/* Copyright (C) 1991, 1995, 1997 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <grp.h>
#include <pwd.h>
#include <limits.h>
#include <sys/types.h>


static void
print_grpname (id, parens)
     gid_t id;
     int parens;
{
  const struct group *const g = getgrgid (id);
  if (g == NULL)
    {
      if (parens)
	return;
      else
	{
	  fprintf (stderr, _("Couldn't find name for group %d\n"), id);
	  exit (EXIT_FAILURE);
	}
    }

  if (parens)
    printf ("(%s)", g->gr_name);
  else
    puts (g->gr_name);
}

static void
print_pwdname (id, parens)
     uid_t id;
     int parens;
{
  const struct passwd *const p = getpwuid (id);
  if (p == NULL)
    {
      if (parens)
	return;
      else
	{
	  fprintf (stderr, _("Couldn't find name for user %d\n"), (int) id);
	  exit (EXIT_FAILURE);
	}
    }

  if (parens)
    printf ("(%s)", p->pw_name);
  else
    puts (p->pw_name);
}

int
main (argc, argv)
     int argc;
     char **argv;
{
  int print_gid = 1, print_uid = 1;
  int real = 0, name = 0;
  int error = 0;
  int c;

  uid_t ruid = getuid (), euid = geteuid ();
  gid_t rgid = getgid (), egid = getegid ();

  while ((c = getopt (argc, argv, "gurn")) != -1)
    switch (c)
      {
      default:
	error = 1;
	break;

      case 'g':
	print_gid = 1;
	print_uid = 0;
	break;

      case 'u':
	print_uid = 1;
	print_gid = 0;
	break;

      case 'r':
	real = 1;
	break;

      case 'n':
	name = 1;
	break;
      }

  if (error || argc != optind)
    {
      fputs (_("Usage: id [-gurn]\n"), stderr);
      exit (EXIT_FAILURE);
    }

  if (print_uid && !print_gid)
    {
      const uid_t uid = real ? ruid : euid;
      if (name)
	print_pwdname (uid, 0);
      else
	printf ("%d\n", (int) uid);
    }
  else if (print_gid && !print_uid)
    {
      const gid_t gid = real ? rgid : egid;
      if (name)
	print_grpname (gid, 0);
      else
	printf ("%d\n", (int) gid);
    }
  else
    {
#if	NGROUPS_MAX > 0
      gid_t groups[NGROUPS_MAX];
      int ngroups;
      ngroups = getgroups (NGROUPS_MAX, groups);
#endif

      printf ("uid=%d", (int) ruid);
      print_pwdname (ruid, 1);
      printf (" gid=%d", (int) rgid);
      print_grpname (rgid, 1);
      if (euid != ruid)
	{
	  printf (" euid=%d", (int) euid);
	  print_pwdname (euid, 1);
	}
      if (egid != rgid)
	{
	  printf (" egid=%d", (int) egid);
	  print_grpname (egid, 1);
	}

#if	NGROUPS > 0
      if (ngroups > 0)
	{
	  size_t i;
	  printf (" groups=%d", (int) groups[0]);
	  print_grpname (groups[0], 1);
	  for (i = 1; i < ngroups; ++i)
	    {
	      printf (", %d", (int) groups[i]);
	      print_grpname (groups[i], 1);
	    }
	}
#endif

      putchar ('\n');
    }

  exit (EXIT_SUCCESS);
}
