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);
169 if (op->numspeed > MAX_SPEED)
170 bb_error_msg_and_die("too many alternate speeds");
172 debug("exiting parse_speeds\n");
175 /* parse_args - parse command-line arguments */
176 static void parse_args(char **argv, struct options *op, char **fakehost_p)
180 opt_complementary = "-2:t+"; /* at least 2 args; -t N */
181 op->flags = getopt32(argv, opt_string,
182 &(op->initstring), fakehost_p, &(op->issue),
183 &(op->login), &op->timeout);
185 if (op->flags & F_INITSTRING) {
186 const char *p = op->initstring;
189 op->initstring = q = xstrdup(p);
190 /* copy optarg into op->initstring decoding \ddd
191 octal codes into chars */
195 *q++ = bb_process_escape_sequence(&p);
202 op->flags ^= F_ISSUE; /* invert flag "show /etc/issue" */
203 debug("after getopt\n");
205 /* we loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
206 op->tty = argv[0]; /* tty name */
207 ts = argv[1]; /* baud rate(s) */
208 if (isdigit(argv[0][0])) {
209 /* a number first, assume it's a speed (BSD style) */
210 op->tty = ts; /* tty name is in argv[1] */
211 ts = argv[0]; /* baud rate(s) */
213 parse_speeds(op, ts);
215 // TODO: if applet_name is set to "getty: TTY", bb_error_msg's get simpler!
219 xsetenv("TERM", argv[2]);
221 debug("exiting parse_args\n");
224 /* open_tty - set up tty as standard { input, output, error } */
225 static void open_tty(const char *tty)
227 /* Set up new standard input, unless we are given an already opened port. */
228 if (NOT_LONE_DASH(tty)) {
233 /* Sanity checks... */
234 // cur_dir_fd = xopen(".", O_DIRECTORY | O_NONBLOCK);
237 // if ((st.st_mode & S_IFMT) != S_IFCHR)
238 // bb_error_msg_and_die("%s: not a character device", tty);
241 tty = xasprintf("/dev/%s", tty); /* will leak it */
243 /* Open the tty as standard input. */
246 /*fd =*/ xopen(tty, O_RDWR | O_NONBLOCK); /* uses fd 0 */
248 // /* Restore current directory */
249 // fchdir(cur_dir_fd);
251 /* Open the tty as standard input, continued */
253 // /* fd is >= cur_dir_fd, and cur_dir_fd gets closed too here: */
257 /* Set proper protections and ownership. */
258 fchown(0, 0, 0); /* 0:0 */
259 fchmod(0, 0620); /* crw--w---- */
262 * Standard input should already be connected to an open port. Make
263 * sure it is open for read/write.
265 if ((fcntl(0, F_GETFL) & O_RDWR) != O_RDWR)
266 bb_error_msg_and_die("stdin is not open for read/write");
270 /* termios_init - initialize termios settings */
271 static void termios_init(struct termios *tp, int speed, struct options *op)
274 * Initial termios settings: 8-bit characters, raw-mode, blocking i/o.
275 * Special characters are set after we have read the login name; all
276 * reads will be done in raw mode anyway. Errors will be dealt with
280 /* flush input and output queues, important for modems! */
281 ioctl(0, TCFLSH, TCIOFLUSH); /* tcflush(0, TCIOFLUSH)? - same */
284 tp->c_cflag = CS8 | HUPCL | CREAD | speed;
285 if (op->flags & F_LOCAL)
286 tp->c_cflag |= CLOCAL;
288 tp->c_iflag = tp->c_lflag = tp->c_line = 0;
289 tp->c_oflag = OPOST | ONLCR;
293 /* Optionally enable hardware flow control */
295 if (op->flags & F_RTSCTS)
296 tp->c_cflag |= CRTSCTS;
299 tcsetattr_stdin_TCSANOW(tp);
301 debug("term_io 2\n");
304 /* auto_baud - extract baud rate from modem status message */
305 static void auto_baud(char *buf, unsigned size_buf, struct termios *tp)
314 * This works only if the modem produces its status code AFTER raising
315 * the DCD line, and if the computer is fast enough to set the proper
316 * baud rate before the message has gone by. We expect a message of the
319 * <junk><number><junk>
321 * The number is interpreted as the baud rate of the incoming call. If the
322 * modem does not tell us the baud rate within one second, we will keep
323 * using the current baud rate. It is advisable to enable BREAK
324 * processing (comma-separated list of baud rates) if the processing of
325 * modem status messages is enabled.
329 * Use 7-bit characters, don't block if input queue is empty. Errors will
330 * be dealt with later on.
