/*
 * Copyright (c) 2000-2001 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/gen.h>
SM_RCSID("@(#)$Id: vsnprintf.c,v 1.21 2001/03/04 23:28:41 ca Exp $")
#include <limits.h>
#include <sm/io.h>
#include "local.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(str, n, fmt, ap)
        char *str;
        size_t n;
        const char *fmt;
        SM_VA_LOCAL_DECL
{
        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 = SmFileMagic;
        fake.f_timeout = SM_TIME_FOREVER;
        fake.f_timeoutstate = SM_TIME_BLOCK;
        fake.f_file = -1;
        fake.f_flags = SMWR | SMSTR;
        fake.f_bf.smb_base = fake.f_p = (unsigned char *)str;
        fake.f_bf.smb_size = fake.f_w = n - 1;
        fake.f_close = NULL;
        fake.f_open = NULL;
        fake.f_read = NULL;
        fake.f_write = NULL;
        fake.f_seek = NULL;
        fake.f_setinfo = fake.f_getinfo = NULL;
        fake.f_type = "sm_vsnprintf:fake";
        ret = sm_io_vfprintf(&fake, SM_TIME_FOREVER, fmt, ap);
        *fake.f_p = 0;
        return ret;
}