blob: e5a2533c09c69b97c4cac21f919cc37dbd6aa984
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
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. |
6 | * |
7 | * option added by Eric Rasmussen <ear@usfirst.org> - 12/28/95 |
8 | * |
9 | * 1999-02-22 Arkadiusz Mickiewicz <misiek@misiek.eu.org> |
10 | * - Added Native Language Support |
11 | * |
12 | * 1999-05-05 Thorsten Kranzkowski <dl8bcu@gmx.net> |
13 | * - Enabled hardware flow control before displaying /etc/issue |
14 | * |
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. |
21 | * |
22 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
23 | */ |
24 | //config:config GETTY |
25 | //config: bool "getty" |
26 | //config: default y |
27 | //config: select FEATURE_SYSLOG |
28 | //config: help |
29 | //config: getty lets you log in on a tty. It is normally invoked by init. |
30 | //config: |
31 | //config: Note that you can save a few bytes by disabling it and |
32 | //config: using login applet directly. |
33 | //config: If you need to reset tty attributes before calling login, |
34 | //config: this script approximates getty: |
35 | //config: |
36 | //config: exec </dev/$1 >/dev/$1 2>&1 || exit 1 |
37 | //config: reset |
38 | //config: stty sane; stty ispeed 38400; stty ospeed 38400 |
39 | //config: printf "%s login: " "`hostname`" |
40 | //config: read -r login |
41 | //config: exec /bin/login "$login" |
42 | |
43 | //applet:IF_GETTY(APPLET(getty, BB_DIR_SBIN, BB_SUID_DROP)) |
44 | |
45 | //kbuild:lib-$(CONFIG_GETTY) += getty.o |
46 | |
47 | #include "libbb.h" |
48 | #include <syslog.h> |
49 | #ifndef IUCLC |
50 | # define IUCLC 0 |
51 | #endif |
52 | |
53 | #ifndef LOGIN_PROCESS |
54 | # undef ENABLE_FEATURE_UTMP |
55 | # undef ENABLE_FEATURE_WTMP |
56 | # define ENABLE_FEATURE_UTMP 0 |
57 | # define ENABLE_FEATURE_WTMP 0 |
58 | #endif |
59 | |
60 | |
61 | /* The following is used for understandable diagnostics */ |
62 | #ifdef DEBUGGING |
63 | static FILE *dbf; |
64 | # define DEBUGTERM "/dev/ttyp0" |
65 | # define debug(...) do { fprintf(dbf, __VA_ARGS__); fflush(dbf); } while (0) |
66 | #else |
67 | # define debug(...) ((void)0) |
68 | #endif |
69 | |
70 | |
71 | /* |
72 | * Things you may want to modify. |
73 | * |
74 | * You may disagree with the default line-editing etc. characters defined |
75 | * below. Note, however, that DEL cannot be used for interrupt generation |
76 | * and for line editing at the same time. |
77 | */ |
78 | #undef _PATH_LOGIN |
79 | #ifdef __BIONIC__ |
80 | #define cfsetspeed(t,s) cfsetispeed(t,s) |
81 | #define _PATH_LOGIN "/system/xbin/login" |
82 | #else |
83 | #define _PATH_LOGIN "/bin/login" |
84 | #endif |
85 | |
86 | /* Displayed before the login prompt. |
87 | * If ISSUE is not defined, getty will never display the contents of the |
88 | * /etc/issue file. You will not want to spit out large "issue" files at the |
89 | * wrong baud rate. |
90 | */ |
91 | #define ISSUE "/etc/issue" |
92 | |
93 | /* Macro to build Ctrl-LETTER. Assumes ASCII dialect */ |
94 | #define CTL(x) ((x) ^ 0100) |
95 | |
96 | /* |
97 | * When multiple baud rates are specified on the command line, |
98 | * the first one we will try is the first one specified. |
99 | */ |
100 | #define MAX_SPEED 10 /* max. nr. of baud rates */ |
101 | |
102 | struct globals { |
