1  /* Copyright (C) 1991-2023 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, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <string.h>
      19  #include <memcopy.h>
      20  
      21  
      22  /* Append SRC on the end of DEST.  */
      23  char *
      24  __strcat_chk (char *dest, const char *src, size_t destlen)
      25  {
      26    char *s1 = dest;
      27    const char *s2 = src;
      28    char c;
      29  
      30    /* Find the end of the string.  */
      31    do
      32      {
      33        if (__glibc_unlikely (destlen-- == 0))
      34  	__chk_fail ();
      35        c = *s1++;
      36      }
      37    while (c != '\0');
      38  
      39    /* Make S1 point before the next character, so we can increment
      40       it while memory is read (wins on pipelined cpus).  */
      41    ++destlen;
      42    s1 -= 2;
      43  
      44    do
      45      {
      46        if (__glibc_unlikely (destlen-- == 0))
      47  	__chk_fail ();
      48        c = *s2++;
      49        *++s1 = c;
      50      }
      51    while (c != '\0');
      52  
      53    return dest;
      54  }