stumpless-sys 0.3.0

// SPDX-License-Identifier: Apache-2.0

/*
 * Copyright 2023 Joel E. Anderson
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdbool.h>
#include <stddef.h>
#include <time.h>
#include "private/config/have_gmtime.h"
#include "private/config/wrapper/thread_safety.h"
#include "private/formatter.h"

/** Used to synchronize access to gmtime return values. */
static config_atomic_bool_t gmtime_free = config_atomic_bool_true;

size_t
gmtime_get_now( char *buffer ) {
  time_t now_time;
  time_t time_result;
  bool locked;
  struct tm *now_tm;
  size_t result = 0;

  time_result = time( &now_time );
  if( time_result == -1 ) {
    return 0;
  }

  do {
    locked = config_compare_exchange_bool( &gmtime_free, true, false );
  } while( !locked );

  now_tm = gmtime( &now_time );
  if( !now_tm ) {
    goto cleanup_and_return;
  }

 result = strftime( buffer,
                    RFC_5424_WHOLE_TIME_BUFFER_SIZE + 1,
                    "%FT%TZ",
                    now_tm );

cleanup_and_return:
  config_write_bool( &gmtime_free, true );
  return result;
}