vsnprintf.c revision 331722 
1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Copyright (c) 2011 The FreeBSD Foundation
9 * All rights reserved.
10 * Portions of this software were developed by David Chisnall
11 * under sponsorship from the FreeBSD Foundation.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 *    notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 *    notice, this list of conditions and the following disclaimer in the
20 *    documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 *    may be used to endorse or promote products derived from this software
23 *    without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38#if defined(LIBC_SCCS) && !defined(lint)
39static char sccsid[] = "@(#)vsnprintf.c	8.1 (Berkeley) 6/4/93";
40#endif /* LIBC_SCCS and not lint */
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: stable/11/lib/libc/stdio/vsnprintf.c 331722 2018-03-29 02:50:57Z eadler $");
43
44#include <errno.h>
45#include <limits.h>
46#include <stdio.h>
47#include "local.h"
48#include "xlocale_private.h"
49
50int
51vsnprintf_l(char * __restrict str, size_t n, locale_t locale,
52		const char * __restrict fmt, __va_list ap)
53{
54	size_t on;
55	int ret;
56	char dummy[2];
57	FILE f = FAKE_FILE;
58	FIX_LOCALE(locale);
59
60	on = n;
61	if (n != 0)
62		n--;
63	if (n > INT_MAX) {
64		errno = EOVERFLOW;
65		*str = '\0';
66		return (EOF);
67	}
68	/* Stdio internals do not deal correctly with zero length buffer */
69	if (n == 0) {
70		if (on > 0)
71	  		*str = '\0';
72		str = dummy;
73		n = 1;
74	}
75	f._flags = __SWR | __SSTR;
76	f._bf._base = f._p = (unsigned char *)str;
77	f._bf._size = f._w = n;
78	ret = __vfprintf(&f, locale, fmt, ap);
79	if (on > 0)
80		*f._p = '\0';
81	return (ret);
82}
83int
84vsnprintf(char * __restrict str, size_t n, const char * __restrict fmt,
85    __va_list ap)
86{
87	return vsnprintf_l(str, n, __get_locale(), fmt, ap);
88}
89