103 | unsigned timeout; |
104 | const char *login; /* login program */ |
105 | const char *fakehost; |
106 | const char *tty_name; |
107 | char *initstring; /* modem init string */ |
108 | const char *issue; /* alternative issue file */ |
109 | int numspeed; /* number of baud rates to try */ |
110 | int speeds[MAX_SPEED]; /* baud rates to be tried */ |
111 | unsigned char eol; /* end-of-line char seen (CR or NL) */ |
112 | struct termios tty_attrs; |
113 | char line_buf[128]; |
114 | }; |
115 | |
116 | #define G (*ptr_to_globals) |
117 | #define INIT_G() do { \ |
118 | SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \ |
119 | } while (0) |
120 | |
121 | //usage:#define getty_trivial_usage |
122 | //usage: "[OPTIONS] BAUD_RATE[,BAUD_RATE]... TTY [TERMTYPE]" |
123 | //usage:#define getty_full_usage "\n\n" |
124 | //usage: "Open TTY, prompt for login name, then invoke /system/xbin/login\n" |
125 | //usage: "\n -h Enable hardware RTS/CTS flow control" |
126 | //usage: "\n -L Set CLOCAL (ignore Carrier Detect state)" |
127 | //usage: "\n -m Get baud rate from modem's CONNECT status message" |
128 | //usage: "\n -n Don't prompt for login name" |
129 | //usage: "\n -w Wait for CR or LF before sending /etc/issue" |
130 | //usage: "\n -i Don't display /etc/issue" |
131 | //usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" |
132 | //usage: "\n -l LOGIN Invoke LOGIN instead of /system/xbin/login" |
133 | //usage: "\n -t SEC Terminate after SEC if no login name is read" |
134 | //usage: "\n -I INITSTR Send INITSTR before anything else" |
135 | //usage: "\n -H HOST Log HOST into the utmp file as the hostname" |
136 | //usage: "\n" |
137 | //usage: "\nBAUD_RATE of 0 leaves it unchanged" |
138 | |
139 | static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:+wn"; |
140 | #define F_INITSTRING (1 << 0) /* -I */ |
141 | #define F_LOCAL (1 << 1) /* -L */ |
142 | #define F_FAKEHOST (1 << 2) /* -H */ |
143 | #define F_CUSTISSUE (1 << 3) /* -f */ |
144 | #define F_RTSCTS (1 << 4) /* -h */ |
145 | #define F_NOISSUE (1 << 5) /* -i */ |
146 | #define F_LOGIN (1 << 6) /* -l */ |
147 | #define F_PARSE (1 << 7) /* -m */ |
148 | #define F_TIMEOUT (1 << 8) /* -t */ |
149 | #define F_WAITCRLF (1 << 9) /* -w */ |
150 | #define F_NOPROMPT (1 << 10) /* -n */ |
151 | |
152 | |
153 | /* convert speed string to speed code; return <= 0 on failure */ |
154 | static int bcode(const char *s) |
155 | { |
156 | int value = bb_strtou(s, NULL, 10); /* yes, int is intended! */ |
157 | if (value < 0) /* bad terminating char, overflow, etc */ |
158 | return value; |
159 | return tty_value_to_baud(value); |
160 | } |
161 | |
162 | /* parse alternate baud rates */ |
163 | static void parse_speeds(char *arg) |
164 | { |
165 | char *cp; |
166 | |
167 | /* NB: at least one iteration is always done */ |
168 | debug("entered parse_speeds\n"); |
169 | while ((cp = strsep(&arg, ",")) != NULL) { |
170 | G.speeds[G.numspeed] = bcode(cp); |
171 | if (G.speeds[G.numspeed] < 0) |
172 | bb_error_msg_and_die("bad speed: %s", cp); |
173 | /* note: arg "0" turns into speed B0 */ |
174 | G.numspeed++; |
175 | if (G.numspeed > MAX_SPEED) |
176 | bb_error_msg_and_die("too many alternate speeds"); |
177 | } |
178 | debug("exiting parse_speeds\n"); |
179 | } |
180 | |
181 | /* parse command-line arguments */ |
