source: MondoRescue/branches/2.2.9/mindi-busybox/loginutils/getty.c@ 2725

/* vi: set sw=4 ts=4: */
/* agetty.c - another getty program for Linux. By W. Z. Venema 1989
 * Ported to Linux by Peter Orbaek <poe@daimi.aau.dk>
 * This program is freely distributable. The entire man-page used to
 * be here. Now read the real man-page agetty.8 instead.
 *
 * option added by Eric Rasmussen <ear@usfirst.org> - 12/28/95
 *
 * 1999-02-22 Arkadiusz Mickiewicz <misiek@misiek.eu.org>
 * - added Native Language Support
 *
 * 1999-05-05 Thorsten Kranzkowski <dl8bcu@gmx.net>
 * - enable hardware flow control before displaying /etc/issue
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include "libbb.h"
#include <syslog.h>

#if ENABLE_FEATURE_UTMP
# include <utmp.h> /* LOGIN_PROCESS */
#endif

#ifndef IUCLC
# define IUCLC 0
#endif

/*
 * Some heuristics to find out what environment we are in: if it is not
 * System V, assume it is SunOS 4.
 */
#ifdef LOGIN_PROCESS                    /* defined in System V utmp.h */
#include <sys/utsname.h>
#else /* if !sysV style, wtmp/utmp code is off */
#undef ENABLE_FEATURE_UTMP
#undef ENABLE_FEATURE_WTMP
#define ENABLE_FEATURE_UTMP 0
#define ENABLE_FEATURE_WTMP 0
#endif  /* LOGIN_PROCESS */

/*
 * Things you may want to modify.
 *
 * You may disagree with the default line-editing etc. characters defined
 * below. Note, however, that DEL cannot be used for interrupt generation
 * and for line editing at the same time.
 */

/* I doubt there are systems which still need this */
#undef HANDLE_ALLCAPS
#undef ANCIENT_BS_KILL_CHARS

#define _PATH_LOGIN "/bin/login"

/* If ISSUE is not defined, getty will never display the contents of the
 * /etc/issue file. You will not want to spit out large "issue" files at the
 * wrong baud rate.
 */
#define ISSUE "/etc/issue"              /* displayed before the login prompt */

/* Some shorthands for control characters. */
#define CTL(x)          ((x) ^ 0100)    /* Assumes ASCII dialect */
#define CR              CTL('M')        /* carriage return */
#define NL              CTL('J')        /* line feed */
#define BS              CTL('H')        /* back space */
#define DEL             CTL('?')        /* delete */

/* Defaults for line-editing etc. characters; you may want to change this. */
#define DEF_ERASE       DEL             /* default erase character */
#define DEF_INTR        CTL('C')        /* default interrupt character */
#define DEF_QUIT        CTL('\\')       /* default quit char */
#define DEF_KILL        CTL('U')        /* default kill char */
#define DEF_EOF         CTL('D')        /* default EOF char */
#define DEF_EOL         '\n'
#define DEF_SWITCH      0               /* default switch char */

/*
 * When multiple baud rates are specified on the command line, the first one
 * we will try is the first one specified.
 */
#define MAX_SPEED       10              /* max. nr. of baud rates */

/* Storage for command-line options. */
struct options {
    int flags;                      /* toggle switches, see below */
    unsigned timeout;               /* time-out period */
    const char *login;              /* login program */
    const char *tty;                /* name of tty */
    const char *initstring;         /* modem init string */
    const char *issue;              /* alternative issue file */
    int numspeed;                   /* number of baud rates to try */
    int speeds[MAX_SPEED];          /* baud rates to be tried */
};

/* Storage for things detected while the login name was read. */
struct chardata {
    unsigned char erase;    /* erase character */
    unsigned char kill;     /* kill character */
    unsigned char eol;      /* end-of-line character */
    unsigned char parity;   /* what parity did we see */
    /* (parity & 1): saw odd parity char with 7th bit set */
    /* (parity & 2): saw even parity char with 7th bit set */
    /* parity == 0: probably 7-bit, space parity? */
    /* parity == 1: probably 7-bit, odd parity? */
    /* parity == 2: probably 7-bit, even parity? */
    /* parity == 3: definitely 8 bit, no parity! */
    /* Hmm... with any value of "parity" 8 bit, no parity is possible */
#ifdef HANDLE_ALLCAPS
    unsigned char capslock; /* upper case without lower case */
#endif
};


