/*
 * Copyright (c) 2000-2002, 2004 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 */


#include "sm/generic.h"
SM_RCSID("@(#)$Id: vsnprintf.c,v 1.9 2004/12/29 23:47:35 ca Exp $")
#include "sm/varargs.h"
#include "sm/limits.h"
#include "sm/io.h"
#include "sm/assert.h"
#include "io-int.h"

/*
**  SM_VSNPRINTF -- format data for "output" into a string
**
**	Assigned 'str' to a "fake" file pointer. This allows common
**	o/p formatting function sm_vprintf() to be used.
**
**	Parameters:
**		str -- location for output
**		n -- maximum size for o/p
**		fmt -- format directives
**		ap -- data unit vectors for use by 'fmt'
**
**	Results:
**		result from sm_io_vfprintf()
**
**	Side Effects:
**		Limits the size ('n') to INT_MAX.
*/

int
sm_vsnprintf(char *str, size_t n, const char *fmt, va_list ap)
{
	int ret;
	char dummy;
	sm_file_T fake;

	/* While snprintf(3) specifies size_t stdio uses an int internally */
	if (n > INT_MAX)
		n = INT_MAX;

	/* Stdio internals do not deal correctly with zero length buffer */
	if (n == 0)
	{
		str = &dummy;
		n = 1;
	}
	fake.sm_magic = SM_FILE_MAGIC;
	fake.f_timeout = SM_TIME_FOREVER;
	f_fd(fake) = -1;
	f_flags(fake) = SMWR | SMSTR;
	f_bfbase(fake) = f_p(fake) = (uchar *)str;
	f_bfsize(fake) = f_w(fake) = n - 1;
	f_read(fake) = NULL;
	f_write(fake) = NULL;
	f_close(fake) = NULL;
	f_open(fake) = NULL;
	f_seek(fake) = NULL;
	f_setinfo(fake) = f_getinfo(fake) = NULL;
	ret = sm_io_vfprintf(&fake, fmt, ap);
	*f_p(fake) = 0;
	return ret;
}