/* Copyright (C) 1991, 1992, 1996, 1997 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, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <errno.h> #include <unistd.h> #include <string.h> #include <stdio.h> #include <limits.h> #include <fcntl.h> #include <utmp.h> /* Return the login name of the user, or NULL if it can't be determined. The returned pointer, if not NULL, is good only until the next call. */ char * getlogin (void) { char tty_pathname[2 + 2 * NAME_MAX]; char *real_tty_path = tty_pathname; char *result = NULL; static char name[UT_NAMESIZE + 1]; struct utmp *ut, line, buffer; /* Get name of tty connected to fd 0. Return NULL 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(). */ if (__ttyname_r (0, real_tty_path, sizeof (tty_pathname)) != 0) return NULL; real_tty_path += 5; /* Remove "/dev/". */ __setutent (); strncpy (line.ut_line, real_tty_path, sizeof line.ut_line); if (__getutline_r (&line, &buffer, &ut) < 0) { if (errno == ESRCH) /* The caller expects ENOENT if nothing is found. */ __set_errno (ENOENT); result = NULL; } else { strncpy (name, ut->ut_user, UT_NAMESIZE); name[UT_NAMESIZE] = '\0'; result = name; } __endutent (); return result; }