182 | static void parse_args(char **argv) |
183 | { |
184 | char *ts; |
185 | int flags; |
186 | |
187 | opt_complementary = "-2"; /* at least 2 args; -t N */ |
188 | flags = getopt32(argv, opt_string, |
189 | &G.initstring, &G.fakehost, &G.issue, |
190 | &G.login, &G.timeout |
191 | ); |
192 | if (flags & F_INITSTRING) { |
193 | G.initstring = xstrdup(G.initstring); |
194 | /* decode \ddd octal codes into chars */ |
195 | strcpy_and_process_escape_sequences(G.initstring, G.initstring); |
196 | } |
197 | argv += optind; |
198 | debug("after getopt\n"); |
199 | |
200 | /* We loosen up a bit and accept both "baudrate tty" and "tty baudrate" */ |
201 | G.tty_name = argv[0]; |
202 | ts = argv[1]; /* baud rate(s) */ |
203 | if (isdigit(argv[0][0])) { |
204 | /* A number first, assume it's a speed (BSD style) */ |
205 | G.tty_name = ts; /* tty name is in argv[1] */ |
206 | ts = argv[0]; /* baud rate(s) */ |
207 | } |
208 | parse_speeds(ts); |
209 | |
210 | if (argv[2]) |
211 | xsetenv("TERM", argv[2]); |
212 | |
213 | debug("exiting parse_args\n"); |
214 | } |
215 | |
216 | /* set up tty as standard input, output, error */ |
217 | static void open_tty(void) |
218 | { |
219 | /* Set up new standard input, unless we are given an already opened port */ |
220 | if (NOT_LONE_DASH(G.tty_name)) { |
221 | if (G.tty_name[0] != '/') |
222 | G.tty_name = xasprintf("/dev/%s", G.tty_name); /* will leak it */ |
223 | |
224 | /* Open the tty as standard input */ |
225 | debug("open(2)\n"); |
226 | close(0); |
227 | xopen(G.tty_name, O_RDWR | O_NONBLOCK); /* uses fd 0 */ |
228 | |
229 | /* Set proper protections and ownership */ |
230 | fchown(0, 0, 0); /* 0:0 */ |
231 | fchmod(0, 0620); /* crw--w---- */ |
232 | } else { |
233 | char *n; |
234 | /* |
235 | * Standard input should already be connected to an open port. |
236 | * Make sure it is open for read/write. |
237 | */ |
238 | if ((fcntl(0, F_GETFL) & (O_RDWR|O_RDONLY|O_WRONLY)) != O_RDWR) |
239 | bb_error_msg_and_die("stdin is not open for read/write"); |
240 | |
241 | /* Try to get real tty name instead of "-" */ |
242 | n = xmalloc_ttyname(0); |
243 | if (n) |
244 | G.tty_name = n; |
245 | } |
246 | applet_name = xasprintf("getty: %s", skip_dev_pfx(G.tty_name)); |
247 | } |
248 | |
249 | static void set_tty_attrs(void) |
250 | { |
251 | if (tcsetattr_stdin_TCSANOW(&G.tty_attrs) < 0) |
252 | bb_perror_msg_and_die("tcsetattr"); |
253 | } |
254 | |
255 | /* We manipulate tty_attrs this way: |
256 | * - first, we read existing tty_attrs |
257 | * - init_tty_attrs modifies some parts and sets it |
258 | * - auto_baud and/or BREAK processing can set different speed and set tty attrs |
259 | * - finalize_tty_attrs again modifies some parts and sets tty attrs before |
260 | * execing login |
261 | */ |
262 | static void init_tty_attrs(int speed) |
263 | { |
264 | /* Try to drain output buffer, with 5 sec timeout. |
265 | * Added on request from users of ~600 baud serial interface |
266 | * with biggish buffer on a 90MHz CPU. |
267 | * They were losing hundreds of bytes of buffered output |
268 | * on tcflush. |
269 | */ |
270 | signal_no_SA_RESTART_empty_mask(SIGALRM, record_signo); |
271 | alarm(5); |
272 | tcdrain(STDIN_FILENO); |
273 | alarm(0); |
274 | |
275 | /* Flush input and output queues, important for modems! */ |
