xref: /dragonfly/contrib/libedit/src/read.c (revision 31524921)
1 /*	$NetBSD: read.c,v 1.71 2014/07/06 18:15:34 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Christos Zoulas of Cornell University.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #include "config.h"
36 #if !defined(lint) && !defined(SCCSID)
37 #if 0
38 static char sccsid[] = "@(#)read.c	8.1 (Berkeley) 6/4/93";
39 #else
40 __RCSID("$NetBSD: read.c,v 1.71 2014/07/06 18:15:34 christos Exp $");
41 #endif
42 #endif /* not lint && not SCCSID */
43 
44 /*
45  * read.c: Clean this junk up! This is horrible code.
46  *	   Terminal read functions
47  */
48 #include <errno.h>
49 #include <fcntl.h>
50 #include <unistd.h>
51 #include <stdlib.h>
52 #include <limits.h>
53 #include "el.h"
54 
55 #define OKCMD	-1	/* must be -1! */
56 
57 private int	read__fixio(int, int);
58 private int	read_preread(EditLine *);
59 private int	read_char(EditLine *, Char *);
60 private int	read_getcmd(EditLine *, el_action_t *, Char *);
61 private void	read_pop(c_macro_t *);
62 
63 /* read_init():
64  *	Initialize the read stuff
65  */
66 protected int
67 read_init(EditLine *el)
68 {
69 	/* builtin read_char */
70 	el->el_read.read_char = read_char;
71 	return 0;
72 }
73 
74 
75 /* el_read_setfn():
76  *	Set the read char function to the one provided.
77  *	If it is set to EL_BUILTIN_GETCFN, then reset to the builtin one.
78  */
79 protected int
80 el_read_setfn(EditLine *el, el_rfunc_t rc)
81 {
82 	el->el_read.read_char = (rc == EL_BUILTIN_GETCFN) ? read_char : rc;
83 	return 0;
84 }
85 
86 
87 /* el_read_getfn():
88  *	return the current read char function, or EL_BUILTIN_GETCFN
89  *	if it is the default one
90  */
91 protected el_rfunc_t
92 el_read_getfn(EditLine *el)
93 {
94        return el->el_read.read_char == read_char ?
95 	    EL_BUILTIN_GETCFN : el->el_read.read_char;
96 }
97 
98 
99 #ifndef MIN
100 #define MIN(A,B) ((A) < (B) ? (A) : (B))
101 #endif
102 
103 #ifdef DEBUG_EDIT
104 private void
105 read_debug(EditLine *el)
106 {
107 
108 	if (el->el_line.cursor > el->el_line.lastchar)
109 		(void) fprintf(el->el_errfile, "cursor > lastchar\r\n");
110 	if (el->el_line.cursor < el->el_line.buffer)
111 		(void) fprintf(el->el_errfile, "cursor < buffer\r\n");
112 	if (el->el_line.cursor > el->el_line.limit)
113 		(void) fprintf(el->el_errfile, "cursor > limit\r\n");
114 	if (el->el_line.lastchar > el->el_line.limit)
115 		(void) fprintf(el->el_errfile, "lastchar > limit\r\n");
116 	if (el->el_line.limit != &el->el_line.buffer[EL_BUFSIZ - 2])
117 		(void) fprintf(el->el_errfile, "limit != &buffer[EL_BUFSIZ-2]\r\n");
118 }
119 #endif /* DEBUG_EDIT */
120 
121 
122 /* read__fixio():
123  *	Try to recover from a read error
124  */
125 /* ARGSUSED */
126 private int
127 read__fixio(int fd __attribute__((__unused__)), int e)
128 {
129 
130 	switch (e) {
131 	case -1:		/* Make sure that the code is reachable */
132 
133 #ifdef EWOULDBLOCK
134 	case EWOULDBLOCK:
135 #ifndef TRY_AGAIN
136 #define TRY_AGAIN
137 #endif
138 #endif /* EWOULDBLOCK */
139 
140 #if defined(POSIX) && defined(EAGAIN)
141 #if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
142 	case EAGAIN:
143 #ifndef TRY_AGAIN
144 #define TRY_AGAIN
145 #endif
146 #endif /* EWOULDBLOCK && EWOULDBLOCK != EAGAIN */
147 #endif /* POSIX && EAGAIN */
148 
149 		e = 0;
150 #ifdef TRY_AGAIN
151 #if defined(F_SETFL) && defined(O_NDELAY)
