xref: /freebsd/libexec/getty/main.c (revision 44d780e32b9d798a93b758fe0957d770e3190988)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1980, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #ifndef lint
33 static const char copyright[] =
34 "@(#) Copyright (c) 1980, 1993\n\
35 	The Regents of the University of California.  All rights reserved.\n";
36 #endif /* not lint */
37 
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)from: main.c	8.1 (Berkeley) 6/20/93";
41 #endif
42 #endif /* not lint */
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
45 
46 #include <sys/param.h>
47 #include <sys/ioctl.h>
48 #include <sys/time.h>
49 #include <sys/resource.h>
50 #include <sys/stat.h>
51 #include <sys/ttydefaults.h>
52 #include <sys/utsname.h>
53 
54 #include <ctype.h>
55 #include <errno.h>
56 #include <fcntl.h>
57 #include <locale.h>
58 #include <libutil.h>
59 #include <setjmp.h>
60 #include <signal.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <syslog.h>
64 #include <termios.h>
65 #include <time.h>
66 #include <unistd.h>
67 
68 #include "gettytab.h"
69 #include "extern.h"
70 #include "pathnames.h"
71 
72 /*
73  * Set the amount of running time that getty should accumulate
74  * before deciding that something is wrong and exit.
75  */
76 #define GETTY_TIMEOUT	60 /* seconds */
77 
78 #undef CTRL
79 #define CTRL(x)  (x&037)
80 
81 /* defines for auto detection of incoming PPP calls (->PAP/CHAP) */
82 
83 #define PPP_FRAME           0x7e  /* PPP Framing character */
84 #define PPP_STATION         0xff  /* "All Station" character */
85 #define PPP_ESCAPE          0x7d  /* Escape Character */
86 #define PPP_CONTROL         0x03  /* PPP Control Field */
87 #define PPP_CONTROL_ESCAPED 0x23  /* PPP Control Field, escaped */
88 #define PPP_LCP_HI          0xc0  /* LCP protocol - high byte */
89 #define PPP_LCP_LOW         0x21  /* LCP protocol - low byte */
90 
91 /* original mode; flags've been reset using values from <sys/ttydefaults.h> */
92 struct termios omode;
93 /* current mode */
94 struct termios tmode;
95 
96 static int crmod, digit, lower, upper;
97 
98 char	hostname[MAXHOSTNAMELEN];
99 static char	name[MAXLOGNAME*3];
100 static char	ttyn[32];
101 
102 #define	OBUFSIZ		128
103 #define	TABBUFSIZ	512
104 
105 static char	defent[TABBUFSIZ];
106 static char	tabent[TABBUFSIZ];
107 static const char	*tname;
108 
109 static char	*env[128];
110 
111 static char partab[] = {
112 	0001,0201,0201,0001,0201,0001,0001,0201,
113 	0202,0004,0003,0205,0005,0206,0201,0001,
114 	0201,0001,0001,0201,0001,0201,0201,0001,
115 	0001,0201,0201,0001,0201,0001,0001,0201,
116 	0200,0000,0000,0200,0000,0200,0200,0000,
117 	0000,0200,0200,0000,0200,0000,0000,0200,
118 	0000,0200,0200,0000,0200,0000,0000,0200,
119 	0200,0000,0000,0200,0000,0200,0200,0000,
120 	0200,0000,0000,0200,0000,0200,0200,0000,
121 	0000,0200,0200,0000,0200,0000,0000,0200,
122 	0000,0200,0200,0000,0200,0000,0000,0200,
123 	0200,0000,0000,0200,0000,0200,0200,0000,
124 	0000,0200,0200,0000,0200,0000,0000,0200,
125 	0200,0000,0000,0200,0000,0200,0200,0000,
126 	0200,0000,0000,0200,0000,0200,0200,0000,
127 	0000,0200,0200,0000,0200,0000,0000,0201
128 };
129 
130 #define	ERASE	tmode.c_cc[VERASE]
131 #define	KILL	tmode.c_cc[VKILL]
132 #define	EOT	tmode.c_cc[VEOF]
133 
134 #define	puts	Gputs
135 
136 static void	defttymode(void);
137 static void	dingdong(int);
138 static void	dogettytab(void);
139 static int	getname(void);
140 static void	interrupt(int);
141 static void	oflush(void);
142 static void	prompt(void);
143 static void	putchr(int);
144 static void	putf(const char *);
145 static void	putpad(const char *);
146 static void	puts(const char *);
147 static void	timeoverrun(int);
148 static char	*get_line(int);
149 static void	setttymode(int);
150 static int	opentty(const char *, int);
151 
152 static jmp_buf timeout;
153 
154 static void
155 dingdong(int signo __unused)
156 {
157 	alarm(0);
158 	longjmp(timeout, 1);
159 }
160 
161 static jmp_buf	intrupt;
162 
163 static void
164 interrupt(int signo __unused)
165 {
166 	longjmp(intrupt, 1);
167 }
168 
169 /*
170  * Action to take when getty is running too long.
