75 lines
2.4 KiB
C
75 lines
2.4 KiB
C
/* Copyright (C) 1991, 1992, 1996 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, 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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/* Return the login name of the user, or NULL if it can't be determined.
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The returned pointer, if not NULL, is good only until the next call. */
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char *
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getlogin (void)
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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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char *result = NULL;
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struct utmp_data utmp_data = { ut_fd: -1 };
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static char name[UT_NAMESIZE + 1];
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struct utmp *ut, line;
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/* Get name of tty connected to fd 0. Return NULL 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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if (__ttyname_r (0, real_tty_path, sizeof (tty_pathname)) < 0)
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return NULL;
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real_tty_path += 5; /* Remove "/dev/". */
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__setutent_r (&utmp_data);
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strncpy (line.ut_line, real_tty_path, sizeof line.ut_line);
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if (__getutline_r (&line, &ut, &utmp_data) < 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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__set_errno (ENOENT);
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result = NULL;
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}
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else
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{
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strncpy (name, ut->ut_user, UT_NAMESIZE);
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name[UT_NAMESIZE] = '\0';
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result = name;
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}
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__endutent_r (&utmp_data);
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return result;
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}
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