152 		if ((e = fcntl(fd, F_GETFL, 0)) == -1)
153 			return -1;
154 
155 		if (fcntl(fd, F_SETFL, e & ~O_NDELAY) == -1)
156 			return -1;
157 		else
158 			e = 1;
159 #endif /* F_SETFL && O_NDELAY */
160 
161 #ifdef FIONBIO
162 		{
163 			int zero = 0;
164 
165 			if (ioctl(fd, FIONBIO, &zero) == -1)
166 				return -1;
167 			else
168 				e = 1;
169 		}
170 #endif /* FIONBIO */
171 
172 #endif /* TRY_AGAIN */
173 		return e ? 0 : -1;
174 
175 	case EINTR:
176 		return 0;
177 
178 	default:
179 		return -1;
180 	}
181 }
182 
183 
184 /* read_preread():
185  *	Try to read the stuff in the input queue;
186  */
187 private int
188 read_preread(EditLine *el)
189 {
190 	int chrs = 0;
191 
192 	if (el->el_tty.t_mode == ED_IO)
193 		return 0;
194 
195 #ifndef WIDECHAR
196 /* FIONREAD attempts to buffer up multiple bytes, and to make that work
197  * properly with partial wide/UTF-8 characters would need some careful work. */
198 #ifdef FIONREAD
199 	(void) ioctl(el->el_infd, FIONREAD, &chrs);
200 	if (chrs > 0) {
201 		char buf[EL_BUFSIZ];
202 
203 		chrs = read(el->el_infd, buf,
204 		    (size_t) MIN(chrs, EL_BUFSIZ - 1));
205 		if (chrs > 0) {
206 			buf[chrs] = '\0';
207 			el_push(el, buf);
208 		}
209 	}
210 #endif /* FIONREAD */
211 #endif
212 	return chrs > 0;
213 }
214 
215 
216 /* el_push():
217  *	Push a macro
218  */
219 public void
220 FUN(el,push)(EditLine *el, const Char *str)
221 {
222 	c_macro_t *ma = &el->el_chared.c_macro;
223 
224 	if (str != NULL && ma->level + 1 < EL_MAXMACRO) {
225 		ma->level++;
226 		if ((ma->macro[ma->level] = Strdup(str)) != NULL)
227 			return;
228 		ma->level--;
229 	}
230 	terminal_beep(el);
231 	terminal__flush(el);
232 }
233 
234 
235 /* read_getcmd():
236  *	Get next command from the input stream, return OKCMD on success.
237  *	Character values > 255 are not looked up in the map, but inserted.
238  */
239 private int
240 read_getcmd(EditLine *el, el_action_t *cmdnum, Char *ch)
241 {
242 	el_action_t cmd;
243 	int num;
244 
245 	el->el_errno = 0;
246 	do {
247 		if ((num = FUN(el,getc)(el, ch)) != 1) {/* if EOF or error */
248 			el->el_errno = num == 0 ? 0 : errno;
249 			return 0;	/* not OKCMD */
250 		}
251 
252 #ifdef	KANJI
253 		if ((*ch & 0200)) {
254 			el->el_state.metanext = 0;
255 			cmd = CcViMap[' '];
256 			break;
257 		} else
258 #endif /* KANJI */
259 
260 		if (el->el_state.metanext) {
261 			el->el_state.metanext = 0;
262 			*ch |= 0200;
263 		}
264 #ifdef WIDECHAR
265 		if (*ch >= N_KEYS)
266 			cmd = ED_INSERT;
267 		else
268 #endif
269 			cmd = el->el_map.current[(unsigned char) *ch];
270 		if (cmd == ED_SEQUENCE_LEAD_IN) {
271 			keymacro_value_t val;
272 			switch (keymacro_get(el, ch, &val)) {
273 			case XK_CMD:
274 				cmd = val.cmd;
275 				break;
276 			case XK_STR:
277 				FUN(el,push)(el, val.str);
278 				break;
279 #ifdef notyet
280 			case XK_EXE:
281 				/* XXX: In the future to run a user function */
282 				RunCommand(val.str);
283 				break;
284 #endif
285 			default:
286 				EL_ABORT((el->el_errfile, "Bad XK_ type \n"));
287 				break;
288 			}
289 		}
290 		if (el->el_map.alt == NULL)
291 			el->el_map.current = el->el_map.key;
292 	} while (cmd == ED_SEQUENCE_LEAD_IN);
293 	*cmdnum = cmd;
294 	return OKCMD;
295 }
296 
297 #ifdef WIDECHAR
298 /* utf8_islead():
299  *	Test whether a byte is a leading byte of a UTF-8 sequence.