276 | tcflush(STDIN_FILENO, TCIOFLUSH); |
277 | |
278 | /* Set speed if it wasn't specified as "0" on command line */ |
279 | if (speed != B0) |
280 | cfsetspeed(&G.tty_attrs, speed); |
281 | |
282 | /* Initial settings: 8-bit characters, raw mode, blocking i/o. |
283 | * Special characters are set after we have read the login name; all |
284 | * reads will be done in raw mode anyway. |
285 | */ |
286 | /* Clear all bits except: */ |
287 | G.tty_attrs.c_cflag &= (0 |
288 | /* 2 stop bits (1 otherwise) |
289 | * Enable parity bit (both on input and output) |
290 | * Odd parity (else even) |
291 | */ |
292 | | CSTOPB | PARENB | PARODD |
293 | #ifdef CMSPAR |
294 | | CMSPAR /* mark or space parity */ |
295 | #endif |
296 | #ifdef CBAUD |
297 | | CBAUD /* (output) baud rate */ |
298 | #endif |
299 | #ifdef CBAUDEX |
300 | | CBAUDEX /* (output) baud rate */ |
301 | #endif |
302 | #ifdef CIBAUD |
303 | | CIBAUD /* input baud rate */ |
304 | #endif |
305 | ); |
306 | /* Set: 8 bits; hang up (drop DTR) on last close; enable receive */ |
307 | G.tty_attrs.c_cflag |= CS8 | HUPCL | CREAD; |
308 | if (option_mask32 & F_LOCAL) { |
309 | /* ignore Carrier Detect pin: |
310 | * opens don't block when CD is low, |
311 | * losing CD doesn't hang up processes whose ctty is this tty |
312 | */ |
313 | G.tty_attrs.c_cflag |= CLOCAL; |
314 | } |
315 | #ifdef CRTSCTS |
316 | if (option_mask32 & F_RTSCTS) |
317 | G.tty_attrs.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */ |
318 | #endif |
319 | G.tty_attrs.c_iflag = 0; |
320 | G.tty_attrs.c_lflag = 0; |
321 | /* non-raw output; add CR to each NL */ |
322 | G.tty_attrs.c_oflag = OPOST | ONLCR; |
323 | |
324 | /* reads would block only if < 1 char is available */ |
325 | G.tty_attrs.c_cc[VMIN] = 1; |
326 | /* no timeout (reads block forever) */ |
327 | G.tty_attrs.c_cc[VTIME] = 0; |
328 | #ifdef __linux__ |
329 | G.tty_attrs.c_line = 0; |
330 | #endif |
331 | |
332 | set_tty_attrs(); |
333 | |
334 | debug("term_io 2\n"); |
335 | } |
336 | |
337 | static void finalize_tty_attrs(void) |
338 | { |
339 | /* software flow control on output (stop sending if XOFF is recvd); |
340 | * and on input (send XOFF when buffer is full) |
341 | */ |
342 | G.tty_attrs.c_iflag |= IXON | IXOFF; |
343 | if (G.eol == '\r') { |
344 | G.tty_attrs.c_iflag |= ICRNL; /* map CR on input to NL */ |
345 | } |
346 | /* Other bits in c_iflag: |
347 | * IXANY Any recvd char enables output (any char is also a XON) |
348 | * INPCK Enable parity check |
349 | * IGNPAR Ignore parity errors (drop bad bytes) |
350 | * PARMRK Mark parity errors with 0xff, 0x00 prefix |
351 | * (else bad byte is received as 0x00) |
352 | * ISTRIP Strip parity bit |
353 | * IGNBRK Ignore break condition |
354 | * BRKINT Send SIGINT on break - maybe set this? |
355 | * INLCR Map NL to CR |
356 | * IGNCR Ignore CR |
357 | * ICRNL Map CR to NL |
358 | * IUCLC Map uppercase to lowercase |
359 | * IMAXBEL Echo BEL on input line too long |
360 | * IUTF8 Appears to affect tty's idea of char widths, |
361 | * observed to improve backspacing through Unicode chars |
362 | */ |
363 | |
364 | /* ICANON line buffered input (NL or EOL or EOF chars end a line); |
365 | * ISIG recognize INT/QUIT/SUSP chars; |
366 | * ECHO echo input chars; |
