xref: /freebsd/contrib/less/decode.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /*
2  * Copyright (C) 1984-2007  Mark Nudelman
3  *
4  * You may distribute under the terms of either the GNU General Public
5  * License or the Less License, as specified in the README file.
6  *
7  * For more information about less, or for information on how to
8  * contact the author, see the README file.
9  */
10 
11 
12 /*
13  * Routines to decode user commands.
14  *
15  * This is all table driven.
16  * A command table is a sequence of command descriptors.
17  * Each command descriptor is a sequence of bytes with the following format:
18  *	<c1><c2>...<cN><0><action>
19  * The characters c1,c2,...,cN are the command string; that is,
20  * the characters which the user must type.
21  * It is terminated by a null <0> byte.
22  * The byte after the null byte is the action code associated
23  * with the command string.
24  * If an action byte is OR-ed with A_EXTRA, this indicates
25  * that the option byte is followed by an extra string.
26  *
27  * There may be many command tables.
28  * The first (default) table is built-in.
29  * Other tables are read in from "lesskey" files.
30  * All the tables are linked together and are searched in order.
31  */
32 
33 #include "less.h"
34 #include "cmd.h"
35 #include "lesskey.h"
36 
37 extern int erase_char, erase2_char, kill_char;
38 extern int secure;
39 
40 #define SK(k) \
41 	SK_SPECIAL_KEY, (k), 6, 1, 1, 1
42 /*
43  * Command table is ordered roughly according to expected
44  * frequency of use, so the common commands are near the beginning.
45  */
46 
47 static unsigned char cmdtable[] =
48 {
49 	'\r',0,				A_F_LINE,
50 	'\n',0,				A_F_LINE,
51 	'e',0,				A_F_LINE,
52 	'j',0,				A_F_LINE,
53 	SK(SK_DOWN_ARROW),0,		A_F_LINE,
54 	CONTROL('E'),0,			A_F_LINE,
55 	CONTROL('N'),0,			A_F_LINE,
56 	'k',0,				A_B_LINE,
57 	'y',0,				A_B_LINE,
58 	CONTROL('Y'),0,			A_B_LINE,
59 	SK(SK_CONTROL_K),0,		A_B_LINE,
60 	CONTROL('P'),0,			A_B_LINE,
61 	SK(SK_UP_ARROW),0,		A_B_LINE,
62 	'J',0,				A_FF_LINE,
63 	'K',0,				A_BF_LINE,
64 	'Y',0,				A_BF_LINE,
65 	'd',0,				A_F_SCROLL,
66 	CONTROL('D'),0,			A_F_SCROLL,
67 	'u',0,				A_B_SCROLL,
68 	CONTROL('U'),0,			A_B_SCROLL,
69 	' ',0,				A_F_SCREEN,
70 	'f',0,				A_F_SCREEN,
71 	CONTROL('F'),0,			A_F_SCREEN,
72 	CONTROL('V'),0,			A_F_SCREEN,
73 	SK(SK_PAGE_DOWN),0,		A_F_SCREEN,
74 	'b',0,				A_B_SCREEN,
75 	CONTROL('B'),0,			A_B_SCREEN,
76 	ESC,'v',0,			A_B_SCREEN,
77 	SK(SK_PAGE_UP),0,		A_B_SCREEN,
78 	'z',0,				A_F_WINDOW,
79 	'w',0,				A_B_WINDOW,
