lib/libc/stdio/vsnprintf.c

   1 /*      $NetBSD: vsnprintf.c,v 1.25 2012/03/15 18:22:31 christos Exp $  */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)vsnprintf.c 8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: vsnprintf.c,v 1.25 2012/03/15 18:22:31 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45
  46 #include <assert.h>
  47 #include <errno.h>
  48 #include <stdio.h>
  49 #include "reentrant.h"
  50 #include "local.h"
  51
  52 #if defined(_FORTIFY_SOURCE) && !defined(__lint__)
  53 #undef vsnprintf
  54 #define vsnprintf _vsnprintf
  55 #endif
  56
  57 #ifdef __weak_alias
  58 __weak_alias(vsnprintf,_vsnprintf)
  59 #endif
  60
  61 int
  62 vsnprintf(char *str, size_t n, const char *fmt, va_list ap)
  63 {
  64         int ret;
  65         FILE f;
  66         struct __sfileext fext;
  67         unsigned char dummy[1];
  68
  69         _DIAGASSERT(n == 0 || str != NULL);
  70         _DIAGASSERT(fmt != NULL);
  71
  72         if ((int)n < 0) {
  73                 errno = EINVAL;
  74                 return -1;
  75         }
  76
  77         _FILEEXT_SETUP(&f, &fext);
  78         f._file = -1;
  79         f._flags = __SWR | __SSTR;
  80         if (n == 0) {
  81                 f._bf._base = f._p = dummy;
  82                 f._bf._size = f._w = 0;
  83         } else {
  84                 f._bf._base = f._p = (unsigned char *)str;
  85                 _DIAGASSERT(__type_fit(int, n - 1));
  86                 f._bf._size = f._w = (int)(n - 1);
  87         }
  88         ret = __vfprintf_unlocked(&f, fmt, ap);
  89         *f._p = 0;
  90         return ret;
  91 }