xref: /freebsd/contrib/less/decode.c (revision 0e6acb26)
1 /*
2  * Copyright (C) 1984-2015  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, see the README file.
8  */
9 
10 
11 /*
12  * Routines to decode user commands.
13  *
14  * This is all table driven.
15  * A command table is a sequence of command descriptors.
16  * Each command descriptor is a sequence of bytes with the following format:
17  *	<c1><c2>...<cN><0><action>
18  * The characters c1,c2,...,cN are the command string; that is,
19  * the characters which the user must type.
20  * It is terminated by a null <0> byte.
21  * The byte after the null byte is the action code associated
22  * with the command string.
23  * If an action byte is OR-ed with A_EXTRA, this indicates
24  * that the option byte is followed by an extra string.
25  *
26  * There may be many command tables.
27  * The first (default) table is built-in.
28  * Other tables are read in from "lesskey" files.
29  * All the tables are linked together and are searched in order.
30  */
31 
32 #include "less.h"
33 #include "cmd.h"
34 #include "lesskey.h"
35 
36 extern int erase_char, erase2_char, kill_char;
37 extern int secure;
38 
39 #define SK(k) \
40 	SK_SPECIAL_KEY, (k), 6, 1, 1, 1
41 /*
42  * Command table is ordered roughly according to expected
43  * frequency of use, so the common commands are near the beginning.
44  */
45 
46 static unsigned char cmdtable[] =
47 {
48 	'\r',0,				A_F_LINE,
49 	'\n',0,				A_F_LINE,
50 	'e',0,				A_F_LINE,
51 	'j',0,				A_F_LINE,
52 	SK(SK_DOWN_ARROW),0,		A_F_LINE,
53 	CONTROL('E'),0,			A_F_LINE,
54 	CONTROL('N'),0,			A_F_LINE,
55 	'k',0,				A_B_LINE,
56 	'y',0,				A_B_LINE,
57 	CONTROL('Y'),0,			A_B_LINE,
58 	SK(SK_CONTROL_K),0,		A_B_LINE,
59 	CONTROL('P'),0,			A_B_LINE,
60 	SK(SK_UP_ARROW),0,		A_B_LINE,
61 	'J',0,				A_FF_LINE,
62 	'K',0,				A_BF_LINE,
63 	'Y',0,				A_BF_LINE,
64 	'd',0,				A_F_SCROLL,
65 	CONTROL('D'),0,			A_F_SCROLL,
66 	'u',0,				A_B_SCROLL,
67 	CONTROL('U'),0,			A_B_SCROLL,
68 	' ',0,				A_F_SCREEN,
69 	'f',0,				A_F_SCREEN,
70 	CONTROL('F'),0,			A_F_SCREEN,
71 	CONTROL('V'),0,			A_F_SCREEN,
72 	SK(SK_PAGE_DOWN),0,		A_F_SCREEN,
73 	'b',0,				A_B_SCREEN,
74 	CONTROL('B'),0,			A_B_SCREEN,
75 	ESC,'v',0,			A_B_SCREEN,
76 	SK(SK_PAGE_UP),0,		A_B_SCREEN,
77 	'z',0,				A_F_WINDOW,
78 	'w',0,				A_B_WINDOW,
79 	ESC,' ',0,			A_FF_SCREEN,
80 	'F',0,				A_F_FOREVER,
81 	ESC,'F',0,			A_F_UNTIL_HILITE,
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,'G',0,			A_GOEND_BUF,
109 	ESC,'>',0,			A_GOEND,
110 	'>',0,				A_GOEND,
111 	SK(SK_END),0,			A_GOEND,
112 	'P',0,				A_GOPOS,
113 
114 	'0',0,				A_DIGIT,
115 	'1',0,				A_DIGIT,
116 	'2',0,				A_DIGIT,
117 	'3',0,				A_DIGIT,
118 	'4',0,				A_DIGIT,
119 	'5',0,				A_DIGIT,
120 	'6',0,				A_DIGIT,
121 	'7',0,				A_DIGIT,
122 	'8',0,				A_DIGIT,
123 	'9',0,				A_DIGIT,
124 	'.',0,				A_DIGIT,
125 
126 	'=',0,				A_STAT,
127 	CONTROL('G'),0,			A_STAT,
128 	':','f',0,			A_STAT,
129 	'/',0,				A_F_SEARCH,
