xref: /freebsd/libexec/getty/main.c (revision 2e1417489338b971e5fd599ff48b5f65df9e8d3b)
1 /*-
2  * Copyright (c) 1980, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 static const char copyright[] =
36 "@(#) Copyright (c) 1980, 1993\n\
37 	The Regents of the University of California.  All rights reserved.\n";
38 #endif /* not lint */
39 
40 #ifndef lint
41 #if 0
42 static char sccsid[] = "@(#)from: main.c	8.1 (Berkeley) 6/20/93";
43 #endif
44 #endif /* not lint */
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
47 
48 #include <sys/param.h>
49 #include <sys/ioctl.h>
50 #include <sys/time.h>
51 #include <sys/resource.h>
52 #include <sys/stat.h>
53 #include <sys/ttydefaults.h>
54 #include <sys/utsname.h>
55 
56 #include <ctype.h>
57 #include <errno.h>
58 #include <fcntl.h>
59 #include <locale.h>
60 #include <libutil.h>
61 #include <setjmp.h>
62 #include <signal.h>
63 #include <stdlib.h>
64 #include <string.h>
65 #include <syslog.h>
66 #include <termios.h>
67 #include <time.h>
68 #include <unistd.h>
69 
70 #include "gettytab.h"
71 #include "extern.h"
72 #include "pathnames.h"
73 
74 /*
75  * Set the amount of running time that getty should accumulate
76  * before deciding that something is wrong and exit.
77  */
78 #define GETTY_TIMEOUT	60 /* seconds */
79 
80 #undef CTRL
81 #define CTRL(x)  (x&037)
82 
83 /* defines for auto detection of incoming PPP calls (->PAP/CHAP) */
84 
85 #define PPP_FRAME           0x7e  /* PPP Framing character */
86 #define PPP_STATION         0xff  /* "All Station" character */
87 #define PPP_ESCAPE          0x7d  /* Escape Character */
88 #define PPP_CONTROL         0x03  /* PPP Control Field */
89 #define PPP_CONTROL_ESCAPED 0x23  /* PPP Control Field, escaped */
90 #define PPP_LCP_HI          0xc0  /* LCP protocol - high byte */
91 #define PPP_LCP_LOW         0x21  /* LCP protocol - low byte */
92 
93 /* original mode; flags've been reset using values from <sys/ttydefaults.h> */
94 struct termios omode;
95 /* current mode */
96 struct termios tmode;
97 
98 int crmod, digit, lower, upper;
99 
100 char	hostname[MAXHOSTNAMELEN];
101 char	name[MAXLOGNAME*3];
102 char	dev[] = _PATH_DEV;
103 char	ttyn[32];
104 
105 #define	OBUFSIZ		128
106 #define	TABBUFSIZ	512
107 
108 char	defent[TABBUFSIZ];
109 char	tabent[TABBUFSIZ];
110 const	char *tname;
111 
112 char	*env[128];
113 
114 char partab[] = {
115 	0001,0201,0201,0001,0201,0001,0001,0201,
116 	0202,0004,0003,0205,0005,0206,0201,0001,
117 	0201,0001,0001,0201,0001,0201,0201,0001,
118 	0001,0201,0201,0001,0201,0001,0001,0201,
119 	0200,0000,0000,0200,0000,0200,0200,0000,
120 	0000,0200,0200,0000,0200,0000,0000,0200,
121 	0000,0200,0200,0000,0200,0000,0000,0200,
122 	0200,0000,0000,0200,0000,0200,0200,0000,
123 	0200,0000,0000,0200,0000,0200,0200,0000,
124 	0000,0200,0200,0000,0200,0000,0000,0200,
125 	0000,0200,0200,0000,0200,0000,0000,0200,
126 	0200,0000,0000,0200,0000,0200,0200,0000,
127 	0000,0200,0200,0000,0200,0000,0000,0200,
128 	0200,0000,0000,0200,0000,0200,0200,0000,
