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      1 /*	$OpenBSD: snprintf.c,v 1.14 2005/10/10 12:00:52 espie 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 
     40 int
     41 snprintf(char *str, size_t n, const char *fmt, ...)
     42 {
     43 	va_list ap;
     44 	int ret;
     45 	char dummy;
     46 	FILE f;
     47 	struct __sfileext fext;
     48 
     49 	/* While snprintf(3) specifies size_t stdio uses an int internally */
     50 	if (n > INT_MAX)
     51 		n = INT_MAX;
     52 	/* Stdio internals do not deal correctly with zero length buffer */
     53 	if (n == 0) {
     54 		str = &dummy;
     55 		n = 1;
     56 	}
     57 	_FILEEXT_SETUP(&f, &fext);
     58 	f._file = -1;
     59 	f._flags = __SWR | __SSTR;
     60 	f._bf._base = f._p = (unsigned char *)str;
     61 	f._bf._size = f._w = n - 1;
     62 	va_start(ap, fmt);
     63 	ret = __vfprintf(&f, fmt, ap);
     64 	va_end(ap);
     65 	*f._p = '\0';
     66 	return (ret);
     67 }
     68