xref: /freebsd/lib/libc/stdio/vsnprintf.c (revision 783d3ff6d7fae619db8a7990b8a6387de0c677b5)
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 int
47 vsnprintf_l(char * __restrict str, size_t n, locale_t locale,
48 		const char * __restrict fmt, __va_list ap)
49 {
50 	size_t on;
51 	int ret;
52 	char dummy[2];
53 	FILE f = FAKE_FILE;
54 	FIX_LOCALE(locale);
55 
56 	on = n;
57 	if (n != 0)
58 		n--;
59 	if (n > INT_MAX) {
60 		errno = EOVERFLOW;
61 		*str = '\0';
62 		return (EOF);
63 	}
64 	/* Stdio internals do not deal correctly with zero length buffer */
65 	if (n == 0) {
66 		if (on > 0)
67 	  		*str = '\0';
68 		str = dummy;
69 		n = 1;
70 	}
71 	f._flags = __SWR | __SSTR;
72 	f._bf._base = f._p = (unsigned char *)str;
73 	f._bf._size = f._w = n;
74 	ret = __vfprintf(&f, locale, fmt, ap);
75 	if (on > 0)
76 		*f._p = '\0';
77 	return (ret);
78 }
79 int
80 vsnprintf(char * __restrict str, size_t n, const char * __restrict fmt,
81     __va_list ap)
82 {
83 	return vsnprintf_l(str, n, __get_locale(), fmt, ap);
84 }
85