92 lines
2.3 KiB
C
92 lines
2.3 KiB
C
/* Reentrant function to return the current login name. Unix version.
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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 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 occured, return the error
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code. Otherwise return 0. */
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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 = 0;
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struct utmp_data utmp_data;
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struct utmp *ut, line;
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{
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int err;
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int d = __open ("/dev/tty", 0);
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if (d < 0)
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return errno;
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result = ttyname_r (d, real_tty_path, sizeof (tty_pathname));
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err = errno;
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(void) close (d);
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if (result < 0)
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{
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__set_errno (err);
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return err;
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}
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}
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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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result = ENOENT;
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else
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result = errno;
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}
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else
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{
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size_t needed = strlen (ut->ut_line) + 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_line, needed);
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result = 0;
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}
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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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