1 /* $NetBSD: strncpy.c,v 1.3 2007/06/04 18:19:28 christos Exp $ */ 2 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 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)strncpy.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 __RCSID("$NetBSD: strncpy.c,v 1.3 2007/06/04 18:19:28 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #if !defined(_KERNEL) && !defined(_STANDALONE) 45 #include <assert.h> 46 #include <string.h> 47 #else 48 #include <lib/libkern/libkern.h> 49 #endif 50 51 #ifdef _FORTIFY_SOURCE 52 #undef strncpy 53 #endif 54 55 /* 56 * Copy src to dst, truncating or null-padding to always copy n bytes. 57 * Return dst. 58 */ 59 char * 60 strncpy(char *dst, const char *src, size_t n) 61 { 62 63 _DIAGASSERT(dst != NULL); 64 _DIAGASSERT(src != NULL); 65 66 if (n != 0) { 67 char *d = dst; 68 const char *s = src; 69 70 do { 71 if ((*d++ = *s++) == 0) { 72 /* NUL pad the remaining n-1 bytes */ 73 while (--n != 0) 74 *d++ = 0; 75 break; 76 } 77 } while (--n != 0); 78 } 79 return (dst); 80 } 81