129 	0200,0000,0000,0200,0000,0200,0200,0000,
130 	0000,0200,0200,0000,0200,0000,0000,0201
131 };
132 
133 #define	ERASE	tmode.c_cc[VERASE]
134 #define	KILL	tmode.c_cc[VKILL]
135 #define	EOT	tmode.c_cc[VEOF]
136 
137 #define	puts	Gputs
138 
139 static void	defttymode(void);
140 static void	dingdong(int);
141 static void	dogettytab(void);
142 static int	getname(void);
143 static void	interrupt(int);
144 static void	oflush(void);
145 static void	prompt(void);
146 static void	putchr(int);
147 static void	putf(const char *);
148 static void	putpad(const char *);
149 static void	puts(const char *);
150 static void	timeoverrun(int);
151 static char	*getline(int);
152 static void	setttymode(int);
153 static int	opentty(const char *, int);
154 
155 jmp_buf timeout;
156 
157 static void
158 dingdong(int signo __unused)
159 {
160 	alarm(0);
161 	longjmp(timeout, 1);
162 }
163 
164 jmp_buf	intrupt;
165 
166 static void
167 interrupt(int signo __unused)
168 {
169 	longjmp(intrupt, 1);
170 }
171 
172 /*
173  * Action to take when getty is running too long.
174  */
175 static void
176 timeoverrun(int signo __unused)
177 {
178 
179 	syslog(LOG_ERR, "getty exiting due to excessive running time");
180 	exit(1);
181 }
182 
183 int
184 main(int argc, char *argv[])
185 {
186 	extern	char **environ;
187 	int first_sleep = 1, first_time = 1;
188 	struct rlimit limit;
189 	int rval;
190 
191 	signal(SIGINT, SIG_IGN);
192 	signal(SIGQUIT, SIG_IGN);
193 
194 	openlog("getty", LOG_ODELAY|LOG_CONS|LOG_PID, LOG_AUTH);
195 	gethostname(hostname, sizeof(hostname) - 1);
196 	hostname[sizeof(hostname) - 1] = '\0';
197 	if (hostname[0] == '\0')
198 		strcpy(hostname, "Amnesiac");
199 
200 	/*
201 	 * Limit running time to deal with broken or dead lines.
202 	 */
203 	(void)signal(SIGXCPU, timeoverrun);
204 	limit.rlim_max = RLIM_INFINITY;
205 	limit.rlim_cur = GETTY_TIMEOUT;
206 	(void)setrlimit(RLIMIT_CPU, &limit);
207 
208 	gettable("default", defent);
209 	gendefaults();
210 	tname = "default";
211 	if (argc > 1)
212 		tname = argv[1];
213 
214 	/*
215 	 * The following is a work around for vhangup interactions
216 	 * which cause great problems getting window systems started.
217 	 * If the tty line is "-", we do the old style getty presuming
218 	 * that the file descriptors are already set up for us.
219 	 * J. Gettys - MIT Project Athena.
220 	 */
221 	if (argc <= 2 || strcmp(argv[2], "-") == 0)
222 	    strcpy(ttyn, ttyname(STDIN_FILENO));
223 	else {
224 	    strcpy(ttyn, dev);
225 	    strncat(ttyn, argv[2], sizeof(ttyn)-sizeof(dev));
226 	    if (strcmp(argv[0], "+") != 0) {
227 		chown(ttyn, 0, 0);
228 		chmod(ttyn, 0600);
229 		revoke(ttyn);
230 
231 		/*
232 		 * Do the first scan through gettytab.
233 		 * Terminal mode parameters will be wrong until
234 		 * defttymode() called, but they're irrelevant for
235 		 * the initial setup of the terminal device.
236 		 */
237 		dogettytab();
238 
239 		/*
240 		 * Init or answer modem sequence has been specified.
