busybox/loginutils/getty.c

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/* 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 tarball for details.
*/
#include "libbb.h"
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#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 */
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#include <sys/utsname.h>
#include <time.h>
#if ENABLE_FEATURE_WTMP
extern void updwtmp(const char *filename, const struct utmp *ut);
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#endif
#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 */
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/*
* 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 */
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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. */
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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);
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;
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if (op->flags & F_INITSTRING) {
const char *p = op->initstring;
char *q;
op->initstring = q = xstrdup(p);
/* 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; /* 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);
// TODO: if applet_name is set to "getty: TTY", bb_error_msg's get simpler!
// grep for "%s:"
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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 ((st.st_mode & S_IFMT) != S_IFCHR)
// bb_error_msg_and_die("%s: not a character device", tty);
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)
{
/*
* 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! */
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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);
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.
*/
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sleep(1);
nread = safe_read(0, buf, size_buf - 1);
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if (nread > 0) {
buf[nread] = '\0';
for (bp = buf; bp < buf + nread; bp++) {
if (isdigit(*bp)) {
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speed = bcode(bp);
if (speed > 0) {
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);
}
/* 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)
{
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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). */
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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);
/* Read name, watch for break, parity, erase, kill, end-of-line. */
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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);
}
/* 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(1, 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(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 {
full_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 = all_is_upcase(logname);
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if (cp->capslock) {
for (bp = logname; *bp; bp++)
if (isupper(*bp))
*bp = tolower(*bp); /* map name to lower case */
}
#endif
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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 */
// 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 */
ioctl_or_perror_and_die(0, TCSETS, tp, "%s: TCSETS", op->tty);
}
#if ENABLE_FEATURE_UTMP
static void touch(const char *filename)
{
if (access(filename, R_OK | W_OK) == -1)
close(open(filename, O_WRONLY | O_CREAT, 0664));
}
/* update_utmp - update our utmp entry */
static void update_utmp(const char *line, char *fakehost)
{
struct utmp ut;
struct utmp *utp;
int mypid = getpid();
/* In case we won't find an entry below... */
memset(&ut, 0, sizeof(ut));
safe_strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
/*
* 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.
*/
touch(_PATH_UTMP);
utmpname(_PATH_UTMP);
setutent();
while ((utp = getutent()) != NULL) {
if (utp->ut_type == INIT_PROCESS && utp->ut_pid == mypid) {
memcpy(&ut, utp, sizeof(ut));
break;
}
}
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));
ut.ut_time = time(NULL);
ut.ut_type = LOGIN_PROCESS;
ut.ut_pid = mypid;
pututline(&ut);
endutent();
#if ENABLE_FEATURE_WTMP
touch(bb_path_wtmp_file);
updwtmp(bb_path_wtmp_file, &ut);
#endif
}
#endif /* CONFIG_FEATURE_UTMP */
int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int getty_main(int argc ATTRIBUTE_UNUSED, char **argv)
{
int n;
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);
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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 */
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die_sleep = 10;
msg_eol = "\r\n";
/* most likely will internally use fd #3 in CLOEXEC mode: */
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openlog(applet_name, LOG_PID, LOG_AUTH);
logmode = LOGMODE_BOTH;
#ifdef DEBUGGING
dbf = xfopen(DEBUGTERM, "w");
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.
*/
ioctl_or_perror_and_die(0, TCGETS, &termios, "%s: TCGETS", options.tty);
#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, getpid());
#endif
#if ENABLE_FEATURE_UTMP
/* Update the utmp file. This tty is ours now! */
update_utmp(options.tty, fakehost);
#endif
/* 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_write(1, options.initstring, strlen(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(0, &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;
termios.c_cflag &= ~CBAUD;
termios.c_cflag |= options.speeds[baud_index];
ioctl(0, TCSETS, &termios);
}
}
/* Disable timer. */
alarm(0);
/* Finalize the termios settings. */
termios_final(&options, &termios, &chardata);
/* Now the newline character should be properly written. */
full_write(1, "\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("%s: can't exec %s", options.tty, options.login);
}