80 	ESC,' ',0,			A_FF_SCREEN,
81 	'F',0,				A_F_FOREVER,
82 	'R',0,				A_FREPAINT,
83 	'r',0,				A_REPAINT,
84 	CONTROL('R'),0,			A_REPAINT,
85 	CONTROL('L'),0,			A_REPAINT,
86 	ESC,'u',0,			A_UNDO_SEARCH,
87 	'g',0,				A_GOLINE,
88 	SK(SK_HOME),0,			A_GOLINE,
89 	'<',0,				A_GOLINE,
90 	ESC,'<',0,			A_GOLINE,
91 	'p',0,				A_PERCENT,
92 	'%',0,				A_PERCENT,
93 	ESC,'[',0,			A_LSHIFT,
94 	ESC,']',0,			A_RSHIFT,
95 	ESC,'(',0,			A_LSHIFT,
96 	ESC,')',0,			A_RSHIFT,
97 	SK(SK_RIGHT_ARROW),0,		A_RSHIFT,
98 	SK(SK_LEFT_ARROW),0,		A_LSHIFT,
99 	'{',0,				A_F_BRACKET|A_EXTRA,	'{','}',0,
100 	'}',0,				A_B_BRACKET|A_EXTRA,	'{','}',0,
101 	'(',0,				A_F_BRACKET|A_EXTRA,	'(',')',0,
102 	')',0,				A_B_BRACKET|A_EXTRA,	'(',')',0,
103 	'[',0,				A_F_BRACKET|A_EXTRA,	'[',']',0,
104 	']',0,				A_B_BRACKET|A_EXTRA,	'[',']',0,
105 	ESC,CONTROL('F'),0,		A_F_BRACKET,
106 	ESC,CONTROL('B'),0,		A_B_BRACKET,
107 	'G',0,				A_GOEND,
108 	ESC,'>',0,			A_GOEND,
109 	'>',0,				A_GOEND,
110 	SK(SK_END),0,			A_GOEND,
111 	'P',0,				A_GOPOS,
112 
113 	'0',0,				A_DIGIT,
114 	'1',0,				A_DIGIT,
115 	'2',0,				A_DIGIT,
116 	'3',0,				A_DIGIT,
117 	'4',0,				A_DIGIT,
118 	'5',0,				A_DIGIT,
119 	'6',0,				A_DIGIT,
120 	'7',0,				A_DIGIT,
121 	'8',0,				A_DIGIT,
122 	'9',0,				A_DIGIT,
123 	'.',0,				A_DIGIT,
124 
125 	'=',0,				A_STAT,
126 	CONTROL('G'),0,			A_STAT,
127 	':','f',0,			A_STAT,
128 	'/',0,				A_F_SEARCH,
129 	'?',0,				A_B_SEARCH,
130 	ESC,'/',0,			A_F_SEARCH|A_EXTRA,	'*',0,
131 	ESC,'?',0,			A_B_SEARCH|A_EXTRA,	'*',0,
132 	'n',0,				A_AGAIN_SEARCH,
133 	ESC,'n',0,			A_T_AGAIN_SEARCH,
134 	'N',0,				A_REVERSE_SEARCH,
135 	ESC,'N',0,			A_T_REVERSE_SEARCH,
136 	'm',0,				A_SETMARK,
137 	'\'',0,				A_GOMARK,
138 	CONTROL('X'),CONTROL('X'),0,	A_GOMARK,
139 	'E',0,				A_EXAMINE,
140 	':','e',0,			A_EXAMINE,
141 	CONTROL('X'),CONTROL('V'),0,	A_EXAMINE,
142 	':','n',0,			A_NEXT_FILE,
143 	':','p',0,			A_PREV_FILE,
144 	't',0,				A_NEXT_TAG,
145 	'T',0,				A_PREV_TAG,
146 	':','x',0,			A_INDEX_FILE,
147 	':','d',0,			A_REMOVE_FILE,
148 	'-',0,				A_OPT_TOGGLE,
149 	':','t',0,			A_OPT_TOGGLE|A_EXTRA,	't',0,
150 	's',0,				A_OPT_TOGGLE|A_EXTRA,	'o',0,
151 	'_',0,				A_DISP_OPTION,
152 	'|',0,				A_PIPE,
153 	'v',0,				A_VISUAL,
154 	'!',0,				A_SHELL,
155 	'+',0,				A_FIRSTCMD,
156 
157 	'H',0,				A_HELP,
158 	'h',0,				A_HELP,
159 	SK(SK_F1),0,			A_HELP,
160 	'V',0,				A_VERSION,
161 	'q',0,				A_QUIT,
162 	'Q',0,				A_QUIT,
163 	':','q',0,			A_QUIT,
164 	':','Q',0,			A_QUIT,
165 	'Z','Z',0,			A_QUIT
166 };
167 
168 static unsigned char edittable[] =
169 {
