1 /* vi: set sw=4 ts=4: */
2 /* agetty.c - another getty program for Linux. By W. Z. Venema 1989
3 * Ported to Linux by Peter Orbaek <poe@daimi.aau.dk>
4 * This program is freely distributable. The entire man-page used to
5 * be here. Now read the real man-page agetty.8 instead.
7 * option added by Eric Rasmussen <ear@usfirst.org> - 12/28/95
9 * 1999-02-22 Arkadiusz Mickiewicz <misiek@misiek.eu.org>
10 * - added Native Language Support
12 * 1999-05-05 Thorsten Kranzkowski <dl8bcu@gmx.net>
13 * - enable hardware flow control before displaying /etc/issue
15 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
21 #if ENABLE_FEATURE_UTMP
22 #include <utmp.h> /* updwtmp() */
26 * Some heuristics to find out what environment we are in: if it is not
27 * System V, assume it is SunOS 4.
29 #ifdef LOGIN_PROCESS /* defined in System V utmp.h */
30 #include <sys/utsname.h>
31 #else /* if !sysV style, wtmp/utmp code is off */
32 #undef ENABLE_FEATURE_UTMP
33 #undef ENABLE_FEATURE_WTMP
34 #define ENABLE_FEATURE_UTMP 0
35 #define ENABLE_FEATURE_WTMP 0
36 #endif /* LOGIN_PROCESS */
39 * Things you may want to modify.
41 * You may disagree with the default line-editing etc. characters defined
42 * below. Note, however, that DEL cannot be used for interrupt generation
43 * and for line editing at the same time.
46 /* I doubt there are systems which still need this */
48 #undef ANCIENT_BS_KILL_CHARS
50 #define _PATH_LOGIN "/bin/login"
52 /* If ISSUE is not defined, getty will never display the contents of the
53 * /etc/issue file. You will not want to spit out large "issue" files at the
56 #define ISSUE "/etc/issue" /* displayed before the login prompt */
58 /* Some shorthands for control characters. */
59 #define CTL(x) ((x) ^ 0100) /* Assumes ASCII dialect */
60 #define CR CTL('M') /* carriage return */
61 #define NL CTL('J') /* line feed */
62 #define BS CTL('H') /* back space */
63 #define DEL CTL('?') /* delete */
65 /* Defaults for line-editing etc. characters; you may want to change this. */
66 #define DEF_ERASE DEL /* default erase character */
67 #define DEF_INTR CTL('C') /* default interrupt character */
68 #define DEF_QUIT CTL('\\') /* default quit char */
69 #define DEF_KILL CTL('U') /* default kill char */
70 #define DEF_EOF CTL('D') /* default EOF char */
72 #define DEF_SWITCH 0 /* default switch char */
75 * When multiple baud rates are specified on the command line, the first one
76 * we will try is the first one specified.
78 #define MAX_SPEED 10 /* max. nr. of baud rates */
80 /* Storage for command-line options. */
82 int flags; /* toggle switches, see below */
83 unsigned timeout; /* time-out period */
84 const char *login; /* login program */
85 const char *tty; /* name of tty */
86 const char *initstring; /* modem init string */
87 const char *issue; /* alternative issue file */
88 int numspeed; /* number of baud rates to try */
89 int speeds[MAX_SPEED]; /* baud rates to be tried */
92 /* Storage for things detected while the login name was read. */
94 unsigned char erase; /* erase character */
95 unsigned char kill; /* kill character */
96 unsigned char eol; /* end-of-line character */
97 unsigned char parity; /* what parity did we see */
98 /* (parity & 1): saw odd parity char with 7th bit set */
99 /* (parity & 2): saw even parity char with 7th bit set */
100 /* parity == 0: probably 7-bit, space parity? */
101 /* parity == 1: probably 7-bit, odd parity? */
