1 /* $OpenBSD: vsnprintf.c,v 1.12 2006/01/06 18:53:04 millert 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 "local.h"
38
39 int
vsnprintf(char * str,size_t n,const char * fmt,__va_list ap)40 vsnprintf(char *str, size_t n, const char *fmt, __va_list ap)
41 {
42 int ret;
43 char dummy;
44 FILE f;
45 struct __sfileext fext;
46
47 _FILEEXT_SETUP(&f, &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 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 = __vfprintf(&f, fmt, ap);
62 *f._p = '\0';
63 return (ret);
64 }
65