333 tp->c_iflag |= ISTRIP; /* enable 8th-bit stripping */
334 vmin = tp->c_cc[VMIN];
335 tp->c_cc[VMIN] = 0; /* don't block if queue empty */
336 tcsetattr_stdin_TCSANOW(tp);
339 * Wait for a while, then read everything the modem has said so far and
340 * try to extract the speed of the dial-in call.
343 nread = safe_read(STDIN_FILENO, buf, size_buf - 1);
346 for (bp = buf; bp < buf + nread; bp++) {
350 tp->c_cflag &= ~CBAUD;
351 tp->c_cflag |= speed;
358 /* Restore terminal settings. Errors will be dealt with later on. */
360 tp->c_cc[VMIN] = vmin;
361 tcsetattr_stdin_TCSANOW(tp);
364 /* do_prompt - show login prompt, optionally preceded by /etc/issue contents */
365 static void do_prompt(struct options *op)
368 print_login_issue(op->issue, op->tty);
370 print_login_prompt();
373 #ifdef HANDLE_ALLCAPS
374 /* all_is_upcase - string contains upper case without lower case */
375 /* returns 1 if true, 0 if false */
376 static int all_is_upcase(const char *s)
385 /* get_logname - get user name, establish parity, speed, erase, kill, eol;
386 * return NULL on BREAK, logname on success */
387 static char *get_logname(char *logname, unsigned size_logname,
388 struct options *op, struct chardata *cp)
391 char c; /* input character, full eight bits */
392 char ascval; /* low 7 bits of input character */
393 int bits; /* # of "1" bits per character */
394 int mask; /* mask with 1 bit up */
395 static const char erase[][3] = {/* backspace-space-backspace */
396 "\010\040\010", /* space parity */
397 "\010\040\010", /* odd parity */
398 "\210\240\210", /* even parity */
399 "\010\040\010", /* 8 bit no parity */
402 /* NB: *cp is pre-initialized with init_chardata */
404 /* Flush pending input (esp. after parsing or switching the baud rate). */
406 ioctl(0, TCFLSH, TCIFLUSH); /* tcflush(0, TCIOFLUSH)? - same */
408 /* Prompt for and read a login name. */
410 while (!logname[0]) {
411 /* Write issue file and prompt, with "parity" bit == 0. */
414 /* Read name, watch for break, parity, erase, kill, end-of-line. */
417 while (cp->eol == '\0') {
419 /* Do not report trivial EINTR/EIO errors. */
420 if (read(STDIN_FILENO, &c, 1) < 1) {
421 if (errno == EINTR || errno == EIO)
423 bb_perror_msg_and_die("%s: read", op->tty);
426 /* BREAK. If we have speeds to try,
427 * return NULL (will switch speeds and return here) */
428 if (c == '\0' && op->numspeed > 1)
431 /* Do parity bit handling. */
432 if (!(op->flags & F_LOCAL) && (c & 0x80)) { /* "parity" bit on? */
435 while (mask & 0x7f) {
437 bits++; /* count "1" bits */
440 /* ... |= 2 - even, 1 - odd */
441 cp->parity |= 2 - (bits & 1);
444 /* Do erase, kill and end-of-line processing. */
449 *bp = '\0'; /* terminate logname */
450 cp->eol = ascval; /* set end-of-line char */
454 #ifdef ANCIENT_BS_KILL_CHARS
457 cp->erase = ascval; /* set erase character */
459 full_write(STDOUT_FILENO, erase[cp->parity], 3);
464 #ifdef ANCIENT_BS_KILL_CHARS
467 cp->kill = ascval; /* set kill character */
468 while (bp > logname) {
469 full_write(STDOUT_FILENO, erase[cp->parity], 3);
476 if (!isprint(ascval)) {
477 /* ignore garbage characters */
478 } else if ((int)(bp - logname) >= size_logname - 1) {
479 bb_error_msg_and_die("%s: input overrun", op->tty);
481 full_write(STDOUT_FILENO, &c, 1); /* echo the character */
482 *bp++ = ascval; /* and store it */
488 /* Handle names with upper case and no lower case. */
490 #ifdef HANDLE_ALLCAPS
491 cp->capslock = all_is_upcase(logname);
493 for (bp = logname; *bp; bp++)
495 *bp = tolower(*bp); /* map name to lower case */
501 /* termios_final - set the final tty mode bits */
502 static void termios_final(struct options *op, struct termios *tp, struct chardata *cp)
504 /* General terminal-independent stuff. */
505 tp->c_iflag |= IXON | IXOFF; /* 2-way flow control */
506 tp->c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
507 /* no longer| ECHOCTL | ECHOPRT */
508 tp->c_oflag |= OPOST;
509 /* tp->c_cflag = 0; */
510 tp->c_cc[VINTR] = DEF_INTR; /* default interrupt */
511 tp->c_cc[VQUIT] = DEF_QUIT; /* default quit */
512 tp->c_cc[VEOF] = DEF_EOF; /* default EOF character */
513 tp->c_cc[VEOL] = DEF_EOL;
514 tp->c_cc[VSWTC] = DEF_SWITCH; /* default switch character */
516 /* Account for special characters seen in input. */
518 tp->c_iflag |= ICRNL; /* map CR in input to NL */
519 tp->c_oflag |= ONLCR; /* map NL in output to CR-NL */
521 tp->c_cc[VERASE] = cp->erase; /* set erase character */
522 tp->c_cc[VKILL] = cp->kill; /* set kill character */
524 /* Account for the presence or absence of parity bits in input. */
525 switch (cp->parity) {
526 case 0: /* space (always 0) parity */
527 // I bet most people go here - they use only 7-bit chars in usernames....