300  */
301 private int
302 utf8_islead(int c)
303 {
304 	return c < 0x80 ||	       /* single byte char */
305 	       (c >= 0xc2 && c <= 0xf4); /* start of multibyte sequence */
306 }
307 #endif
308 
309 /* read_char():
310  *	Read a character from the tty.
311  */
312 private int
313 read_char(EditLine *el, Char *cp)
314 {
315 	ssize_t num_read;
316 	int tried = 0;
317 	char cbuf[MB_LEN_MAX];
318 	size_t cbp = 0;
319 	int bytes = 0;
320 
321  again:
322 	el->el_signal->sig_no = 0;
323 	while ((num_read = read(el->el_infd, cbuf + cbp, (size_t)1)) == -1) {
324 		int e = errno;
325 		switch (el->el_signal->sig_no) {
326 		case SIGCONT:
327 			FUN(el,set)(el, EL_REFRESH);
328 			/*FALLTHROUGH*/
329 		case SIGWINCH:
330 			sig_set(el);
331 			goto again;
332 		default:
333 			break;
334 		}
335 		if (!tried && read__fixio(el->el_infd, e) == 0)
336 			tried = 1;
337 		else {
338 			errno = e;
339 			*cp = '\0';
340 			return -1;
341 		}
342 	}
343 
344 	/* Test for EOF */
345 	if (num_read == 0) {
346 		errno = 0;
347 		*cp = '\0';
348 		return 0;
349 	}
350 
351 #ifdef WIDECHAR
352 	if (el->el_flags & CHARSET_IS_UTF8) {
353 		if (!utf8_islead((unsigned char)cbuf[0]))
354 			goto again; /* discard the byte we read and try again */
355 		++cbp;
356 		if ((bytes = ct_mbtowc(cp, cbuf, cbp)) == -1) {
357 			ct_mbtowc_reset;
358 			if (cbp >= MB_LEN_MAX) { /* "shouldn't happen" */
359 				errno = EILSEQ;
360 				*cp = '\0';
361 				return -1;
362 			}
363 			goto again;
364 		}
365 	} else if (isascii((unsigned char)cbuf[0]) ||
366 		/* we don't support other multibyte charsets */
367 		++cbp != 1 ||
368 		/* Try non-ASCII characters in a 8-bit character set */
369 		(bytes = ct_mbtowc(cp, cbuf, cbp)) != 1)
370 #endif
371 		*cp = (unsigned char)cbuf[0];
372 
373 	if ((el->el_flags & IGNORE_EXTCHARS) && bytes > 1) {
374 		cbp = 0; /* skip this character */
375 		goto again;
376 	}
377 
378 	return (int)num_read;
379 }
380 
381 /* read_pop():
382  *	Pop a macro from the stack
383  */
384 private void
385 read_pop(c_macro_t *ma)
386 {
387 	int i;
388 
389 	el_free(ma->macro[0]);
390 	for (i = 0; i < ma->level; i++)
391 		ma->macro[i] = ma->macro[i + 1];
392 	ma->level--;
393 	ma->offset = 0;
394 }
395 
396 /* el_getc():
397  *	Read a character
398  */
399 public int
400 FUN(el,getc)(EditLine *el, Char *cp)
401 {
402 	int num_read;
403 	c_macro_t *ma = &el->el_chared.c_macro;
404 
405 	terminal__flush(el);
406 	for (;;) {
407 		if (ma->level < 0) {
408 			if (!read_preread(el))
409 				break;
410 		}
411 
412 		if (ma->level < 0)
413 			break;
414 
415 		if (ma->macro[0][ma->offset] == '\0') {
416 			read_pop(ma);
417 			continue;
418 		}
419 
420 		*cp = ma->macro[0][ma->offset++];
421 
422 		if (ma->macro[0][ma->offset] == '\0') {
423 			/* Needed for QuoteMode On */
