/*
 * Copyright (c) 2005 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 *
 * 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: strvprintf.c,v 1.2 2005/12/07 00:49:46 ca Exp $")
#include "sm/varargs.h"
#include "sm/io.h"
#include "sm/assert.h"
#include "sm/limits.h"
#include "sm/str.h"
#include "io-int.h"

/*
**  SM_STRVPRINTF -- format data for "output" into a str (append!)
**
**	Parameters:
**		str -- str
**		fmt -- the formatting directives
**		ap -- data unit vectors for use by 'fmt'
**
**	Returns:
**		Failure: error code from sm_io_vfprintf()
**		Success: length of str if all characters would have been
**			written, not including the trailing '\0',
**			up to a maximum of INT_MAX, as if there was
**			no buffer size limitation.
**			If the result >= sm_str_getmax(str)
**			then the output was truncated.
**
**	Side Effects:
**		If n > 0, then between 0 and n-len(str) bytes of formatted
**		output are written into 'str', followed by a '\0'.
**		str may be "resized" if necessary.
*/

int
sm_strvprintf(sm_str_P str, char const *fmt, va_list ap)
{
	uint n, l;
	int ret;
	sm_file_T fake;

	SM_REQUIRE(str != NULL);
	SM_REQUIRE(fmt != NULL);

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

	/* question: put this into a static?? */
	fake.sm_magic = SM_FILE_MAGIC;
	f_fd(fake) = -1;
	f_flags(fake) = SMWR|SMSTRSTR;
	fake.f_cookie = (void *)str;
	f_bfbase(fake) = f_p(fake) = str->sm_str_base + l;
	f_bfsize(fake) = f_w(fake) = n ? n - 1 : 0;
	fake.f_timeout = SM_TIME_FOREVER;
	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);
	sm_str_term(str);
	return ret + l;
}