170 	'\t',0,	    			EC_F_COMPLETE,	/* TAB */
171 	'\17',0,			EC_B_COMPLETE,	/* BACKTAB */
172 	SK(SK_BACKTAB),0,		EC_B_COMPLETE,	/* BACKTAB */
173 	ESC,'\t',0,			EC_B_COMPLETE,	/* ESC TAB */
174 	CONTROL('L'),0,			EC_EXPAND,	/* CTRL-L */
175 	CONTROL('V'),0,			EC_LITERAL,	/* BACKSLASH */
176 	CONTROL('A'),0,			EC_LITERAL,	/* BACKSLASH */
177    	ESC,'l',0,			EC_RIGHT,	/* ESC l */
178 	SK(SK_RIGHT_ARROW),0,		EC_RIGHT,	/* RIGHTARROW */
179 	ESC,'h',0,			EC_LEFT,	/* ESC h */
180 	SK(SK_LEFT_ARROW),0,		EC_LEFT,	/* LEFTARROW */
181 	ESC,'b',0,			EC_W_LEFT,	/* ESC b */
182 	ESC,SK(SK_LEFT_ARROW),0,	EC_W_LEFT,	/* ESC LEFTARROW */
183 	SK(SK_CTL_LEFT_ARROW),0,	EC_W_LEFT,	/* CTRL-LEFTARROW */
184 	ESC,'w',0,			EC_W_RIGHT,	/* ESC w */
185 	ESC,SK(SK_RIGHT_ARROW),0,	EC_W_RIGHT,	/* ESC RIGHTARROW */
186 	SK(SK_CTL_RIGHT_ARROW),0,	EC_W_RIGHT,	/* CTRL-RIGHTARROW */
187 	ESC,'i',0,			EC_INSERT,	/* ESC i */
188 	SK(SK_INSERT),0,		EC_INSERT,	/* INSERT */
189 	ESC,'x',0,			EC_DELETE,	/* ESC x */
190 	SK(SK_DELETE),0,		EC_DELETE,	/* DELETE */
191 	ESC,'X',0,			EC_W_DELETE,	/* ESC X */
192 	ESC,SK(SK_DELETE),0,		EC_W_DELETE,	/* ESC DELETE */
193 	SK(SK_CTL_DELETE),0,		EC_W_DELETE,	/* CTRL-DELETE */
194 	SK(SK_CTL_BACKSPACE),0,		EC_W_BACKSPACE, /* CTRL-BACKSPACE */
195 	ESC,'\b',0,			EC_W_BACKSPACE,	/* ESC BACKSPACE */
196 	ESC,'0',0,			EC_HOME,	/* ESC 0 */
197 	SK(SK_HOME),0,			EC_HOME,	/* HOME */
198 	ESC,'$',0,			EC_END,		/* ESC $ */
199 	SK(SK_END),0,			EC_END,		/* END */
200 	ESC,'k',0,			EC_UP,		/* ESC k */
201 	SK(SK_UP_ARROW),0,		EC_UP,		/* UPARROW */
202 	ESC,'j',0,			EC_DOWN,	/* ESC j */
203 	SK(SK_DOWN_ARROW),0,		EC_DOWN,	/* DOWNARROW */
204 };
205 
206 /*
207  * Structure to support a list of command tables.
208  */
209 struct tablelist
210 {
211 	struct tablelist *t_next;
212 	char *t_start;
213 	char *t_end;
214 };
215 
216 /*
217  * List of command tables and list of line-edit tables.
218  */
219 static struct tablelist *list_fcmd_tables = NULL;
220 static struct tablelist *list_ecmd_tables = NULL;
221 static struct tablelist *list_var_tables = NULL;
222 static struct tablelist *list_sysvar_tables = NULL;
223 
224 
225 /*
226  * Expand special key abbreviations in a command table.
227  */
228 	static void
229 expand_special_keys(table, len)
230 	char *table;
231 	int len;
232 {
233 	register char *fm;
234 	register char *to;
235 	register int a;
236 	char *repl;
237 	int klen;
238 
239 	for (fm = table;  fm < table + len; )
240 	{
241 		/*
242 		 * Rewrite each command in the table with any
243 		 * special key abbreviations expanded.
