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c8727fa6e5
The old implementation uses fd 0 to determine the login TTY. This was needed because using /dev/tty it is not possible to deduce the login TTY. For some time now there is the pseudo-file /proc/self/loginuid which directly helps us to find the user. Prefer using this file. It also works if stdin is closed, redirected, or re-opened.
105 lines
3.2 KiB
C
105 lines
3.2 KiB
C
/* Reentrant function to return the current login name. Unix version.
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Copyright (C) 1991,92,96,97,98,2002,2010 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdio.h>
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#include <limits.h>
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#include <fcntl.h>
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#include <utmp.h>
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#include "../login/utmp-private.h"
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/* Return at most NAME_LEN characters of the login name of the user in NAME.
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If it cannot be determined or some other error occurred, return the error
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code. Otherwise return 0. */
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#ifdef STATIC
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STATIC
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#endif
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int
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getlogin_r (name, name_len)
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char *name;
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size_t name_len;
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{
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char tty_pathname[2 + 2 * NAME_MAX];
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char *real_tty_path = tty_pathname;
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int result;
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struct utmp *ut, line, buffer;
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/* Get name of tty connected to fd 0. Return if not a tty or
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if fd 0 isn't open. Note that a lot of documentation says that
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getlogin() is based on the controlling terminal---what they
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really mean is "the terminal connected to standard input". The
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getlogin() implementation of DEC Unix, SunOS, Solaris, HP-UX all
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return NULL if fd 0 has been closed, so this is the compatible
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thing to do. Note that ttyname(open("/dev/tty")) on those
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systems returns /dev/tty, so that is not a possible solution for
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getlogin(). */
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result = __ttyname_r (0, real_tty_path, sizeof (tty_pathname));
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if (result != 0)
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return result;
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real_tty_path += 5; /* Remove "/dev/". */
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strncpy (line.ut_line, real_tty_path, sizeof line.ut_line);
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/* We don't use the normal entry points __setutent et al, because we
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want setutent + getutline_r + endutent all to happen with the lock
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held so that our search is thread-safe. */
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__libc_lock_lock (__libc_utmp_lock);
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(*__libc_utmp_jump_table->setutent) ();
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result = (*__libc_utmp_jump_table->getutline_r) (&line, &buffer, &ut);
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if (result < 0)
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{
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if (errno == ESRCH)
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/* The caller expects ENOENT if nothing is found. */
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result = ENOENT;
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else
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result = errno;
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}
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(*__libc_utmp_jump_table->endutent) ();
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__libc_utmp_jump_table = &__libc_utmp_unknown_functions;
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__libc_lock_unlock (__libc_utmp_lock);
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if (result == 0)
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{
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size_t needed = strlen (ut->ut_user) + 1;
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if (needed > name_len)
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{
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__set_errno (ERANGE);
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result = ERANGE;
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}
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else
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{
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memcpy (name, ut->ut_user, needed);
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result = 0;
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}
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}
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return result;
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}
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#ifndef STATIC
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libc_hidden_def (getlogin_r)
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#endif
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