fix: hook the log lock into log_printfv

The Arduino core already links with --wrap=log_printf for the ESP
Insights hook in libesp_diagnostics, so defining __wrap_log_printf
failed to link with a duplicate definition. That hook prints through
log_printfv, so wrap that instead and take the lock there.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

platformio.ini

@@ -37,8 +37,9 @@ build_flags =
 	-DCONFIG_ESP_COREDUMP_CHECKSUM_CRC32=1
 	-DCONFIG_ESP_TASK_WDT_PANIC=1
 	-DCONFIG_ESP_COREDUMP_DECODE_INFO=1
-	; Route log_printf through src/LogLock.cpp so lines from both cores don't interleave.
+	; Route log_printfv through src/LogLock.cpp so lines from both cores don't
-	-Wl,--wrap=log_printf
+	; interleave.  The core already wraps log_printf for ESP Insights.
+	-Wl,--wrap=log_printfv
 monitor_speed = 115200
 monitor_filters = 
 	time

src/LogLock.cpp

@@ -1,20 +1,21 @@
 // Prints each log line whole.
 //
-// The Arduino core's log_printf() writes with ets_printf() and has its UART
+// The Arduino core's log_printfv() writes with ets_printf() and has its UART
 // lock commented out, so lines logged at the same time from async_tcp (core 0)
 // and loop() (core 1) come out interleaved character by character.  It also
 // formats short lines into one static buffer shared by every task.
 //
-// platformio.ini links with -Wl,--wrap=log_printf so every ESP_LOGx/log_x call
+// The core already links with --wrap=log_printf, which sends every
-// lands here and takes this lock around the core's log_printfv().
+// ESP_LOGx/log_x call to the ESP Insights hook in libesp_diagnostics, and that
+// hook prints through log_printfv().  platformio.ini adds
+// -Wl,--wrap=log_printfv so that call lands here and takes this lock.
 #include <Arduino.h>
 #include <stdarg.h>
 #include "freertos/FreeRTOS.h"
 #include "freertos/semphr.h"
 #include "freertos/task.h"
 
-// Defined in the core's esp32-hal-uart.c but not declared in a header.
+extern "C" int __real_log_printfv(const char *format, va_list arg);
-extern "C" int log_printfv(const char *format, va_list arg);
 
 // Created during static initialisation, before anything can race for it.  A
 // constructor that logs before this runs simply goes unlocked.
@@ -23,14 +24,11 @@ static SemaphoreHandle_t logMutex = xSemaphoreCreateRecursiveMutex();
 // task stuck mid-log can only garble output, not hang another task.
 #define LOG_LOCK_WAIT_MS 50
 
-extern "C" int __wrap_log_printf(const char *format, ...) {
+extern "C" int __wrap_log_printfv(const char *format, va_list arg) {
   // No blocking before the scheduler runs, in an ISR or in a critical section.
   const bool canLock = logMutex && xTaskGetSchedulerState() == taskSCHEDULER_RUNNING && xPortCanYield();
   const bool locked = canLock && xSemaphoreTakeRecursive(logMutex, pdMS_TO_TICKS(LOG_LOCK_WAIT_MS)) == pdTRUE;
-  va_list arg;
+  int len = __real_log_printfv(format, arg);
-  va_start(arg, format);
-  int len = log_printfv(format, arg);
-  va_end(arg);
   if(locked) xSemaphoreGiveRecursive(logMutex);
   return len;
 }