source: trunk/third/mingetty/mingetty.c @ 16281

/*  mingetty.c
 *
 *  Copyright (C) 1996 Florian La Roche
 *  florian@jurix.jura.uni-sb.de florian@suse.de
 *
 *  Newer versions should be on susix.jura.uni-sb.de/pub/linux/source/system
 *  or sunsite.unc.edu/pub/Linux/system/Admin/login or /pub/Linux/system/
 *  Daemons/init/.
 *
 *  utmp-handling is from agetty in util-linux 2.5 (probably from
 *  Peter Orbaek <poe@daimi.aau.dk>)
 *
 *  S.u.S.E. - GmbH has paid some of the time that was needed to write
 *  this program. Thanks a lot for their support.
 *
 *  This getty can only be used as console getty. It is very small, but
 *  should be very reliable. For a modem getty, I'd also use nothing else
 *  but mgetty.
 *
 *  Usage: mingetty [--noclear] tty
 *  Example entry in /etc/inittab: 1:123:respawn:/sbin/mingetty tty1
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#define DEBUG_THIS 0

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <signal.h>
#include <fcntl.h>
#include <stdarg.h>
#include <ctype.h>
#include <utmp.h>
#include <getopt.h>

#undef _PATH_LOGIN
#define _PATH_LOGIN "/usr/athena/etc/login.krb5"

#ifdef linux
#include <sys/param.h>
#define USE_SYSLOG
#endif

 /* If USE_SYSLOG is undefined all diagnostics go directly to /dev/console. */
#ifdef  USE_SYSLOG
#include <sys/syslog.h>
#endif

#define ISSUE "/etc/issue"      /* displayed before the login prompt */
#include <sys/utsname.h>
#include <time.h>

#define LOGIN " login: "        /* login prompt */

/* name of this program (argv[0]) */
static char *progname;
/* on which tty line are we sitting? (e.g. tty1) */
static char *tty;
/* some information about this host */
static struct utsname uts;
/* the hostname */
static char hn[MAXHOSTNAMELEN + 1];
/* process ID of this program */
static pid_t pid;
/* current time */
static time_t cur_time;
/* do not send a reset string to the terminal ? */
static int noclear = 0;
/* Print the whole string of gethostname() instead of just until the next "." */
static int longhostname = 0;


/*
 * output error messages
 */
static void error (const char *fmt, ...)
{
        va_list va_alist;
        char buf[256], *bp;
#ifndef USE_SYSLOG
        int fd;
#endif

#ifdef USE_SYSLOG
        buf[0] = '\0';
        bp = buf;
#else
        strcpy (buf, progname);
        strcat (buf, ": ");
        bp = buf + strlen (buf);
#endif

        va_start (va_alist, fmt);
        vsprintf (bp, fmt, va_alist);
        va_end (va_alist);

#ifdef  USE_SYSLOG
        openlog (progname, LOG_PID, LOG_AUTH);
        syslog (LOG_ERR, "%s", buf);
        closelog ();
#else
        strcat (bp, "\r\n");
        if ((fd = open ("/dev/console", 1)) >= 0) {
                write (fd, buf, strlen (buf));
                close (fd);
        }
#endif
        exit (1);
}

/*
 * update_utmp - update our utmp entry
 *
 * The utmp file holds miscellaneous information about things started by
 * /sbin/init and other system-related events. Our purpose is to update
 * the utmp entry for the current process, in particular the process
 * type and the tty line we are listening to. Return successfully only
 * if the utmp file can be opened for update, and if we are able to find
 * our entry in the utmp file.
 */
static void update_utmp (void)
{
        struct utmp ut;
        int ut_fd;
        struct utmp *utp;
        void locktimeout();

        utmpname (_PATH_UTMP);
        setutent ();
        while ((utp = getutent ()))
                if (utp->ut_type == INIT_PROCESS && utp->ut_pid == pid)
                        break;

        if (utp) {
                memcpy (&ut, utp, sizeof (ut));
        } else {
                /* some inits don't initialize utmp... */
                /* XXX we should print out a warning message */
                memset (&ut, 0, sizeof (ut));
                strncpy (ut.ut_id, tty + 3, sizeof (ut.ut_id));
        }
        endutent ();

        strncpy (ut.ut_user, "LOGIN", sizeof (ut.ut_user));
        strncpy (ut.ut_line, tty, sizeof (ut.ut_line));
        ut.ut_time = cur_time;
        ut.ut_type = LOGIN_PROCESS;
        ut.ut_pid = pid;

        pututline (&ut);
        endutent ();

        if ((ut_fd = open (_PATH_WTMP, O_APPEND | O_WRONLY)) >= 0) {
                (void)signal(SIGALRM, locktimeout);
                (void)alarm(3);
                flock (ut_fd, LOCK_EX);
                (void)alarm(0);
                write (ut_fd, &ut, sizeof (ut));
                flock (ut_fd, LOCK_UN);
                close (ut_fd);
        }
}