171  */
172 static void
173 timeoverrun(int signo __unused)
174 {
175 
176 	syslog(LOG_ERR, "getty exiting due to excessive running time");
177 	exit(1);
178 }
179 
180 int
181 main(int argc, char *argv[])
182 {
183 	int first_sleep = 1, first_time = 1;
184 	struct rlimit limit;
185 	int rval;
186 
187 	signal(SIGINT, SIG_IGN);
188 	signal(SIGQUIT, SIG_IGN);
189 
190 	openlog("getty", LOG_CONS|LOG_PID, LOG_AUTH);
191 	gethostname(hostname, sizeof(hostname) - 1);
192 	hostname[sizeof(hostname) - 1] = '\0';
193 	if (hostname[0] == '\0')
194 		strcpy(hostname, "Amnesiac");
195 
196 	/*
197 	 * Limit running time to deal with broken or dead lines.
198 	 */
199 	(void)signal(SIGXCPU, timeoverrun);
200 	limit.rlim_max = RLIM_INFINITY;
201 	limit.rlim_cur = GETTY_TIMEOUT;
202 	(void)setrlimit(RLIMIT_CPU, &limit);
203 
204 	gettable("default", defent);
205 	gendefaults();
206 	tname = "default";
207 	if (argc > 1)
208 		tname = argv[1];
209 
210 	/*
211 	 * The following is a work around for vhangup interactions
212 	 * which cause great problems getting window systems started.
213 	 * If the tty line is "-", we do the old style getty presuming
214 	 * that the file descriptors are already set up for us.
215 	 * J. Gettys - MIT Project Athena.
216 	 */
217 	if (argc <= 2 || strcmp(argv[2], "-") == 0)
218 	    strcpy(ttyn, ttyname(STDIN_FILENO));
219 	else {
220 	    strcpy(ttyn, _PATH_DEV);
221 	    strlcat(ttyn, argv[2], sizeof(ttyn));
222 	    if (strcmp(argv[0], "+") != 0) {
223 		chown(ttyn, 0, 0);
224 		chmod(ttyn, 0600);
225 		revoke(ttyn);
226 
227 		/*
228 		 * Do the first scan through gettytab.
229 		 * Terminal mode parameters will be wrong until
230 		 * defttymode() called, but they're irrelevant for
231 		 * the initial setup of the terminal device.
232 		 */
233 		dogettytab();
234 
235 		/*
236 		 * Init or answer modem sequence has been specified.
