libiberty/strndup.c

   1 /* Implement the strndup function.
   2    Copyright (C) 2005-2020 Free Software Foundation, Inc.
   3    Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.
   4
   5 This file is part of the libiberty library.
   6 Libiberty is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public
   8 License as published by the Free Software Foundation; either
   9 version 2 of the License, or (at your option) any later version.
  10
  11 Libiberty is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with libiberty; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  19 Boston, MA 02110-1301, USA.  */
  20
  21 /*
  22
  23 @deftypefn Extension char* strndup (const char *@var{s}, size_t @var{n})
  24
  25 Returns a pointer to a copy of @var{s} with at most @var{n} characters
  26 in memory obtained from @code{malloc}, or @code{NULL} if insufficient
  27 memory was available.  The result is always NUL terminated.
  28
  29 @end deftypefn
  30
  31 */
  32
  33 #include "ansidecl.h"
  34 #include <stddef.h>
  35
  36 extern size_t   strnlen (const char *s, size_t maxlen);
  37 extern PTR      malloc (size_t);
  38 extern PTR      memcpy (PTR, const PTR, size_t);
  39
  40 char *
  41 strndup (const char *s, size_t n)
  42 {
  43   char *result;
  44   size_t len = strnlen (s, n);
  45
  46   result = (char *) malloc (len + 1);
  47   if (!result)
  48     return 0;
  49
  50   result[len] = '\0';
  51   return (char *) memcpy (result, s, len);
  52 }