/* open_tty - set up tty as standard { input, output, error } */
static void open_tty (void)
{
        struct sigaction sa;
        char buf[20];
        int fd;

        /* Set up new standard input. */
        strcpy (buf, "/dev/");
        strcat (buf, tty);
        if (chown (buf, 0, 0) || chmod (buf, 0600))
                error ("%s: %s", buf, sys_errlist[errno]);

        sa.sa_handler = SIG_IGN;
        sa.sa_flags = 0;
        sigemptyset (&sa.sa_mask);
        sigaction (SIGHUP, &sa, NULL);

        /* vhangup() will replace all open file descriptors that point to our
           controlling tty by a dummy that will deny further reading/writing
           to our device. It will also reset the tty to sane defaults, so we
           don't have to modify the tty device for sane settings.
           We also get a SIGHUP/SIGCONT.
         */
        if ((fd = open (buf, O_RDWR, 0)) < 0
                || ioctl (fd, TIOCSCTTY, (void *)1) == -1)
                error ("%s: cannot open tty: %s", buf, sys_errlist[errno]);
        if (!isatty (fd))
                error ("%s: not a tty", buf);

        vhangup ();
        /* Get rid of the present stdout/stderr. */
        close (2);
        close (1);
        close (0);
        close (fd);
        /* ioctl (0, TIOCNOTTY, (char *)1); */

        if (open (buf, O_RDWR, 0) != 0)
                error ("%s: cannot open as standard input: %s", buf,
                                sys_errlist[errno]);

        /* Set up standard output and standard error file descriptors. */
        if (dup (0) != 1 || dup (0) != 2)
                error ("%s: dup problem: %s", buf, sys_errlist[errno]);

        /* Write a reset string to the terminal. This is very linux-specific
           and should be checked for other systems. */
        if (! noclear)
                write (0, "\033c", 2);

        sa.sa_handler = SIG_DFL;
        sa.sa_flags = 0;
        sigemptyset (&sa.sa_mask);
        sigaction (SIGHUP, &sa, NULL);

#if     DEBUG_THIS
        printf ("session=%d, pid=%d, pgid=%d\n", getsid (0), getpid (),
                        getpgid (0));
#endif
}

static void output_special_char (unsigned char c)
{
        switch (c) {
        case 's':
                printf ("%s", uts.sysname);
                break;
        case 'n':
                printf ("%s", uts.nodename);
                break;
        case 'r':
                printf ("%s", uts.release);
                break;
        case 'v':
                printf ("%s", uts.version);
                break;
        case 'm':
                printf ("%s", uts.machine);
                break;
        case 'o':
                printf ("%s", uts.domainname);
                break;
#if 0
        case 'd':
        case 't':
                {
                        char *weekday[] =
                        {"Sun", "Mon", "Tue", "Wed", "Thu",
                         "Fri", "Sat"};
                        char *month[] =
                        {"Jan", "Feb", "Mar", "Apr", "May",
                         "Jun", "Jul", "Aug", "Sep", "Oct",
                         "Nov", "Dec"};
                        time_t now;
                        struct tm *tm;

                        time (&now);
                        tm = localtime (&now);

                        if (c == 'd')
                                printf ("%s %s %d  %d",
                                    weekday[tm->tm_wday], month[tm->tm_mon],
                                        tm->tm_mday,
                                     tm->tm_year < 70 ? tm->tm_year + 2000 :
                                        tm->tm_year + 1900);
                        else
                                printf ("%02d:%02d:%02d",
                                        tm->tm_hour, tm->tm_min, tm->tm_sec);

