1: /* Copyright (C) 1991, 1997, 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: 
   21: #include <memcopy.h>
   22: 
   23: 
   24: char *
   25: __strncat_chk (s1, s2, n, s1len)
   26:      char *s1;
   27:      const char *s2;
   28:      size_t n;
   29:      size_t s1len;
   30: {
   31:   reg_char c;
   32:   char *s = s1;
   33: 
   34:   /* Find the end of S1.  */
   35:   do
   36:     {
   37:       if (__builtin_expect (s1len-- == 0, 0))
   38:         __chk_fail ();
   39:       c = *s1++;
   40:     }
   41:   while (c != '\0');
   42: 
   43:   /* Make S1 point before next character, so we can increment
   44:      it while memory is read (wins on pipelined cpus).  */
   45:   ++s1len;
   46:   s1 -= 2;
   47: 
   48:   if (n >= 4)
   49:     {
   50:       size_t n4 = n >> 2;
   51:       do
   52:         {
   53:           if (__builtin_expect (s1len-- == 0, 0))
   54:             __chk_fail ();
   55:           c = *s2++;
   56:           *++s1 = c;
   57:           if (c == '\0')
   58:             return s;
   59:           if (__builtin_expect (s1len-- == 0, 0))
   60:             __chk_fail ();
   61:           c = *s2++;
   62:           *++s1 = c;
   63:           if (c == '\0')
   64:             return s;
   65:           if (__builtin_expect (s1len-- == 0, 0))
   66:             __chk_fail ();
   67:           c = *s2++;
   68:           *++s1 = c;
   69:           if (c == '\0')
   70:             return s;
   71:           if (__builtin_expect (s1len-- == 0, 0))
   72:             __chk_fail ();
   73:           c = *s2++;
   74:           *++s1 = c;
   75:           if (c == '\0')
   76:             return s;
   77:         } while (--n4 > 0);
   78:       n &= 3;
   79:     }
   80: 
   81:   while (n > 0)
   82:     {
   83:       if (__builtin_expect (s1len-- == 0, 0))
   84:         __chk_fail ();
   85:       c = *s2++;
   86:       *++s1 = c;
   87:       if (c == '\0')
   88:         return s;
   89:       n--;
   90:     }
   91: 
   92:   if (c != '\0')
   93:     {
   94:       if (__builtin_expect (s1len-- == 0, 0))
   95:         __chk_fail ();
   96:       *++s1 = '\0';
   97:     }
   98: 
   99:   return s;
  100: }