1/*-
2 * SPDX-License-Identifier: MIT-CMU
3 *
4 * Mach Operating System
5 * Copyright (c) 1991,1990 Carnegie Mellon University
6 * All Rights Reserved.
7 *
8 * Permission to use, copy, modify and distribute this software and its
9 * documentation is hereby granted, provided that both the copyright
10 * notice and this permission notice appear in all copies of the
11 * software, derivative works or modified versions, and any portions
12 * thereof, and that both notices appear in supporting documentation.
13 *
14 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
15 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
16 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17 *
18 * Carnegie Mellon requests users of this software to return to
19 *
20 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
21 *  School of Computer Science
22 *  Carnegie Mellon University
23 *  Pittsburgh PA 15213-3890
24 *
25 * any improvements or extensions that they make and grant Carnegie the
26 * rights to redistribute these changes.
27 */
28/*
29 *	Author: David B. Golub, Carnegie Mellon University
30 *	Date:	7/90
31 */
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/cons.h>
36#include <sys/sysctl.h>
37
38#include <ddb/ddb.h>
39#include <ddb/db_output.h>
40
41/*
42 * Character input and editing.
43 */
44
45/*
46 * We don't track output position while editing input,
47 * since input always ends with a new-line.  We just
48 * reset the line position at the end.
49 */
50static char *	db_lbuf_start;	/* start of input line buffer */
51static char *	db_lbuf_end;	/* end of input line buffer */
52static char *	db_lc;		/* current character */
53static char *	db_le;		/* one past last character */
54
55/*
56 * Raw input buffer, processed only for certain control characters.
57 */
58#define	DB_RAW_SIZE	512
59static char	db_raw[DB_RAW_SIZE];
60static u_int	db_raw_pos;
61static u_int	db_raw_cnt;
62static int	db_raw_warned;
63static int	ddb_prioritize_control_input = 1;
64SYSCTL_INT(_debug_ddb, OID_AUTO, prioritize_control_input, CTLFLAG_RWTUN,
65    &ddb_prioritize_control_input, 0,
66    "Drop input when the buffer fills in order to keep servicing ^C/^S/^Q");
67
68/*
69 * Simple input line history support.
70 */
71static char	db_lhistory[2048];
72static int	db_lhistlsize, db_lhistidx, db_lhistcur;
73static int	db_lhist_nlines;
74
75#define	CTRL(c)		((c) & 0x1f)
76#define	BLANK		' '
77#define	BACKUP		'\b'
78
79static void	db_delete(int n, int bwd);
80static int	db_inputchar(int c);
81static void	db_putnchars(int c, int count);
82static void	db_putstring(char *s, int count);
83static int	db_raw_pop(void);
84static void	db_raw_push(int);
85static int	db_raw_space(void);
86
87static void
88db_putstring(char *s, int count)
89{
90	while (--count >= 0)
91	    cnputc(*s++);
92}
93
94static void
95db_putnchars(int c, int count)
96{
97	while (--count >= 0)
98	    cnputc(c);
99}
100
101/*
102 * Delete N characters, forward or backward
103 */
104#define	DEL_FWD		0
105#define	DEL_BWD		1
106static void
107db_delete(int n, int bwd)
108{
109	char *p;
110
111	if (bwd) {
112	    db_lc -= n;
113	    db_putnchars(BACKUP, n);
114	}
115	for (p = db_lc; p < db_le-n; p++) {
116	    *p = *(p+n);
117	    cnputc(*p);
118	}
119	db_putnchars(BLANK, n);
120	db_putnchars(BACKUP, db_le - db_lc);
121	db_le -= n;
122}
123
124/* returns true at end-of-line */
125static int
126db_inputchar(int c)
127{
128	static int escstate;
129
130	if (escstate == 1) {
131		/* ESC seen, look for [ or O */
132		if (c == '[' || c == 'O')
133			escstate++;
134		else
135			escstate = 0; /* re-init state machine */
136		return (0);
137	} else if (escstate == 2) {
138		escstate = 0;
139		/*
140		 * If a valid cursor key has been found, translate
141		 * into an emacs-style control key, and fall through.
142		 * Otherwise, drop off.