237 		 */
238 		if (IC || AC) {
239 			if (!opentty(ttyn, O_RDWR|O_NONBLOCK))
240 				exit(1);
241 			defttymode();
242 			setttymode(1);
243 		}
244 
245 		if (IC) {
246 			if (getty_chat(IC, CT, DC) > 0) {
247 				syslog(LOG_ERR, "modem init problem on %s", ttyn);
248 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
249 				exit(1);
250 			}
251 		}
252 
253 		if (AC) {
254 			fd_set rfds;
255 			struct timeval to;
256 			int i;
257 
258 			FD_ZERO(&rfds);
259 			FD_SET(0, &rfds);
260         		to.tv_sec = RT;
261         		to.tv_usec = 0;
262 			i = select(32, &rfds, NULL, NULL, RT ? &to : NULL);
263         		if (i < 0) {
264 				syslog(LOG_ERR, "select %s: %m", ttyn);
265 			} else if (i == 0) {
266 				syslog(LOG_NOTICE, "recycle tty %s", ttyn);
267 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
268 				exit(0);  /* recycle for init */
269 			}
270 			i = getty_chat(AC, CT, DC);
271 			if (i > 0) {
272 				syslog(LOG_ERR, "modem answer problem on %s", ttyn);
273 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
274 				exit(1);
275 			}
276 		} else { /* maybe blocking open */
277 			if (!opentty(ttyn, O_RDWR | (NC ? O_NONBLOCK : 0 )))
278 				exit(1);
279 		}
280 	    }
281 	}
282 
283 	defttymode();
284 	for (;;) {
285 
286 		/*
287 		 * if a delay was specified then sleep for that
288 		 * number of seconds before writing the initial prompt
289 		 */
290 		if (first_sleep && DE) {
291 		    sleep(DE);
292 		    /* remove any noise */
293 		    (void)tcflush(STDIN_FILENO, TCIOFLUSH);
294 		}
295 		first_sleep = 0;
296 
297 		setttymode(0);
298 		if (AB) {
299 			tname = autobaud();
300 			dogettytab();
301 			continue;
302 		}
303 		if (PS) {
304 			tname = portselector();
305 			dogettytab();
306 			continue;
307 		}
308 		if (CL && *CL)
309 			putpad(CL);
310 		edithost(HE);
311 
312 		/* if this is the first time through this, and an
313 		   issue file has been given, then send it */
314 		if (first_time && IF) {
315 			int fd;
316 
317 			if ((fd = open(IF, O_RDONLY)) != -1) {
318 				char * cp;
319 
320 				while ((cp = get_line(fd)) != NULL) {
321 					  putf(cp);
322 				}
323 				close(fd);
324 			}
325 		}
326 		first_time = 0;
327 
328 		if (IMP && *IMP && !(PL && PP))
329 			system(IMP);
330 		if (IM && *IM && !(PL && PP))
331 			putf(IM);
332 		if (setjmp(timeout)) {
333 			cfsetispeed(&tmode, B0);
334 			cfsetospeed(&tmode, B0);
335 			(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
336 			exit(1);
337 		}
338 		if (TO) {
339 			signal(SIGALRM, dingdong);
340 			alarm(TO);
341 		}
342 
343 		rval = 0;
344 		if (AL) {
345 			const char *p = AL;
346 			char *q = name;
347 
348 			while (*p && q < &name[sizeof name - 1]) {
349 				if (isupper(*p))
350 					upper = 1;
351 				else if (islower(*p))
352 					lower = 1;
353 				else if (isdigit(*p))
354 					digit = 1;
355 				*q++ = *p++;
356 			}
357 		} else if (!(PL && PP))
358 			rval = getname();
359 		if (rval == 2 || (PL && PP)) {
360 			oflush();
361 			alarm(0);
362 			limit.rlim_max = RLIM_INFINITY;
363 			limit.rlim_cur = RLIM_INFINITY;
364 			(void)setrlimit(RLIMIT_CPU, &limit);
365 			execle(PP, "ppplogin", ttyn, (char *) 0, env);
366 			syslog(LOG_ERR, "%s: %m", PP);
367 			exit(1);
368 		} else if (rval || AL) {
369 			int i;
370 
371 			oflush();
372 			alarm(0);
373 			signal(SIGALRM, SIG_DFL);
374 			if (name[0] == '\0')
375 				continue;
376 			if (name[0] == '-') {
377 				puts("user names may not start with '-'.");
378 				continue;
379 			}
380 			if (!(upper || lower || digit)) {
381 				if (AL) {
382 					syslog(LOG_ERR,
383 					    "invalid auto-login name: %s", AL);
384 					exit(1);
385 				} else
386 					continue;
387 			}
388 			set_flags(2);
389 			if (crmod) {
390 				tmode.c_iflag |= ICRNL;
391 				tmode.c_oflag |= ONLCR;
392 			}
393 #if REALLY_OLD_TTYS