241 		 */
242 		if (IC || AC) {
243 			if (!opentty(ttyn, O_RDWR|O_NONBLOCK))
244 				exit(1);
245 			defttymode();
246 			setttymode(1);
247 		}
248 
249 		if (IC) {
250 			if (getty_chat(IC, CT, DC) > 0) {
251 				syslog(LOG_ERR, "modem init problem on %s", ttyn);
252 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
253 				exit(1);
254 			}
255 		}
256 
257 		if (AC) {
258 			int i, rfds;
259 			struct timeval to;
260 
261         		rfds = 1 << 0;	/* FD_SET */
262         		to.tv_sec = RT;
263         		to.tv_usec = 0;
264         		i = select(32, (fd_set*)&rfds, (fd_set*)NULL,
265         			       (fd_set*)NULL, RT ? &to : NULL);
266         		if (i < 0) {
267 				syslog(LOG_ERR, "select %s: %m", ttyn);
268 			} else if (i == 0) {
269 				syslog(LOG_NOTICE, "recycle tty %s", ttyn);
270 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
271 				exit(0);  /* recycle for init */
272 			}
273 			i = getty_chat(AC, CT, DC);
274 			if (i > 0) {
275 				syslog(LOG_ERR, "modem answer problem on %s", ttyn);
276 				(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
277 				exit(1);
278 			}
279 		} else { /* maybe blocking open */
280 			if (!opentty(ttyn, O_RDWR | (NC ? O_NONBLOCK : 0 )))
281 				exit(1);
282 		}
283 	    }
284 	}
285 
286 	defttymode();
287 	for (;;) {
288 
289 		/*
290 		 * if a delay was specified then sleep for that
291 		 * number of seconds before writing the initial prompt
292 		 */
293 		if (first_sleep && DE) {
294 		    sleep(DE);
295 		    /* remove any noise */
296 		    (void)tcflush(STDIN_FILENO, TCIOFLUSH);
297 		}
298 		first_sleep = 0;
299 
300 		setttymode(0);
301 		if (AB) {
302 			tname = autobaud();
303 			dogettytab();
304 			continue;
305 		}
306 		if (PS) {
307 			tname = portselector();
308 			dogettytab();
309 			continue;
310 		}
311 		if (CL && *CL)
312 			putpad(CL);
313 		edithost(HE);
314 
315 		/* if this is the first time through this, and an
316 		   issue file has been given, then send it */
317 		if (first_time && IF) {
318 			int fd;
319 
320 			if ((fd = open(IF, O_RDONLY)) != -1) {
321 				char * cp;
322 
323 				while ((cp = getline(fd)) != NULL) {
324 					  putf(cp);
325 				}
326 				close(fd);
327 			}
328 		}
329 		first_time = 0;
330 
331 		if (IM && *IM && !(PL && PP))
332 			putf(IM);
333 		if (setjmp(timeout)) {
334 			cfsetispeed(&tmode, B0);
335 			cfsetospeed(&tmode, B0);
336 			(void)tcsetattr(STDIN_FILENO, TCSANOW, &tmode);
337 			exit(1);
338 		}
339 		if (TO) {
340 			signal(SIGALRM, dingdong);
341 			alarm(TO);
342 		}
343 
344 		rval = 0;
345 		if (AL) {
346 			const char *p = AL;
347 			char *q = name;
348 
349 			while (*p && q < &name[sizeof name - 1]) {
350 				if (isupper(*p))
351 					upper = 1;
352 				else if (islower(*p))
353 					lower = 1;
354 				else if (isdigit(*p))
355 					digit = 1;
356 				*q++ = *p++;
357 			}
358 		} else if (!(PL && PP))
359 			rval = getname();