130 	'?',0,				A_B_SEARCH,
131 	ESC,'/',0,			A_F_SEARCH|A_EXTRA,	'*',0,
132 	ESC,'?',0,			A_B_SEARCH|A_EXTRA,	'*',0,
133 	'n',0,				A_AGAIN_SEARCH,
134 	ESC,'n',0,			A_T_AGAIN_SEARCH,
135 	'N',0,				A_REVERSE_SEARCH,
136 	ESC,'N',0,			A_T_REVERSE_SEARCH,
137 	'&',0,				A_FILTER,
138 	'm',0,				A_SETMARK,
139 	'\'',0,				A_GOMARK,
140 	CONTROL('X'),CONTROL('X'),0,	A_GOMARK,
141 	'E',0,				A_EXAMINE,
142 	':','e',0,			A_EXAMINE,
143 	CONTROL('X'),CONTROL('V'),0,	A_EXAMINE,
144 	':','n',0,			A_NEXT_FILE,
145 	':','p',0,			A_PREV_FILE,
146 	't',0,				A_NEXT_TAG,
147 	'T',0,				A_PREV_TAG,
148 	':','x',0,			A_INDEX_FILE,
149 	':','d',0,			A_REMOVE_FILE,
150 	'-',0,				A_OPT_TOGGLE,
151 	':','t',0,			A_OPT_TOGGLE|A_EXTRA,	't',0,
152 	's',0,				A_OPT_TOGGLE|A_EXTRA,	'o',0,
153 	'_',0,				A_DISP_OPTION,
154 	'|',0,				A_PIPE,
155 	'v',0,				A_VISUAL,
156 	'!',0,				A_SHELL,
157 	'+',0,				A_FIRSTCMD,
158 
159 	'H',0,				A_HELP,
160 	'h',0,				A_HELP,
161 	SK(SK_F1),0,			A_HELP,
162 	'V',0,				A_VERSION,
163 	'q',0,				A_QUIT,
164 	'Q',0,				A_QUIT,
165 	':','q',0,			A_QUIT,
166 	':','Q',0,			A_QUIT,
167 	'Z','Z',0,			A_QUIT
168 };
169 
170 static unsigned char edittable[] =
171 {
172 	'\t',0,	    			EC_F_COMPLETE,	/* TAB */
173 	'\17',0,			EC_B_COMPLETE,	/* BACKTAB */
174 	SK(SK_BACKTAB),0,		EC_B_COMPLETE,	/* BACKTAB */
175 	ESC,'\t',0,			EC_B_COMPLETE,	/* ESC TAB */
176 	CONTROL('L'),0,			EC_EXPAND,	/* CTRL-L */
177 	CONTROL('V'),0,			EC_LITERAL,	/* BACKSLASH */
178 	CONTROL('A'),0,			EC_LITERAL,	/* BACKSLASH */
179    	ESC,'l',0,			EC_RIGHT,	/* ESC l */
180 	SK(SK_RIGHT_ARROW),0,		EC_RIGHT,	/* RIGHTARROW */
181 	ESC,'h',0,			EC_LEFT,	/* ESC h */
182 	SK(SK_LEFT_ARROW),0,		EC_LEFT,	/* LEFTARROW */
183 	ESC,'b',0,			EC_W_LEFT,	/* ESC b */
184 	ESC,SK(SK_LEFT_ARROW),0,	EC_W_LEFT,	/* ESC LEFTARROW */
185 	SK(SK_CTL_LEFT_ARROW),0,	EC_W_LEFT,	/* CTRL-LEFTARROW */
186 	ESC,'w',0,			EC_W_RIGHT,	/* ESC w */
187 	ESC,SK(SK_RIGHT_ARROW),0,	EC_W_RIGHT,	/* ESC RIGHTARROW */
188 	SK(SK_CTL_RIGHT_ARROW),0,	EC_W_RIGHT,	/* CTRL-RIGHTARROW */
189 	ESC,'i',0,			EC_INSERT,	/* ESC i */
190 	SK(SK_INSERT),0,		EC_INSERT,	/* INSERT */
191 	ESC,'x',0,			EC_DELETE,	/* ESC x */
192 	SK(SK_DELETE),0,		EC_DELETE,	/* DELETE */
193 	ESC,'X',0,			EC_W_DELETE,	/* ESC X */
194 	ESC,SK(SK_DELETE),0,		EC_W_DELETE,	/* ESC DELETE */
195 	SK(SK_CTL_DELETE),0,		EC_W_DELETE,	/* CTRL-DELETE */
196 	SK(SK_CTL_BACKSPACE),0,		EC_W_BACKSPACE, /* CTRL-BACKSPACE */
197 	ESC,'\b',0,			EC_W_BACKSPACE,	/* ESC BACKSPACE */
198 	ESC,'0',0,			EC_HOME,	/* ESC 0 */
199 	SK(SK_HOME),0,			EC_HOME,	/* HOME */
200 	ESC,'$',0,			EC_END,		/* ESC $ */
201 	SK(SK_END),0,			EC_END,		/* END */
202 	ESC,'k',0,			EC_UP,		/* ESC k */
203 	SK(SK_UP_ARROW),0,		EC_UP,		/* UPARROW */
204 	ESC,'j',0,			EC_DOWN,	/* ESC j */
205 	SK(SK_DOWN_ARROW),0,		EC_DOWN,	/* DOWNARROW */
206 	CONTROL('G'),0,			EC_ABORT,	/* CTRL-G */
207 };
208 
209 /*
210  * Structure to support a list of command tables.
