debug/strcat_chk.c

   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 /* Append SRC on the end of DEST.  */
  24 char *
  25 __strcat_chk (dest, src, destlen)
  26      char *dest;
  27      const char *src;
  28      size_t destlen;
  29 {
  30   char *s1 = dest;
  31   const char *s2 = src;
  32   reg_char c;
  33
  34   /* Find the end of the string.  */
  35   do
  36     {
  37       if (__builtin_expect (destlen-- == 0, 0))
  38         __chk_fail ();
  39       c = *s1++;
  40     }
  41   while (c != '\0');
  42
  43   /* Make S1 point before the next character, so we can increment
  44      it while memory is read (wins on pipelined cpus).  */
  45   ++destlen;
  46   s1 -= 2;
  47
  48   do
  49     {
  50       if (__builtin_expect (destlen-- == 0, 0))
  51         __chk_fail ();
  52       c = *s2++;
  53       *++s1 = c;
  54     }
  55   while (c != '\0');
  56
  57   return dest;
  58 }