string/strncat.c

   1 /* Copyright (C) 1991-2017 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    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19
  20 #ifndef STRNCAT
  21 # undef strncat
  22 # define STRNCAT  strncat
  23 #endif
  24
  25 char *
  26 STRNCAT (char *s1, const char *s2, size_t n)
  27 {
  28   char *s = s1;
  29
  30   /* Find the end of S1.  */
  31   s1 += strlen (s1);
  32
  33   size_t ss = __strnlen (s2, n);
  34
  35   s1[ss] = '\0';
  36   memcpy (s1, s2, ss);
  37
  38   return s;
  39 }