/*-
 * Copyright (c) 2014-2018 MongoDB, Inc.
 * Copyright (c) 2008-2014 WiredTiger, Inc.
 *	All rights reserved.
 *
 * See the file LICENSE for redistribution information.
 */

#include "wt_internal.h"

/*
 * __wt_vsnprintf_len_incr --
 *	POSIX vsnprintf convenience function, incrementing the returned size.
 */
int
__wt_vsnprintf_len_incr(
    char *buf, size_t size, size_t *retsizep, const char *fmt, va_list ap)
{
	int len;

	/*
	 * WiredTiger calls with length 0 to get the needed buffer size. Call
	 * the count only version in this case, _vsnprintf_s will invoke the
	 * invalid parameter handler if count is less than or equal to zero.
	 */
	if (size == 0) {
		*retsizep += (size_t)_vscprintf(fmt, ap);
		return (0);
	}

	/*
	 * Additionally, the invalid parameter handler is invoked if buffer or
	 * format is a NULL pointer.
	 */
	if (buf == NULL || fmt == NULL)
		return (EINVAL);

	/*
	 * If the storage required to store the data and a terminating null
	 * exceeds size, the invalid parameter handler is invoked, unless
	 * count is _TRUNCATE, in which case as much of the string as will
	 * fit in the buffer is written and -1 returned.
	 */
	if ((len = _vsnprintf_s(buf, size, _TRUNCATE, fmt, ap)) >= 0) {
		*retsizep += (size_t)len;
		return (0);
	}

	/* Return the buffer size required. */
	if (len == -1)
		*retsizep += (size_t)_vscprintf(fmt, ap);

	return (0);
}