211  */
212 struct tablelist
213 {
214 	struct tablelist *t_next;
215 	char *t_start;
216 	char *t_end;
217 };
218 
219 /*
220  * List of command tables and list of line-edit tables.
221  */
222 static struct tablelist *list_fcmd_tables = NULL;
223 static struct tablelist *list_ecmd_tables = NULL;
224 static struct tablelist *list_var_tables = NULL;
225 static struct tablelist *list_sysvar_tables = NULL;
226 
227 
228 /*
229  * Expand special key abbreviations in a command table.
230  */
231 	static void
232 expand_special_keys(char *table, int len)
233 {
234 	char *fm;
235 	char *to;
236 	int a;
237 	char *repl;
238 	int klen;
239 
240 	for (fm = table;  fm < table + len; )
241 	{
242 		/*
243 		 * Rewrite each command in the table with any
244 		 * special key abbreviations expanded.
245 		 */
246 		for (to = fm;  *fm != '\0'; )
247 		{
248 			if (*fm != SK_SPECIAL_KEY)
249 			{
250 				*to++ = *fm++;
251 				continue;
252 			}
253 			/*
254 			 * After SK_SPECIAL_KEY, next byte is the type
255 			 * of special key (one of the SK_* contants),
256 			 * and the byte after that is the number of bytes,
257 			 * N, reserved by the abbreviation (including the
258 			 * SK_SPECIAL_KEY and key type bytes).
259 			 * Replace all N bytes with the actual bytes
260 			 * output by the special key on this terminal.
261 			 */
262 			repl = special_key_str(fm[1]);
263 			klen = fm[2] & 0377;
264 			fm += klen;
265 			if (repl == NULL || (int) strlen(repl) > klen)
266 				repl = "\377";
267 			while (*repl != '\0')
268 				*to++ = *repl++;
269 		}
270 		*to++ = '\0';
271 		/*
272 		 * Fill any unused bytes between end of command and
273 		 * the action byte with A_SKIP.
274 		 */
275 		while (to <= fm)
276 			*to++ = A_SKIP;
277 		fm++;
278 		a = *fm++ & 0377;
279 		if (a & A_EXTRA)
280 		{
281 			while (*fm++ != '\0')
282 				continue;
283 		}
284 	}
285 }
286 
287 /*
288  * Initialize the command lists.
289  */
290 	public void
291 init_cmds(void)
292 {
293 	/*
294 	 * Add the default command tables.
295 	 */
296 	add_fcmd_table((char*)cmdtable, sizeof(cmdtable));
297 	add_ecmd_table((char*)edittable, sizeof(edittable));
298 #if USERFILE
299 	/*
300 	 * For backwards compatibility,
301 	 * try to add tables in the OLD system lesskey file.
302 	 */
303 #ifdef BINDIR
304 	add_hometable(NULL, BINDIR "/.sysless", 1);
305 #endif
306 	/*
307 	 * Try to add the tables in the system lesskey file.
308 	 */
309 	add_hometable("LESSKEY_SYSTEM", LESSKEYFILE_SYS, 1);
310 	/*
311 	 * Try to add the tables in the standard lesskey file "$HOME/.less".
312 	 */
313 	add_hometable("LESSKEY", LESSKEYFILE, 0);
314 #endif
315 }
316 
317 /*
318  * Add a command table.
319  */
320 	static int
321 add_cmd_table(struct tablelist **tlist, char *buf, int len)
322 {
323 	struct tablelist *t;
324 
325 	if (len == 0)
326 		return (0);
327 	/*
328 	 * Allocate a tablelist structure, initialize it,
329 	 * and link it into the list of tables.
330 	 */
331 	if ((t = (struct tablelist *)
332 			calloc(1, sizeof(struct tablelist))) == NULL)
333 	{
334 		return (-1);
335 	}
336 	expand_special_keys(buf, len);
337 	t->t_start = buf;
338 	t->t_end = buf + len;
339 	t->t_next = *tlist;
340 	*tlist = t;
341 	return (0);
342 }
343 
344 /*
345  * Add a command table.
