1 /* vi: set sw=4 ts=4: */
3 * Based on agetty - another getty program for Linux. By W. Z. Venema 1989
4 * Ported to Linux by Peter Orbaek <poe@daimi.aau.dk>
5 * This program is freely distributable.
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 * - Enabled hardware flow control before displaying /etc/issue
15 * 2011-01 Venys Vlasenko
16 * - Removed parity detection code. It can't work reliably:
17 * if all chars received have bit 7 cleared and odd (or even) parity,
18 * it is impossible to determine whether other side is 8-bit,no-parity
19 * or 7-bit,odd(even)-parity. It also interferes with non-ASCII usernames.
20 * - From now on, we assume that parity is correctly set.
22 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
32 # undef ENABLE_FEATURE_UTMP
33 # undef ENABLE_FEATURE_WTMP
34 # define ENABLE_FEATURE_UTMP 0
35 # define ENABLE_FEATURE_WTMP 0
39 /* The following is used for understandable diagnostics */
42 # define DEBUGTERM "/dev/ttyp0"
43 # define debug(...) do { fprintf(dbf, __VA_ARGS__); fflush(dbf); } while (0)
45 # define debug(...) ((void)0)
50 * Things you may want to modify.
52 * You may disagree with the default line-editing etc. characters defined
53 * below. Note, however, that DEL cannot be used for interrupt generation
54 * and for line editing at the same time.
57 #define _PATH_LOGIN "/bin/login"
59 /* Displayed before the login prompt.
60 * If ISSUE is not defined, getty will never display the contents of the
61 * /etc/issue file. You will not want to spit out large "issue" files at the
64 #define ISSUE "/etc/issue"
66 /* Some shorthands for control characters */
67 #define CTL(x) ((x) ^ 0100) /* Assumes ASCII dialect */
68 #define BS CTL('H') /* back space */
69 #define DEL CTL('?') /* delete */
71 /* Defaults for line-editing etc. characters; you may want to change this */
72 #define DEF_INTR CTL('C') /* default interrupt character */
73 #define DEF_QUIT CTL('\\') /* default quit char */
74 #define DEF_KILL CTL('U') /* default kill char */
75 #define DEF_EOF CTL('D') /* default EOF char */
77 #define DEF_SWITCH 0 /* default switch char (none) */
80 * When multiple baud rates are specified on the command line,
81 * the first one we will try is the first one specified.
83 #define MAX_SPEED 10 /* max. nr. of baud rates */
87 const char *login; /* login program */
90 char *initstring; /* modem init string */
91 const char *issue; /* alternative issue file */
92 int numspeed; /* number of baud rates to try */
93 int speeds[MAX_SPEED]; /* baud rates to be tried */
94 unsigned char eol; /* end-of-line char seen (CR or NL) */
95 struct termios tty_attrs;
99 #define G (*ptr_to_globals)
100 #define INIT_G() do { \
101 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
104 //usage:#define getty_trivial_usage
105 //usage: "[OPTIONS] BAUD_RATE[,BAUD_RATE]... TTY [TERMTYPE]"
106 //usage:#define getty_full_usage "\n\n"
107 //usage: "Open TTY, prompt for login name, then invoke /bin/login\n"
108 //usage: "\n -h Enable hardware RTS/CTS flow control"
109 //usage: "\n -L Set CLOCAL (ignore Carrier Detect state)"
110 //usage: "\n -m Get baud rate from modem's CONNECT status message"
111 //usage: "\n -n Don't prompt for login name"
112 //usage: "\n -w Wait for CR or LF before sending /etc/issue"
113 //usage: "\n -i Don't display /etc/issue"
114 //usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue"
115 //usage: "\n -l LOGIN Invoke LOGIN instead of /bin/login"
116 //usage: "\n -t SEC Terminate after SEC if no login name is read"
117 //usage: "\n -I INITSTR Send INITSTR before anything else"
118 //usage: "\n -H HOST Log HOST into the utmp file as the hostname"
120 //usage: "\nBAUD_RATE of 0 leaves it unchanged"
122 static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn";
123 #define F_INITSTRING (1 << 0) /* -I */
124 #define F_LOCAL (1 << 1) /* -L */
