libiberty/strndup.c

   1 /* Implement the strndup function.
   2    Copyright (C) 2005 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., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, 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 #ifdef ANSI_PROTOTYPES
  35 #include <stddef.h>
  36 #else
  37 #define size_t unsigned long
  38 #endif
  39
  40 extern size_t   strlen PARAMS ((const char*));
  41 extern PTR      malloc PARAMS ((size_t));
  42 extern PTR      memcpy PARAMS ((PTR, const PTR, size_t));
  43
  44 char *
  45 strndup(s, n)
  46      const char *s;
  47      size_t n;
  48 {
  49   char *result;
  50   size_t len = strlen (s);
  51
  52   if (n < len)
  53     len = n;
  54
  55   result = malloc (len + 1);
  56   if (!result)
  57     return 0;
  58
  59   result[len] = '\0';
  60   return memcpy (result, s, len);
  61 }