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.
27 #if ENABLE_FEATURE_UTMP
28 # include <utmp.h> /* LOGIN_PROCESS */
35 # undef ENABLE_FEATURE_UTMP
36 # undef ENABLE_FEATURE_WTMP
37 # define ENABLE_FEATURE_UTMP 0
38 # define ENABLE_FEATURE_WTMP 0
42 /* The following is used for understandable diagnostics */
45 # define DEBUGTERM "/dev/ttyp0"
46 # define debug(...) do { fprintf(dbf, __VA_ARGS__); fflush(dbf); } while (0)
48 # define debug(...) ((void)0)
53 * Things you may want to modify.
55 * You may disagree with the default line-editing etc. characters defined
56 * below. Note, however, that DEL cannot be used for interrupt generation
57 * and for line editing at the same time.
60 #define _PATH_LOGIN "/bin/login"
62 /* Displayed before the login prompt.
63 * If ISSUE is not defined, getty will never display the contents of the
64 * /etc/issue file. You will not want to spit out large "issue" files at the
67 #define ISSUE "/etc/issue"
69 /* Some shorthands for control characters */
70 #define CTL(x) ((x) ^ 0100) /* Assumes ASCII dialect */
71 #define BS CTL('H') /* back space */
72 #define DEL CTL('?') /* delete */
74 /* Defaults for line-editing etc. characters; you may want to change this */
75 #define DEF_INTR CTL('C') /* default interrupt character */
76 #define DEF_QUIT CTL('\\') /* default quit char */
77 #define DEF_KILL CTL('U') /* default kill char */
78 #define DEF_EOF CTL('D') /* default EOF char */
80 #define DEF_SWITCH 0 /* default switch char (none) */
83 * When multiple baud rates are specified on the command line,
84 * the first one we will try is the first one specified.
86 #define MAX_SPEED 10 /* max. nr. of baud rates */
89 unsigned timeout; /* time-out period */
90 const char *login; /* login program */
92 const char *tty; /* name of tty */
93 const char *initstring; /* modem init string */
94 const char *issue; /* alternative issue file */
95 int numspeed; /* number of baud rates to try */
96 int speeds[MAX_SPEED]; /* baud rates to be tried */
97 unsigned char eol; /* end-of-line char seen (CR or NL) */
98 struct termios termios; /* terminal mode bits */
102 #define G (*ptr_to_globals)
103 #define INIT_G() do { \
104 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
107 //usage:#define getty_trivial_usage
108 //usage: "[OPTIONS] BAUD_RATE[,BAUD_RATE]... TTY [TERMTYPE]"
109 //usage:#define getty_full_usage "\n\n"
110 //usage: "Open a tty, prompt for a login name, then invoke /bin/login\n"
111 //usage: "\nOptions:"
112 //usage: "\n -h Enable hardware (RTS/CTS) flow control"
113 //usage: "\n -i Don't display /etc/issue"
114 //usage: "\n -L Local line, set CLOCAL on it"
115 //usage: "\n -m Get baud rate from modem's CONNECT status message"
116 //usage: "\n -w Wait for CR or LF before sending /etc/issue"
117 //usage: "\n -n Don't prompt for a login name"
118 //usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue"
119 //usage: "\n -l LOGIN Invoke LOGIN instead of /bin/login"
120 //usage: "\n -t SEC Terminate after SEC if no username is read"
121 //usage: "\n -I INITSTR Send INITSTR before anything else"
122 //usage: "\n -H HOST Log HOST into the utmp file as the hostname"
124 //usage: "\nBAUD_RATE of 0 leaves it unchanged"
126 static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn";
127 #define F_INITSTRING (1 << 0) /* -I */
128 #define F_LOCAL (1 << 1) /* -L */
129 #define F_FAKEHOST (1 << 2) /* -H */
130 #define F_CUSTISSUE (1 << 3) /* -f */