346  */
347 	public void
348 add_fcmd_table(char *buf, int len)
349 {
350 	if (add_cmd_table(&list_fcmd_tables, buf, len) < 0)
351 		error("Warning: some commands disabled", NULL_PARG);
352 }
353 
354 /*
355  * Add an editing command table.
356  */
357 	public void
358 add_ecmd_table(char *buf, int len)
359 {
360 	if (add_cmd_table(&list_ecmd_tables, buf, len) < 0)
361 		error("Warning: some edit commands disabled", NULL_PARG);
362 }
363 
364 /*
365  * Add an environment variable table.
366  */
367 	static void
368 add_var_table(struct tablelist **tlist, char *buf, int len)
369 {
370 	if (add_cmd_table(tlist, buf, len) < 0)
371 		error("Warning: environment variables from lesskey file unavailable", NULL_PARG);
372 }
373 
374 /*
375  * Search a single command table for the command string in cmd.
376  */
377 	static int
378 cmd_search(char *cmd, char *table, char *endtable, char **sp)
379 {
380 	char *p;
381 	char *q;
382 	int a;
383 
384 	*sp = NULL;
385 	for (p = table, q = cmd;  p < endtable;  p++, q++)
386 	{
387 		if (*p == *q)
388 		{
389 			/*
390 			 * Current characters match.
391 			 * If we're at the end of the string, we've found it.
392 			 * Return the action code, which is the character
393 			 * after the null at the end of the string
394 			 * in the command table.
395 			 */
396 			if (*p == '\0')
397 			{
398 				a = *++p & 0377;
399 				while (a == A_SKIP)
400 					a = *++p & 0377;
401 				if (a == A_END_LIST)
402 				{
403 					/*
404 					 * We get here only if the original
405 					 * cmd string passed in was empty ("").
406 					 * I don't think that can happen,
407 					 * but just in case ...
408 					 */
409 					return (A_UINVALID);
410 				}
411 				/*
412 				 * Check for an "extra" string.
413 				 */
414 				if (a & A_EXTRA)
415 				{
416 					*sp = ++p;
417 					a &= ~A_EXTRA;
418 				}
419 				return (a);
420 			}
421 		} else if (*q == '\0')
422 		{
423 			/*
424 			 * Hit the end of the user's command,
425 			 * but not the end of the string in the command table.
426 			 * The user's command is incomplete.
427 			 */
428 			return (A_PREFIX);
429 		} else
430 		{
431 			/*
432 			 * Not a match.
433 			 * Skip ahead to the next command in the
434 			 * command table, and reset the pointer
435 			 * to the beginning of the user's command.
436 			 */
437 			if (*p == '\0' && p[1] == A_END_LIST)
438 			{
439 				/*
440 				 * A_END_LIST is a special marker that tells
441 				 * us to abort the cmd search.
442 				 */
443 				return (A_UINVALID);
444 			}
445 			while (*p++ != '\0')
446 				continue;
447 			while (*p == A_SKIP)
448 				p++;
449 			if (*p & A_EXTRA)
450 				while (*++p != '\0')
451 					continue;
452 			q = cmd-1;
453 		}
454 	}
455 	/*
456 	 * No match found in the entire command table.
457 	 */
458 	return (A_INVALID);
459 }
460 
461 /*
462  * Decode a command character and return the associated action.
463  * The "extra" string, if any, is returned in sp.
464  */
465 	static int
466 cmd_decode(struct tablelist *tlist, char *cmd, char **sp)
467 {
468 	struct tablelist *t;
469 	int action = A_INVALID;
470 
471 	/*
472 	 * Search thru all the command tables.
473 	 * Stop when we find an action which is not A_INVALID.
474 	 */
475 	for (t = tlist;  t != NULL;  t = t->t_next)
476 	{
477 		action = cmd_search(cmd, t->t_start, t->t_end, sp);
478 		if (action != A_INVALID)
479 			break;
480 	}
481 	if (action == A_UINVALID)
482 		action = A_INVALID;
483 	return (action);
484 }
485 
486 /*
487  * Decode a command from the cmdtables list.
488  */
489 	public int
490 fcmd_decode(char *cmd, char **sp)
491 {
492 	return (cmd_decode(list_fcmd_tables, cmd, sp));
493 }
494 
495 /*
496  * Decode a command from the edittables list.
497  */
498 	public int
499 ecmd_decode(char *cmd, char **sp)
500 {
501 	return (cmd_decode(list_ecmd_tables, cmd, sp));
502 }
503 
504 /*
505  * Get the value of an environment variable.