125 #define F_FAKEHOST (1 << 2) /* -H */
126 #define F_CUSTISSUE (1 << 3) /* -f */
127 #define F_RTSCTS (1 << 4) /* -h */
128 #define F_NOISSUE (1 << 5) /* -i */
129 #define F_LOGIN (1 << 6) /* -l */
130 #define F_PARSE (1 << 7) /* -m */
131 #define F_TIMEOUT (1 << 8) /* -t */
132 #define F_WAITCRLF (1 << 9) /* -w */
133 #define F_NOPROMPT (1 << 10) /* -n */
136 /* convert speed string to speed code; return <= 0 on failure */
137 static int bcode(const char *s)
139 int value = bb_strtou(s, NULL, 10); /* yes, int is intended! */
140 if (value < 0) /* bad terminating char, overflow, etc */
142 return tty_value_to_baud(value);
145 /* parse alternate baud rates */
146 static void parse_speeds(char *arg)
150 /* NB: at least one iteration is always done */
151 debug("entered parse_speeds\n");
152 while ((cp = strsep(&arg, ",")) != NULL) {
153 G.speeds[G.numspeed] = bcode(cp);
154 if (G.speeds[G.numspeed] < 0)
155 bb_error_msg_and_die("bad speed: %s", cp);
156 /* note: arg "0" turns into speed B0 */
158 if (G.numspeed > MAX_SPEED)
159 bb_error_msg_and_die("too many alternate speeds");
161 debug("exiting parse_speeds\n");
164 /* parse command-line arguments */
165 static void parse_args(char **argv)
170 opt_complementary = "-2:t+"; /* at least 2 args; -t N */
171 flags = getopt32(argv, opt_string,
172 &G.initstring, &G.fakehost, &G.issue,
175 if (flags & F_INITSTRING) {
176 G.initstring = xstrdup(G.initstring);
177 /* decode \ddd octal codes into chars */
178 strcpy_and_process_escape_sequences(G.initstring, G.initstring);
181 debug("after getopt\n");
183 /* We loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
184 G.tty_name = argv[0];
185 ts = argv[1]; /* baud rate(s) */
186 if (isdigit(argv[0][0])) {
187 /* A number first, assume it's a speed (BSD style) */
188 G.tty_name = ts; /* tty name is in argv[1] */
189 ts = argv[0]; /* baud rate(s) */
194 xsetenv("TERM", argv[2]);
196 debug("exiting parse_args\n");
199 /* set up tty as standard input, output, error */
200 static void open_tty(void)
202 /* Set up new standard input, unless we are given an already opened port */
203 if (NOT_LONE_DASH(G.tty_name)) {
204 if (G.tty_name[0] != '/')
205 G.tty_name = xasprintf("/dev/%s", G.tty_name); /* will leak it */
207 /* Open the tty as standard input */
210 xopen(G.tty_name, O_RDWR | O_NONBLOCK); /* uses fd 0 */
212 /* Set proper protections and ownership */
213 fchown(0, 0, 0); /* 0:0 */
214 fchmod(0, 0620); /* crw--w---- */
218 * Standard input should already be connected to an open port.
219 * Make sure it is open for read/write.
221 if ((fcntl(0, F_GETFL) & (O_RDWR|O_RDONLY|O_WRONLY)) != O_RDWR)
222 bb_error_msg_and_die("stdin is not open for read/write");
224 /* Try to get real tty name instead of "-" */
225 n = xmalloc_ttyname(0);
229 applet_name = xasprintf("getty: %s", skip_dev_pfx(G.tty_name));
232 static void set_tty_attrs(void)
234 if (tcsetattr_stdin_TCSANOW(&G.tty_attrs) < 0)
235 bb_perror_msg_and_die("tcsetattr");
238 /* We manipulate tty_attrs this way:
239 * - first, we read existing tty_attrs
240 * - init_tty_attrs modifies some parts and sets it
241 * - auto_baud and/or BREAK processing can set different speed and set tty attrs
242 * - finalize_tty_attrs again modifies some parts and sets tty attrs before
245 static void init_tty_attrs(int speed)
247 /* Try to drain output buffer, with 5 sec timeout.
248 * Added on request from users of ~600 baud serial interface
249 * with biggish buffer on a 90MHz CPU.
250 * They were losing hundreds of bytes of buffered output
253 signal_no_SA_RESTART_empty_mask(SIGALRM, record_signo);
255 tcdrain(STDIN_FILENO);
258 /* Flush input and output queues, important for modems! */
259 tcflush(STDIN_FILENO, TCIOFLUSH);
261 /* Set speed if it wasn't specified as "0" on command line */
263 cfsetspeed(&G.tty_attrs, speed);
265 /* Initial settings: 8-bit characters, raw mode, blocking i/o.
