lib/strlcpy.c

   1 /* Copy a null-terminated string to a fixed-size buffer, with length checking.
   2  * Copyright (C) 2016 Free Software Foundation, Inc.
   3  * This file is part of the GNU C Library.
   4  *
   5  * The GNU C Library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * The GNU C Library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with the GNU C Library; if not, see
  17  * <http://www.gnu.org/licenses/>.
  18  */
  19
  20 /* adapted for Quagga from glibc patch submission originally from
  21  * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
  22
  23 #include <string.h>
  24
  25 #include "config.h"
  26
  27 #ifndef HAVE_STRLCPY
  28 #undef strlcpy
  29
  30 size_t
  31 strlcpy (char *__restrict dest, const char *__restrict src, size_t size);
  32
  33 size_t
  34 strlcpy (char *__restrict dest, const char *__restrict src, size_t size)
  35 {
  36   size_t src_length = strlen (src);
  37
  38   if (__builtin_expect (src_length >= size, 0))
  39     {
  40       if (size > 0)
  41         {
  42           /* Copy the leading portion of the string.  The last
  43              character is subsequently overwritten with the NUL
  44              terminator, but the destination size is usually a
  45              multiple of a small power of two, so writing it twice
  46              should be more efficient than copying an odd number of
  47              bytes.  */
  48           memcpy (dest, src, size);
  49           dest[size - 1] = '\0';
  50         }
  51     }
  52   else
  53       /* Copy the string and its terminating NUL character.  */
  54       memcpy (dest, src, src_length + 1);
  55   return src_length;
  56 }
  57 #endif /* HAVE_STRLCPY */