xref: /freebsd/lib/libc/stdio/vsnprintf.c (revision 8aac90f18aef7c9eea906c3ff9a001ca7b94f375)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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  * Copyright (c) 2011 The FreeBSD Foundation
11  *
12  * Portions of this software were developed by David Chisnall
13  * under sponsorship from the FreeBSD Foundation.
14  *
15  * Redistribution and use in source and binary forms, with or without
16  * modification, are permitted provided that the following conditions
17  * are met:
18  * 1. Redistributions of source code must retain the above copyright
19  *    notice, this list of conditions and the following disclaimer.
20  * 2. Redistributions in binary form must reproduce the above copyright
21  *    notice, this list of conditions and the following disclaimer in the
22  *    documentation and/or other materials provided with the distribution.
23  * 3. Neither the name of the University nor the names of its contributors
24  *    may be used to endorse or promote products derived from this software
25  *    without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37  * SUCH DAMAGE.
38  */
39 
40 #include <errno.h>
41 #include <limits.h>
42 #include <stdio.h>
43 #include "local.h"
44 #include "xlocale_private.h"
45 
46 #undef vsnprintf	/* _FORTIFY_SOURCE */
47 
48 int
49 vsnprintf_l(char * __restrict str, size_t n, locale_t locale,
50 		const char * __restrict fmt, __va_list ap)
51 {
52 	size_t on;
53 	int ret;
54 	char dummy[2];
55 	FILE f = FAKE_FILE;
56 	FIX_LOCALE(locale);
57 
58 	on = n;
59 	if (n != 0)
60 		n--;
61 	if (n > INT_MAX) {
62 		errno = EOVERFLOW;
63 		*str = '\0';
64 		return (EOF);
65 	}
66 	/* Stdio internals do not deal correctly with zero length buffer */
67 	if (n == 0) {
68 		if (on > 0)
69 	  		*str = '\0';
70 		str = dummy;
71 		n = 1;
72 	}
73 	f._flags = __SWR | __SSTR;
74 	f._bf._base = f._p = (unsigned char *)str;
75 	f._bf._size = f._w = n;
76 	ret = __vfprintf(&f, locale, fmt, ap);
77 	if (on > 0)
78 		*f._p = '\0';
79 	return (ret);
80 }
81 int
82 vsnprintf(char * __restrict str, size_t n, const char * __restrict fmt,
83     __va_list ap)
84 {
85 	return vsnprintf_l(str, n, __get_locale(), fmt, ap);
86 }
87