367 | * ECHOE echo BS-SP-BS on erase character; |
368 | * ECHOK echo kill char specially, not as ^c (ECHOKE controls how exactly); |
369 | * ECHOKE erase all input via BS-SP-BS on kill char (else go to next line) |
370 | * ECHOCTL Echo ctrl chars as ^c (else echo verbatim: |
371 | * e.g. up arrow emits "ESC-something" and thus moves cursor up!) |
372 | */ |
373 | G.tty_attrs.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE | ECHOCTL; |
374 | /* Other bits in c_lflag: |
375 | * XCASE Map uppercase to \lowercase [tried, doesn't work] |
376 | * ECHONL Echo NL even if ECHO is not set |
377 | * ECHOPRT On erase, echo erased chars |
378 | * [qwe<BS><BS><BS> input looks like "qwe\ewq/" on screen] |
379 | * NOFLSH Don't flush input buffer after interrupt or quit chars |
380 | * IEXTEN Enable extended functions (??) |
381 | * [glibc says it enables c_cc[LNEXT] "enter literal char" |
382 | * and c_cc[VDISCARD] "toggle discard buffered output" chars] |
383 | * FLUSHO Output being flushed (c_cc[VDISCARD] is in effect) |
384 | * PENDIN Retype pending input at next read or input char |
385 | * (c_cc[VREPRINT] is being processed) |
386 | * TOSTOP Send SIGTTOU for background output |
387 | * (why "stty sane" unsets this bit?) |
388 | */ |
389 | |
390 | G.tty_attrs.c_cc[VINTR] = CTL('C'); |
391 | G.tty_attrs.c_cc[VQUIT] = CTL('\\'); |
392 | G.tty_attrs.c_cc[VEOF] = CTL('D'); |
393 | G.tty_attrs.c_cc[VEOL] = '\n'; |
394 | #ifdef VSWTC |
395 | G.tty_attrs.c_cc[VSWTC] = 0; |
396 | #endif |
397 | #ifdef VSWTCH |
398 | G.tty_attrs.c_cc[VSWTCH] = 0; |
399 | #endif |
400 | G.tty_attrs.c_cc[VKILL] = CTL('U'); |
401 | /* Other control chars: |
402 | * VEOL2 |
403 | * VERASE, VWERASE - (word) erase. we may set VERASE in get_logname |
404 | * VREPRINT - reprint current input buffer |
405 | * VLNEXT, VDISCARD, VSTATUS |
406 | * VSUSP, VDSUSP - send (delayed) SIGTSTP |
407 | * VSTART, VSTOP - chars used for IXON/IXOFF |
408 | */ |
409 | |
410 | set_tty_attrs(); |
411 | |
412 | /* Now the newline character should be properly written */ |
413 | full_write(STDOUT_FILENO, "\n", 1); |
414 | } |
415 | |
416 | /* extract baud rate from modem status message */ |
417 | static void auto_baud(void) |
418 | { |
419 | int nread; |
420 | |
421 | /* |
422 | * This works only if the modem produces its status code AFTER raising |
423 | * the DCD line, and if the computer is fast enough to set the proper |
424 | * baud rate before the message has gone by. We expect a message of the |
425 | * following format: |
426 | * |
427 | * <junk><number><junk> |
428 | * |
429 | * The number is interpreted as the baud rate of the incoming call. If the |
430 | * modem does not tell us the baud rate within one second, we will keep |
431 | * using the current baud rate. It is advisable to enable BREAK |
432 | * processing (comma-separated list of baud rates) if the processing of |
433 | * modem status messages is enabled. |
434 | */ |
435 | |
436 | G.tty_attrs.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */ |
437 | set_tty_attrs(); |
438 | |
439 | /* |
440 | * Wait for a while, then read everything the modem has said so far and |
441 | * try to extract the speed of the dial-in call. |
442 | */ |
443 | sleep(1); |
444 | nread = safe_read(STDIN_FILENO, G.line_buf, sizeof(G.line_buf) - 1); |
