source: MondoRescue/branches/2.2.5/mindi-busybox/loginutils/getty.c

/* 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 Mi¶kiewicz <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 tarball for details.
 *
 */

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

#if ENABLE_FEATURE_UTMP
#include <utmp.h>
#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 */
#define SYSV_STYLE                      /* select System V style getty */
#include <sys/utsname.h>
#include <time.h>
#if ENABLE_FEATURE_WTMP
extern void updwtmp(const char *filename, const struct utmp *ut);
static void update_utmp(const char *line);
#endif
#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

#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 FIRST_SPEED     0

/* Storage for command-line options. */

#define MAX_SPEED       10              /* max. nr. of baud rates */

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 */
};

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

/* 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 */
#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
};

/* The following is used for understandable diagnostics. */

/* Fake hostname for ut_host specified on command line. */
static char *fakehost = NULL;

/* ... */
#ifdef DEBUGGING
#define debug(s) fprintf(dbf,s); fflush(dbf)
#define DEBUGTERM "/dev/ttyp0"
static FILE *dbf;
#else
#define debug(s) /* nothing */
#endif


/* bcode - convert speed string to speed code; return 0 on failure */
static int bcode(const char *s)
{
    int r;
    unsigned value = bb_strtou(s, NULL, 10);
    if (errno) {
        return -1;
    }
    r = tty_value_to_baud(value);
    if (r > 0) {
        return r;
    }
    return 0;
}


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

    debug("entered parse_speeds\n");
    for (cp = strtok(arg, ","); cp != 0; cp = strtok((char *) 0, ",")) {
        if ((op->speeds[op->numspeed++] = bcode(cp)) <= 0)
            bb_error_msg_and_die("bad speed: %s", cp);
        if (op->numspeed > MAX_SPEED)
            bb_error_msg_and_die("too many alternate speeds");
    }
    debug("exiting parsespeeds\n");
}


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

    op->flags = getopt32(argv, opt_string,
        &(op->initstring), &fakehost, &(op->issue),
        &(op->login), &ts);
    if (op->flags & F_INITSTRING) {
        const char *p = op->initstring;
        char *q;

        op->initstring = q = xstrdup(op->initstring);
        /* copy optarg into op->initstring decoding \ddd
           octal codes into chars */
        while (*p) {
            if (*p == '\\') {
                p++;
                *q++ = bb_process_escape_sequence(&p);
            } else {
                *q++ = *p++;
            }
        }
        *q = '\0';
    }
    op->flags ^= F_ISSUE;           /* revert flag show /etc/issue */
    if (op->flags & F_TIMEOUT) {
        op->timeout = xatoul_range(ts, 1, INT_MAX);
    }
    argv += optind;
    argc -= optind;
    debug("after getopt loop\n");
    if (argc < 2)          /* check parameter count */
        bb_show_usage();

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

    if (argv[2])
        setenv("TERM", argv[2], 1);

    debug("exiting parseargs\n");
}

/* open_tty - set up tty as standard { input, output, error } */
static void open_tty(const char *tty, struct termios *tp, int local)
{
    int chdir_to_root = 0;

    /* Set up new standard input, unless we are given an already opened port. */
    if (NOT_LONE_DASH(tty)) {
        struct stat st;
        int fd;

        /* Sanity checks... */
        xchdir("/dev");
        chdir_to_root = 1;
        xstat(tty, &st);
        if ((st.st_mode & S_IFMT) != S_IFCHR)
            bb_error_msg_and_die("%s: not a character device", tty);

        /* Open the tty as standard input. */
        debug("open(2)\n");
        fd = xopen(tty, O_RDWR | O_NONBLOCK);
        xdup2(fd, 0);
        while (fd > 2)
            close(fd--);
    } 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");
    }

    /* Replace current standard output/error fd's with new ones */
    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.
     */
    ioctl_or_perror_and_die(0, TCGETS, tp, "%s: TCGETS", tty);