131 #define F_RTSCTS (1 << 4) /* -h */
132 #define F_NOISSUE (1 << 5) /* -i */
133 #define F_LOGIN (1 << 6) /* -l */
134 #define F_PARSE (1 << 7) /* -m */
135 #define F_TIMEOUT (1 << 8) /* -t */
136 #define F_WAITCRLF (1 << 9) /* -w */
137 #define F_NOPROMPT (1 << 10) /* -n */
140 /* convert speed string to speed code; return <= 0 on failure */
141 static int bcode(const char *s)
143 int value = bb_strtou(s, NULL, 10); /* yes, int is intended! */
144 if (value < 0) /* bad terminating char, overflow, etc */
146 return tty_value_to_baud(value);
149 /* parse alternate baud rates */
150 static void parse_speeds(char *arg)
154 /* NB: at least one iteration is always done */
155 debug("entered parse_speeds\n");
156 while ((cp = strsep(&arg, ",")) != NULL) {
157 G.speeds[G.numspeed] = bcode(cp);
158 if (G.speeds[G.numspeed] < 0)
159 bb_error_msg_and_die("bad speed: %s", cp);
160 /* note: arg "0" turns into speed B0 */
162 if (G.numspeed > MAX_SPEED)
163 bb_error_msg_and_die("too many alternate speeds");
165 debug("exiting parse_speeds\n");
168 /* parse command-line arguments */
169 static void parse_args(char **argv)
174 opt_complementary = "-2:t+"; /* at least 2 args; -t N */
175 flags = getopt32(argv, opt_string,
176 &G.initstring, &G.fakehost, &G.issue,
179 if (flags & F_INITSTRING) {
180 G.initstring = xstrdup(G.initstring);
181 /* decode \ddd octal codes into chars */
182 strcpy_and_process_escape_sequences((char*)G.initstring, G.initstring);
185 debug("after getopt\n");
187 /* We loosen up a bit and accept both "baudrate tty" and "tty baudrate" */
188 G.tty = argv[0]; /* tty name */
189 ts = argv[1]; /* baud rate(s) */
190 if (isdigit(argv[0][0])) {
191 /* A number first, assume it's a speed (BSD style) */
192 G.tty = ts; /* tty name is in argv[1] */
193 ts = argv[0]; /* baud rate(s) */
196 applet_name = xasprintf("getty: %s", G.tty);
199 xsetenv("TERM", argv[2]);
201 debug("exiting parse_args\n");
204 /* set up tty as standard input, output, error */
205 static void open_tty(void)
207 /* Set up new standard input, unless we are given an already opened port */
208 if (NOT_LONE_DASH(G.tty)) {
210 G.tty = xasprintf("/dev/%s", G.tty); /* will leak it */
212 /* Open the tty as standard input */
215 xopen(G.tty, O_RDWR | O_NONBLOCK); /* uses fd 0 */
217 /* Set proper protections and ownership */
218 fchown(0, 0, 0); /* 0:0 */
219 fchmod(0, 0620); /* crw--w---- */
222 * Standard input should already be connected to an open port. Make
223 * sure it is open for read/write.
225 if ((fcntl(0, F_GETFL) & (O_RDWR|O_RDONLY|O_WRONLY)) != O_RDWR)
226 bb_error_msg_and_die("stdin is not open for read/write");
230 /* We manipulate termios this way:
231 * - first, we read existing termios settings
232 * - termios_init modifies some parts and sets it
233 * - auto_baud and/or BREAK processing can set different speed and set termios
234 * - termios_final again modifies some parts and sets termios before
237 static void termios_init(int speed)
239 /* Flush input and output queues, important for modems!
240 * Users report losing previously queued output chars, and I hesitate
241 * to use tcdrain here instead of tcflush - I imagine it can block.
242 * Using small sleep instead.
244 usleep(100*1000); /* 0.1 sec */
245 tcflush(STDIN_FILENO, TCIOFLUSH);
247 /* Set speed if it wasn't specified as "0" on command line */
249 cfsetspeed(&G.termios, speed);
252 * Initial termios settings: 8-bit characters, raw-mode, blocking i/o.