394 			if (upper || UC)
395 				tmode.sg_flags |= LCASE;
396 			if (lower || LC)
397 				tmode.sg_flags &= ~LCASE;
398 #endif
399 			if (tcsetattr(STDIN_FILENO, TCSANOW, &tmode) < 0) {
400 				syslog(LOG_ERR, "tcsetattr %s: %m", ttyn);
401 				exit(1);
402 			}
403 			signal(SIGINT, SIG_DFL);
404 			for (i = 0; environ[i] != (char *)0; i++)
405 				env[i] = environ[i];
406 			makeenv(&env[i]);
407 
408 			limit.rlim_max = RLIM_INFINITY;
409 			limit.rlim_cur = RLIM_INFINITY;
410 			(void)setrlimit(RLIMIT_CPU, &limit);
411 			execle(LO, "login", AL ? "-fp" : "-p", name,
412 			    (char *) 0, env);
413 			syslog(LOG_ERR, "%s: %m", LO);
414 			exit(1);
415 		}
416 		alarm(0);
417 		signal(SIGALRM, SIG_DFL);
418 		signal(SIGINT, SIG_IGN);
419 		if (NX && *NX) {
420 			tname = NX;
421 			dogettytab();
422 		}
423 	}
424 }
425 
426 static int
427 opentty(const char *tty, int flags)
428 {
429 	int failopenlogged = 0, i, saved_errno;
430 
431 	while ((i = open(tty, flags)) == -1)
432 	{
433 		saved_errno = errno;
434 		if (!failopenlogged) {
435 			syslog(LOG_ERR, "open %s: %m", tty);
436 			failopenlogged = 1;
437 		}
438 		if (saved_errno == ENOENT)
439 			return 0;
440 		sleep(60);
441 	}
442 	if (login_tty(i) < 0) {
443 		if (daemon(0,0) < 0) {
444 			syslog(LOG_ERR,"daemon: %m");
445 			close(i);
446 			return 0;
447 		}
448 		if (login_tty(i) < 0) {
449 			syslog(LOG_ERR, "login_tty %s: %m", tty);
450 			close(i);
451 			return 0;
452 		}
453 	}
454 	return 1;
455 }
456 
457 static void
458 defttymode(void)
459 {
460 	struct termios def;
461 
462 	/* Start with default tty settings. */
463 	if (tcgetattr(STDIN_FILENO, &tmode) < 0) {
464 		syslog(LOG_ERR, "tcgetattr %s: %m", ttyn);
465 		exit(1);
466 	}
467 	omode = tmode; /* fill c_cc for dogettytab() */
468 	dogettytab();
469 	/*
470 	 * Don't rely on the driver too much, and initialize crucial
471 	 * things according to <sys/ttydefaults.h>.  Avoid clobbering
472 	 * the c_cc[] settings however, the console drivers might wish
473 	 * to leave their idea of the preferred VERASE key value
474 	 * there.
475 	 */
476 	cfmakesane(&def);
477 	tmode.c_iflag = def.c_iflag;
478 	tmode.c_oflag = def.c_oflag;
479 	tmode.c_lflag = def.c_lflag;
480 	tmode.c_cflag = def.c_cflag;
481 	if (NC)
482 		tmode.c_cflag |= CLOCAL;
483 	omode = tmode;
484 }
485 
486 static void
487 setttymode(int raw)
488 {
489 	int off = 0;
490 
491 	(void)tcflush(STDIN_FILENO, TCIOFLUSH);	/* clear out the crap */
492 	ioctl(STDIN_FILENO, FIONBIO, &off);	/* turn off non-blocking mode */
493 	ioctl(STDIN_FILENO, FIOASYNC, &off);	/* ditto for async mode */
494 
495 	if (IS)
496 		cfsetispeed(&tmode, speed(IS));
497 	else if (SP)
498 		cfsetispeed(&tmode, speed(SP));
499 	if (OS)
500 		cfsetospeed(&tmode, speed(OS));
501 	else if (SP)
502 		cfsetospeed(&tmode, speed(SP));
503 	set_flags(0);
504 	setchars();
505 	if (raw)
506 		cfmakeraw(&tmode);
507 	if (tcsetattr(STDIN_FILENO, TCSANOW, &tmode) < 0) {
508 		syslog(LOG_ERR, "tcsetattr %s: %m", ttyn);
509 		exit(1);
510 	}
511 }
512 
513 
514 static int
515 getname(void)
516 {
517 	int c;
518 	char *np;
519 	unsigned char cs;
520 	int ppp_state = 0;
521 	int ppp_connection = 0;
522 
523 	/*
524 	 * Interrupt may happen if we use CBREAK mode
525 	 */
526 	if (setjmp(intrupt)) {
527 		signal(SIGINT, SIG_IGN);
528 		return (0);
529 	}
530 	signal(SIGINT, interrupt);
531 	set_flags(1);
532 	prompt();
533 	oflush();
534 	if (PF > 0) {
535 		sleep(PF);
536 		PF = 0;
537 	}
538 	if (tcsetattr(STDIN_FILENO, TCSANOW, &tmode) < 0) {
539 		syslog(LOG_ERR, "%s: %m", ttyn);
540 		exit(1);
541 	}
542 	crmod = digit = lower = upper = 0;
543 	np = name;
544 	for (;;) {
545 		oflush();
546 		if (read(STDIN_FILENO, &cs, 1) <= 0)
547 			exit(0);
548 		if ((c = cs&0177) == 0)
549 			return (0);
550 
551 		/* PPP detection state machine..