244 		 */
245 		for (to = fm;  *fm != '\0'; )
246 		{
247 			if (*fm != SK_SPECIAL_KEY)
248 			{
249 				*to++ = *fm++;
250 				continue;
251 			}
252 			/*
253 			 * After SK_SPECIAL_KEY, next byte is the type
254 			 * of special key (one of the SK_* contants),
255 			 * and the byte after that is the number of bytes,
256 			 * N, reserved by the abbreviation (including the
257 			 * SK_SPECIAL_KEY and key type bytes).
258 			 * Replace all N bytes with the actual bytes
259 			 * output by the special key on this terminal.
260 			 */
261 			repl = special_key_str(fm[1]);
262 			klen = fm[2] & 0377;
263 			fm += klen;
264 			if (repl == NULL || (int) strlen(repl) > klen)
265 				repl = "\377";
266 			while (*repl != '\0')
267 				*to++ = *repl++;
268 		}
269 		*to++ = '\0';
270 		/*
271 		 * Fill any unused bytes between end of command and
272 		 * the action byte with A_SKIP.
273 		 */
274 		while (to <= fm)
275 			*to++ = A_SKIP;
276 		fm++;
277 		a = *fm++ & 0377;
278 		if (a & A_EXTRA)
279 		{
280 			while (*fm++ != '\0')
281 				continue;
282 		}
283 	}
284 }
285 
286 /*
287  * Initialize the command lists.
288  */
289 	public void
290 init_cmds()
291 {
292 	/*
293 	 * Add the default command tables.
294 	 */
295 	add_fcmd_table((char*)cmdtable, sizeof(cmdtable));
296 	add_ecmd_table((char*)edittable, sizeof(edittable));
297 #if USERFILE
298 	/*
299 	 * For backwards compatibility,
300 	 * try to add tables in the OLD system lesskey file.
301 	 */
302 #ifdef BINDIR
303 	add_hometable(NULL, BINDIR "/.sysless", 1);
304 #endif
305 	/*
306 	 * Try to add the tables in the system lesskey file.
307 	 */
308 	add_hometable("LESSKEY_SYSTEM", LESSKEYFILE_SYS, 1);
309 	/*
310 	 * Try to add the tables in the standard lesskey file "$HOME/.less".
311 	 */
312 	add_hometable("LESSKEY", LESSKEYFILE, 0);
313 #endif
314 }
315 
316 /*
317  * Add a command table.
318  */
319 	static int
320 add_cmd_table(tlist, buf, len)
321 	struct tablelist **tlist;
322 	char *buf;
323 	int len;
324 {
325 	register struct tablelist *t;
326 
327 	if (len == 0)
328 		return (0);
329 	/*
330 	 * Allocate a tablelist structure, initialize it,
331 	 * and link it into the list of tables.
332 	 */
333 	if ((t = (struct tablelist *)
334 			calloc(1, sizeof(struct tablelist))) == NULL)
335 	{
336 		return (-1);
337 	}
338 	expand_special_keys(buf, len);
339 	t->t_start = buf;
340 	t->t_end = buf + len;
341 	t->t_next = *tlist;
342 	*tlist = t;
343 	return (0);
344 }
345 
346 /*
347  * Add a command table.
348  */
349 	public void
350 add_fcmd_table(buf, len)
351 	char *buf;
352 	int len;
353 {
354 	if (add_cmd_table(&list_fcmd_tables, buf, len) < 0)
355 		error("Warning: some commands disabled", NULL_PARG);
356 }
357 
358 /*
359  * Add an editing command table.
360  */
361 	public void
362 add_ecmd_table(buf, len)
363 	char *buf;
364 	int len;
365 {
366 	if (add_cmd_table(&list_ecmd_tables, buf, len) < 0)
367 		error("Warning: some edit commands disabled", NULL_PARG);
368 }
369 
370 /*
371  * Add an environment variable table.
372  */
373 	static void
374 add_var_table(tlist, buf, len)
375 	struct tablelist **tlist;
376 	char *buf;
377 	int len;
378 {
379 	if (add_cmd_table(tlist, buf, len) < 0)
380 		error("Warning: environment variables from lesskey file unavailable", NULL_PARG);
381 }
382 
383 /*
384  * Search a single command table for the command string in cmd.