102 /* parity == 2: probably 7-bit, even parity? */
103 /* parity == 3: definitely 8 bit, no parity! */
104 /* Hmm... with any value of "parity" 8 bit, no parity is possible */
105 #ifdef HANDLE_ALLCAPS
106 unsigned char capslock; /* upper case without lower case */
111 /* Initial values for the above. */
112 static const struct chardata init_chardata = {
113 DEF_ERASE, /* default erase character */
114 DEF_KILL, /* default kill character */
115 13, /* default eol char */
116 0, /* space parity */
117 #ifdef HANDLE_ALLCAPS
122 static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn";
123 #define F_INITSTRING (1 << 0) /* -I initstring is set */
124 #define F_LOCAL (1 << 1) /* -L force local */
125 #define F_FAKEHOST (1 << 2) /* -H fake hostname */
126 #define F_CUSTISSUE (1 << 3) /* -f give alternative issue file */
127 #define F_RTSCTS (1 << 4) /* -h enable RTS/CTS flow control */
128 #define F_ISSUE (1 << 5) /* -i display /etc/issue */
129 #define F_LOGIN (1 << 6) /* -l non-default login program */
130 #define F_PARSE (1 << 7) /* -m process modem status messages */
131 #define F_TIMEOUT (1 << 8) /* -t time out */
132 #define F_WAITCRLF (1 << 9) /* -w wait for CR or LF */
133 #define F_NOPROMPT (1 << 10) /* -n don't ask for login name */
136 #define line_buf bb_common_bufsiz1
138 /* The following is used for understandable diagnostics. */
141 #define DEBUGTERM "/dev/ttyp0"
142 #define debug(...) do { fprintf(dbf, __VA_ARGS__); fflush(dbf); } while (0)
144 #define debug(...) ((void)0)
148 /* bcode - convert speed string to speed code; return <= 0 on failure */
149 static int bcode(const char *s)
151 int value = bb_strtou(s, NULL, 10); /* yes, int is intended! */
152 if (value < 0) /* bad terminating char, overflow, etc */
154 return tty_value_to_baud(value);
157 /* parse_speeds - parse alternate baud rates */
158 static void parse_speeds(struct options *op, char *arg)
162 /* NB: at least one iteration is always done */
163 debug("entered parse_speeds\n");
164 while ((cp = strsep(&arg, ",")) != NULL) {
165 op->speeds[op->numspeed] = bcode(cp);
166 if (op->speeds[op->numspeed] < 0)
167 bb_error_msg_and_die("bad speed: %s", cp);
168 /* note: arg "0" turns into speed B0 */
170 if (op->numspeed > MAX_SPEED)
171 bb_error_msg_and_die("too many alternate speeds");
173 debug("exiting parse_speeds\n");
176 /* parse_args - parse command-line arguments */
177 static void parse_args(char **argv, struct options *op, char **fakehost_p)
181 opt_complementary = "-2:t+"; /* at least 2 args; -t N */
182 op->flags = getopt32(argv, opt_string,
183 &(op->initstring), fakehost_p, &(op->issue),
184 &(op->login), &op->timeout);
186 if (op->flags & F_INITSTRING) {
187 const char *p = op->initstring;
190 op->initstring = q = xstrdup(p);
191 /* copy optarg into op->initstring decoding \ddd
192 octal codes into chars */
196 *q++ = bb_process_escape_sequence(&p);
203 op->flags ^= F_ISSUE; /* invert flag "show /etc/issue" */
204 debug("after getopt\n");
206 /* we loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
207 op->tty = argv[0]; /* tty name */
208 ts = argv[1]; /* baud rate(s) */
209 if (isdigit(argv[0][0])) {
210 /* a number first, assume it's a speed (BSD style) */
211 op->tty = ts; /* tty name is in argv[1] */
212 ts = argv[0]; /* baud rate(s) */
214 parse_speeds(op, ts);
216 // TODO: if applet_name is set to "getty: TTY", bb_error_msg's get simpler!