    /*
     * It seems to be a terminal. Set proper protections and ownership. Mode
     * 0622 is suitable for SYSV <4 because /bin/login does not change
     * protections. SunOS 4 login will change the protections to 0620 (write
     * access for group tty) after the login has succeeded.
     */

#ifdef DEBIAN
#warning Debian /dev/vcs[a]NN hack is deprecated and will be removed
    {
        /* tty to root.dialout 660 */
        struct group *gr;
        int id;

        gr = getgrnam("dialout");
        id = gr ? gr->gr_gid : 0;
        chown(tty, 0, id);
        chmod(tty, 0660);

        /* vcs,vcsa to root.sys 600 */
        if (!strncmp(tty, "tty", 3) && isdigit(tty[3])) {
            char *vcs, *vcsa;

            vcs = xstrdup(tty);
            vcsa = xmalloc(strlen(tty) + 2);
            strcpy(vcs, "vcs");
            strcpy(vcs + 3, tty + 3);
            strcpy(vcsa, "vcsa");
            strcpy(vcsa + 4, tty + 3);

            gr = getgrnam("sys");
            id = gr ? gr->gr_gid : 0;
            chown(vcs, 0, id);
            chmod(vcs, 0600);
            chown(vcsa, 0, id);
            chmod(vcs, 0600);

            free(vcs);
            free(vcsa);
        }
    }
#else
    if (NOT_LONE_DASH(tty)) {
        chown(tty, 0, 0);        /* 0:0 */
        chmod(tty, 0622);        /* crw--w--w- */
    }
#endif
    if (chdir_to_root)
        xchdir("/");
}

/* termios_init - initialize termios settings */
static void termios_init(struct termios *tp, int speed, struct options *op)
{
    /*
     * 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.
     */
#ifdef __linux__
    /* flush input and output queues, important for modems! */
    ioctl(0, TCFLSH, TCIOFLUSH);
#endif

    tp->c_cflag = CS8 | HUPCL | CREAD | speed;
    if (op->flags & F_LOCAL) {
        tp->c_cflag |= CLOCAL;
    }

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

    /* Optionally enable hardware flow control */

#ifdef  CRTSCTS
    if (op->flags & F_RTSCTS)
        tp->c_cflag |= CRTSCTS;
#endif

    ioctl(0, TCSETS, tp);

    /* go to blocking input even in local mode */
    ndelay_off(0);

    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 */
    ioctl(0, TCSETS, 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 = read(0, buf, size_buf - 1);
    if (nread > 0) {
        buf[nread] = '\0';
        for (bp = buf; bp < buf + nread; bp++) {
            if (isascii(*bp) && isdigit(*bp)) {
                speed = bcode(bp);
                if (speed) {
                    tp->c_cflag &= ~CBAUD;
                    tp->c_cflag |= speed;
                }
                break;
            }
        }
    }
    /* Restore terminal settings. Errors will be dealt with later on. */

    tp->c_iflag = iflag;
    tp->c_cc[VMIN] = vmin;
    ioctl(0, TCSETS, tp);
}

/* next_speed - select next baud rate */
static void next_speed(struct termios *tp, struct options *op)
{
    static int baud_index = FIRST_SPEED;    /* current speed index */

    baud_index = (baud_index + 1) % op->numspeed;
    tp->c_cflag &= ~CBAUD;
    tp->c_cflag |= op->speeds[baud_index];
    ioctl(0, TCSETS, tp);
}


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

#ifdef HANDLE_ALLCAPS
/* caps_lock - string contains upper case without lower case */
/* returns 1 if true, 0 if false */
static int caps_lock(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 failure, logname on success */
static char *get_logname(char *logname, unsigned size_logname,
        struct options *op, struct chardata *cp, struct termios *tp)
{
    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 */
        "\210\240\210",                 /* no parity */
    };