266 * Special characters are set after we have read the login name; all
267 * reads will be done in raw mode anyway.
269 /* Clear all bits except: */
270 G.tty_attrs.c_cflag &= (0
271 /* 2 stop bits (1 otherwise)
272 * Enable parity bit (both on input and output)
273 * Odd parity (else even)
275 | CSTOPB | PARENB | PARODD
277 | CMSPAR /* mark or space parity */
279 | CBAUD /* (output) baud rate */
281 | CBAUDEX /* (output) baud rate */
284 | CIBAUD /* input baud rate */
287 /* Set: 8 bits; hang up (drop DTR) on last close; enable receive */
288 G.tty_attrs.c_cflag |= CS8 | HUPCL | CREAD;
289 if (option_mask32 & F_LOCAL) {
290 /* ignore Carrier Detect pin:
291 * opens don't block when CD is low,
292 * losing CD doesn't hang up processes whose ctty is this tty
294 G.tty_attrs.c_cflag |= CLOCAL;
297 if (option_mask32 & F_RTSCTS)
298 G.tty_attrs.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */
300 G.tty_attrs.c_iflag = 0;
301 G.tty_attrs.c_lflag = 0;
302 /* non-raw output; add CR to each NL */
303 G.tty_attrs.c_oflag = OPOST | ONLCR;
305 G.tty_attrs.c_cc[VMIN] = 1; /* block reads if < 1 char is available */
306 G.tty_attrs.c_cc[VTIME] = 0; /* no timeout (reads block forever) */
308 G.tty_attrs.c_line = 0;
313 debug("term_io 2\n");
316 static void finalize_tty_attrs(void)
318 /* software flow control on output (stop sending if XOFF is recvd);
319 * and on input (send XOFF when buffer is full)
321 G.tty_attrs.c_iflag |= IXON | IXOFF;
323 G.tty_attrs.c_iflag |= ICRNL; /* map CR on input to NL */
325 /* Other bits in c_iflag:
326 * IXANY Any recvd char enables output (any char is also a XON)
327 * INPCK Enable parity check
328 * IGNPAR Ignore parity errors (drop bad bytes)
329 * PARMRK Mark parity errors with 0xff, 0x00 prefix
330 * (else bad byte is received as 0x00)
331 * ISTRIP Strip parity bit
332 * IGNBRK Ignore break condition
333 * BRKINT Send SIGINT on break - maybe set this?
337 * IUCLC Map uppercase to lowercase
338 * IMAXBEL Echo BEL on input line too long
339 * IUTF8 Appears to affect tty's idea of char widths,
340 * observed to improve backspacing through Unicode chars
343 /* line buffered input (NL or EOL or EOF chars end a line);
344 * recognize INT/QUIT/SUSP chars;
346 * echo BS-SP-BS on erase character;
347 * echo kill char specially, not as ^c (ECHOKE controls how exactly);
348 * erase all input via BS-SP-BS on kill char (else go to next line)
350 G.tty_attrs.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
351 /* Other bits in c_lflag:
352 * XCASE Map uppercase to \lowercase [tried, doesn't work]
353 * ECHONL Echo NL even if ECHO is not set
354 * ECHOCTL Echo ctrl chars as ^c (else don't echo) - maybe set this?
355 * ECHOPRT On erase, echo erased chars
356 * [qwe<BS><BS><BS> input looks like "qwe\ewq/" on screen]
357 * NOFLSH Don't flush input buffer after interrupt or quit chars
358 * IEXTEN Enable extended functions (??)
359 * [glibc says it enables c_cc[LNEXT] "enter literal char"
360 * and c_cc[VDISCARD] "toggle discard buffered output" chars]
361 * FLUSHO Output being flushed (c_cc[VDISCARD] is in effect)
362 * PENDIN Retype pending input at next read or input char
363 * (c_cc[VREPRINT] is being processed)
364 * TOSTOP Send SIGTTOU for background output
365 * (why "stty sane" unsets this bit?)
