/*
 * 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: snprintf.c,v 1.24 2006/10/12 21:50:10 ca Exp $")
#include <limits.h>
#include <sm/varargs.h>
#include <sm/io.h>
#include <sm/string.h>
#include "local.h"

/*
**  SM_SNPRINTF -- format a string to a memory location of restricted size
**
**      Parameters:
**              str -- memory location to place formatted string
**              n -- size of buffer pointed to by str, capped to
**                      a maximum of INT_MAX
**              fmt -- the formatting directives
**              ... -- the data to satisfy the formatting
**
**      Returns:
**              Failure: -1
**              Success: number of bytes that would have been written
**                      to str, not including the trailing '\0',
**                      up to a maximum of INT_MAX, as if there was
**                      no buffer size limitation.  If the result >= n
**                      then the output was truncated.
**
**      Side Effects:
**              If n > 0, then between 0 and n-1 bytes of formatted output
**              are written into 'str', followed by a '\0'.
*/

int
#if SM_VA_STD
sm_snprintf(char *str, size_t n, char const *fmt, ...)
#else /* SM_VA_STD */
sm_snprintf(str, n, fmt, va_alist)
        char *str;
        size_t n;
        char *fmt;
        va_dcl
#endif /* SM_VA_STD */
{
        int ret;
        SM_VA_LOCAL_DECL
        SM_FILE_T fake;

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

        /* XXX put this into a static? */
        fake.sm_magic = SmFileMagic;
        fake.f_file = -1;
        fake.f_flags = SMWR | SMSTR;
        fake.f_cookie = &fake;
        fake.f_bf.smb_base = fake.f_p = (unsigned char *)str;
        fake.f_bf.smb_size = fake.f_w = n ? n - 1 : 0;
        fake.f_timeout = SM_TIME_FOREVER;
        fake.f_timeoutstate = SM_TIME_BLOCK;
        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_snprintf:fake";
        ret = sm_io_vfprintf(&fake, SM_TIME_FOREVER, fmt, ap);
        if (n > 0)
                *fake.f_p = '\0';
        SM_VA_END(ap);
        return ret;
}