/* Reentrant function to return the current login name.  Unix version.

   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 <errno.h>

#include <unistd.h>

#include <string.h>

#include <stdio.h>

#include <limits.h>

#include <fcntl.h>

#include <utmp.h>

#include "../login/utmp-private.h"

/* Return at most NAME_LEN characters of the login name of the user in NAME.

   If it cannot be determined or some other error occurred, return the error

   code.  Otherwise return 0.  */

#ifdef STATIC

STATIC

#endif

int

__getlogin_r (char *name, size_t name_len)

{

  char tty_pathname[2 + 2 * NAME_MAX];

  char *real_tty_path = tty_pathname;

  int result;

  struct utmp *ut, line, buffer;

  /* Get name of tty connected to fd 0.  Return if not a tty or

     if fd 0 isn't open.  Note that a lot of documentation says that

     getlogin() is based on the controlling terminal---what they

     really mean is "the terminal connected to standard input".  The

     getlogin() implementation of DEC Unix, SunOS, Solaris, HP-UX all

     return NULL if fd 0 has been closed, so this is the compatible

     thing to do.  Note that ttyname(open("/dev/tty")) on those

     systems returns /dev/tty, so that is not a possible solution for

     getlogin().  */

  result = __ttyname_r (0, real_tty_path, sizeof (tty_pathname));

  if (result != 0)

    return result;

  real_tty_path += 5;		/* Remove "/dev/".  */

  strncpy (line.ut_line, real_tty_path, sizeof line.ut_line);

  /* We don't use the normal entry points __setutent et al, because we

     want setutent + getutline_r + endutent all to happen with the lock

     held so that our search is thread-safe.  */

  __libc_lock_lock (__libc_utmp_lock);

  (*__libc_utmp_jump_table->setutent) ();

  result = (*__libc_utmp_jump_table->getutline_r) (&line, &buffer, &ut);

  if (result < 0)

    {

      if (errno == ESRCH)

	/* The caller expects ENOENT if nothing is found.  */

	result = ENOENT;

      else

	result = errno;

    }

  (*__libc_utmp_jump_table->endutent) ();

  __libc_utmp_jump_table = &__libc_utmp_unknown_functions;

  __libc_lock_unlock (__libc_utmp_lock);

  if (result == 0)

    {

      size_t needed = __strnlen (ut->ut_user, UT_NAMESIZE) + 1;

      if (needed > name_len)

	{

	  __set_errno (ERANGE);

	  result = ERANGE;

	}

      else

	{

	  memcpy (name, ut->ut_user, needed - 1);

	  name[needed - 1] = 0;

	  result = 0;

	}

    }

  return result;

}

#ifndef STATIC

libc_hidden_def (__getlogin_r)

weak_alias (__getlogin_r, getlogin_r)

libc_hidden_weak (getlogin_r)

#endif