src/utmpx/wtmpx.c

/* Common utmpx implementation
 * Copyright 2015-2023 Rivoreo
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 */

#include "utmpx.h"
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

void updwtmpx(const char *wtmpx_file, const struct utmpx *utx) {
	int fd = open(wtmpx_file, O_WRONLY | O_APPEND);
	if(fd == -1) return;
	size_t written = 0;
	do {
		int s = write(fd, (const char *)utx + written, sizeof *utx - written);
		if(s < 0) {
			if(errno == EINTR) continue;
			break;
		}
		written += s;
	} while(written < sizeof *utx);
	close(fd);
}