/* Initial values for the above. */
static const struct chardata init_chardata = {
    DEF_ERASE,                              /* default erase character */
    DEF_KILL,                               /* default kill character */
    13,                                     /* default eol char */
    0,                                      /* space parity */
#ifdef HANDLE_ALLCAPS
    0,                                      /* no capslock */
#endif
};

static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn";
#define F_INITSTRING    (1 << 0)        /* -I initstring is set */
#define F_LOCAL         (1 << 1)        /* -L force local */
#define F_FAKEHOST      (1 << 2)        /* -H fake hostname */
#define F_CUSTISSUE     (1 << 3)        /* -f give alternative issue file */
#define F_RTSCTS        (1 << 4)        /* -h enable RTS/CTS flow control */
#define F_ISSUE         (1 << 5)        /* -i display /etc/issue */
#define F_LOGIN         (1 << 6)        /* -l non-default login program */
#define F_PARSE         (1 << 7)        /* -m process modem status messages */
#define F_TIMEOUT       (1 << 8)        /* -t time out */
#define F_WAITCRLF      (1 << 9)        /* -w wait for CR or LF */
#define F_NOPROMPT      (1 << 10)       /* -n don't ask for login name */


#define line_buf bb_common_bufsiz1

/* The following is used for understandable diagnostics. */
#ifdef DEBUGGING
static FILE *dbf;
#define DEBUGTERM "/dev/ttyp0"
#define debug(...) do { fprintf(dbf, __VA_ARGS__); fflush(dbf); } while (0)
#else
#define debug(...) ((void)0)
#endif


/* bcode - convert speed string to speed code; return <= 0 on failure */
static int bcode(const char *s)
{
    int value = bb_strtou(s, NULL, 10); /* yes, int is intended! */
    if (value < 0) /* bad terminating char, overflow, etc */
        return value;
    return tty_value_to_baud(value);
}

/* parse_speeds - parse alternate baud rates */
static void parse_speeds(struct options *op, char *arg)
{
    char *cp;

    /* NB: at least one iteration is always done */
    debug("entered parse_speeds\n");
    while ((cp = strsep(&arg, ",")) != NULL) {
        op->speeds[op->numspeed] = bcode(cp);
        if (op->speeds[op->numspeed] < 0)
            bb_error_msg_and_die("bad speed: %s", cp);
        /* note: arg "0" turns into speed B0 */
        op->numspeed++;
        if (op->numspeed > MAX_SPEED)
            bb_error_msg_and_die("too many alternate speeds");
    }
    debug("exiting parse_speeds\n");
}

/* parse_args - parse command-line arguments */
static void parse_args(char **argv, struct options *op, char **fakehost_p)
{
    char *ts;

    opt_complementary = "-2:t+"; /* at least 2 args; -t N */
    op->flags = getopt32(argv, opt_string,
        &(op->initstring), fakehost_p, &(op->issue),
        &(op->login), &op->timeout);
    argv += optind;
    if (op->flags & F_INITSTRING) {
        op->initstring = xstrdup(op->initstring);
        /* decode \ddd octal codes into chars */
        strcpy_and_process_escape_sequences((char*)op->initstring, op->initstring);
    }
    op->flags ^= F_ISSUE;           /* invert flag "show /etc/issue" */
    debug("after getopt\n");

    /* we loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
    op->tty = argv[0];      /* tty name */
    ts = argv[1];           /* baud rate(s) */
    if (isdigit(argv[0][0])) {
        /* a number first, assume it's a speed (BSD style) */
        op->tty = ts;   /* tty name is in argv[1] */
        ts = argv[0];   /* baud rate(s) */
    }
    parse_speeds(op, ts);
    applet_name = xasprintf("getty: %s", op->tty);

    if (argv[2])
        xsetenv("TERM", argv[2]);

    debug("exiting parse_args\n");
}

/* open_tty - set up tty as standard { input, output, error } */
static void open_tty(const char *tty)
{
    /* Set up new standard input, unless we are given an already opened port. */
    if (NOT_LONE_DASH(tty)) {
//      struct stat st;
//      int cur_dir_fd;
//      int fd;

