lib/libc/stdio/snprintf.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * @(#)snprintf.c       8.1 (Berkeley) 6/4/93
  33  * $FreeBSD: src/lib/libc/stdio/snprintf.c,v 1.22 2008/04/17 22:17:54 jhb Exp $
  34  * $DragonFly: src/lib/libc/stdio/snprintf.c,v 1.7 2006/03/02 18:05:30 joerg Exp $
  35  */
  36
  37 #include <limits.h>
  38 #include <stdio.h>
  39 #include <stdarg.h>
  40
  41 #include "local.h"
  42 #include "priv_stdio.h"
  43
  44 int
  45 snprintf(char * __restrict str, size_t n, const char * __restrict fmt, ...)
  46 {
  47         size_t on;
  48         int ret;
  49         va_list ap;
  50         FILE f;
  51
  52         on = n;
  53         if (n != 0)
  54                 n--;
  55         if (n > INT_MAX)
  56                 n = INT_MAX;
  57         va_start(ap, fmt);
  58         f.pub._fileno = -1;
  59         f.pub._flags = __SWR | __SSTR;
  60         f._bf._base = f.pub._p = (unsigned char *)str;
  61         f._bf._size = f.pub._w = n;
  62         memset(WCIO_GET(&f), 0, sizeof(struct wchar_io_data));
  63         ret = __vfprintf(&f, fmt, ap);
  64         if (on > 0)
  65                 *f.pub._p = '\0';
  66         va_end(ap);
  67         return (ret);
  68 }