lib/libc/stdio/snprintf.c

   1 /*      $NetBSD: snprintf.c,v 1.21 2007/06/03 17:39:26 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[] = "@(#)snprintf.c  8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: snprintf.c,v 1.21 2007/06/03 17:39:26 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 <stdarg.h>
  49 #include <stdio.h>
  50
  51 #include "reentrant.h"
  52 #include "local.h"
  53
  54 #if defined(_FORTIFY_SOURCE) && !defined(__lint__)
  55 #undef snprintf
  56 #define snprintf _snprintf
  57 #endif
  58
  59 #ifdef __weak_alias
  60 __weak_alias(snprintf,_snprintf)
  61 #endif
  62
  63 int
  64 snprintf(char *str, size_t n, char const *fmt, ...)
  65 {
  66         int ret;
  67         va_list ap;
  68         FILE f;
  69         struct __sfileext fext;
  70         unsigned char dummy[1];
  71
  72         _DIAGASSERT(n == 0 || str != NULL);
  73         _DIAGASSERT(fmt != NULL);
  74
  75         if ((int)n < 0) {
  76                 errno = EINVAL;
  77                 return (-1);
  78         }
  79         va_start(ap, fmt);
  80         _FILEEXT_SETUP(&f, &fext);
  81         f._file = -1;
  82         f._flags = __SWR | __SSTR;
  83         if (n == 0) {
  84                 f._bf._base = f._p = dummy;
  85                 f._bf._size = f._w = 0;
  86         } else {
  87                 f._bf._base = f._p = (unsigned char *)str;
  88                 f._bf._size = f._w = n - 1;
  89         }
  90         ret = __vfprintf_unlocked(&f, fmt, ap);
  91         *f._p = 0;
  92         va_end(ap);
  93         return (ret);
  94 }