        /* Sanity checks... */
//      cur_dir_fd = xopen(".", O_DIRECTORY | O_NONBLOCK);
//      xchdir("/dev");
//      xstat(tty, &st);
//      if (!S_ISCHR(st.st_mode))
//          bb_error_msg_and_die("not a character device");

        if (tty[0] != '/')
            tty = xasprintf("/dev/%s", tty); /* will leak it */

        /* Open the tty as standard input. */
        debug("open(2)\n");
        close(0);
        /*fd =*/ xopen(tty, O_RDWR | O_NONBLOCK); /* uses fd 0 */

//      /* Restore current directory */
//      fchdir(cur_dir_fd);

        /* Open the tty as standard input, continued */
//      xmove_fd(fd, 0);
//      /* fd is >= cur_dir_fd, and cur_dir_fd gets closed too here: */
//      while (fd > 2)
//          close(fd--);

        /* Set proper protections and ownership. */
        fchown(0, 0, 0);        /* 0:0 */
        fchmod(0, 0620);        /* crw--w---- */
    } else {
        /*
         * Standard input should already be connected to an open port. Make
         * sure it is open for read/write.
         */
        if ((fcntl(0, F_GETFL) & O_RDWR) != O_RDWR)
            bb_error_msg_and_die("stdin is not open for read/write");
    }
}

/* termios_init - initialize termios settings */
static void termios_init(struct termios *tp, int speed, struct options *op)
{
    speed_t ispeed, ospeed;
    /*
     * Initial termios settings: 8-bit characters, raw-mode, blocking i/o.
     * Special characters are set after we have read the login name; all
     * reads will be done in raw mode anyway. Errors will be dealt with
     * later on.
     */
    /* flush input and output queues, important for modems! */
    tcflush(0, TCIOFLUSH);
    ispeed = ospeed = speed;
    if (speed == B0) {
        /* Speed was specified as "0" on command line.
         * Just leave it unchanged */
        ispeed = cfgetispeed(tp);
        ospeed = cfgetospeed(tp);
    }
    tp->c_cflag = CS8 | HUPCL | CREAD;
    if (op->flags & F_LOCAL)
        tp->c_cflag |= CLOCAL;
    cfsetispeed(tp, ispeed);
    cfsetospeed(tp, ospeed);

    tp->c_iflag = tp->c_lflag = 0;
    tp->c_oflag = OPOST | ONLCR;
    tp->c_cc[VMIN] = 1;
    tp->c_cc[VTIME] = 0;
#ifdef __linux__
    tp->c_line = 0;
#endif

    /* Optionally enable hardware flow control */
#ifdef CRTSCTS
    if (op->flags & F_RTSCTS)
        tp->c_cflag |= CRTSCTS;
#endif

    tcsetattr_stdin_TCSANOW(tp);

    debug("term_io 2\n");
}

/* auto_baud - extract baud rate from modem status message */
static void auto_baud(char *buf, unsigned size_buf, struct termios *tp)
{
    int speed;
    int vmin;
    unsigned iflag;
    char *bp;
    int nread;

    /*
     * This works only if the modem produces its status code AFTER raising
     * the DCD line, and if the computer is fast enough to set the proper
     * baud rate before the message has gone by. We expect a message of the
     * following format:
     *
     * <junk><number><junk>
     *
     * The number is interpreted as the baud rate of the incoming call. If the
     * modem does not tell us the baud rate within one second, we will keep
     * using the current baud rate. It is advisable to enable BREAK
     * processing (comma-separated list of baud rates) if the processing of
     * modem status messages is enabled.
     */

    /*
     * Use 7-bit characters, don't block if input queue is empty. Errors will
     * be dealt with later on.
     */
    iflag = tp->c_iflag;
    tp->c_iflag |= ISTRIP;          /* enable 8th-bit stripping */
    vmin = tp->c_cc[VMIN];
    tp->c_cc[VMIN] = 0;             /* don't block if queue empty */
    tcsetattr_stdin_TCSANOW(tp);

    /*
     * Wait for a while, then read everything the modem has said so far and
     * try to extract the speed of the dial-in call.
     */
    sleep(1);
    nread = safe_read(STDIN_FILENO, buf, size_buf - 1);
    if (nread > 0) {
        buf[nread] = '\0';
        for (bp = buf; bp < buf + nread; bp++) {
            if (isdigit(*bp)) {
                speed = bcode(bp);
                if (speed > 0)
                    cfsetspeed(tp, speed);
                break;
            }
        }
    }