    /* Initialize kill, erase, parity etc. (also after switching speeds). */

    *cp = init_chardata;

    /* Flush pending input (esp. after parsing or switching the baud rate). */

    sleep(1);
    ioctl(0, TCFLSH, TCIFLUSH);

    /* 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, tp);

        /* 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. */
            if (read(0, &c, 1) < 1) {
                if (errno == EINTR || errno == EIO)
                    exit(0);
                bb_perror_msg_and_die("%s: read", op->tty);
            }

            /* Do BREAK handling elsewhere. */
            if (c == '\0' && op->numspeed > 1)
                return NULL;

            /* Do parity bit handling. */
            ascval = c & 0177;
            if (c != ascval) {       /* "parity" bit on ? */
                bits = 1;
                mask = 1;
                while (mask & 0177) {
                    if (mask & ascval)
                        bits++; /* count "1" bits */
                    mask <<= 1;
                }
                /* ... |= 2 - even, 1 - odd */
                cp->parity |= 2 - (bits & 1);
            }

            /* Do erase, kill and end-of-line processing. */
            switch (ascval) {
            case CR:
            case NL:
                *bp = '\0';             /* terminate logname */
                cp->eol = ascval;       /* set end-of-line char */
                break;
            case BS:
            case DEL:
            case '#':
                cp->erase = ascval;     /* set erase character */
                if (bp > logname) {
                    write(1, erase[cp->parity], 3);
                    bp--;
                }
                break;
            case CTL('U'):
            case '@':
                cp->kill = ascval;      /* set kill character */
                while (bp > logname) {
                    write(1, erase[cp->parity], 3);
                    bp--;
                }
                break;
            case CTL('D'):
                exit(0);
            default:
                if (!isascii(ascval) || !isprint(ascval)) {
                    /* ignore garbage characters */
                } else if (bp - logname >= size_logname - 1) {
                    bb_error_msg_and_die("%s: input overrun", op->tty);
                } else {
                    write(1, &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 = caps_lock(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;
    tp->c_cc[VSWTC] = DEF_SWITCH;   /* default switch character */

    /* 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 */
        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;
        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 */

    ioctl_or_perror_and_die(0, TCSETS, tp, "%s: TCSETS", op->tty);
}


#ifdef SYSV_STYLE
#if ENABLE_FEATURE_UTMP
/* update_utmp - update our utmp entry */
static void update_utmp(const char *line)
{
    struct utmp ut;
    struct utmp *utp;
    time_t t;
    int mypid = getpid();

    /*
     * 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.
     */
    if (access(_PATH_UTMP, R_OK|W_OK) == -1) {
        close(creat(_PATH_UTMP, 0664));
    }
    utmpname(_PATH_UTMP);
    setutent();
    while ((utp = getutent())
           && !(utp->ut_type == INIT_PROCESS && utp->ut_pid == mypid))
        /* nothing */;

    if (utp) {
        memcpy(&ut, utp, sizeof(ut));
    } else {
        /* some inits don't initialize utmp... */
        memset(&ut, 0, sizeof(ut));
        safe_strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
    }
    /* endutent(); */

    strcpy(ut.ut_user, "LOGIN");
    safe_strncpy(ut.ut_line, line, sizeof(ut.ut_line));
    if (fakehost)
        safe_strncpy(ut.ut_host, fakehost, sizeof(ut.ut_host));
    time(&t);
    ut.ut_time = t;
    ut.ut_type = LOGIN_PROCESS;
    ut.ut_pid = mypid;

    pututline(&ut);
    endutent();

#if ENABLE_FEATURE_WTMP
    if (access(bb_path_wtmp_file, R_OK|W_OK) == -1)
        close(creat(bb_path_wtmp_file, 0664));
    updwtmp(bb_path_wtmp_file, &ut);
#endif
}

