vsnprintf.c (2639B)
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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char rcsid[] = "$OpenBSD: vsnprintf.c,v 1.5 1998/07/27 02:28:28 millert Exp $"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <limits.h> 42 #include <stdio.h> 43 44 int 45 vsnprintf(str, n, fmt, ap) 46 char *str; 47 size_t n; 48 const char *fmt; 49 _BSD_VA_LIST_ ap; 50 { 51 int ret; 52 char dummy; 53 FILE f; 54 55 /* While snprintf(3) specifies size_t stdio uses an int internally */ 56 if (n > INT_MAX) 57 n = INT_MAX; 58 /* Stdio internals do not deal correctly with zero length buffer */ 59 if (n == 0) { 60 str = &dummy; 61 n = 1; 62 } 63 f._file = -1; 64 f._flags = __SWR | __SSTR; 65 f._bf._base = f._p = (unsigned char *)str; 66 f._bf._size = f._w = n - 1; 67 ret = vfprintf(&f, fmt, ap); 68 *f._p = 0; 69 return (ret); 70 }