    /* Restore terminal settings. Errors will be dealt with later on. */
    tp->c_iflag = iflag;
    tp->c_cc[VMIN] = vmin;
    tcsetattr_stdin_TCSANOW(tp);
}

/* do_prompt - show login prompt, optionally preceded by /etc/issue contents */
static void do_prompt(struct options *op)
{
#ifdef ISSUE
    print_login_issue(op->issue, op->tty);
#endif
    print_login_prompt();
}

#ifdef HANDLE_ALLCAPS
/* all_is_upcase - string contains upper case without lower case */
/* returns 1 if true, 0 if false */
static int all_is_upcase(const char *s)
{
    while (*s)
        if (islower(*s++))
            return 0;
    return 1;
}
#endif

/* get_logname - get user name, establish parity, speed, erase, kill, eol;
 * return NULL on BREAK, logname on success */
static char *get_logname(char *logname, unsigned size_logname,
        struct options *op, struct chardata *cp)
{
    char *bp;
    char c;                         /* input character, full eight bits */
    char ascval;                    /* low 7 bits of input character */
    int bits;                       /* # of "1" bits per character */
    int mask;                       /* mask with 1 bit up */
    static const char erase[][3] = {/* backspace-space-backspace */
        "\010\040\010",                 /* space parity */
        "\010\040\010",                 /* odd parity */
        "\210\240\210",                 /* even parity */
        "\010\040\010",                 /* 8 bit no parity */
    };

    /* NB: *cp is pre-initialized with init_chardata */

    /* Flush pending input (esp. after parsing or switching the baud rate). */
    sleep(1);
    tcflush(0, TCIOFLUSH);

    /* Prompt for and read a login name. */
    logname[0] = '\0';
    while (!logname[0]) {
        /* Write issue file and prompt, with "parity" bit == 0. */
        do_prompt(op);

        /* Read name, watch for break, parity, erase, kill, end-of-line. */
        bp = logname;
        cp->eol = '\0';
        while (cp->eol == '\0') {

            /* Do not report trivial EINTR/EIO errors. */
            errno = EINTR; /* make read of 0 bytes be silent too */
            if (read(STDIN_FILENO, &c, 1) < 1) {
                if (errno == EINTR || errno == EIO)
                    exit(EXIT_SUCCESS);
                bb_perror_msg_and_die(bb_msg_read_error);
            }

            /* BREAK. If we have speeds to try,
             * return NULL (will switch speeds and return here) */
            if (c == '\0' && op->numspeed > 1)
                return NULL;

            /* Do parity bit handling. */
            if (!(op->flags & F_LOCAL) && (c & 0x80)) {       /* "parity" bit on? */
                bits = 1;
                mask = 1;
                while (mask & 0x7f) {
                    if (mask & c)
                        bits++; /* count "1" bits */
                    mask <<= 1;
                }
                /* ... |= 2 - even, 1 - odd */
                cp->parity |= 2 - (bits & 1);
            }

            /* Do erase, kill and end-of-line processing. */
            ascval = c & 0x7f;
            switch (ascval) {
            case CR:
            case NL:
                *bp = '\0';             /* terminate logname */
                cp->eol = ascval;       /* set end-of-line char */
                break;
            case BS:
            case DEL:
#ifdef ANCIENT_BS_KILL_CHARS
            case '#':
#endif
                cp->erase = ascval;     /* set erase character */
                if (bp > logname) {
                    full_write(STDOUT_FILENO, erase[cp->parity], 3);
                    bp--;
                }
                break;
            case CTL('U'):
#ifdef ANCIENT_BS_KILL_CHARS
            case '@':
#endif
                cp->kill = ascval;      /* set kill character */
                while (bp > logname) {
                    full_write(STDOUT_FILENO, erase[cp->parity], 3);
                    bp--;
                }
                break;
            case CTL('D'):
                exit(EXIT_SUCCESS);
            default:
                if (ascval < ' ') {
                    /* ignore garbage characters */
                } else if ((int)(bp - logname) >= size_logname - 1) {
                    bb_error_msg_and_die("input overrun");
                } else {
                    full_write(STDOUT_FILENO, &c, 1); /* echo the character */
                    *bp++ = ascval; /* and store it */
                }
                break;
            }
        }
    }
    /* Handle names with upper case and no lower case. */