220 xsetenv("TERM", argv[2]);
222 debug("exiting parse_args\n");
225 /* open_tty - set up tty as standard { input, output, error } */
226 static void open_tty(const char *tty)
228 /* Set up new standard input, unless we are given an already opened port. */
229 if (NOT_LONE_DASH(tty)) {
234 /* Sanity checks... */
235 // cur_dir_fd = xopen(".", O_DIRECTORY | O_NONBLOCK);
238 // if ((st.st_mode & S_IFMT) != S_IFCHR)
239 // bb_error_msg_and_die("%s: not a character device", tty);
242 tty = xasprintf("/dev/%s", tty); /* will leak it */
244 /* Open the tty as standard input. */
247 /*fd =*/ xopen(tty, O_RDWR | O_NONBLOCK); /* uses fd 0 */
249 // /* Restore current directory */
250 // fchdir(cur_dir_fd);
252 /* Open the tty as standard input, continued */
254 // /* fd is >= cur_dir_fd, and cur_dir_fd gets closed too here: */
258 /* Set proper protections and ownership. */
259 fchown(0, 0, 0); /* 0:0 */
260 fchmod(0, 0620); /* crw--w---- */
263 * Standard input should already be connected to an open port. Make
264 * sure it is open for read/write.
266 if ((fcntl(0, F_GETFL) & O_RDWR) != O_RDWR)
267 bb_error_msg_and_die("stdin is not open for read/write");
271 /* termios_init - initialize termios settings */
272 static void termios_init(struct termios *tp, int speed, struct options *op)
274 speed_t ispeed, ospeed;
276 * Initial termios settings: 8-bit characters, raw-mode, blocking i/o.
277 * Special characters are set after we have read the login name; all
278 * reads will be done in raw mode anyway. Errors will be dealt with
282 /* flush input and output queues, important for modems! */
283 ioctl(0, TCFLSH, TCIOFLUSH); /* tcflush(0, TCIOFLUSH)? - same */
285 ispeed = ospeed = speed;
287 /* Speed was specified as "0" on command line.
288 * Just leave it unchanged */
289 ispeed = cfgetispeed(tp);
290 ospeed = cfgetospeed(tp);
292 tp->c_cflag = CS8 | HUPCL | CREAD;
293 if (op->flags & F_LOCAL)
294 tp->c_cflag |= CLOCAL;
295 cfsetispeed(tp, ispeed);
296 cfsetospeed(tp, ospeed);
298 tp->c_iflag = tp->c_lflag = tp->c_line = 0;
299 tp->c_oflag = OPOST | ONLCR;
303 /* Optionally enable hardware flow control */
305 if (op->flags & F_RTSCTS)
306 tp->c_cflag |= CRTSCTS;
309 tcsetattr_stdin_TCSANOW(tp);
311 debug("term_io 2\n");
314 /* auto_baud - extract baud rate from modem status message */
315 static void auto_baud(char *buf, unsigned size_buf, struct termios *tp)
324 * This works only if the modem produces its status code AFTER raising
325 * the DCD line, and if the computer is fast enough to set the proper
326 * baud rate before the message has gone by. We expect a message of the
329 * <junk><number><junk>
331 * The number is interpreted as the baud rate of the incoming call. If the
332 * modem does not tell us the baud rate within one second, we will keep
333 * using the current baud rate. It is advisable to enable BREAK
334 * processing (comma-separated list of baud rates) if the processing of
335 * modem status messages is enabled.
339 * Use 7-bit characters, don't block if input queue is empty. Errors will
340 * be dealt with later on.
343 tp->c_iflag |= ISTRIP; /* enable 8th-bit stripping */
344 vmin = tp->c_cc[VMIN];
345 tp->c_cc[VMIN] = 0; /* don't block if queue empty */
346 tcsetattr_stdin_TCSANOW(tp);
349 * Wait for a while, then read everything the modem has said so far and
350 * try to extract the speed of the dial-in call.