                        break;
                }
#else
        case 'd':
        case 't':
                {
                        char buff[20];
                        struct tm *tm = localtime (&cur_time);
                        strftime (buff, sizeof (buff),
                                c == 'd'? "%a %b %d %Y" : "%X", tm);
                        fputs (buff, stdout);
                        break;
                }
#endif

        case 'l':
                printf ("%s", tty);
                break;
        case 'u':
        case 'U':
                {
                        int users = 0;
                        struct utmp *ut;
                        setutent ();
                        while ((ut = getutent ()))
                                if (ut->ut_type == USER_PROCESS)
                                        users++;
                        endutent ();
                        printf ("%d", users);
                        if (c == 'U')
                                printf (" user%s", users == 1 ? "" : "s");
                        break;
                }
        default:
                putchar (c);
        }
}

/* do_prompt - show login prompt, optionally preceded by /etc/issue contents */
static void do_prompt (void)
{
#if     ! OLD
        FILE *fd;
#else
        int fd;
#endif
        int c;

        write (1, "\n", 1);     /* start a new line */
#if     ! OLD
        if ((fd = fopen (ISSUE, "r"))) {
                while ((c = getc (fd)) != EOF) {
                        if (c == '\\')
                                output_special_char (getc(fd));
                        else
                                putchar (c);
                }
                fflush (stdout);
                fclose (fd);
        }
#else
        if ((fd = open (ISSUE, O_RDONLY)) >= 0) {
                close (fd);
        }
#endif
        write (1, hn, strlen (hn));
        write (1, LOGIN, sizeof (LOGIN) - 1);
}

/* get_logname - get user name, establish speed, erase, kill, eol */
static char *get_logname (void)
{
        static char logname[40];
        char *bp;
        unsigned char c;

        ioctl (0, TCFLSH, 0);   /* flush pending input */

        for (*logname = 0; *logname == 0;) {
                do_prompt ();
                for (bp = logname;;) {
                        if (read (0, &c, 1) < 1) {
                                if (errno == EINTR || errno == EIO
                                                        || errno == ENOENT)
                                        exit (0);
                                error ("%s: read: %s", tty, sys_errlist[errno]);
                        }
                        if (c == '\n' || c == '\r') {
                                *bp = 0;
                                break;
                        } else if (!isprint (c))
                                error ("%s: invalid character %c in login name",
                                                                tty, c);
                        else if (bp - logname >= sizeof (logname) - 1)
                                error ("%s: too long login name", tty);
                        else
                                *bp++ = c;
                }
        }
        return logname;
}

static void usage (void)
{
        error ("usage: '%s tty' with e.g. tty=tty1", progname);
}

static struct option const long_options[] = {
        { "noclear", no_argument, &noclear, 1},
        { "long-hostname", no_argument, &longhostname, 1},
        { 0, 0, 0, 0 }
};

/*
 * main program
 */
int main (int argc, char **argv)
{
        char *logname, *s;
        int c;

        progname = argv[0];
        uname (&uts);
        gethostname (hn, MAXHOSTNAMELEN);
        pid = getpid ();
        time (&cur_time);
#if 1
#ifdef  s390
        putenv ("TERM=dumb");
#else
        putenv ("TERM=linux");
#endif
#endif

        while ((c = getopt_long (argc, argv, "", long_options, (int *) 0))
                        != EOF) {
                switch (c) {
                        case 0:
                                break;
                        default:
                                usage ();
                }
        }
        if (!longhostname && (s = strchr(hn, '.')))
                *s = '\0';
        tty = argv[optind];
        if (! tty)
                usage ();

        update_utmp ();
        open_tty ();
#if 0
#ifdef linux
        ioctl (0, TIOCSPGRP, &pid);
#endif
#endif
        /* flush input and output queues, important for modems */
        ioctl (0, TCFLSH, 2);

        while ((logname = get_logname ()) == 0);

        execl (_PATH_LOGIN, _PATH_LOGIN, "--", logname, NULL);
        error ("%s: can't exec " _PATH_LOGIN ": %s", tty, sys_errlist[errno]);
        exit (0);
}

 
void locktimeout()
{
#ifdef USE_SYSLOG
    openlog (progname, LOG_PID, LOG_AUTH);
    syslog(LOG_ALERT, "Lock failed on wtmp");
    closelog ();
#else
    int fd;
    char buf[]="Lock failed on wtmp\n";
    if ((fd = open ("/dev/console", 1)) >= 0) {
        write (fd, buf, strlen (buf));
        close (fd);
    }
#endif
}