445 | if (nread > 0) { |
446 | int speed; |
447 | char *bp; |
448 | G.line_buf[nread] = '\0'; |
449 | for (bp = G.line_buf; bp < G.line_buf + nread; bp++) { |
450 | if (isdigit(*bp)) { |
451 | speed = bcode(bp); |
452 | if (speed > 0) |
453 | cfsetspeed(&G.tty_attrs, speed); |
454 | break; |
455 | } |
456 | } |
457 | } |
458 | |
459 | /* Restore terminal settings */ |
460 | G.tty_attrs.c_cc[VMIN] = 1; /* restore to value set by init_tty_attrs */ |
461 | set_tty_attrs(); |
462 | } |
463 | |
464 | /* get user name, establish parity, speed, erase, kill, eol; |
465 | * return NULL on BREAK, logname on success |
466 | */ |
467 | static char *get_logname(void) |
468 | { |
469 | char *bp; |
470 | char c; |
471 | |
472 | /* Flush pending input (esp. after parsing or switching the baud rate) */ |
473 | usleep(100*1000); /* 0.1 sec */ |
474 | tcflush(STDIN_FILENO, TCIFLUSH); |
475 | |
476 | /* Prompt for and read a login name */ |
477 | do { |
478 | /* Write issue file and prompt */ |
479 | #ifdef ISSUE |
480 | if (!(option_mask32 & F_NOISSUE)) |
481 | print_login_issue(G.issue, G.tty_name); |
482 | #endif |
483 | print_login_prompt(); |
484 | |
485 | /* Read name, watch for break, erase, kill, end-of-line */ |
486 | bp = G.line_buf; |
487 | while (1) { |
488 | /* Do not report trivial EINTR/EIO errors */ |
489 | errno = EINTR; /* make read of 0 bytes be silent too */ |
490 | if (read(STDIN_FILENO, &c, 1) < 1) { |
491 | finalize_tty_attrs(); |
492 | if (errno == EINTR || errno == EIO) |
493 | exit(EXIT_SUCCESS); |
494 | bb_perror_msg_and_die(bb_msg_read_error); |
495 | } |
496 | |
497 | switch (c) { |
498 | case '\r': |
499 | case '\n': |
500 | *bp = '\0'; |
501 | G.eol = c; |
502 | goto got_logname; |
503 | case CTL('H'): |
504 | case 0x7f: |
505 | G.tty_attrs.c_cc[VERASE] = c; |
506 | if (bp > G.line_buf) { |
507 | full_write(STDOUT_FILENO, "\010 \010", 3); |
508 | bp--; |
509 | } |
510 | break; |
511 | case CTL('U'): |
512 | while (bp > G.line_buf) { |
513 | full_write(STDOUT_FILENO, "\010 \010", 3); |
514 | bp--; |
515 | } |
516 | break; |
517 | case CTL('C'): |
518 | case CTL('D'): |
519 | finalize_tty_attrs(); |
520 | exit(EXIT_SUCCESS); |
521 | case '\0': |
522 | /* BREAK. If we have speeds to try, |
523 | * return NULL (will switch speeds and return here) */ |
524 | if (G.numspeed > 1) |
525 | return NULL; |
526 | /* fall through and ignore it */ |
527 | default: |
528 | if ((unsigned char)c < ' ') { |
529 | /* ignore garbage characters */ |
530 | } else if ((int)(bp - G.line_buf) < (int)sizeof(G.line_buf) - 1) { |
531 | /* echo and store the character */ |
532 | full_write(STDOUT_FILENO, &c, 1); |
533 | *bp++ = c; |
534 | } |
535 | break; |
536 | } |
537 | } /* end of get char loop */ |
538 | got_logname: ; |
539 | } while (G.line_buf[0] == '\0'); /* while logname is empty */ |
540 | |
541 | return G.line_buf; |
542 | } |
543 | |
544 | static void alarm_handler(int sig UNUSED_PARAM) |
545 | { |
546 | finalize_tty_attrs(); |
547 | _exit(EXIT_SUCCESS); |
548 | } |
549 | |
550 | static void sleep10(void) |
551 | { |
552 | sleep(10); |
553 | } |
554 | |
555 | int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
556 | int getty_main(int argc UNUSED_PARAM, char **argv) |
557 | { |
558 | int n; |
559 | pid_t pid, tsid; |
560 | char *logname; |