353 nread = safe_read(STDIN_FILENO, buf, size_buf - 1);
356 for (bp = buf; bp < buf + nread; bp++) {
360 tp->c_cflag &= ~CBAUD;
361 tp->c_cflag |= speed;
368 /* Restore terminal settings. Errors will be dealt with later on. */
370 tp->c_cc[VMIN] = vmin;
371 tcsetattr_stdin_TCSANOW(tp);
374 /* do_prompt - show login prompt, optionally preceded by /etc/issue contents */
375 static void do_prompt(struct options *op)
378 print_login_issue(op->issue, op->tty);
380 print_login_prompt();
383 #ifdef HANDLE_ALLCAPS
384 /* all_is_upcase - string contains upper case without lower case */
385 /* returns 1 if true, 0 if false */
386 static int all_is_upcase(const char *s)
395 /* get_logname - get user name, establish parity, speed, erase, kill, eol;
396 * return NULL on BREAK, logname on success */
397 static char *get_logname(char *logname, unsigned size_logname,
398 struct options *op, struct chardata *cp)
401 char c; /* input character, full eight bits */
402 char ascval; /* low 7 bits of input character */
403 int bits; /* # of "1" bits per character */
404 int mask; /* mask with 1 bit up */
405 static const char erase[][3] = {/* backspace-space-backspace */
406 "\010\040\010", /* space parity */
407 "\010\040\010", /* odd parity */
408 "\210\240\210", /* even parity */
409 "\010\040\010", /* 8 bit no parity */
412 /* NB: *cp is pre-initialized with init_chardata */
414 /* Flush pending input (esp. after parsing or switching the baud rate). */
416 ioctl(0, TCFLSH, TCIFLUSH); /* tcflush(0, TCIOFLUSH)? - same */
418 /* Prompt for and read a login name. */
420 while (!logname[0]) {
421 /* Write issue file and prompt, with "parity" bit == 0. */
424 /* Read name, watch for break, parity, erase, kill, end-of-line. */
427 while (cp->eol == '\0') {
429 /* Do not report trivial EINTR/EIO errors. */
430 if (read(STDIN_FILENO, &c, 1) < 1) {
431 if (errno == EINTR || errno == EIO)
433 bb_perror_msg_and_die("%s: read", op->tty);
436 /* BREAK. If we have speeds to try,
437 * return NULL (will switch speeds and return here) */
438 if (c == '\0' && op->numspeed > 1)
441 /* Do parity bit handling. */
442 if (!(op->flags & F_LOCAL) && (c & 0x80)) { /* "parity" bit on? */
445 while (mask & 0x7f) {
447 bits++; /* count "1" bits */
450 /* ... |= 2 - even, 1 - odd */
451 cp->parity |= 2 - (bits & 1);
454 /* Do erase, kill and end-of-line processing. */
459 *bp = '\0'; /* terminate logname */
460 cp->eol = ascval; /* set end-of-line char */
464 #ifdef ANCIENT_BS_KILL_CHARS
467 cp->erase = ascval; /* set erase character */
469 full_write(STDOUT_FILENO, erase[cp->parity], 3);
474 #ifdef ANCIENT_BS_KILL_CHARS
477 cp->kill = ascval; /* set kill character */
478 while (bp > logname) {
479 full_write(STDOUT_FILENO, erase[cp->parity], 3);
486 if (!isprint(ascval)) {
487 /* ignore garbage characters */
488 } else if ((int)(bp - logname) >= size_logname - 1) {
489 bb_error_msg_and_die("%s: input overrun", op->tty);
491 full_write(STDOUT_FILENO, &c, 1); /* echo the character */
492 *bp++ = ascval; /* and store it */
498 /* Handle names with upper case and no lower case. */
500 #ifdef HANDLE_ALLCAPS
501 cp->capslock = all_is_upcase(logname);
503 for (bp = logname; *bp; bp++)
505 *bp = tolower(*bp); /* map name to lower case */
511 /* termios_final - set the final tty mode bits */
512 static void termios_final(struct options *op, struct termios *tp, struct chardata *cp)
514 /* General terminal-independent stuff. */
515 tp->c_iflag |= IXON | IXOFF; /* 2-way flow control */
516 tp->c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
517 /* no longer| ECHOCTL | ECHOPRT */
518 tp->c_oflag |= OPOST;
519 /* tp->c_cflag = 0; */
520 tp->c_cc[VINTR] = DEF_INTR; /* default interrupt */
521 tp->c_cc[VQUIT] = DEF_QUIT; /* default quit */
522 tp->c_cc[VEOF] = DEF_EOF; /* default EOF character */
523 tp->c_cc[VEOL] = DEF_EOL;
524 tp->c_cc[VSWTC] = DEF_SWITCH; /* default switch character */
526 /* Account for special characters seen in input. */
528 tp->c_iflag |= ICRNL; /* map CR in input to NL */
529 tp->c_oflag |= ONLCR; /* map NL in output to CR-NL */
531 tp->c_cc[VERASE] = cp->erase; /* set erase character */
532 tp->c_cc[VKILL] = cp->kill; /* set kill character */
534 /* Account for the presence or absence of parity bits in input. */
535 switch (cp->parity) {
536 case 0: /* space (always 0) parity */
537 // I bet most people go here - they use only 7-bit chars in usernames....