#endif /* CONFIG_FEATURE_UTMP */
#endif /* SYSV_STYLE */


int getty_main(int argc, char **argv);
int getty_main(int argc, char **argv)
{
    int nullfd;
    char *logname = NULL;           /* 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 = {
        0,                      /* show /etc/issue (SYSV_STYLE) */
        0,                      /* no timeout */
        _PATH_LOGIN,            /* default login program */
        "tty1",                 /* default tty line */
        "",                     /* modem init string */
#ifdef ISSUE
        ISSUE,                  /* default issue file */
#else
        NULL,
#endif
        0,                      /* no baud rates known yet */
    };

    /* Already too late because of theoretical
     * possibility of getty --help somehow triggered
     * inadvertently before we reach this. Oh well. */
    logmode = LOGMODE_NONE;
    setsid();
    nullfd = xopen(bb_dev_null, O_RDWR);
    /* dup2(nullfd, 0); - no, because of possible "getty - 9600" */
    /* open_tty() will take care of fd# 0 anyway */
    dup2(nullfd, 1);
    dup2(nullfd, 2);
    while (nullfd > 2) close(nullfd--);
    /* We want special flavor of error_msg_and_die */
    die_sleep = 10;
    msg_eol = "\r\n";
    openlog(applet_name, LOG_PID, LOG_AUTH);
    logmode = LOGMODE_BOTH;

#ifdef DEBUGGING
    dbf = xfopen(DEBUGTERM, "w");

    {
        int i;

        for (i = 1; i < argc; i++) {
            debug(argv[i]);
            debug("\n");
        }
    }
#endif

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

#ifdef SYSV_STYLE
#if ENABLE_FEATURE_UTMP
    /* Update the utmp file. */
    update_utmp(options.tty);
#endif
#endif

    debug("calling open_tty\n");
    /* Open the tty as standard { input, output, error }. */
    open_tty(options.tty, &termios, options.flags & F_LOCAL);

#ifdef __linux__
    {
        int iv;

        iv = getpid();
        ioctl(0, TIOCSPGRP, &iv);
    }
#endif
    /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
    debug("calling termios_init\n");
    termios_init(&termios, options.speeds[FIRST_SPEED], &options);

    /* write the modem init string and DON'T flush the buffers */
    if (options.flags & F_INITSTRING) {
        debug("writing init string\n");
        write(1, options.initstring, strlen(options.initstring));
    }

    if (!(options.flags & F_LOCAL)) {
        /* go to blocking write mode unless -L is specified */
        ndelay_off(1);
    }

    /* Optionally detect the baud rate from the modem status message. */
    debug("before autobaud\n");
    if (options.flags & F_PARSE)
        auto_baud(bb_common_bufsiz1, sizeof(bb_common_bufsiz1), &termios);

    /* Set the optional timer. */
    if (options.timeout)
        alarm(options.timeout);

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

        debug("waiting for cr-lf\n");
        while (read(0, &ch, 1) == 1) {
            ch &= 0x7f;                     /* strip "parity bit" */
#ifdef DEBUGGING
            fprintf(dbf, "read %c\n", ch);
#endif
            if (ch == '\n' || ch == '\r')
                break;
        }
    }

    chardata = init_chardata;
    if (!(options.flags & F_NOPROMPT)) {
        /* Read the login name. */
        debug("reading login name\n");
        logname = get_logname(bb_common_bufsiz1, sizeof(bb_common_bufsiz1),
                &options, &chardata, &termios);
        while (logname == NULL)
            next_speed(&termios, &options);
    }

    /* Disable timer. */

    if (options.timeout)
        alarm(0);

    /* Finalize the termios settings. */

    termios_final(&options, &termios, &chardata);

    /* Now the newline character should be properly written. */

    write(1, "\n", 1);

    /* Let the login program take care of password validation. */

    execl(options.login, options.login, "--", logname, (char *) 0);
    bb_error_msg_and_die("%s: can't exec %s", options.tty, options.login);
}