fixup! wui: Replace the SNTP reset with per-pass reconciliation

Author: henrikosorensen

lib/WUI/sntp/sntp_client.c

@@ -4,7 +4,6 @@
 #include "wui_api.h"
 #include "tcpip.h"
 
-#include <stdio.h>
 #include <string.h>
 
 #include <option/has_esp.h>
@@ -64,9 +63,12 @@ void sntp_client_step(void) {
         return;
     }
 
-    snprintf(sntp_applied_server, sizeof(sntp_applied_server), "%s", configured);
-
     LOCK_TCPIP_CORE();
+    // The copy itself must happen under the lock too: lwIP still holds a
+    // pointer to this same buffer from the previous start, and the tcpip
+    // thread may be reading it in an in-flight request. The lock excludes
+    // that reader while the buffer changes; the restart below re-registers it.
+    strlcpy(sntp_applied_server, configured, sizeof(sntp_applied_server));
     sntp_client_start();
     UNLOCK_TCPIP_CORE();
     sntp_running = true;

tests/unit/lib/WUI/sntp/CMakeLists.txt

@@ -7,6 +7,7 @@ function(add_sntp_client_test target stub_dir)
     ${target}
     # Not really tests, just stuffings to satisfy the linker.
     ${CMAKE_CURRENT_SOURCE_DIR}/missing_functions.c
+    ${CMAKE_SOURCE_DIR}/tests/stubs/strlcpy.c
     # The tests.
     ${CMAKE_CURRENT_SOURCE_DIR}/sntp_client_tests.cpp
     # Tested files.