424 			read_pop(ma);
425 		}
426 
427 		return 1;
428 	}
429 
430 #ifdef DEBUG_READ
431 	(void) fprintf(el->el_errfile, "Turning raw mode on\n");
432 #endif /* DEBUG_READ */
433 	if (tty_rawmode(el) < 0)/* make sure the tty is set up correctly */
434 		return 0;
435 
436 #ifdef DEBUG_READ
437 	(void) fprintf(el->el_errfile, "Reading a character\n");
438 #endif /* DEBUG_READ */
439 	num_read = (*el->el_read.read_char)(el, cp);
440 	if (num_read < 0)
441 		el->el_errno = errno;
442 #ifdef WIDECHAR
443 	if (el->el_flags & NARROW_READ)
444 		*cp = *(char *)(void *)cp;
445 #endif
446 #ifdef DEBUG_READ
447 	(void) fprintf(el->el_errfile, "Got it %c\n", *cp);
448 #endif /* DEBUG_READ */
449 	return num_read;
450 }
451 
452 protected void
453 read_prepare(EditLine *el)
454 {
455 	if (el->el_flags & HANDLE_SIGNALS)
456 		sig_set(el);
457 	if (el->el_flags & NO_TTY)
458 		return;
459 	if ((el->el_flags & (UNBUFFERED|EDIT_DISABLED)) == UNBUFFERED)
460 		tty_rawmode(el);
461 
462 	/* This is relatively cheap, and things go terribly wrong if
463 	   we have the wrong size. */
464 	el_resize(el);
465 	re_clear_display(el);	/* reset the display stuff */
466 	ch_reset(el, 0);
467 	re_refresh(el);		/* print the prompt */
468 
469 	if (el->el_flags & UNBUFFERED)
470 		terminal__flush(el);
471 }
472 
473 protected void
474 read_finish(EditLine *el)
475 {
476 	if ((el->el_flags & UNBUFFERED) == 0)
477 		(void) tty_cookedmode(el);
478 	if (el->el_flags & HANDLE_SIGNALS)
479 		sig_clr(el);
480 }
481 
482 public const Char *
483 FUN(el,gets)(EditLine *el, int *nread)
484 {
485 	int retval;
486 	el_action_t cmdnum = 0;
487 	int num;		/* how many chars we have read at NL */
488 	Char ch, *cp;
489 	int crlf = 0;
490 	int nrb;
491 #ifdef FIONREAD
492 	c_macro_t *ma = &el->el_chared.c_macro;
493 #endif /* FIONREAD */
494 
495 	if (nread == NULL)
496 		nread = &nrb;
497 	*nread = 0;
498 
499 	if (el->el_flags & NO_TTY) {
500 		size_t idx;
501 
502 		cp = el->el_line.buffer;
503 		while ((num = (*el->el_read.read_char)(el, cp)) == 1) {
504 			/* make sure there is space for next character */
505 			if (cp + 1 >= el->el_line.limit) {
506 				idx = (size_t)(cp - el->el_line.buffer);
507 				if (!ch_enlargebufs(el, (size_t)2))
508 					break;
509 				cp = &el->el_line.buffer[idx];
510 			}
511 			cp++;
512 			if (el->el_flags & UNBUFFERED)
513 				break;
514 			if (cp[-1] == '\r' || cp[-1] == '\n')
515 				break;
516 		}
517 		if (num == -1) {
518 			if (errno == EINTR)
519 				cp = el->el_line.buffer;
520 			el->el_errno = errno;
521 		}
522 
523 		goto noedit;
524 	}
525 
526 
527 #ifdef FIONREAD
528 	if (el->el_tty.t_mode == EX_IO && ma->level < 0) {
529 		long chrs = 0;
530 
531 		(void) ioctl(el->el_infd, FIONREAD, &chrs);
532 		if (chrs == 0) {
533 			if (tty_rawmode(el) < 0) {
534 				errno = 0;