385  */
386 	static int
387 cmd_search(cmd, table, endtable, sp)
388 	char *cmd;
389 	char *table;
390 	char *endtable;
391 	char **sp;
392 {
393 	register char *p;
394 	register char *q;
395 	register int a;
396 
397 	*sp = NULL;
398 	for (p = table, q = cmd;  p < endtable;  p++, q++)
399 	{
400 		if (*p == *q)
401 		{
402 			/*
403 			 * Current characters match.
404 			 * If we're at the end of the string, we've found it.
405 			 * Return the action code, which is the character
406 			 * after the null at the end of the string
407 			 * in the command table.
408 			 */
409 			if (*p == '\0')
410 			{
411 				a = *++p & 0377;
412 				while (a == A_SKIP)
413 					a = *++p & 0377;
414 				if (a == A_END_LIST)
415 				{
416 					/*
417 					 * We get here only if the original
418 					 * cmd string passed in was empty ("").
419 					 * I don't think that can happen,
420 					 * but just in case ...
421 					 */
422 					return (A_UINVALID);
423 				}
424 				/*
425 				 * Check for an "extra" string.
426 				 */
427 				if (a & A_EXTRA)
428 				{
429 					*sp = ++p;
430 					a &= ~A_EXTRA;
431 				}
432 				return (a);
433 			}
434 		} else if (*q == '\0')
435 		{
436 			/*
437 			 * Hit the end of the user's command,
438 			 * but not the end of the string in the command table.
439 			 * The user's command is incomplete.
440 			 */
441 			return (A_PREFIX);
442 		} else
443 		{
444 			/*
445 			 * Not a match.
446 			 * Skip ahead to the next command in the
447 			 * command table, and reset the pointer
448 			 * to the beginning of the user's command.
449 			 */
450 			if (*p == '\0' && p[1] == A_END_LIST)
451 			{
452 				/*
453 				 * A_END_LIST is a special marker that tells
454 				 * us to abort the cmd search.
455 				 */
456 				return (A_UINVALID);
457 			}
458 			while (*p++ != '\0')
459 				continue;
460 			while (*p == A_SKIP)
461 				p++;
462 			if (*p & A_EXTRA)
463 				while (*++p != '\0')
464 					continue;
465 			q = cmd-1;
466 		}
467 	}
468 	/*
469 	 * No match found in the entire command table.
470 	 */
471 	return (A_INVALID);
472 }
473 
474 /*
475  * Decode a command character and return the associated action.
476  * The "extra" string, if any, is returned in sp.
477  */
478 	static int
479 cmd_decode(tlist, cmd, sp)
480 	struct tablelist *tlist;
481 	char *cmd;
482 	char **sp;
483 {
484 	register struct tablelist *t;
485 	register int action = A_INVALID;
486 
487 	/*
488 	 * Search thru all the command tables.
489 	 * Stop when we find an action which is not A_INVALID.
490 	 */
491 	for (t = tlist;  t != NULL;  t = t->t_next)
492 	{
493 		action = cmd_search(cmd, t->t_start, t->t_end, sp);
494 		if (action != A_INVALID)
495 			break;
496 	}
497 	if (action == A_UINVALID)
498 		action = A_INVALID;
499 	return (action);
500 }
501 
502 /*
503  * Decode a command from the cmdtables list.
504  */
505 	public int
506 fcmd_decode(cmd, sp)
507 	char *cmd;
508 	char **sp;
509 {
510 	return (cmd_decode(list_fcmd_tables, cmd, sp));
511 }
512 
513 /*
514  * Decode a command from the edittables list.
515  */
516 	public int
517 ecmd_decode(cmd, sp)
518 	char *cmd;
519 	char **sp;
520 {
521 	return (cmd_decode(list_ecmd_tables, cmd, sp));
522 }
523 
524 /*
525  * Get the value of an environment variable.
526  * Looks first in the lesskey file, then in the real environment.
527  */
528 	public char *
529 lgetenv(var)
530 	char *var;
531 {
532 	int a;
533 	char *s;
534 
535 	a = cmd_decode(list_var_tables, var, &s);
536 	if (a == EV_OK)
537 		return (s);
538 	s = getenv(var);
539 	if (s != NULL && *s != '\0')
540 		return (s);
541 	a = cmd_decode(list_sysvar_tables, var, &s);
542 	if (a == EV_OK)
543 		return (s);
544 	return (NULL);
545 }
546 
547 #if USERFILE
548 /*
549  * Get an "integer" from a lesskey file.
