1/* Copyright (C) 1993, 1995-1997, 2002-2003, 2005 Free Software Foundation, Inc. 2 3 NOTE: The canonical source of this file is maintained with the GNU C Library. 4 Bugs can be reported to bug-glibc@gnu.org. 5 6 This program is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by the 8 Free Software Foundation; either version 2, or (at your option) any 9 later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 19 USA. */ 20 21/* This is almost copied from strncpy.c, written by Torbjorn Granlund. */ 22 23#ifdef HAVE_CONFIG_H 24# include <config.h> 25#endif 26 27/* Specification. */ 28#include "stpncpy.h" 29 30#ifndef weak_alias 31# define __stpncpy stpncpy 32#endif 33 34/* Copy no more than N bytes of SRC to DST, returning a pointer past the 35 last non-NUL byte written into DST. */ 36char * 37__stpncpy (char *dest, const char *src, size_t n) 38{ 39 char c; 40 char *s = dest; 41 42 if (n >= 4) 43 { 44 size_t n4 = n >> 2; 45 46 for (;;) 47 { 48 c = *src++; 49 *dest++ = c; 50 if (c == '\0') 51 break; 52 c = *src++; 53 *dest++ = c; 54 if (c == '\0') 55 break; 56 c = *src++; 57 *dest++ = c; 58 if (c == '\0') 59 break; 60 c = *src++; 61 *dest++ = c; 62 if (c == '\0') 63 break; 64 if (--n4 == 0) 65 goto last_chars; 66 } 67 n -= dest - s; 68 goto zero_fill; 69 } 70 71 last_chars: 72 n &= 3; 73 if (n == 0) 74 return dest; 75 76 for (;;) 77 { 78 c = *src++; 79 --n; 80 *dest++ = c; 81 if (c == '\0') 82 break; 83 if (n == 0) 84 return dest; 85 } 86 87 zero_fill: 88 while (n-- > 0) 89 dest[n] = '\0'; 90 91 return dest - 1; 92} 93#ifdef weak_alias 94weak_alias (__stpncpy, stpncpy) 95#endif 96