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 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char rcsid[] = "$OpenBSD: vsnprintf.c,v 1.7 2004/09/28 18:12:44 otto Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <limits.h> 38 #include <stdio.h> 39 40 int 41 vsnprintf(char *str, size_t n, const char *fmt, _BSD_VA_LIST_ ap) 42 { 43 int ret; 44 char dummy; 45 FILE f; 46 47 /* While snprintf(3) specifies size_t stdio uses an int internally */ 48 if (n > INT_MAX) 49 n = INT_MAX; 50 /* Stdio internals do not deal correctly with zero length buffer */ 51 if (n == 0) { 52 str = &dummy; 53 n = 1; 54 } 55 f._file = -1; 56 f._flags = __SWR | __SSTR; 57 f._bf._base = f._p = (unsigned char *)str; 58 f._bf._size = f._w = n - 1; 59 ret = vfprintf(&f, fmt, ap); 60 *f._p = 0; 61 return (ret); 62 } 63