lib/libc/stdio/vsnprintf.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  * Copyright (c) 2011 The FreeBSD Foundation
   9  * All rights reserved.
  10  * Portions of this software were developed by David Chisnall
  11  * under sponsorship from the FreeBSD Foundation.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  * @(#)vsnprintf.c      8.1 (Berkeley) 6/4/93
  38  * $FreeBSD: head/lib/libc/stdio/vsnprintf.c 249808 2013-04-23 13:33:13Z emaste $
  39  */
  40
  41
  42 #include <errno.h>
  43 #include <limits.h>
  44 #include <stdio.h>
  45 #include "local.h"
  46 #include "xlocale_private.h"
  47
  48 int
  49 vsnprintf_l(char * __restrict str, size_t n, locale_t locale,
  50                 const char * __restrict fmt, __va_list ap)
  51 {
  52         size_t on;
  53         int ret;
  54         char dummy[2];
  55         FILE f = FAKE_FILE;
  56         FIX_LOCALE(locale);
  57
  58         on = n;
  59         if (n != 0)
  60                 n--;
  61         if (n > INT_MAX) {
  62                 errno = EOVERFLOW;
  63                 *str = '\0';
  64                 return (EOF);
  65         }
  66         /* Stdio internals do not deal correctly with zero length buffer */
  67         if (n == 0) {
  68                 if (on > 0)
  69                         *str = '\0';
  70                 str = dummy;
  71                 n = 1;
  72         }
  73         f.pub._flags = __SWR | __SSTR;
  74         f._bf._base = f.pub._p = (unsigned char *)str;
  75         f._bf._size = f.pub._w = n;
  76         ret = __vfprintf(&f, locale, fmt, ap);
  77         if (on > 0)
  78                 *f.pub._p = '\0';
  79         return (ret);
  80 }
  81 int
  82 vsnprintf(char * __restrict str, size_t n, const char * __restrict fmt,
  83     __va_list ap)
  84 {
  85         return vsnprintf_l(str, n, __get_locale(), fmt, ap);
  86 }