550  * Integers are stored in a funny format:
551  * two bytes, low order first, in radix KRADIX.
552  */
553 	static int
554 gint(sp)
555 	char **sp;
556 {
557 	int n;
558 
559 	n = *(*sp)++;
560 	n += *(*sp)++ * KRADIX;
561 	return (n);
562 }
563 
564 /*
565  * Process an old (pre-v241) lesskey file.
566  */
567 	static int
568 old_lesskey(buf, len)
569 	char *buf;
570 	int len;
571 {
572 	/*
573 	 * Old-style lesskey file.
574 	 * The file must end with either
575 	 *     ...,cmd,0,action
576 	 * or  ...,cmd,0,action|A_EXTRA,string,0
577 	 * So the last byte or the second to last byte must be zero.
578 	 */
579 	if (buf[len-1] != '\0' && buf[len-2] != '\0')
580 		return (-1);
581 	add_fcmd_table(buf, len);
582 	return (0);
583 }
584 
585 /*
586  * Process a new (post-v241) lesskey file.
587  */
588 	static int
589 new_lesskey(buf, len, sysvar)
590 	char *buf;
591 	int len;
592 	int sysvar;
593 {
594 	char *p;
595 	register int c;
596 	register int n;
597 
598 	/*
599 	 * New-style lesskey file.
600 	 * Extract the pieces.
601 	 */
602 	if (buf[len-3] != C0_END_LESSKEY_MAGIC ||
603 	    buf[len-2] != C1_END_LESSKEY_MAGIC ||
604 	    buf[len-1] != C2_END_LESSKEY_MAGIC)
605 		return (-1);
606 	p = buf + 4;
607 	for (;;)
608 	{
609 		c = *p++;
610 		switch (c)
611 		{
612 		case CMD_SECTION:
613 			n = gint(&p);
614 			add_fcmd_table(p, n);
615 			p += n;
616 			break;
617 		case EDIT_SECTION:
618 			n = gint(&p);
619 			add_ecmd_table(p, n);
620 			p += n;
621 			break;
622 		case VAR_SECTION:
623 			n = gint(&p);
624 			add_var_table((sysvar) ?
625 				&list_sysvar_tables : &list_var_tables, p, n);
626 			p += n;
627 			break;
628 		case END_SECTION:
629 			return (0);
630 		default:
631 			/*
632 			 * Unrecognized section type.
633 			 */
634 			return (-1);
635 		}
636 	}
637 }
638 
639 /*
640  * Set up a user command table, based on a "lesskey" file.
641  */
642 	public int
643 lesskey(filename, sysvar)
644 	char *filename;
645 	int sysvar;
646 {
647 	register char *buf;
648 	register POSITION len;
649 	register long n;
650 	register int f;
651 
652 	if (secure)
653 		return (1);
654 	/*
655 	 * Try to open the lesskey file.
656 	 */
657 	filename = shell_unquote(filename);
658 	f = open(filename, OPEN_READ);
659 	free(filename);
660 	if (f < 0)
661 		return (1);
662 
663 	/*
664 	 * Read the file into a buffer.
665 	 * We first figure out the size of the file and allocate space for it.
666 	 * {{ Minimal error checking is done here.
667 	 *    A garbage .less file will produce strange results.
668 	 *    To avoid a large amount of error checking code here, we
669 	 *    rely on the lesskey program to generate a good .less file. }}
670 	 */
671 	len = filesize(f);
672 	if (len == NULL_POSITION || len < 3)
673 	{
674 		/*
675 		 * Bad file (valid file must have at least 3 chars).
676 		 */
677 		close(f);
678 		return (-1);
679 	}
680 	if ((buf = (char *) calloc((int)len, sizeof(char))) == NULL)
681 	{
682 		close(f);
683 		return (-1);
684 	}
685 	if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
686 	{
687 		free(buf);
688 		close(f);
689 		return (-1);
690 	}
691 	n = read(f, buf, (unsigned int) len);
692 	close(f);
693 	if (n != len)
694 	{
695 		free(buf);
696 		return (-1);
697 	}
698 
699 	/*
700 	 * Figure out if this is an old-style (before version 241)
701 	 * or new-style lesskey file format.