143		 */
144		switch (c) {
145		case 'A':	/* up */
146			c = CTRL('p');
147			break;
148		case 'B':	/* down */
149			c = CTRL('n');
150			break;
151		case 'C':	/* right */
152			c = CTRL('f');
153			break;
154		case 'D':	/* left */
155			c = CTRL('b');
156			break;
157		default:
158			return (0);
159		}
160	}
161
162	switch (c) {
163	    case CTRL('['):
164		escstate = 1;
165		break;
166	    case CTRL('b'):
167		/* back up one character */
168		if (db_lc > db_lbuf_start) {
169		    cnputc(BACKUP);
170		    db_lc--;
171		}
172		break;
173	    case CTRL('f'):
174		/* forward one character */
175		if (db_lc < db_le) {
176		    cnputc(*db_lc);
177		    db_lc++;
178		}
179		break;
180	    case CTRL('a'):
181		/* beginning of line */
182		while (db_lc > db_lbuf_start) {
183		    cnputc(BACKUP);
184		    db_lc--;
185		}
186		break;
187	    case CTRL('e'):
188		/* end of line */
189		while (db_lc < db_le) {
190		    cnputc(*db_lc);
191		    db_lc++;
192		}
193		break;
194	    case CTRL('h'):
195	    case 0177:
196		/* erase previous character */
197		if (db_lc > db_lbuf_start)
198		    db_delete(1, DEL_BWD);
199		break;
200	    case CTRL('d'):
201		/* erase next character */
202		if (db_lc < db_le)
203		    db_delete(1, DEL_FWD);
204		break;
205	    case CTRL('u'):
206	    case CTRL('c'):
207		/* kill entire line: */
208		/* at first, delete to beginning of line */
209		if (db_lc > db_lbuf_start)
210		    db_delete(db_lc - db_lbuf_start, DEL_BWD);
211		/* FALLTHROUGH */
212	    case CTRL('k'):
213		/* delete to end of line */
214		if (db_lc < db_le)
215		    db_delete(db_le - db_lc, DEL_FWD);
216		break;
217	    case CTRL('t'):
218		/* twiddle last 2 characters */
219		if (db_lc >= db_lbuf_start + 2) {
220		    c = db_lc[-2];
221		    db_lc[-2] = db_lc[-1];
222		    db_lc[-1] = c;
223		    cnputc(BACKUP);
224		    cnputc(BACKUP);
225		    cnputc(db_lc[-2]);
226		    cnputc(db_lc[-1]);
227		}
228		break;
229	    case CTRL('w'):
230		/* erase previous word */
231		for (; db_lc > db_lbuf_start;) {
232		    if (*(db_lc - 1) != ' ')
233			break;
234		    db_delete(1, DEL_BWD);
235		}
236		for (; db_lc > db_lbuf_start;) {
237		    if (*(db_lc - 1) == ' ')
238			break;
239		    db_delete(1, DEL_BWD);
240		}
241		break;
242	    case CTRL('r'):
243		db_putstring("^R\n", 3);
244	    redraw:
245		if (db_le > db_lbuf_start) {
246		    db_putstring(db_lbuf_start, db_le - db_lbuf_start);
247		    db_putnchars(BACKUP, db_le - db_lc);
248		}
249		break;
250	    case CTRL('p'):
251		/* Make previous history line the active one. */
252		if (db_lhistcur >= 0) {
253		    bcopy(db_lhistory + db_lhistcur * db_lhistlsize,
254			  db_lbuf_start, db_lhistlsize);
255		    db_lhistcur--;
256		    goto hist_redraw;
257		}
258		break;
259	    case CTRL('n'):
260		/* Make next history line the active one. */
261		if (db_lhistcur < db_lhistidx - 1) {
262		    db_lhistcur += 2;
263		    bcopy(db_lhistory + db_lhistcur * db_lhistlsize,
264			  db_lbuf_start, db_lhistlsize);
265		} else {
266		    /*
267		     * ^N through tail of history, reset the
268		     * buffer to zero length.
269		     */
270		    *db_lbuf_start = '\0';
271		    db_lhistcur = db_lhistidx;
272		}
273
274	    hist_redraw:
275		db_putnchars(BACKUP, db_lc - db_lbuf_start);
276		db_putnchars(BLANK, db_le - db_lbuf_start);
277		db_putnchars(BACKUP, db_le - db_lbuf_start);
278		db_le = strchr(db_lbuf_start, '\0');
279		if (db_le[-1] == '\r' || db_le[-1] == '\n')
280		    *--db_le = '\0';
281		db_lc = db_le;
282		goto redraw;
283
284	    case -1:
285		/*
286		 * eek! the console returned eof.