253 * Special characters are set after we have read the login name; all
254 * reads will be done in raw mode anyway. Errors will be dealt with
257 G.termios.c_cflag = CS8 | HUPCL | CREAD;
258 if (option_mask32 & F_LOCAL)
259 G.termios.c_cflag |= CLOCAL;
260 G.termios.c_iflag = 0;
261 G.termios.c_lflag = 0;
262 G.termios.c_oflag = OPOST | ONLCR;
263 G.termios.c_cc[VMIN] = 1;
264 G.termios.c_cc[VTIME] = 0;
266 G.termios.c_line = 0;
269 if (option_mask32 & F_RTSCTS)
270 G.termios.c_cflag |= CRTSCTS;
273 tcsetattr_stdin_TCSANOW(&G.termios);
275 debug("term_io 2\n");
278 static void termios_final(void)
280 /* General terminal-independent stuff */
281 G.termios.c_iflag |= IXON | IXOFF; /* 2-way flow control */
282 G.termios.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE;
283 /* no longer in lflag: | ECHOCTL | ECHOPRT */
284 G.termios.c_oflag |= OPOST;
285 /* G.termios.c_cflag = 0; */
286 G.termios.c_cc[VINTR] = DEF_INTR;
287 G.termios.c_cc[VQUIT] = DEF_QUIT;
288 G.termios.c_cc[VEOF] = DEF_EOF;
289 G.termios.c_cc[VEOL] = DEF_EOL;
291 G.termios.c_cc[VSWTC] = DEF_SWITCH;
294 G.termios.c_cc[VSWTCH] = DEF_SWITCH;
297 /* Account for special characters seen in input */
299 G.termios.c_iflag |= ICRNL; /* map CR in input to NL */
300 /* already done by termios_init */
301 /* G.termios.c_oflag |= ONLCR; map NL in output to CR-NL */
303 G.termios.c_cc[VKILL] = DEF_KILL;
306 /* Optionally enable hardware flow control */
307 if (option_mask32 & F_RTSCTS)
308 G.termios.c_cflag |= CRTSCTS;
311 /* Finally, make the new settings effective */
312 if (tcsetattr_stdin_TCSANOW(&G.termios) < 0)
313 bb_perror_msg_and_die("tcsetattr");
316 /* extract baud rate from modem status message */
317 static void auto_baud(void)
322 * This works only if the modem produces its status code AFTER raising
323 * the DCD line, and if the computer is fast enough to set the proper
324 * baud rate before the message has gone by. We expect a message of the
327 * <junk><number><junk>
329 * The number is interpreted as the baud rate of the incoming call. If the
330 * modem does not tell us the baud rate within one second, we will keep
331 * using the current baud rate. It is advisable to enable BREAK
332 * processing (comma-separated list of baud rates) if the processing of
333 * modem status messages is enabled.
337 * Don't block if input queue is empty.
338 * Errors will be dealt with later on.
340 G.termios.c_cc[VMIN] = 0; /* don't block if queue empty */
341 tcsetattr_stdin_TCSANOW(&G.termios);
344 * Wait for a while, then read everything the modem has said so far and
345 * try to extract the speed of the dial-in call.
348 nread = safe_read(STDIN_FILENO, G.line_buf, sizeof(G.line_buf) - 1);
352 G.line_buf[nread] = '\0';
353 for (bp = G.line_buf; bp < G.line_buf + nread; bp++) {
357 cfsetspeed(&G.termios, speed);
363 /* Restore terminal settings. Errors will be dealt with later on */
364 G.termios.c_cc[VMIN] = 1; /* restore to value set by termios_init */
365 tcsetattr_stdin_TCSANOW(&G.termios);
368 /* get user name, establish parity, speed, erase, kill, eol;
369 * return NULL on BREAK, logname on success
371 static char *get_logname(void)
376 /* Flush pending input (esp. after parsing or switching the baud rate) */
377 usleep(100*1000); /* 0.1 sec */
378 tcflush(STDIN_FILENO, TCIOFLUSH);
380 /* Prompt for and read a login name */
381 G.line_buf[0] = '\0';
382 while (!G.line_buf[0]) {
383 /* Write issue file and prompt */
385 if (!(option_mask32 & F_NOISSUE))
386 print_login_issue(G.issue, G.tty);
388 print_login_prompt();
390 /* Read name, watch for break, parity, erase, kill, end-of-line */
394 /* Do not report trivial EINTR/EIO errors */
395 errno = EINTR; /* make read of 0 bytes be silent too */
396 if (read(STDIN_FILENO, &c, 1) < 1) {
397 if (errno == EINTR || errno == EIO)
399 bb_perror_msg_and_die(bb_msg_read_error);
402 /* BREAK. If we have speeds to try,
403 * return NULL (will switch speeds and return here) */
404 if (c == '\0' && G.numspeed > 1)
407 /* Do erase, kill and end-of-line processing */
416 G.termios.c_cc[VERASE] = c;
417 if (bp > G.line_buf) {
