/* Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <pwd.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

/* Return the username of the caller.

   If S is not NULL, it points to a buffer of at least L_cuserid bytes

   into which the name is copied; otherwise, a static buffer is used.  */

char *

cuserid (char *s)

{

  static char name[L_cuserid];

  char buf[NSS_BUFLEN_PASSWD];

  struct passwd pwent;

  struct passwd *pwptr;

  if (__getpwuid_r (__geteuid (), &pwent, buf, sizeof (buf), &pwptr)

      || pwptr == NULL)

    {

      if (s != NULL)

	s[0] = '\0';

      return s;

    }

  if (s == NULL)

    s = name;

  s[L_cuserid - 1] = '\0';

  return strncpy (s, pwptr->pw_name, L_cuserid - 1);

}