#ifdef HANDLE_ALLCAPS
    cp->capslock = all_is_upcase(logname);
    if (cp->capslock) {
        for (bp = logname; *bp; bp++)
            if (isupper(*bp))
                *bp = tolower(*bp);     /* map name to lower case */
    }
#endif
    return logname;
}

/* termios_final - set the final tty mode bits */
static void termios_final(struct options *op, struct termios *tp, struct chardata *cp)
{
    /* General terminal-independent stuff. */
    tp->c_iflag |= IXON | IXOFF;    /* 2-way flow control */
    tp->c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
    /* no longer| ECHOCTL | ECHOPRT */
    tp->c_oflag |= OPOST;
    /* tp->c_cflag = 0; */
    tp->c_cc[VINTR] = DEF_INTR;     /* default interrupt */
    tp->c_cc[VQUIT] = DEF_QUIT;     /* default quit */
    tp->c_cc[VEOF] = DEF_EOF;       /* default EOF character */
    tp->c_cc[VEOL] = DEF_EOL;
#ifdef VSWTC
    tp->c_cc[VSWTC] = DEF_SWITCH;   /* default switch character */
#endif

    /* Account for special characters seen in input. */
    if (cp->eol == CR) {
        tp->c_iflag |= ICRNL;   /* map CR in input to NL */
        tp->c_oflag |= ONLCR;   /* map NL in output to CR-NL */
    }
    tp->c_cc[VERASE] = cp->erase;   /* set erase character */
    tp->c_cc[VKILL] = cp->kill;     /* set kill character */

    /* Account for the presence or absence of parity bits in input. */
    switch (cp->parity) {
    case 0:                                 /* space (always 0) parity */
// I bet most people go here - they use only 7-bit chars in usernames....
        break;
    case 1:                                 /* odd parity */
        tp->c_cflag |= PARODD;
        /* FALLTHROUGH */
    case 2:                                 /* even parity */
        tp->c_cflag |= PARENB;
        tp->c_iflag |= INPCK | ISTRIP;
        /* FALLTHROUGH */
    case (1 | 2):                           /* no parity bit */
        tp->c_cflag &= ~CSIZE;
        tp->c_cflag |= CS7;
// FIXME: wtf? case 3: we saw both even and odd 8-bit bytes -
// it's probably some umlauts etc, but definitely NOT 7-bit!!!
// Entire parity detection madness here just begs for deletion...
        break;
    }

    /* Account for upper case without lower case. */
#ifdef HANDLE_ALLCAPS
    if (cp->capslock) {
        tp->c_iflag |= IUCLC;
        tp->c_lflag |= XCASE;
        tp->c_oflag |= OLCUC;
    }
#endif
    /* Optionally enable hardware flow control */
#ifdef CRTSCTS
    if (op->flags & F_RTSCTS)
        tp->c_cflag |= CRTSCTS;
#endif

    /* Finally, make the new settings effective */
    if (tcsetattr_stdin_TCSANOW(tp) < 0)
        bb_perror_msg_and_die("tcsetattr");
}

int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int getty_main(int argc UNUSED_PARAM, char **argv)
{
    int n;
    pid_t pid;
    char *fakehost = NULL;          /* Fake hostname for ut_host */
    char *logname;                  /* login name, given to /bin/login */
    /* Merging these into "struct local" may _seem_ to reduce
     * parameter passing, but today's gcc will inline
     * statics which are called once anyway, so don't do that */
    struct chardata chardata;       /* set by get_logname() */
    struct termios termios;         /* terminal mode bits */
    struct options options;

    chardata = init_chardata;

    memset(&options, 0, sizeof(options));
    options.login = _PATH_LOGIN;    /* default login program */
    options.tty = "tty1";           /* default tty line */
    options.initstring = "";        /* modem init string */
#ifdef ISSUE
    options.issue = ISSUE;          /* default issue file */
#endif

    /* Parse command-line arguments. */
    parse_args(argv, &options, &fakehost);

    logmode = LOGMODE_NONE;

    /* Create new session, lose controlling tty, if any */
    /* docs/ctty.htm says:
     * "This is allowed only when the current process
     *  is not a process group leader" - is this a problem? */
    setsid();
    /* close stdio, and stray descriptors, just in case */
    n = xopen(bb_dev_null, O_RDWR);
    /* dup2(n, 0); - no, we need to handle "getty - 9600" too */
    xdup2(n, 1);
    xdup2(n, 2);
    while (n > 2)
        close(n--);

