libiberty/stpncpy.c

/* Implement the stpncpy function.
   Copyright (C) 2003-2025 Free Software Foundation, Inc.
   Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.

This file is part of the libiberty library.
Libiberty is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

Libiberty is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
Boston, MA 02110-1301, USA.  */

/*

@deftypefn Supplemental char* stpncpy (char *@var{dst}, const char *@var{src}, @
  size_t @var{len})

Copies the string @var{src} into @var{dst}, copying exactly @var{len}
and padding with zeros if necessary.  If @var{len} < strlen(@var{src})
then return @var{dst} + @var{len}, otherwise returns @var{dst} +
strlen(@var{src}).

@end deftypefn

*/

#include <ansidecl.h>
#include <stddef.h>

extern size_t strlen (const char *);
extern char *strncpy (char *, const char *, size_t);

char *
stpncpy (char *dst, const char *src, size_t len)
{
  size_t n = strlen (src);
  if (n > len)
    n = len;
  return strncpy (dst, src, len) + n;
}