561 | |
562 | INIT_G(); |
563 | G.login = _PATH_LOGIN; /* default login program */ |
564 | #ifdef ISSUE |
565 | G.issue = ISSUE; /* default issue file */ |
566 | #endif |
567 | G.eol = '\r'; |
568 | |
569 | /* Parse command-line arguments */ |
570 | parse_args(argv); |
571 | |
572 | /* Create new session and pgrp, lose controlling tty */ |
573 | pid = setsid(); /* this also gives us our pid :) */ |
574 | if (pid < 0) { |
575 | int fd; |
576 | /* :( |
577 | * docs/ctty.htm says: |
578 | * "This is allowed only when the current process |
579 | * is not a process group leader". |
580 | * Thus, setsid() will fail if we _already_ are |
581 | * a session leader - which is quite possible for getty! |
582 | */ |
583 | pid = getpid(); |
584 | if (getsid(0) != pid) { |
585 | //for debugging: |
586 | //bb_perror_msg_and_die("setsid failed:" |
587 | // " pid %d ppid %d" |
588 | // " sid %d pgid %d", |
589 | // pid, getppid(), |
590 | // getsid(0), getpgid(0)); |
591 | bb_perror_msg_and_die("setsid"); |
592 | /* |
593 | * When we can end up here? |
594 | * Example: setsid() fails when run alone in interactive shell: |
595 | * # getty 115200 /dev/tty2 |
596 | * because shell's child (getty) is put in a new process group. |
597 | * But doesn't fail if shell is not interactive |
598 | * (and therefore doesn't create process groups for pipes), |
599 | * or if getty is not the first process in the process group: |
600 | * # true | getty 115200 /dev/tty2 |
601 | */ |
602 | } |
603 | /* Looks like we are already a session leader. |
604 | * In this case (setsid failed) we may still have ctty, |
605 | * and it may be different from tty we need to control! |
606 | * If we still have ctty, on Linux ioctl(TIOCSCTTY) |
607 | * (which we are going to use a bit later) always fails - |
608 | * even if we try to take ctty which is already ours! |
609 | * Try to drop old ctty now to prevent that. |
610 | * Use O_NONBLOCK: old ctty may be a serial line. |
611 | */ |
612 | fd = open("/dev/tty", O_RDWR | O_NONBLOCK); |
613 | if (fd >= 0) { |
614 | /* TIOCNOTTY sends SIGHUP to the foreground |
615 | * process group - which may include us! |
616 | * Make sure to not die on it: |
617 | */ |
618 | sighandler_t old = signal(SIGHUP, SIG_IGN); |
619 | ioctl(fd, TIOCNOTTY); |
620 | close(fd); |
621 | signal(SIGHUP, old); |
622 | } |
623 | } |
624 | |
625 | /* Close stdio, and stray descriptors, just in case */ |
626 | n = xopen(bb_dev_null, O_RDWR); |
627 | /* dup2(n, 0); - no, we need to handle "getty - 9600" too */ |
628 | xdup2(n, 1); |
629 | xdup2(n, 2); |
630 | while (n > 2) |
631 | close(n--); |
632 | |
633 | /* Logging. We want special flavor of error_msg_and_die */ |
634 | die_func = sleep10; |
635 | msg_eol = "\r\n"; |
636 | /* most likely will internally use fd #3 in CLOEXEC mode: */ |
637 | openlog(applet_name, LOG_PID, LOG_AUTH); |
638 | logmode = LOGMODE_BOTH; |
639 | |
640 | #ifdef DEBUGGING |
641 | dbf = xfopen_for_write(DEBUGTERM); |
642 | for (n = 1; argv[n]; n++) { |
643 | debug(argv[n]); |
644 | debug("\n"); |
645 | } |
646 | #endif |
647 | |
648 | /* Open the tty as standard input, if it is not "-" */ |
649 | debug("calling open_tty\n"); |
650 | open_tty(); |
651 | ndelay_off(STDIN_FILENO); |
652 | debug("duping\n"); |
653 | xdup2(STDIN_FILENO, 1); |