529 case 1: /* odd parity */
530 tp->c_cflag |= PARODD;
532 case 2: /* even parity */
533 tp->c_cflag |= PARENB;
534 tp->c_iflag |= INPCK | ISTRIP;
536 case (1 | 2): /* no parity bit */
537 tp->c_cflag &= ~CSIZE;
539 // FIXME: wtf? case 3: we saw both even and odd 8-bit bytes -
540 // it's probably some umlauts etc, but definitely NOT 7-bit!!!
541 // Entire parity detection madness here just begs for deletion...
545 /* Account for upper case without lower case. */
546 #ifdef HANDLE_ALLCAPS
548 tp->c_iflag |= IUCLC;
549 tp->c_lflag |= XCASE;
550 tp->c_oflag |= OLCUC;
553 /* Optionally enable hardware flow control */
555 if (op->flags & F_RTSCTS)
556 tp->c_cflag |= CRTSCTS;
559 /* Finally, make the new settings effective */
560 /* It's tcsetattr_stdin_TCSANOW() + error check */
561 ioctl_or_perror_and_die(0, TCSETS, tp, "%s: TCSETS", op->tty);
564 #if ENABLE_FEATURE_UTMP
565 static void touch(const char *filename)
567 if (access(filename, R_OK | W_OK) == -1)
568 close(open(filename, O_WRONLY | O_CREAT, 0664));
571 /* update_utmp - update our utmp entry */
572 static void update_utmp(const char *line, char *fakehost)
576 int mypid = getpid();
578 /* In case we won't find an entry below... */
579 memset(&ut, 0, sizeof(ut));
580 safe_strncpy(ut.ut_id, line + 3, sizeof(ut.ut_id));
583 * The utmp file holds miscellaneous information about things started by
584 * /sbin/init and other system-related events. Our purpose is to update
585 * the utmp entry for the current process, in particular the process type
586 * and the tty line we are listening to. Return successfully only if the
587 * utmp file can be opened for update, and if we are able to find our
588 * entry in the utmp file.
592 utmpname(_PATH_UTMP);
594 while ((utp = getutent()) != NULL) {
595 if (utp->ut_type == INIT_PROCESS && utp->ut_pid == mypid) {
596 memcpy(&ut, utp, sizeof(ut));
601 strcpy(ut.ut_user, "LOGIN");
602 safe_strncpy(ut.ut_line, line, sizeof(ut.ut_line));
604 safe_strncpy(ut.ut_host, fakehost, sizeof(ut.ut_host));
605 ut.ut_tv.tv_sec = time(NULL);
606 ut.ut_type = LOGIN_PROCESS;
612 #if ENABLE_FEATURE_WTMP
613 touch(bb_path_wtmp_file);
614 updwtmp(bb_path_wtmp_file, &ut);
617 #endif /* CONFIG_FEATURE_UTMP */
619 int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
620 int getty_main(int argc UNUSED_PARAM, char **argv)
623 char *fakehost = NULL; /* Fake hostname for ut_host */
624 char *logname; /* login name, given to /bin/login */
625 /* Merging these into "struct local" may _seem_ to reduce
626 * parameter passing, but today's gcc will inline
627 * statics which are called once anyway, so don't do that */
628 struct chardata chardata; /* set by get_logname() */
629 struct termios termios; /* terminal mode bits */
630 struct options options;
632 chardata = init_chardata;
634 memset(&options, 0, sizeof(options));
635 options.login = _PATH_LOGIN; /* default login program */
636 options.tty = "tty1"; /* default tty line */
637 options.initstring = ""; /* modem init string */
639 options.issue = ISSUE; /* default issue file */
642 /* Parse command-line arguments. */
643 parse_args(argv, &options, &fakehost);
645 logmode = LOGMODE_NONE;
647 /* Create new session, lose controlling tty, if any */
648 /* docs/ctty.htm says:
649 * "This is allowed only when the current process
650 * is not a process group leader" - is this a problem? */
652 /* close stdio, and stray descriptors, just in case */
653 n = xopen(bb_dev_null, O_RDWR);
654 /* dup2(n, 0); - no, we need to handle "getty - 9600" too */
