as part
of the network initialization.

Adds a network:stop/0 and a second start to the test_wifi_example esp32-simtest to help catch
future problems with stopping and restarting the network.

Closes #1449

Signed-off-by: Winford <winford@object.stream>

Author: UncleGrumpy

CHANGELOG.md

@@ -27,6 +27,7 @@ certain VM instructions are used.
 - Fixed an issue where a timeout would occur immediately in a race condition
 - Fixed SPI close command
 - Added missing lock on socket structure
+- Fix `network:stop/0` on ESP32 so the network can be started again
 
 ## [0.6.5] - 2024-10-15
 

src/platforms/esp32/components/avm_builtins/network_driver.c

@@ -811,6 +811,9 @@ static void stop_network(Context *ctx)
 {
     // Stop unregister event callbacks so they dont trigger during shutdown.
     esp_event_handler_unregister(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler);
+    esp_event_handler_unregister(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler);
+    esp_event_handler_unregister(IP_EVENT, IP_EVENT_AP_STAIPASSIGNED, &event_handler);
+    esp_event_handler_unregister(sntp_event_base, SNTP_EVENT_BASE_SYNC, &event_handler);
 
     esp_netif_t *sta_wifi_interface = esp_netif_get_handle_from_ifkey("WIFI_STA_DEF");
     esp_netif_t *ap_wifi_interface = esp_netif_get_handle_from_ifkey("WIFI_AP_DEF");
@@ -830,12 +833,6 @@ static void stop_network(Context *ctx)
     // Stop sntp (ignore OK, or not configured error)
     esp_sntp_stop();
 
-    // Delete network event loop
-    esp_err_t err = esp_event_loop_delete_default();
-    if (err != ESP_OK) {
-        ESP_LOGE(TAG, "Invalid state error while deleting event loop, continuing network shutdown...");
-    }
-
     // Destroy existing netif interfaces
     if (ap_wifi_interface != NULL) {
         esp_netif_destroy_default_wifi(ap_wifi_interface);

src/platforms/esp32/test/main/test_erl_sources/test_wifi_example.erl

@@ -25,6 +25,8 @@
 start() ->
     case verify_platform(atomvm:platform()) of
         ok ->
+            ok = start_network(),
+            ok = network:stop(),
             start_network(),
             loop(0);
         Error ->