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 /* adapted for Quagga from glibc patch submission originally from
  20  * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
  21
  22 #include <string.h>
  23
  24 #include "config.h"
  25
  26 #ifndef HAVE_STRLCPY
  27 #undef strlcpy
  28
  29 size_t
  30 strlcpy (char *__restrict dest, const char *__restrict src, size_t size);
  31
  32 size_t
  33 strlcpy (char *__restrict dest, const char *__restrict src, size_t size)
  34 {
  35   size_t src_length = strlen (src);
  36
  37   if (__builtin_expect (src_length >= size, 0))
  38     {
  39       if (size > 0)
  40         {
  41           /* Copy the leading portion of the string.  The last
  42              character is subsequently overwritten with the NUL
  43              terminator, but the destination size is usually a
  44              multiple of a small power of two, so writing it twice
  45              should be more efficient than copying an odd number of
  46              bytes.  */
  47           memcpy (dest, src, size);
  48           dest[size - 1] = '\0';
  49         }
  50     }
  51   else
  52       /* Copy the string and its terminating NUL character.  */
  53       memcpy (dest, src, src_length + 1);
  54   return src_length;
  55 }
  56 #endif /* HAVE_STRLCPY */