/* whoami -- print effective userid
   Copyright (C) 89, 90, 91, 92, 93, 94, 1995 Free Software Foundation, Inc.

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

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* Equivalent to `id -un'. */
/* Written by Richard Mlynarik. */

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>
#include <getopt.h>

#include "version.h"
#include "system.h"

/* The name this program was run with. */
char *program_name;

/* If non-zero, display usage information and exit.  */
static int show_help;

/* If non-zero, print the version on standard output and exit.  */
static int show_version;

static struct option const long_options[] =
{
  {"help", no_argument, &show_help, 1},
  {"version", no_argument, &show_version, 1},
  {0, 0, 0, 0}
};

static void
usage (status)
     int status;
{
  if (status != 0)
    fprintf (stderr, "Try `%s --help' for more information.\n",
	     program_name);
  else
    {
      printf ("Usage: %s [OPTION]...\n", program_name);
      printf ("\
\n\
  --help      display this help and exit\n\
  --version   output version information and exit\n\
\n\
Same as id -un.\n\
");
    }
  exit (status);
}

void
main (argc, argv)
     int argc;
     char *argv[];
{
  register struct passwd *pw;
  register uid_t uid;
  int c;

  program_name = argv[0];

  while ((c = getopt_long (argc, argv, "", long_options, (int *) 0)) != EOF)
    {
      switch (c)
	{
	case 0:
	  break;

	default:
	  usage (1);
	}
    }

  if (show_version)
    {
      printf ("whoami - %s\n", version_string);
      exit (0);
    }

  if (show_help)
    usage (0);


  if (optind != argc)
    usage (1);

  uid = geteuid ();
  pw = getpwuid (uid);
  if (pw)
    {
      puts (pw->pw_name);
      exit (0);
    }
  fprintf (stderr, "%s: cannot find username for UID %u\n",
	   program_name, (unsigned) uid);
  exit (1);
}