1: /* Copyright (C) 1991, 1997, 2003, 2004 Free Software Foundation, Inc.
    2:    This file is part of the GNU C Library.
    3: 
    4:    The GNU C Library is free software; you can redistribute it and/or
    5:    modify it under the terms of the GNU Lesser General Public
    6:    License as published by the Free Software Foundation; either
    7:    version 2.1 of the License, or (at your option) any later version.
    8: 
    9:    The GNU C Library is distributed in the hope that it will be useful,
   10:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   11:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   12:    Lesser General Public License for more details.
   13: 
   14:    You should have received a copy of the GNU Lesser General Public
   15:    License along with the GNU C Library; if not, write to the Free
   16:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   17:    02111-1307 USA.  */
   18: 
   19: #include <string.h>
   20: #include <memcopy.h>
   21: 
   22: 
   23: char *
   24: __strncpy_chk (s1, s2, n, s1len)
   25:      char *s1;
   26:      const char *s2;
   27:      size_t n;
   28:      size_t s1len;
   29: {
   30:   reg_char c;
   31:   char *s = s1;
   32: 
   33:   if (__builtin_expect (s1len < n, 0))
   34:     __chk_fail ();
   35: 
   36:   --s1;
   37: 
   38:   if (n >= 4)
   39:     {
   40:       size_t n4 = n >> 2;
   41: 
   42:       for (;;)
   43:         {
   44:           c = *s2++;
   45:           *++s1 = c;
   46:           if (c == '\0')
   47:             break;
   48:           c = *s2++;
   49:           *++s1 = c;
   50:           if (c == '\0')
   51:             break;
   52:           c = *s2++;
   53:           *++s1 = c;
   54:           if (c == '\0')
   55:             break;
   56:           c = *s2++;
   57:           *++s1 = c;
   58:           if (c == '\0')
   59:             break;
   60:           if (--n4 == 0)
   61:             goto last_chars;
   62:         }
   63:       n = n - (s1 - s) - 1;
   64:       if (n == 0)
   65:         return s;
   66:       goto zero_fill;
   67:     }
   68: 
   69:  last_chars:
   70:   n &= 3;
   71:   if (n == 0)
   72:     return s;
   73: 
   74:   do
   75:     {
   76:       c = *s2++;
   77:       *++s1 = c;
   78:       if (--n == 0)
   79:         return s;
   80:     }
   81:   while (c != '\0');
   82: 
   83:  zero_fill:
   84:   do
   85:     *++s1 = '\0';
   86:   while (--n > 0);
   87: 
   88:   return s;
   89: }