660 /* Logging. We want special flavor of error_msg_and_die */
663 /* most likely will internally use fd #3 in CLOEXEC mode: */
664 openlog(applet_name, LOG_PID, LOG_AUTH);
665 logmode = LOGMODE_BOTH;
668 dbf = xfopen_for_write(DEBUGTERM);
669 for (n = 1; argv[n]; n++) {
675 /* Open the tty as standard input, if it is not "-" */
676 /* If it's not "-" and not taken yet, it will become our ctty */
677 debug("calling open_tty\n");
678 open_tty(options.tty);
685 * The following ioctl will fail if stdin is not a tty, but also when
686 * there is noise on the modem control lines. In the latter case, the
687 * common course of action is (1) fix your cables (2) give the modem more
688 * time to properly reset after hanging up. SunOS users can achieve (2)
689 * by patching the SunOS kernel variable "zsadtrlow" to a larger value;
690 * 5 seconds seems to be a good value.
692 /* tcgetattr() + error check */
693 ioctl_or_perror_and_die(0, TCGETS, &termios, "%s: TCGETS", options.tty);
696 // FIXME: do we need this? Otherwise "-" case seems to be broken...
697 // /* Forcibly make fd 0 our controlling tty, even if another session
698 // * has it as a ctty. (Another session loses ctty). */
699 // ioctl(0, TIOCSCTTY, (void*)1);
700 /* Make ourself a foreground process group within our session */
701 tcsetpgrp(0, getpid());
704 #if ENABLE_FEATURE_UTMP
705 /* Update the utmp file. This tty is ours now! */
706 update_utmp(options.tty, fakehost);
709 /* Initialize the termios settings (raw mode, eight-bit, blocking i/o). */
710 debug("calling termios_init\n");
711 termios_init(&termios, options.speeds[0], &options);
713 /* Write the modem init string and DON'T flush the buffers */
714 if (options.flags & F_INITSTRING) {
715 debug("writing init string\n");
716 /* todo: use xwrite_str? */
717 full_write(STDOUT_FILENO, options.initstring, strlen(options.initstring));
720 /* Optionally detect the baud rate from the modem status message */
721 debug("before autobaud\n");
722 if (options.flags & F_PARSE)
723 auto_baud(line_buf, sizeof(line_buf), &termios);
725 /* Set the optional timer */
726 alarm(options.timeout); /* if 0, alarm is not set */
728 /* Optionally wait for CR or LF before writing /etc/issue */
729 if (options.flags & F_WAITCRLF) {
732 debug("waiting for cr-lf\n");
733 while (safe_read(STDIN_FILENO, &ch, 1) == 1) {
734 debug("read %x\n", (unsigned char)ch);
735 ch &= 0x7f; /* strip "parity bit" */
736 if (ch == '\n' || ch == '\r')
742 if (!(options.flags & F_NOPROMPT)) {
743 /* NB:termios_init already set line speed
744 * to options.speeds[0] */
748 /* Read the login name. */
749 debug("reading login name\n");
750 logname = get_logname(line_buf, sizeof(line_buf),
751 &options, &chardata);
754 /* we are here only if options.numspeed > 1 */
755 baud_index = (baud_index + 1) % options.numspeed;
756 termios.c_cflag &= ~CBAUD;
757 termios.c_cflag |= options.speeds[baud_index];
758 tcsetattr_stdin_TCSANOW(&termios);
765 /* Finalize the termios settings. */
766 termios_final(&options, &termios, &chardata);
768 /* Now the newline character should be properly written. */
769 full_write(STDOUT_FILENO, "\n", 1);
771 /* Let the login program take care of password validation. */
772 /* We use PATH because we trust that root doesn't set "bad" PATH,
773 * and getty is not suid-root applet. */
774 /* With -n, logname == NULL, and login will ask for username instead */
775 BB_EXECLP(options.login, options.login, "--", logname, NULL);
776 bb_error_msg_and_die("%s: can't exec %s", options.tty, options.login);