702 	 */
703 	if (buf[0] != C0_LESSKEY_MAGIC || buf[1] != C1_LESSKEY_MAGIC ||
704 	    buf[2] != C2_LESSKEY_MAGIC || buf[3] != C3_LESSKEY_MAGIC)
705 		return (old_lesskey(buf, (int)len));
706 	return (new_lesskey(buf, (int)len, sysvar));
707 }
708 
709 /*
710  * Add the standard lesskey file "$HOME/.less"
711  */
712 	public void
713 add_hometable(envname, def_filename, sysvar)
714 	char *envname;
715 	char *def_filename;
716 	int sysvar;
717 {
718 	char *filename;
719 	PARG parg;
720 
721 	if (envname != NULL && (filename = lgetenv(envname)) != NULL)
722 		filename = save(filename);
723 	else if (sysvar)
724 		filename = save(def_filename);
725 	else
726 		filename = homefile(def_filename);
727 	if (filename == NULL)
728 		return;
729 	if (lesskey(filename, sysvar) < 0)
730 	{
731 		parg.p_string = filename;
732 		error("Cannot use lesskey file \"%s\"", &parg);
733 	}
734 	free(filename);
735 }
736 #endif
737 
738 /*
739  * See if a char is a special line-editing command.
740  */
741 	public int
742 editchar(c, flags)
743 	int c;
744 	int flags;
745 {
746 	int action;
747 	int nch;
748 	char *s;
749 	char usercmd[MAX_CMDLEN+1];
750 
751 	/*
752 	 * An editing character could actually be a sequence of characters;
753 	 * for example, an escape sequence sent by pressing the uparrow key.
754 	 * To match the editing string, we use the command decoder
755 	 * but give it the edit-commands command table
756 	 * This table is constructed to match the user's keyboard.
757 	 */
758 	if (c == erase_char || c == erase2_char)
759 		return (EC_BACKSPACE);
760 	if (c == kill_char)
761 		return (EC_LINEKILL);
762 
763 	/*
764 	 * Collect characters in a buffer.
765 	 * Start with the one we have, and get more if we need them.
766 	 */
767 	nch = 0;
768 	do {
769 	  	if (nch > 0)
770 			c = getcc();
771 		usercmd[nch] = c;
772 		usercmd[nch+1] = '\0';
773 		nch++;
774 		action = ecmd_decode(usercmd, &s);
775 	} while (action == A_PREFIX);
776 
777 	if (flags & EC_NORIGHTLEFT)
778 	{
779 		switch (action)
780 		{
781 		case EC_RIGHT:
782 		case EC_LEFT:
783 			action = A_INVALID;
784 			break;
785 		}
786 	}
787 #if CMD_HISTORY
788 	if (flags & EC_NOHISTORY)
789 	{
790 		/*
791 		 * The caller says there is no history list.
792 		 * Reject any history-manipulation action.
793 		 */
794 		switch (action)
795 		{
796 		case EC_UP:
797 		case EC_DOWN:
798 			action = A_INVALID;
799 			break;
800 		}
801 	}
802 #endif
803 #if TAB_COMPLETE_FILENAME
804 	if (flags & EC_NOCOMPLETE)
805 	{
806 		/*
807 		 * The caller says we don't want any filename completion cmds.
808 		 * Reject them.
809 		 */
810 		switch (action)
811 		{
812 		case EC_F_COMPLETE:
813 		case EC_B_COMPLETE:
814 		case EC_EXPAND:
815 			action = A_INVALID;
816 			break;
817 		}
818 	}
819 #endif
820 	if ((flags & EC_PEEK) || action == A_INVALID)
821 	{
822 		/*
823 		 * We're just peeking, or we didn't understand the command.
824 		 * Unget all the characters we read in the loop above.
825 		 * This does NOT include the original character that was
826 		 * passed in as a parameter.
827 		 */
828 		while (nch > 1)
829 		{
830 			ungetcc(usercmd[--nch]);
831 		}
832 	} else
833 	{
834 		if (s != NULL)
835 			ungetsc(s);
836 	}
837 	return action;
838 }
839 
840