1/* Copyright (C) 1993, 1995-1997, 2002-2003, 2005-2007 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 3 of the License, or 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, see <http://www.gnu.org/licenses/>. */ 18 19/* This is almost copied from strncpy.c, written by Torbjorn Granlund. */ 20 21#include <config.h> 22 23/* Specification. */ 24#include <string.h> 25 26#ifndef weak_alias 27# define __stpncpy stpncpy 28#endif 29 30/* Copy no more than N bytes of SRC to DST, returning a pointer past the 31 last non-NUL byte written into DST. */ 32char * 33__stpncpy (char *dest, const char *src, size_t n) 34{ 35 char c; 36 char *s = dest; 37 38 if (n >= 4) 39 { 40 size_t n4 = n >> 2; 41 42 for (;;) 43 { 44 c = *src++; 45 *dest++ = c; 46 if (c == '\0') 47 break; 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 if (--n4 == 0) 61 goto last_chars; 62 } 63 n -= dest - s; 64 goto zero_fill; 65 } 66 67 last_chars: 68 n &= 3; 69 if (n == 0) 70 return dest; 71 72 for (;;) 73 { 74 c = *src++; 75 --n; 76 *dest++ = c; 77 if (c == '\0') 78 break; 79 if (n == 0) 80 return dest; 81 } 82 83 zero_fill: 84 while (n-- > 0) 85 dest[n] = '\0'; 86 87 return dest - 1; 88} 89#ifdef weak_alias 90weak_alias (__stpncpy, stpncpy) 91#endif 92