368 G.tty_attrs.c_cc[VINTR] = DEF_INTR;
369 G.tty_attrs.c_cc[VQUIT] = DEF_QUIT;
370 G.tty_attrs.c_cc[VEOF] = DEF_EOF;
371 G.tty_attrs.c_cc[VEOL] = DEF_EOL;
373 G.tty_attrs.c_cc[VSWTC] = DEF_SWITCH;
376 G.tty_attrs.c_cc[VSWTCH] = DEF_SWITCH;
378 G.tty_attrs.c_cc[VKILL] = DEF_KILL;
379 /* Other control chars:
381 * VERASE, VWERASE - (word) erase. we may set VERASE in get_logname
382 * VREPRINT - reprint current input buffer
383 * VLNEXT, VDISCARD, VSTATUS
384 * VSUSP, VDSUSP - send (delayed) SIGTSTP
385 * VSTART, VSTOP - chars used for IXON/IXOFF
391 /* extract baud rate from modem status message */
392 static void auto_baud(void)
397 * This works only if the modem produces its status code AFTER raising
398 * the DCD line, and if the computer is fast enough to set the proper
399 * baud rate before the message has gone by. We expect a message of the
402 * <junk><number><junk>
404 * The number is interpreted as the baud rate of the incoming call. If the
405 * modem does not tell us the baud rate within one second, we will keep
406 * using the current baud rate. It is advisable to enable BREAK
407 * processing (comma-separated list of baud rates) if the processing of
408 * modem status messages is enabled.
411 G.tty_attrs.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */
415 * Wait for a while, then read everything the modem has said so far and
416 * try to extract the speed of the dial-in call.
419 nread = safe_read(STDIN_FILENO, G.line_buf, sizeof(G.line_buf) - 1);
423 G.line_buf[nread] = '\0';
424 for (bp = G.line_buf; bp < G.line_buf + nread; bp++) {
428 cfsetspeed(&G.tty_attrs, speed);
434 /* Restore terminal settings */
435 G.tty_attrs.c_cc[VMIN] = 1; /* restore to value set by init_tty_attrs */
439 /* get user name, establish parity, speed, erase, kill, eol;
440 * return NULL on BREAK, logname on success
442 static char *get_logname(void)
447 /* Flush pending input (esp. after parsing or switching the baud rate) */
448 usleep(100*1000); /* 0.1 sec */
449 tcflush(STDIN_FILENO, TCIFLUSH);
451 /* Prompt for and read a login name */
452 G.line_buf[0] = '\0';
453 while (!G.line_buf[0]) {
454 /* Write issue file and prompt */
456 if (!(option_mask32 & F_NOISSUE))
457 print_login_issue(G.issue, G.tty_name);
459 print_login_prompt();
461 /* Read name, watch for break, parity, erase, kill, end-of-line */
465 /* Do not report trivial EINTR/EIO errors */
466 errno = EINTR; /* make read of 0 bytes be silent too */
467 if (read(STDIN_FILENO, &c, 1) < 1) {
468 if (errno == EINTR || errno == EIO)
470 bb_perror_msg_and_die(bb_msg_read_error);
473 /* BREAK. If we have speeds to try,
474 * return NULL (will switch speeds and return here) */
475 if (c == '\0' && G.numspeed > 1)
478 /* Do erase, kill and end-of-line processing */
487 G.tty_attrs.c_cc[VERASE] = c;
488 if (bp > G.line_buf) {
489 full_write(STDOUT_FILENO, "\010 \010", 3);
494 while (bp > G.line_buf) {
495 full_write(STDOUT_FILENO, "\010 \010", 3);
502 if ((unsigned char)c < ' ') {
503 /* ignore garbage characters */
504 } else if ((int)(bp - G.line_buf) < sizeof(G.line_buf) - 1) {
505 /* echo and store the character */
506 full_write(STDOUT_FILENO, &c, 1);
511 } /* end of get char loop */
513 } /* while logname is empty */
518 static void alarm_handler(int sig UNUSED_PARAM)
520 finalize_tty_attrs();
524 int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
525 int getty_main(int argc UNUSED_PARAM, char **argv)
532 G.login = _PATH_LOGIN; /* default login program */
534 G.issue = ISSUE; /* default issue file */
538 /* Parse command-line arguments */
541 /* Create new session and pgrp, lose controlling tty */
542 pid = setsid(); /* this also gives us our pid :) */
546 * docs/ctty.htm says:
547 * "This is allowed only when the current process
548 * is not a process group leader".
549 * Thus, setsid() will fail if we _already_ are
550 * a session leader - which is quite possible for getty!