287		 * probably that means we HAVE no console.. we should try bail
288		 * XXX
289		 */
290		c = '\r';
291	    case '\n':
292		/* FALLTHROUGH */
293	    case '\r':
294		*db_le++ = c;
295		return (1);
296	    default:
297		if (db_le == db_lbuf_end) {
298		    cnputc('\007');
299		}
300		else if (c >= ' ' && c <= '~') {
301		    char *p;
302
303		    for (p = db_le; p > db_lc; p--)
304			*p = *(p-1);
305		    *db_lc++ = c;
306		    db_le++;
307		    cnputc(c);
308		    db_putstring(db_lc, db_le - db_lc);
309		    db_putnchars(BACKUP, db_le - db_lc);
310		}
311		break;
312	}
313	return (0);
314}
315
316/* Get a character from the console, first checking the raw input buffer. */
317int
318db_getc(void)
319{
320	int c;
321
322	if (db_raw_cnt == 0) {
323		c = cngetc();
324	} else {
325		c = db_raw_pop();
326		if (c == '\r')
327			c = '\n';
328	}
329	return (c);
330}
331
332/* Whether the raw input buffer has space to accept another character. */
333static int
334db_raw_space(void)
335{
336
337	return (db_raw_cnt < DB_RAW_SIZE);
338}
339
340/* Un-get a character from the console by buffering it. */
341static void
342db_raw_push(int c)
343{
344
345	if (!db_raw_space())
346		db_error(NULL);
347	db_raw[(db_raw_pos + db_raw_cnt++) % DB_RAW_SIZE] = c;
348}
349
350/* Drain a character from the raw input buffer. */
351static int
352db_raw_pop(void)
353{
354
355	if (db_raw_cnt == 0)
356		return (-1);
357	db_raw_cnt--;
358	db_raw_warned = 0;
359	return (db_raw[db_raw_pos++ % DB_RAW_SIZE]);
360}
361
362int
363db_readline(char *lstart, int lsize)
364{
365
366	if (lsize < 2)
367		return (0);
368	if (lsize != db_lhistlsize) {
369		/*
370		 * (Re)initialize input line history.  Throw away any
371		 * existing history.
372		 */
373		db_lhist_nlines = sizeof(db_lhistory) / lsize;
374		db_lhistlsize = lsize;
375		db_lhistidx = -1;
376	}
377	db_lhistcur = db_lhistidx;
378
379	db_force_whitespace();	/* synch output position */
380
381	db_lbuf_start = lstart;
382	db_lbuf_end   = lstart + lsize - 2;	/* Will append NL and NUL. */
383	db_lc = lstart;
384	db_le = lstart;
385
386	while (!db_inputchar(db_getc()))
387	    continue;
388
389	db_capture_write(lstart, db_le - db_lbuf_start);
390	db_printf("\n");	/* synch output position */
391	*db_le = 0;
392
393	if (db_le - db_lbuf_start > 1) {
394	    /* Maintain input line history for non-empty lines. */
395	    if (++db_lhistidx == db_lhist_nlines) {
396		/* Rotate history. */
397		bcopy(db_lhistory + db_lhistlsize, db_lhistory,
398		      db_lhistlsize * (db_lhist_nlines - 1));
399		db_lhistidx--;
400	    }
401	    bcopy(lstart, db_lhistory + db_lhistidx * db_lhistlsize,
402		  db_lhistlsize);
403	}
404
405	return (db_le - db_lbuf_start);
406}
407
408static void
409db_do_interrupt(const char *reason)
410{
411
412	/* Do a pager quit too because some commands have jmpbuf handling. */
413	db_disable_pager();
414	db_pager_quit = 1;
415	db_error(reason);
416}
417
418void
419db_check_interrupt(void)
420{
421	int	c;
422
423	/*
424	 * Check console input for control characters.  Non-control input is
425	 * buffered.  When buffer space is exhausted, either stop responding to
426	 * control input or drop further non-control input on the floor.
427	 */
428	for (;;) {
429		if (!ddb_prioritize_control_input && !db_raw_space())
430			return;
431		c = cncheckc();
432		switch (c) {
433		case -1:		/* no character */
434			return;
435
436		case CTRL('c'):
437			db_do_interrupt("^C");
438			/*NOTREACHED*/
439
440		case CTRL('s'):
441			do {
442				c = cncheckc();
443				if (c == CTRL('c'))
444					db_do_interrupt("^C");
445			} while (c != CTRL('q'));
446			break;
447
448		default:
449			if (db_raw_space()) {
450				db_raw_push(c);
451			} else if (!db_raw_warned) {
452				db_raw_warned = 1;
453				db_printf("\n--Exceeded input buffer--\n");
454			}
455			break;
456		}
457	}
458}
459