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glibc  2.9
strcat_chk.c
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00001 /* Copyright (C) 1991, 1997, 2003, 2004 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <string.h>
00020 #include <memcopy.h>
00021 
00022 
00023 /* Append SRC on the end of DEST.  */
00024 char *
00025 __strcat_chk (dest, src, destlen)
00026      char *dest;
00027      const char *src;
00028      size_t destlen;
00029 {
00030   char *s1 = dest;
00031   const char *s2 = src;
00032   reg_char c;
00033 
00034   /* Find the end of the string.  */
00035   do
00036     {
00037       if (__builtin_expect (destlen-- == 0, 0))
00038        __chk_fail ();
00039       c = *s1++;
00040     }
00041   while (c != '\0');
00042 
00043   /* Make S1 point before the next character, so we can increment
00044      it while memory is read (wins on pipelined cpus).  */
00045   ++destlen;
00046   s1 -= 2;
00047 
00048   do
00049     {
00050       if (__builtin_expect (destlen-- == 0, 0))
00051        __chk_fail ();
00052       c = *s2++;
00053       *++s1 = c;
00054     }
00055   while (c != '\0');
00056 
00057   return dest;
00058 }