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/* Reentrant function to return the current login name. Unix version.
Copyright (C) 1991-2021 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
<https://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_setutent ();
result = __libc_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_endutent ();
__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
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