552 		   Look for sequences:
553 		   PPP_FRAME, PPP_STATION, PPP_ESCAPE, PPP_CONTROL_ESCAPED or
554 		   PPP_FRAME, PPP_STATION, PPP_CONTROL (deviant from RFC)
555 		   See RFC1662.
556 		   Derived from code from Michael Hancock, <michaelh@cet.co.jp>
557 		   and Erik 'PPP' Olson, <eriko@wrq.com>
558 		 */
559 
560 		if (PP && (cs == PPP_FRAME)) {
561 			ppp_state = 1;
562 		} else if (ppp_state == 1 && cs == PPP_STATION) {
563 			ppp_state = 2;
564 		} else if (ppp_state == 2 && cs == PPP_ESCAPE) {
565 			ppp_state = 3;
566 		} else if ((ppp_state == 2 && cs == PPP_CONTROL)
567 			|| (ppp_state == 3 && cs == PPP_CONTROL_ESCAPED)) {
568 			ppp_state = 4;
569 		} else if (ppp_state == 4 && cs == PPP_LCP_HI) {
570 			ppp_state = 5;
571 		} else if (ppp_state == 5 && cs == PPP_LCP_LOW) {
572 			ppp_connection = 1;
573 			break;
574 		} else {
575 			ppp_state = 0;
576 		}
577 
578 		if (c == EOT || c == CTRL('d'))
579 			exit(0);
580 		if (c == '\r' || c == '\n' || np >= &name[sizeof name-1]) {
581 			putf("\r\n");
582 			break;
583 		}
584 		if (islower(c))
585 			lower = 1;
586 		else if (isupper(c))
587 			upper = 1;
588 		else if (c == ERASE || c == '\b' || c == 0177) {
589 			if (np > name) {
590 				np--;
591 				if (cfgetospeed(&tmode) >= 1200)
592 					puts("\b \b");
593 				else
594 					putchr(cs);
595 			}
596 			continue;
597 		} else if (c == KILL || c == CTRL('u')) {
598 			putchr('\r');
599 			if (cfgetospeed(&tmode) < 1200)
600 				putchr('\n');
601 			/* this is the way they do it down under ... */
602 			else if (np > name)
603 				puts("                                     \r");
604 			prompt();
605 			digit = lower = upper = 0;
606 			np = name;
607 			continue;
608 		} else if (isdigit(c))
609 			digit = 1;
610 		if (IG && (c <= ' ' || c > 0176))
611 			continue;
612 		*np++ = c;
613 		putchr(cs);
614 	}
615 	signal(SIGINT, SIG_IGN);
616 	*np = 0;
617 	if (c == '\r')
618 		crmod = 1;
619 	if ((upper && !lower && !LC) || UC)
620 		for (np = name; *np; np++)
621 			if (isupper(*np))
622 				*np = tolower(*np);
623 	return (1 + ppp_connection);
624 }
625 
626 static void
627 putpad(const char *s)
628 {
629 	int pad = 0;
630 	speed_t ospeed = cfgetospeed(&tmode);
631 
632 	if (isdigit(*s)) {
633 		while (isdigit(*s)) {
634 			pad *= 10;
635 			pad += *s++ - '0';
636 		}
637 		pad *= 10;
638 		if (*s == '.' && isdigit(s[1])) {
639 			pad += s[1] - '0';
640 			s += 2;
641 		}
642 	}
643 
644 	puts(s);
645 	/*
646 	 * If no delay needed, or output speed is
647 	 * not comprehensible, then don't try to delay.