539 case 1: /* odd parity */
540 tp->c_cflag |= PARODD;
542 case 2: /* even parity */
543 tp->c_cflag |= PARENB;
544 tp->c_iflag |= INPCK | ISTRIP;
546 case (1 | 2): /* no parity bit */
547 tp->c_cflag &= ~CSIZE;
549 // FIXME: wtf? case 3: we saw both even and odd 8-bit bytes -
550 // it's probably some umlauts etc, but definitely NOT 7-bit!!!
551 // Entire parity detection madness here just begs for deletion...
555 /* Account for upper case without lower case. */
556 #ifdef HANDLE_ALLCAPS
558 tp->c_iflag |= IUCLC;
559 tp->c_lflag |= XCASE;
560 tp->c_oflag |= OLCUC;
563 /* Optionally enable hardware flow control */
565 if (op->flags & F_RTSCTS)
566 tp->c_cflag |= CRTSCTS;
569 /* Finally, make the new settings effective */
570 /* It's tcsetattr_stdin_TCSANOW() + error check */
571 ioctl_or_perror_and_die(0, TCSETS, tp, "%s: TCSETS", op->tty);
574 #if ENABLE_FEATURE_UTMP
575 static void touch(const char *filename)
577 if (access(filename, R_OK | W_OK) == -1)
578 close(open(filename, O_WRONLY | O_CREAT, 0664));
581 /* update_utmp - update our utmp entry */
582 static void update_utmp(const char *line, char *fakehost)
586 int mypid = getpid();
588 /* In case we won't find an entry below... */
589 memset(&ut, 0, sizeof(ut));
590 safe_strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
593 * The utmp file holds miscellaneous information about things started by
594 * /sbin/init and other system-related events. Our purpose is to update
595 * the utmp entry for the current process, in particular the process type
596 * and the tty line we are listening to. Return successfully only if the
597 * utmp file can be opened for update, and if we are able to find our
598 * entry in the utmp file.
602 utmpname(_PATH_UTMP);
604 while ((utp = getutent()) != NULL) {
605 if (utp->ut_type == INIT_PROCESS && utp->ut_pid == mypid) {
606 memcpy(&ut, utp, sizeof(ut));
611 strcpy(ut.ut_user, "LOGIN");
612 safe_strncpy(ut.ut_line, line, sizeof(ut.ut_line));
614 safe_strncpy(ut.ut_host, fakehost, sizeof(ut.ut_host));
615 ut.ut_tv.tv_sec = time(NULL);
616 ut.ut_type = LOGIN_PROCESS;
622 #if ENABLE_FEATURE_WTMP
623 touch(bb_path_wtmp_file);
624 updwtmp(bb_path_wtmp_file, &ut);
627 #endif /* CONFIG_FEATURE_UTMP */
629 int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
630 int getty_main(int argc UNUSED_PARAM, char **argv)
633 char *fakehost = NULL; /* Fake hostname for ut_host */
634 char *logname; /* login name, given to /bin/login */
635 /* Merging these into "struct local" may _seem_ to reduce
636 * parameter passing, but today's gcc will inline
637 * statics which are called once anyway, so don't do that */
638 struct chardata chardata; /* set by get_logname() */
639 struct termios termios; /* terminal mode bits */
640 struct options options;
642 chardata = init_chardata;
644 memset(&options, 0, sizeof(options));
645 options.login = _PATH_LOGIN; /* default login program */
646 options.tty = "tty1"; /* default tty line */
647 options.initstring = ""; /* modem init string */
649 options.issue = ISSUE; /* default issue file */
652 /* Parse command-line arguments. */
653 parse_args(argv, &options, &fakehost);
655 logmode = LOGMODE_NONE;
657 /* Create new session, lose controlling tty, if any */
658 /* docs/ctty.htm says:
659 * "This is allowed only when the current process
660 * is not a process group leader" - is this a problem? */
662 /* close stdio, and stray descriptors, just in case */
663 n = xopen(bb_dev_null, O_RDWR);
664 /* dup2(n, 0); - no, we need to handle "getty - 9600" too */
670 /* Logging. We want special flavor of error_msg_and_die */
673 /* most likely will internally use fd #3 in CLOEXEC mode: */
674 openlog(applet_name, LOG_PID, LOG_AUTH);
675 logmode = LOGMODE_BOTH;
678 dbf = xfopen_for_write(DEBUGTERM);
679 for (n = 1; argv[n]; n++) {
685 /* Open the tty as standard input, if it is not "-" */
686 /* If it's not "-" and not taken yet, it will become our ctty */
687 debug("calling open_tty\n");
688 open_tty(options.tty);
695 * The following ioctl will fail if stdin is not a tty, but also when
696 * there is noise on the modem control lines. In the latter case, the
697 * common course of action is (1) fix your cables (2) give the modem more
698 * time to properly reset after hanging up. SunOS users can achieve (2)
699 * by patching the SunOS kernel variable "zsadtrlow" to a larger value;
700 * 5 seconds seems to be a good value.