654 | xdup2(STDIN_FILENO, 2); |
655 | |
656 | /* Steal ctty if we don't have it yet */ |
657 | tsid = tcgetsid(STDIN_FILENO); |
658 | if (tsid < 0 || pid != tsid) { |
659 | if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) < 0) |
660 | bb_perror_msg_and_die("TIOCSCTTY"); |
661 | } |
662 | |
663 | #ifdef __linux__ |
664 | /* Make ourself a foreground process group within our session */ |
665 | if (tcsetpgrp(STDIN_FILENO, pid) < 0) |
666 | bb_perror_msg_and_die("tcsetpgrp"); |
667 | #endif |
668 | |
669 | /* |
670 | * The following ioctl will fail if stdin is not a tty, but also when |
671 | * there is noise on the modem control lines. In the latter case, the |
672 | * common course of action is (1) fix your cables (2) give the modem more |
673 | * time to properly reset after hanging up. SunOS users can achieve (2) |
674 | * by patching the SunOS kernel variable "zsadtrlow" to a larger value; |
675 | * 5 seconds seems to be a good value. |
676 | */ |
677 | if (tcgetattr(STDIN_FILENO, &G.tty_attrs) < 0) |
678 | bb_perror_msg_and_die("tcgetattr"); |
679 | |
680 | /* Update the utmp file. This tty is ours now! */ |
681 | update_utmp(pid, LOGIN_PROCESS, G.tty_name, "LOGIN", G.fakehost); |
682 | |
683 | /* Initialize tty attrs (raw mode, eight-bit, blocking i/o) */ |
684 | debug("calling init_tty_attrs\n"); |
685 | init_tty_attrs(G.speeds[0]); |
686 | |
687 | /* Write the modem init string and DON'T flush the buffers */ |
688 | if (option_mask32 & F_INITSTRING) { |
689 | debug("writing init string\n"); |
690 | full_write1_str(G.initstring); |
691 | } |
692 | |
693 | /* Optionally detect the baud rate from the modem status message */ |
694 | debug("before autobaud\n"); |
695 | if (option_mask32 & F_PARSE) |
696 | auto_baud(); |
697 | |
698 | /* Set the optional timer */ |
699 | signal(SIGALRM, alarm_handler); |
700 | alarm(G.timeout); /* if 0, alarm is not set */ |
701 | |
702 | /* Optionally wait for CR or LF before writing /etc/issue */ |
703 | if (option_mask32 & F_WAITCRLF) { |
704 | char ch; |
705 | debug("waiting for cr-lf\n"); |
706 | while (safe_read(STDIN_FILENO, &ch, 1) == 1) { |
707 | debug("read %x\n", (unsigned char)ch); |
708 | if (ch == '\n' || ch == '\r') |
709 | break; |
710 | } |
711 | } |
712 | |
713 | logname = NULL; |
714 | if (!(option_mask32 & F_NOPROMPT)) { |
715 | /* NB: init_tty_attrs already set line speed |
716 | * to G.speeds[0] */ |
717 | int baud_index = 0; |
718 | |
719 | while (1) { |
720 | /* Read the login name */ |
721 | debug("reading login name\n"); |
722 | logname = get_logname(); |
723 | if (logname) |
724 | break; |
725 | /* We are here only if G.numspeed > 1 */ |
726 | baud_index = (baud_index + 1) % G.numspeed; |
727 | cfsetspeed(&G.tty_attrs, G.speeds[baud_index]); |
728 | set_tty_attrs(); |
729 | } |
730 | } |
731 | |
732 | /* Disable timer */ |
733 | alarm(0); |
734 | |
735 | finalize_tty_attrs(); |
736 | |
737 | /* Let the login program take care of password validation */ |
738 | /* We use PATH because we trust that root doesn't set "bad" PATH, |
739 | * and getty is not suid-root applet */ |
740 | /* With -n, logname == NULL, and login will ask for username instead */ |
741 | BB_EXECLP(G.login, G.login, "--", logname, (char *)0); |
742 | bb_error_msg_and_die("can't execute '%s'", G.login); |
743 | } |
744 |