535 				*nread = 0;
536 				return NULL;
537 			}
538 		}
539 	}
540 #endif /* FIONREAD */
541 
542 	if ((el->el_flags & UNBUFFERED) == 0)
543 		read_prepare(el);
544 
545 	if (el->el_flags & EDIT_DISABLED) {
546 		size_t idx;
547 
548 		if ((el->el_flags & UNBUFFERED) == 0)
549 			cp = el->el_line.buffer;
550 		else
551 			cp = el->el_line.lastchar;
552 
553 		terminal__flush(el);
554 
555 		while ((num = (*el->el_read.read_char)(el, cp)) == 1) {
556 			/* make sure there is space next character */
557 			if (cp + 1 >= el->el_line.limit) {
558 				idx = (size_t)(cp - el->el_line.buffer);
559 				if (!ch_enlargebufs(el, (size_t)2))
560 					break;
561 				cp = &el->el_line.buffer[idx];
562 			}
563 			cp++;
564 			crlf = cp[-1] == '\r' || cp[-1] == '\n';
565 			if (el->el_flags & UNBUFFERED)
566 				break;
567 			if (crlf)
568 				break;
569 		}
570 
571 		if (num == -1) {
572 			if (errno == EINTR)
573 				cp = el->el_line.buffer;
574 			el->el_errno = errno;
575 		}
576 
577 		goto noedit;
578 	}
579 
580 	for (num = OKCMD; num == OKCMD;) {	/* while still editing this
581 						 * line */
582 #ifdef DEBUG_EDIT
583 		read_debug(el);
584 #endif /* DEBUG_EDIT */
585 		/* if EOF or error */
586 		if ((num = read_getcmd(el, &cmdnum, &ch)) != OKCMD) {
587 			num = -1;
588 #ifdef DEBUG_READ
589 			(void) fprintf(el->el_errfile,
590 			    "Returning from el_gets %d\n", num);
591 #endif /* DEBUG_READ */
592 			break;
593 		}
594 		if (el->el_errno == EINTR) {
595 			el->el_line.buffer[0] = '\0';
596 			el->el_line.lastchar =
597 			    el->el_line.cursor = el->el_line.buffer;
598 			break;
599 		}
600 		if ((size_t)cmdnum >= el->el_map.nfunc) {	/* BUG CHECK command */
601 #ifdef DEBUG_EDIT
602 			(void) fprintf(el->el_errfile,
603 			    "ERROR: illegal command from key 0%o\r\n", ch);
604 #endif /* DEBUG_EDIT */
605 			continue;	/* try again */
606 		}
607 		/* now do the real command */
608 #ifdef DEBUG_READ
609 		{
610 			el_bindings_t *b;
611 			for (b = el->el_map.help; b->name; b++)
612 				if (b->func == cmdnum)
613 					break;
614 			if (b->name)
615 				(void) fprintf(el->el_errfile,
616 				    "Executing %s\n", b->name);
617 			else
618 				(void) fprintf(el->el_errfile,
619 				    "Error command = %d\n", cmdnum);
620 		}
621 #endif /* DEBUG_READ */
622 		/* vi redo needs these way down the levels... */
623 		el->el_state.thiscmd = cmdnum;
624 		el->el_state.thisch = ch;
625 		if (el->el_map.type == MAP_VI &&
626 		    el->el_map.current == el->el_map.key &&
627 		    el->el_chared.c_redo.pos < el->el_chared.c_redo.lim) {
628 			if (cmdnum == VI_DELETE_PREV_CHAR &&
629 			    el->el_chared.c_redo.pos != el->el_chared.c_redo.buf
630 			    && Isprint(el->el_chared.c_redo.pos[-1]))
631 				el->el_chared.c_redo.pos--;
632 			else
633 				*el->el_chared.c_redo.pos++ = ch;
