lib/strlcpy.c

   1 // SPDX-License-Identifier: LGPL-2.1-or-later
   2 /* Copy a null-terminated string to a fixed-size buffer, with length checking.
   3  * Copyright (C) 2016 Free Software Foundation, Inc.
   4  * This file is part of the GNU C Library.
   5  */
   6
   7 /* adapted for Quagga from glibc patch submission originally from
   8  * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
   9
  10 #ifdef HAVE_CONFIG_H
  11 #include "config.h"
  12 #endif
  13
  14 #include <string.h>
  15
  16 #ifndef HAVE_STRLCPY
  17 #undef strlcpy
  18
  19 size_t strlcpy(char *__restrict dest,
  20                const char *__restrict src, size_t destsize);
  21
  22 size_t strlcpy(char *__restrict dest,
  23                const char *__restrict src, size_t destsize)
  24 {
  25         size_t src_length = strlen(src);
  26
  27         if (__builtin_expect(src_length >= destsize, 0)) {
  28                 if (destsize > 0) {
  29                         /*
  30                          * Copy the leading portion of the string.  The last
  31                          * character is subsequently overwritten with the NUL
  32                          * terminator, but the destination destsize is usually
  33                          * a multiple of a small power of two, so writing it
  34                          * twice should be more efficient than copying an odd
  35                          * number of bytes.
  36                          */
  37                         memcpy(dest, src, destsize);
  38                         dest[destsize - 1] = '\0';
  39                 }
  40         } else
  41                 /* Copy the string and its terminating NUL character.  */
  42                 memcpy(dest, src, src_length + 1);
  43         return src_length;
  44 }
  45 #endif /* HAVE_STRLCPY */