553 if (getsid(0) != pid)
554 bb_perror_msg_and_die("setsid");
555 /* Looks like we are already a session leader.
556 * In this case (setsid failed) we may still have ctty,
557 * and it may be different from tty we need to control!
558 * If we still have ctty, on Linux ioctl(TIOCSCTTY)
559 * (which we are going to call a bit later) always fails.
560 * Try to drop ctty now to prevent that.
562 fd = open("/dev/tty", O_RDWR);
564 ioctl(fd, TIOCNOTTY);
569 /* Close stdio, and stray descriptors, just in case */
570 n = xopen(bb_dev_null, O_RDWR);
571 /* dup2(n, 0); - no, we need to handle "getty - 9600" too */
577 /* Logging. We want special flavor of error_msg_and_die */
580 /* most likely will internally use fd #3 in CLOEXEC mode: */
581 openlog(applet_name, LOG_PID, LOG_AUTH);
582 logmode = LOGMODE_BOTH;
585 dbf = xfopen_for_write(DEBUGTERM);
586 for (n = 1; argv[n]; n++) {
592 /* Open the tty as standard input, if it is not "-" */
593 debug("calling open_tty\n");
595 ndelay_off(STDIN_FILENO);
597 xdup2(STDIN_FILENO, 1);
598 xdup2(STDIN_FILENO, 2);
600 /* Steal ctty if we don't have it yet */
601 tsid = tcgetsid(STDIN_FILENO);
602 if (tsid < 0 || pid != tsid) {
603 if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) < 0)
604 bb_perror_msg_and_die("TIOCSCTTY");
608 /* Make ourself a foreground process group within our session */
609 if (tcsetpgrp(STDIN_FILENO, pid) < 0)
610 bb_perror_msg_and_die("tcsetpgrp");
614 * The following ioctl will fail if stdin is not a tty, but also when
615 * there is noise on the modem control lines. In the latter case, the
616 * common course of action is (1) fix your cables (2) give the modem more
617 * time to properly reset after hanging up. SunOS users can achieve (2)
618 * by patching the SunOS kernel variable "zsadtrlow" to a larger value;
619 * 5 seconds seems to be a good value.
621 if (tcgetattr(STDIN_FILENO, &G.tty_attrs) < 0)
622 bb_perror_msg_and_die("tcgetattr");
624 /* Update the utmp file. This tty is ours now! */
625 update_utmp(pid, LOGIN_PROCESS, G.tty_name, "LOGIN", G.fakehost);
627 /* Initialize tty attrs (raw mode, eight-bit, blocking i/o) */
628 debug("calling init_tty_attrs\n");
629 init_tty_attrs(G.speeds[0]);
631 /* Write the modem init string and DON'T flush the buffers */
632 if (option_mask32 & F_INITSTRING) {
633 debug("writing init string\n");
634 full_write1_str(G.initstring);
637 /* Optionally detect the baud rate from the modem status message */
638 debug("before autobaud\n");
639 if (option_mask32 & F_PARSE)
642 /* Set the optional timer */
643 signal(SIGALRM, alarm_handler);
644 alarm(G.timeout); /* if 0, alarm is not set */
646 /* Optionally wait for CR or LF before writing /etc/issue */
647 if (option_mask32 & F_WAITCRLF) {
649 debug("waiting for cr-lf\n");
650 while (safe_read(STDIN_FILENO, &ch, 1) == 1) {
651 debug("read %x\n", (unsigned char)ch);
652 if (ch == '\n' || ch == '\r')
658 if (!(option_mask32 & F_NOPROMPT)) {
659 /* NB: init_tty_attrs already set line speed
664 /* Read the login name */
665 debug("reading login name\n");
666 logname = get_logname();
669 /* We are here only if G.numspeed > 1 */
670 baud_index = (baud_index + 1) % G.numspeed;
671 cfsetspeed(&G.tty_attrs, G.speeds[baud_index]);
679 finalize_tty_attrs();
681 /* Now the newline character should be properly written */
682 full_write(STDOUT_FILENO, "\n", 1);
684 /* Let the login program take care of password validation */
685 /* We use PATH because we trust that root doesn't set "bad" PATH,
686 * and getty is not suid-root applet */
687 /* With -n, logname == NULL, and login will ask for username instead */
688 BB_EXECLP(G.login, G.login, "--", logname, NULL);
689 bb_error_msg_and_die("can't execute '%s'", G.login);