esp32-alarm-clock/main/time_conversion.c

/*
 * SPDX-FileCopyrightText: 2023 Helmut Pozimski <helmut@pozimski.eu>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 */

#include <freertos/FreeRTOS.h>
#include <freertos/semphr.h>

#include <time.h>

#include "configuration.h"
 
static SemaphoreHandle_t mutex = NULL;
 
struct tm* convert_to_local(struct tm *timeinfo) {
	if (mutex == NULL) {
		mutex = xSemaphoreCreateMutex();
	}
	xSemaphoreTake(mutex, portMAX_DELAY);
	setenv("TZ", "GMT+0GMT+0", 1);
   tzset();
   time_t epoch_time = mktime(timeinfo);
   setenv("TZ", LOCAL_TIMEZONE, 1);
   tzset();
   struct tm* result = localtime(&epoch_time);
   setenv("TZ", "GMT+0GMT+0", 1);
	tzset();
	xSemaphoreGive(mutex);
	return result;
}