634 		}
635 		retval = (*el->el_map.func[cmdnum]) (el, ch);
636 #ifdef DEBUG_READ
637 		(void) fprintf(el->el_errfile,
638 			"Returned state %d\n", retval );
639 #endif /* DEBUG_READ */
640 
641 		/* save the last command here */
642 		el->el_state.lastcmd = cmdnum;
643 
644 		/* use any return value */
645 		switch (retval) {
646 		case CC_CURSOR:
647 			re_refresh_cursor(el);
648 			break;
649 
650 		case CC_REDISPLAY:
651 			re_clear_lines(el);
652 			re_clear_display(el);
653 			/* FALLTHROUGH */
654 
655 		case CC_REFRESH:
656 			re_refresh(el);
657 			break;
658 
659 		case CC_REFRESH_BEEP:
660 			re_refresh(el);
661 			terminal_beep(el);
662 			break;
663 
664 		case CC_NORM:	/* normal char */
665 			break;
666 
667 		case CC_ARGHACK:	/* Suggested by Rich Salz */
668 			/* <rsalz@pineapple.bbn.com> */
669 			continue;	/* keep going... */
670 
671 		case CC_EOF:	/* end of file typed */
672 			if ((el->el_flags & UNBUFFERED) == 0)
673 				num = 0;
674 			else if (num == -1) {
675 				*el->el_line.lastchar++ = CONTROL('d');
676 				el->el_line.cursor = el->el_line.lastchar;
677 				num = 1;
678 			}
679 			break;
680 
681 		case CC_NEWLINE:	/* normal end of line */
682 			num = (int)(el->el_line.lastchar - el->el_line.buffer);
683 			break;
684 
685 		case CC_FATAL:	/* fatal error, reset to known state */
686 #ifdef DEBUG_READ
687 			(void) fprintf(el->el_errfile,
688 			    "*** editor fatal ERROR ***\r\n\n");
689 #endif /* DEBUG_READ */
690 			/* put (real) cursor in a known place */
691 			re_clear_display(el);	/* reset the display stuff */
692 			ch_reset(el, 1);	/* reset the input pointers */
693 			re_refresh(el); /* print the prompt again */
694 			break;
695 
696 		case CC_ERROR:
697 		default:	/* functions we don't know about */
698 #ifdef DEBUG_READ
699 			(void) fprintf(el->el_errfile,
700 			    "*** editor ERROR ***\r\n\n");
701 #endif /* DEBUG_READ */
702 			terminal_beep(el);
703 			terminal__flush(el);
704 			break;
705 		}
706 		el->el_state.argument = 1;
707 		el->el_state.doingarg = 0;
708 		el->el_chared.c_vcmd.action = NOP;
709 		if (el->el_flags & UNBUFFERED)
710 			break;
711 	}
712 
713 	terminal__flush(el);		/* flush any buffered output */
714 	/* make sure the tty is set up correctly */
715 	if ((el->el_flags & UNBUFFERED) == 0) {
716 		read_finish(el);
717 		*nread = num != -1 ? num : 0;
718 	} else {
719 		*nread = (int)(el->el_line.lastchar - el->el_line.buffer);
720 	}
721 	goto done;
722 noedit:
723 	el->el_line.cursor = el->el_line.lastchar = cp;
724 	*cp = '\0';
725 	*nread = (int)(el->el_line.cursor - el->el_line.buffer);
726 done:
727 	if (*nread == 0) {
728 		if (num == -1) {
729 			*nread = -1;
730 			errno = el->el_errno;
731 		}
732 		return NULL;
733 	} else
734 		return el->el_line.buffer;
735 }
736