648 	 */
649 	if (pad == 0 || ospeed <= 0)
650 		return;
651 
652 	/*
653 	 * Round up by a half a character frame, and then do the delay.
654 	 * Too bad there are no user program accessible programmed delays.
655 	 * Transmitting pad characters slows many terminals down and also
656 	 * loads the system.
657 	 */
658 	pad = (pad * ospeed + 50000) / 100000;
659 	while (pad--)
660 		putchr(*PC);
661 }
662 
663 static void
664 puts(const char *s)
665 {
666 	while (*s)
667 		putchr(*s++);
668 }
669 
670 static char	outbuf[OBUFSIZ];
671 static int	obufcnt = 0;
672 
673 static void
674 putchr(int cc)
675 {
676 	char c;
677 
678 	c = cc;
679 	if (!NP) {
680 		c |= partab[c&0177] & 0200;
681 		if (OP)
682 			c ^= 0200;
683 	}
684 	if (!UB) {
685 		outbuf[obufcnt++] = c;
686 		if (obufcnt >= OBUFSIZ)
687 			oflush();
688 	} else
689 		write(STDOUT_FILENO, &c, 1);
690 }
691 
692 static void
693 oflush(void)
694 {
695 	if (obufcnt)
696 		write(STDOUT_FILENO, outbuf, obufcnt);
697 	obufcnt = 0;
698 }
699 
700 static void
701 prompt(void)
702 {
703 
704 	putf(LM);
705 	if (CO)
706 		putchr('\n');
707 }
708 
709 
710 static char *
711 get_line(int fd)
712 {
713 	size_t i = 0;
714 	static char linebuf[512];
715 
716 	/*
717 	 * This is certainly slow, but it avoids having to include
718 	 * stdio.h unnecessarily. Issue files should be small anyway.
719 	 */
720 	while (i < (sizeof linebuf - 3) && read(fd, linebuf+i, 1)==1) {
721 		if (linebuf[i] == '\n') {
722 			/* Don't rely on newline mode, assume raw */
723 			linebuf[i++] = '\r';
724 			linebuf[i++] = '\n';
725 			linebuf[i] = '\0';
726 			return linebuf;
727 		}
728 		++i;
729 	}
730 	linebuf[i] = '\0';
731 	return i ? linebuf : 0;
732 }
733 
734 static void
735 putf(const char *cp)
736 {
737 	time_t t;
738 	char *slash, db[100];
739 
740 	static struct utsname kerninfo;
741 
742 	if (!*kerninfo.sysname)
743 		uname(&kerninfo);
744 
745 	while (*cp) {
746 		if (*cp != '%') {
747 			putchr(*cp++);
748 			continue;
749 		}
750 		switch (*++cp) {
751 
752 		case 't':
753 			slash = strrchr(ttyn, '/');
754 			if (slash == (char *) 0)
755 				puts(ttyn);
756 			else
757 				puts(&slash[1]);
758 			break;
759 
760 		case 'h':
761 			puts(editedhost);
762 			break;
763 
764 		case 'd': {
765 			t = (time_t)0;
766 			(void)time(&t);
767 			if (Lo)
768 				(void)setlocale(LC_TIME, Lo);
769 			(void)strftime(db, sizeof(db), DF, localtime(&t));
770 			puts(db);
771 			break;
772 
773 		case 's':
774 			puts(kerninfo.sysname);
775 			break;
776 
777 		case 'm':
778 			puts(kerninfo.machine);
779 			break;
780 
781 		case 'r':
782 			puts(kerninfo.release);
783 			break;
784 
785 		case 'v':
786 			puts(kerninfo.version);
787 			break;
788 		}
789 
790 		case '%':
791 			putchr('%');
792 			break;
793 		}
794 		cp++;
795 	}
796 }
797 
798 /*
799  * Read a gettytab database entry and perform necessary quirks.
800  */
801 static void
802 dogettytab(void)
803 {
804 
805 	/* Read the database entry. */
806 	gettable(tname, tabent);
807 
808 	/*
809 	 * Avoid inheriting the parity values from the default entry
810 	 * if any of them is set in the current entry.
811 	 * Mixing different parity settings is unreasonable.
812 	 */
813 	if (OPset || EPset || APset || NPset)
814 		OPset = EPset = APset = NPset = 1;
815 
816 	/* Fill in default values for unset capabilities. */
817 	setdefaults();
818 }
819