702 /* tcgetattr() + error check */
703 ioctl_or_perror_and_die(0, TCGETS, &termios, "%s: TCGETS", options.tty);
706 // FIXME: do we need this? Otherwise "-" case seems to be broken...
707 // /* Forcibly make fd 0 our controlling tty, even if another session
708 // * has it as a ctty. (Another session loses ctty). */
709 // ioctl(0, TIOCSCTTY, (void*)1);
710 /* Make ourself a foreground process group within our session */
711 tcsetpgrp(0, getpid());
714 #if ENABLE_FEATURE_UTMP
715 /* Update the utmp file. This tty is ours now! */
716 update_utmp(options.tty, fakehost);
719 /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
720 debug("calling termios_init\n");
721 termios_init(&termios, options.speeds[0], &options);
723 /* Write the modem init string and DON'T flush the buffers */
724 if (options.flags & F_INITSTRING) {
725 debug("writing init string\n");
726 /* todo: use xwrite_str? */
727 full_write(STDOUT_FILENO, options.initstring, strlen(options.initstring));
730 /* Optionally detect the baud rate from the modem status message */
731 debug("before autobaud\n");
732 if (options.flags & F_PARSE)
733 auto_baud(line_buf, sizeof(line_buf), &termios);
735 /* Set the optional timer */
736 alarm(options.timeout); /* if 0, alarm is not set */
738 /* Optionally wait for CR or LF before writing /etc/issue */
739 if (options.flags & F_WAITCRLF) {
742 debug("waiting for cr-lf\n");
743 while (safe_read(STDIN_FILENO, &ch, 1) == 1) {
744 debug("read %x\n", (unsigned char)ch);
745 ch &= 0x7f; /* strip "parity bit" */
746 if (ch == '\n' || ch == '\r')
752 if (!(options.flags & F_NOPROMPT)) {
753 /* NB:termios_init already set line speed
754 * to options.speeds[0] */
758 /* Read the login name. */
759 debug("reading login name\n");
760 logname = get_logname(line_buf, sizeof(line_buf),
761 &options, &chardata);
764 /* we are here only if options.numspeed > 1 */
765 baud_index = (baud_index + 1) % options.numspeed;
766 cfsetispeed(&termios, options.speeds[baud_index]);
767 cfsetospeed(&termios, options.speeds[baud_index]);
768 tcsetattr_stdin_TCSANOW(&termios);
775 /* Finalize the termios settings. */
776 termios_final(&options, &termios, &chardata);
778 /* Now the newline character should be properly written. */
779 full_write(STDOUT_FILENO, "\n", 1);
781 /* Let the login program take care of password validation. */
782 /* We use PATH because we trust that root doesn't set "bad" PATH,
783 * and getty is not suid-root applet. */
784 /* With -n, logname == NULL, and login will ask for username instead */
785 BB_EXECLP(options.login, options.login, "--", logname, NULL);
786 bb_error_msg_and_die("%s: can't exec %s", options.tty, options.login);