360 		if (rval == 2 || (PL && PP)) {
361 			oflush();
362 			alarm(0);
363 			limit.rlim_max = RLIM_INFINITY;
364 			limit.rlim_cur = RLIM_INFINITY;
365 			(void)setrlimit(RLIMIT_CPU, &limit);
366 			execle(PP, "ppplogin", ttyn, (char *) 0, env);
367 			syslog(LOG_ERR, "%s: %m", PP);
368 			exit(1);
369 		} else if (rval || AL) {
370 			int i;
371 
372 			oflush();
373 			alarm(0);
374 			signal(SIGALRM, SIG_DFL);
375 			if (name[0] == '\0')
376 				continue;
377 			if (name[0] == '-') {
378 				puts("user names may not start with '-'.");
379 				continue;
380 			}
381 			if (!(upper || lower || digit)) {
382 				if (AL) {
383 					syslog(LOG_ERR,
384 					    "invalid auto-login name: %s", AL);
385 					exit(1);
386 				} else
387 					continue;
388 			}
389 			set_flags(2);
390 			if (crmod) {
391 				tmode.c_iflag |= ICRNL;
392 				tmode.c_oflag |= ONLCR;
393 			}
394 #if REALLY_OLD_TTYS
395 			if (upper || UC)
396 				tmode.sg_flags |= LCASE;
397 			if (lower || LC)
398 				tmode.sg_flags &= ~LCASE;
399 #endif
400 			if (tcsetattr(STDIN_FILENO, TCSANOW, &tmode) < 0) {
401 				syslog(LOG_ERR, "tcsetattr %s: %m", ttyn);
402 				exit(1);
403 			}
404 			signal(SIGINT, SIG_DFL);
405 			for (i = 0; environ[i] != (char *)0; i++)
406 				env[i] = environ[i];
407 			makeenv(&env[i]);
408 
409 			limit.rlim_max = RLIM_INFINITY;
410 			limit.rlim_cur = RLIM_INFINITY;
411 			(void)setrlimit(RLIMIT_CPU, &limit);
412 			execle(LO, "login", AL ? "-fp" : "-p", name,
413 			    (char *) 0, env);
414 			syslog(LOG_ERR, "%s: %m", LO);
415 			exit(1);
416 		}
417 		alarm(0);
418 		signal(SIGALRM, SIG_DFL);
419 		signal(SIGINT, SIG_IGN);
420 		if (NX && *NX) {
421 			tname = NX;
422 			dogettytab();
423 		}
424 	}
425 }
426 
427 static int
428 opentty(const char *tty, int flags)
429 {
430 	int i;
431 	int failopenlogged = 0;
432 
433 	while ((i = open(tty, flags)) == -1)
434 	{
435 		if (!failopenlogged) {
436 			syslog(LOG_ERR, "open %s: %m", tty);
437 			failopenlogged = 1;
438 		}
439 		sleep(60);
440 	}
441 	if (login_tty(i) < 0) {
442 		if (daemon(0,0) < 0) {
443 			syslog(LOG_ERR,"daemon: %m");
444 			close(i);
445 			return 0;
446 		}
447 		if (login_tty(i) < 0) {
448 			syslog(LOG_ERR, "login_tty %s: %m", tty);
449 			close(i);
450 			return 0;
451 		}
452 	}
453 	return 1;
454 }
455 
456 static void
457 defttymode(void)
458 {
459 	struct termios def;
460 
461 	/* Start with default tty settings. */
462 	if (tcgetattr(STDIN_FILENO, &tmode) < 0) {
463 		syslog(LOG_ERR, "tcgetattr %s: %m", ttyn);
464 		exit(1);
465 	}
466 	omode = tmode; /* fill c_cc for dogettytab() */
467 	dogettytab();
468 	/*
469 	 * Don't rely on the driver too much, and initialize crucial
470 	 * things according to <sys/ttydefaults.h>.  Avoid clobbering
471 	 * the c_cc[] settings however, the console drivers might wish
472 	 * to leave their idea of the preferred VERASE key value
473 	 * there.