418 full_write(STDOUT_FILENO, "\010 \010", 3);
423 while (bp > G.line_buf) {
424 full_write(STDOUT_FILENO, "\010 \010", 3);
431 if ((unsigned char)c < ' ') {
432 /* ignore garbage characters */
433 } else if ((int)(bp - G.line_buf) < sizeof(G.line_buf) - 1) {
434 /* echo and store the character */
435 full_write(STDOUT_FILENO, &c, 1);
440 } /* end of get char loop */
442 } /* while logname is empty */
447 int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
448 int getty_main(int argc UNUSED_PARAM, char **argv)
455 G.login = _PATH_LOGIN; /* default login program */
457 G.issue = ISSUE; /* default issue file */
461 /* Parse command-line arguments */
464 logmode = LOGMODE_NONE;
466 /* Create new session, lose controlling tty, if any */
467 /* docs/ctty.htm says:
468 * "This is allowed only when the current process
469 * is not a process group leader" - is this a problem? */
471 /* close stdio, and stray descriptors, just in case */
472 n = xopen(bb_dev_null, O_RDWR);
473 /* dup2(n, 0); - no, we need to handle "getty - 9600" too */
479 /* Logging. We want special flavor of error_msg_and_die */
482 /* most likely will internally use fd #3 in CLOEXEC mode: */
483 openlog(applet_name, LOG_PID, LOG_AUTH);
484 logmode = LOGMODE_BOTH;
487 dbf = xfopen_for_write(DEBUGTERM);
488 for (n = 1; argv[n]; n++) {
494 /* Open the tty as standard input, if it is not "-" */
495 /* If it's not "-" and not taken yet, it will become our ctty */
496 debug("calling open_tty\n");
504 * The following ioctl will fail if stdin is not a tty, but also when
505 * there is noise on the modem control lines. In the latter case, the
506 * common course of action is (1) fix your cables (2) give the modem more
507 * time to properly reset after hanging up. SunOS users can achieve (2)
508 * by patching the SunOS kernel variable "zsadtrlow" to a larger value;
509 * 5 seconds seems to be a good value.
511 if (tcgetattr(STDIN_FILENO, &G.termios) < 0)
512 bb_perror_msg_and_die("tcgetattr");
516 // FIXME: do we need this? Otherwise "-" case seems to be broken...
517 // /* Forcibly make fd 0 our controlling tty, even if another session
518 // * has it as a ctty. (Another session loses ctty). */
519 // ioctl(STDIN_FILENO, TIOCSCTTY, (void*)1);
520 /* Make ourself a foreground process group within our session */
521 tcsetpgrp(STDIN_FILENO, pid);
524 /* Update the utmp file. This tty is ours now! */
525 update_utmp(pid, LOGIN_PROCESS, G.tty, "LOGIN", G.fakehost);
527 /* Initialize the termios settings (raw mode, eight-bit, blocking i/o) */
528 debug("calling termios_init\n");
529 termios_init(G.speeds[0]);
531 /* Write the modem init string and DON'T flush the buffers */
532 if (option_mask32 & F_INITSTRING) {
533 debug("writing init string\n");
534 full_write1_str(G.initstring);
537 /* Optionally detect the baud rate from the modem status message */
538 debug("before autobaud\n");
539 if (option_mask32 & F_PARSE)
542 /* Set the optional timer */
543 alarm(G.timeout); /* if 0, alarm is not set */
545 /* Optionally wait for CR or LF before writing /etc/issue */
546 if (option_mask32 & F_WAITCRLF) {
548 debug("waiting for cr-lf\n");
549 while (safe_read(STDIN_FILENO, &ch, 1) == 1) {
550 debug("read %x\n", (unsigned char)ch);
551 if (ch == '\n' || ch == '\r')
557 if (!(option_mask32 & F_NOPROMPT)) {
558 /* NB: termios_init already set line speed
563 /* Read the login name */
564 debug("reading login name\n");
565 logname = get_logname();
568 /* We are here only if G.numspeed > 1 */
569 baud_index = (baud_index + 1) % G.numspeed;
570 cfsetspeed(&G.termios, G.speeds[baud_index]);
571 tcsetattr_stdin_TCSANOW(&G.termios);
578 /* Finalize the termios settings */
581 /* Now the newline character should be properly written */
582 full_write(STDOUT_FILENO, "\n", 1);
584 /* Let the login program take care of password validation */
585 /* We use PATH because we trust that root doesn't set "bad" PATH,
586 * and getty is not suid-root applet */
587 /* With -n, logname == NULL, and login will ask for username instead */
588 BB_EXECLP(G.login, G.login, "--", logname, NULL);
589 bb_error_msg_and_die("can't execute '%s'", G.login);