91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
/* Copyright (C) 1991, 1992 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 <ansidecl.h>
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#include <stddef.h>
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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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/* Defined in ttyname.c. */
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extern char *__ttyname;
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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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DEFUN_VOID(getlogin)
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{
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char save_tty_pathname[2 + 2 * NAME_MAX];
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char *save_ttyname;
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char *real_tty_path;
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char *result = NULL;
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FILE *f;
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static struct utmp ut;
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if (__ttyname == NULL)
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save_ttyname = NULL;
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else
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save_ttyname = strcpy (save_tty_pathname, __ttyname);
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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 NULL;
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real_tty_path = ttyname (d);
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err = errno;
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(void) close (d);
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if (real_tty_path == NULL)
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{
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errno = err;
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return NULL;
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}
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}
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real_tty_path += 5; /* Remove "/dev/". */
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f = fopen ("/etc/utmp", "r");
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if (f != NULL)
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{
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while (fread ((PTR) &ut, sizeof(ut), 1, f) == 1)
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if (!strncmp (ut.ut_line, real_tty_path, sizeof (ut.ut_line)))
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{
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result = ut.ut_name;
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/* The name is not null-terminated if
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it is as long as sizeof (ut.ut_name). */
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result[sizeof (ut.ut_name)] = '\0';
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break;
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}
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(void) fclose (f);
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}
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if (save_ttyname != NULL)
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strcpy (__ttyname, save_ttyname);
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if (result == NULL)
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errno = ENOENT;
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return result;
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}
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