474 	 */
475 	cfmakesane(&def);
476 	tmode.c_iflag = def.c_iflag;
477 	tmode.c_oflag = def.c_oflag;
478 	tmode.c_lflag = def.c_lflag;
479 	tmode.c_cflag = def.c_cflag;
480 	if (NC)
481 		tmode.c_cflag |= CLOCAL;
482 	omode = tmode;
483 }
484 
485 static void
486 setttymode(int raw)
487 {
488 	int off = 0;
489 
490 	(void)tcflush(STDIN_FILENO, TCIOFLUSH);	/* clear out the crap */
491 	ioctl(STDIN_FILENO, FIONBIO, &off);	/* turn off non-blocking mode */
492 	ioctl(STDIN_FILENO, FIOASYNC, &off);	/* ditto for async mode */
493 
494 	if (IS)
495 		cfsetispeed(&tmode, speed(IS));
496 	else if (SP)
497 		cfsetispeed(&tmode, speed(SP));
498 	if (OS)
499 		cfsetospeed(&tmode, speed(OS));
500 	else if (SP)
501 		cfsetospeed(&tmode, speed(SP));
502 	set_flags(0);
503 	setchars();
504 	if (raw)
505 		cfmakeraw(&tmode);
506 	if (tcsetattr(STDIN_FILENO, TCSANOW, &tmode) < 0) {
507 		syslog(LOG_ERR, "tcsetattr %s: %m", ttyn);
508 		exit(1);
509 	}
510 }
511 
512 
513 static int
514 getname(void)
515 {
516 	int c;
517 	char *np;
518 	unsigned char cs;
519 	int ppp_state = 0;
520 	int ppp_connection = 0;
521 
522 	/*
523 	 * Interrupt may happen if we use CBREAK mode
524 	 */
525 	if (setjmp(intrupt)) {
526 		signal(SIGINT, SIG_IGN);
527 		return (0);
528 	}
529 	signal(SIGINT, interrupt);
530 	set_flags(1);
531 	prompt();
532 	oflush();
533 	if (PF > 0) {
534 		sleep(PF);
535 		PF = 0;
536 	}
537 	if (tcsetattr(STDIN_FILENO, TCSANOW, &tmode) < 0) {
538 		syslog(LOG_ERR, "%s: %m", ttyn);
539 		exit(1);
540 	}
541 	crmod = digit = lower = upper = 0;
542 	np = name;
543 	for (;;) {
544 		oflush();
545 		if (read(STDIN_FILENO, &cs, 1) <= 0)
546 			exit(0);
547 		if ((c = cs&0177) == 0)
548 			return (0);
549 
550 		/* PPP detection state machine..
551 		   Look for sequences:
552 		   PPP_FRAME, PPP_STATION, PPP_ESCAPE, PPP_CONTROL_ESCAPED or
553 		   PPP_FRAME, PPP_STATION, PPP_CONTROL (deviant from RFC)
554 		   See RFC1662.
555 		   Derived from code from Michael Hancock, <michaelh@cet.co.jp>
556 		   and Erik 'PPP' Olson, <eriko@wrq.com>
557 		 */
558 
559 		if (PP && (cs == PPP_FRAME)) {
560 			ppp_state = 1;
561 		} else if (ppp_state == 1 && cs == PPP_STATION) {
562 			ppp_state = 2;
563 		} else if (ppp_state == 2 && cs == PPP_ESCAPE) {
564 			ppp_state = 3;
565 		} else if ((ppp_state == 2 && cs == PPP_CONTROL)
566 			|| (ppp_state == 3 && cs == PPP_CONTROL_ESCAPED)) {
567 			ppp_state = 4;
568 		} else if (ppp_state == 4 && cs == PPP_LCP_HI) {
569 			ppp_state = 5;
570 		} else if (ppp_state == 5 && cs == PPP_LCP_LOW) {
571 			ppp_connection = 1;
572 			break;
573 		} else {
574 			ppp_state = 0;
575 		}
576 
577 		if (c == EOT || c == CTRL('d'))
578 			exit(0);
579 		if (c == '\r' || c == '\n' || np >= &name[sizeof name-1]) {
580 			putf("\r\n");
581 			break;
582 		}
583 		if (islower(c))
584 			lower = 1;
585 		else if (isupper(c))
586 			upper = 1;
587 		else if (c == ERASE || c == '\b' || c == 0177) {
588 			if (np > name) {
589 				np--;
590 				if (cfgetospeed(&tmode) >= 1200)
591 					puts("\b \b");
592 				else
