snprintf/snprintf.c

   1 /*      $OpenBSD: snprintf.c,v 1.16 2009/10/22 01:23:16 guenther Exp $ */
   2 /*-
   3  * Copyright (c) 1990, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * This code is derived from software contributed to Berkeley by
   7  * Chris Torek.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <limits.h>
  35 #include <stdio.h>
  36 #include <string.h>
  37 #include <stdarg.h>
  38 #include "local.h"
  39 #include "ust_snprintf.h"
  40
  41 int ust_safe_vsnprintf(char *str, size_t n, const char *fmt, va_list ap)
  42 {
  43         int ret;
  44         char dummy;
  45         LFILE f;
  46         struct __sfileext fext;
  47
  48         /* While snprintf(3) specifies size_t stdio uses an int internally */
  49         if (n > INT_MAX)
  50                 n = INT_MAX;
  51         /* Stdio internals do not deal correctly with zero length buffer */
  52         if (n == 0) {
  53                 str = &dummy;
  54                 n = 1;
  55         }
  56         _FILEEXT_SETUP(&f, &fext);
  57         f._file = -1;
  58         f._flags = __SWR | __SSTR;
  59         f._bf._base = f._p = (unsigned char *)str;
  60         f._bf._size = f._w = n - 1;
  61         ret = ust_safe_vfprintf(&f, fmt, ap);
  62         *f._p = '\0';
  63         return (ret);
  64 }
  65
  66 int ust_safe_snprintf(char *str, size_t n, const char *fmt, ...)
  67 {
  68         va_list ap;
  69         int ret;
  70
  71         va_start(ap, fmt);
  72         ret = ust_safe_vsnprintf(str, n, fmt, ap);
  73         va_end(ap);
  74
  75         return ret;
  76 }