libssp/strcat-chk.c

   1 /* Checking strcat.
   2    Copyright (C) 1991-2017 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 In addition to the permissions in the GNU General Public License, the
  12 Free Software Foundation gives you unlimited permission to link the
  13 compiled version of this file into combinations with other programs,
  14 and to distribute those combinations without any restriction coming
  15 from the use of this file.  (The General Public License restrictions
  16 do apply in other respects; for example, they cover modification of
  17 the file, and distribution when not linked into a combine
  18 executable.)
  19
  20 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  21 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  22 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  23 for more details.
  24
  25 Under Section 7 of GPL version 3, you are granted additional
  26 permissions described in the GCC Runtime Library Exception, version
  27 3.1, as published by the Free Software Foundation.
  28
  29 You should have received a copy of the GNU General Public License and
  30 a copy of the GCC Runtime Library Exception along with this program;
  31 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  32 <http://www.gnu.org/licenses/>.  */
  33
  34
  35 #include "config.h"
  36 #include <ssp/ssp.h>
  37 #ifdef HAVE_STRING_H
  38 # include <string.h>
  39 #endif
  40
  41 extern void __chk_fail (void) __attribute__((__noreturn__));
  42
  43 char *
  44 __strcat_chk (char *__restrict__ dest, const char *__restrict__ src,
  45               size_t slen)
  46 {
  47   char *s1 = dest;
  48   const char *s2 = src;
  49   char c;
  50
  51   do
  52     {
  53       if (slen-- == 0)
  54         __chk_fail ();
  55       c = *s1++;
  56     }
  57   while (c != '\0');
  58
  59   ++slen;
  60   s1 -= 2;
  61
  62   do
  63     {
  64       if (slen-- == 0)
  65         __chk_fail ();
  66       c = *s2++;
  67       *++s1 = c;
  68     }
  69   while (c != '\0');
  70
  71   return dest;
  72 }