    /* Logging. We want special flavor of error_msg_and_die */
    die_sleep = 10;
    msg_eol = "\r\n";
    /* most likely will internally use fd #3 in CLOEXEC mode: */
    openlog(applet_name, LOG_PID, LOG_AUTH);
    logmode = LOGMODE_BOTH;

#ifdef DEBUGGING
    dbf = xfopen_for_write(DEBUGTERM);
    for (n = 1; argv[n]; n++) {
        debug(argv[n]);
        debug("\n");
    }
#endif

    /* Open the tty as standard input, if it is not "-" */
    /* If it's not "-" and not taken yet, it will become our ctty */
    debug("calling open_tty\n");
    open_tty(options.tty);
    ndelay_off(0);
    debug("duping\n");
    xdup2(0, 1);
    xdup2(0, 2);

    /*
     * The following ioctl will fail if stdin is not a tty, but also when
     * there is noise on the modem control lines. In the latter case, the
     * common course of action is (1) fix your cables (2) give the modem more
     * time to properly reset after hanging up. SunOS users can achieve (2)
     * by patching the SunOS kernel variable "zsadtrlow" to a larger value;
     * 5 seconds seems to be a good value.
     */
    if (tcgetattr(0, &termios) < 0)
        bb_perror_msg_and_die("tcgetattr");

    pid = getpid();
#ifdef __linux__
// FIXME: do we need this? Otherwise "-" case seems to be broken...
    // /* Forcibly make fd 0 our controlling tty, even if another session
    //  * has it as a ctty. (Another session loses ctty). */
    // ioctl(0, TIOCSCTTY, (void*)1);
    /* Make ourself a foreground process group within our session */
    tcsetpgrp(0, pid);
#endif

    /* Update the utmp file. This tty is ours now! */
    update_utmp(pid, LOGIN_PROCESS, options.tty, "LOGIN", fakehost);

    /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
    debug("calling termios_init\n");
    termios_init(&termios, options.speeds[0], &options);

    /* Write the modem init string and DON'T flush the buffers */
    if (options.flags & F_INITSTRING) {
        debug("writing init string\n");
        full_write1_str(options.initstring);
    }

    /* Optionally detect the baud rate from the modem status message */
    debug("before autobaud\n");
    if (options.flags & F_PARSE)
        auto_baud(line_buf, sizeof(line_buf), &termios);

    /* Set the optional timer */
    alarm(options.timeout); /* if 0, alarm is not set */

    /* Optionally wait for CR or LF before writing /etc/issue */
    if (options.flags & F_WAITCRLF) {
        char ch;

        debug("waiting for cr-lf\n");
        while (safe_read(STDIN_FILENO, &ch, 1) == 1) {
            debug("read %x\n", (unsigned char)ch);
            ch &= 0x7f;                     /* strip "parity bit" */
            if (ch == '\n' || ch == '\r')
                break;
        }
    }

    logname = NULL;
    if (!(options.flags & F_NOPROMPT)) {
        /* NB:termios_init already set line speed
         * to options.speeds[0] */
        int baud_index = 0;

        while (1) {
            /* Read the login name. */
            debug("reading login name\n");
            logname = get_logname(line_buf, sizeof(line_buf),
                    &options, &chardata);
            if (logname)
                break;
            /* we are here only if options.numspeed > 1 */
            baud_index = (baud_index + 1) % options.numspeed;
            cfsetispeed(&termios, options.speeds[baud_index]);
            cfsetospeed(&termios, options.speeds[baud_index]);
            tcsetattr_stdin_TCSANOW(&termios);
        }
    }

    /* Disable timer. */
    alarm(0);

    /* Finalize the termios settings. */
    termios_final(&options, &termios, &chardata);

    /* Now the newline character should be properly written. */
    full_write(STDOUT_FILENO, "\n", 1);

    /* Let the login program take care of password validation. */
    /* We use PATH because we trust that root doesn't set "bad" PATH,
     * and getty is not suid-root applet. */
    /* With -n, logname == NULL, and login will ask for username instead */
    BB_EXECLP(options.login, options.login, "--", logname, NULL);
    bb_error_msg_and_die("can't execute '%s'", options.login);
}