593 					putchr(cs);
594 			}
595 			continue;
596 		} else if (c == KILL || c == CTRL('u')) {
597 			putchr('\r');
598 			if (cfgetospeed(&tmode) < 1200)
599 				putchr('\n');
600 			/* this is the way they do it down under ... */
601 			else if (np > name)
602 				puts("                                     \r");
603 			prompt();
604 			digit = lower = upper = 0;
605 			np = name;
606 			continue;
607 		} else if (isdigit(c))
608 			digit = 1;
609 		if (IG && (c <= ' ' || c > 0176))
610 			continue;
611 		*np++ = c;
612 		putchr(cs);
613 	}
614 	signal(SIGINT, SIG_IGN);
615 	*np = 0;
616 	if (c == '\r')
617 		crmod = 1;
618 	if ((upper && !lower && !LC) || UC)
619 		for (np = name; *np; np++)
620 			if (isupper(*np))
621 				*np = tolower(*np);
622 	return (1 + ppp_connection);
623 }
624 
625 static void
626 putpad(const char *s)
627 {
628 	int pad = 0;
629 	speed_t ospeed = cfgetospeed(&tmode);
630 
631 	if (isdigit(*s)) {
632 		while (isdigit(*s)) {
633 			pad *= 10;
634 			pad += *s++ - '0';
635 		}
636 		pad *= 10;
637 		if (*s == '.' && isdigit(s[1])) {
638 			pad += s[1] - '0';
639 			s += 2;
640 		}
641 	}
642 
643 	puts(s);
644 	/*
645 	 * If no delay needed, or output speed is
646 	 * not comprehensible, then don't try to delay.
647 	 */
648 	if (pad == 0 || ospeed <= 0)
649 		return;
650 
651 	/*
652 	 * Round up by a half a character frame, and then do the delay.
653 	 * Too bad there are no user program accessible programmed delays.
654 	 * Transmitting pad characters slows many terminals down and also
655 	 * loads the system.
656 	 */
657 	pad = (pad * ospeed + 50000) / 100000;
658 	while (pad--)
659 		putchr(*PC);
660 }
661 
662 static void
663 puts(const char *s)
664 {
665 	while (*s)
666 		putchr(*s++);
667 }
668 
669 char	outbuf[OBUFSIZ];
670 int	obufcnt = 0;
671 
672 static void
673 putchr(int cc)
674 {
675 	char c;
676 
677 	c = cc;
678 	if (!NP) {
679 		c |= partab[c&0177] & 0200;
680 		if (OP)
681 			c ^= 0200;
682 	}
683 	if (!UB) {
684 		outbuf[obufcnt++] = c;
685 		if (obufcnt >= OBUFSIZ)
686 			oflush();
687 	} else
688 		write(STDOUT_FILENO, &c, 1);
689 }
690 
691 static void
692 oflush(void)
693 {
694 	if (obufcnt)
695 		write(STDOUT_FILENO, outbuf, obufcnt);
696 	obufcnt = 0;
697 }
698 
699 static void
700 prompt(void)
701 {
702 
703 	putf(LM);
704 	if (CO)
705 		putchr('\n');
706 }
707 
708 
709 static char *
710 getline(int fd)
711 {
712 	int i = 0;
713 	static char linebuf[512];
714 
715 	/*
716 	 * This is certainly slow, but it avoids having to include
717 	 * stdio.h unnecessarily. Issue files should be small anyway.
718 	 */
719 	while (i < (sizeof linebuf - 3) && read(fd, linebuf+i, 1)==1) {
720 		if (linebuf[i] == '\n') {
721 			/* Don't rely on newline mode, assume raw */
722 			linebuf[i++] = '\r';
723 			linebuf[i++] = '\n';
724 			linebuf[i] = '\0';
725 			return linebuf;
726 		}
727 		++i;
728 	}
729 	linebuf[i] = '\0';
730 	return i ? linebuf : 0;
731 }
732 
733 static void
734 putf(const char *cp)
735 {
736 	extern char editedhost[];
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