506  * Looks first in the lesskey file, then in the real environment.
507  */
508 	public char *
509 lgetenv(char *var)
510 {
511 	int a;
512 	char *s;
513 
514 	a = cmd_decode(list_var_tables, var, &s);
515 	if (a == EV_OK)
516 		return (s);
517 	s = getenv(var);
518 	if (s != NULL && *s != '\0')
519 		return (s);
520 	a = cmd_decode(list_sysvar_tables, var, &s);
521 	if (a == EV_OK)
522 		return (s);
523 	return (NULL);
524 }
525 
526 #if USERFILE
527 /*
528  * Get an "integer" from a lesskey file.
529  * Integers are stored in a funny format:
530  * two bytes, low order first, in radix KRADIX.
531  */
532 	static int
533 gint(char **sp)
534 {
535 	int n;
536 
537 	n = *(*sp)++;
538 	n += *(*sp)++ * KRADIX;
539 	return (n);
540 }
541 
542 /*
543  * Process an old (pre-v241) lesskey file.
544  */
545 	static int
546 old_lesskey(char *buf, int len)
547 {
548 	/*
549 	 * Old-style lesskey file.
550 	 * The file must end with either
551 	 *     ...,cmd,0,action
552 	 * or  ...,cmd,0,action|A_EXTRA,string,0
553 	 * So the last byte or the second to last byte must be zero.
554 	 */
555 	if (buf[len-1] != '\0' && buf[len-2] != '\0')
556 		return (-1);
557 	add_fcmd_table(buf, len);
558 	return (0);
559 }
560 
561 /*
562  * Process a new (post-v241) lesskey file.
563  */
564 	static int
565 new_lesskey(char *buf, int len, int sysvar)
566 {
567 	char *p;
568 	int c;
569 	int n;
570 
571 	/*
572 	 * New-style lesskey file.
573 	 * Extract the pieces.
574 	 */
575 	if (buf[len-3] != C0_END_LESSKEY_MAGIC ||
576 	    buf[len-2] != C1_END_LESSKEY_MAGIC ||
577 	    buf[len-1] != C2_END_LESSKEY_MAGIC)
578 		return (-1);
579 	p = buf + 4;
580 	for (;;)
581 	{
582 		c = *p++;
583 		switch (c)
584 		{
585 		case CMD_SECTION:
586 			n = gint(&p);
587 			add_fcmd_table(p, n);
588 			p += n;
589 			break;
590 		case EDIT_SECTION:
591 			n = gint(&p);
592 			add_ecmd_table(p, n);
593 			p += n;
594 			break;
595 		case VAR_SECTION:
596 			n = gint(&p);
597 			add_var_table((sysvar) ?
598 				&list_sysvar_tables : &list_var_tables, p, n);
599 			p += n;
600 			break;
601 		case END_SECTION:
602 			return (0);
603 		default:
604 			/*
605 			 * Unrecognized section type.
606 			 */
607 			return (-1);
608 		}
609 	}
610 }
611 
612 /*
613  * Set up a user command table, based on a "lesskey" file.
614  */
615 	public int
616 lesskey(char *filename, int sysvar)
617 {
618 	char *buf;
619 	POSITION len;
620 	long n;
621 	int f;
622 
623 	if (secure)
624 		return (1);
625 	/*
626 	 * Try to open the lesskey file.
627 	 */
628 	filename = shell_unquote(filename);
629 	f = open(filename, OPEN_READ);
630 	free(filename);
631 	if (f < 0)
632 		return (1);
633 
634 	/*
635 	 * Read the file into a buffer.
636 	 * We first figure out the size of the file and allocate space for it.
637 	 * {{ Minimal error checking is done here.
638 	 *    A garbage .less file will produce strange results.
639 	 *    To avoid a large amount of error checking code here, we
640 	 *    rely on the lesskey program to generate a good .less file. }}
641 	 */
642 	len = filesize(f);
643 	if (len == NULL_POSITION || len < 3)
644 	{
645 		/*
646 		 * Bad file (valid file must have at least 3 chars).
647 		 */
648 		close(f);
649 		return (-1);
650 	}
651 	if ((buf = (char *) calloc((int)len, sizeof(char))) == NULL)
652 	{
653 		close(f);
654 		return (-1);
655 	}
656 	if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
657 	{
658 		free(buf);
659 		close(f);
660 		return (-1);
661 	}
662 	n = read(f, buf, (unsigned int) len);
663 	close(f);
664 	if (n != len)
665 	{
666 		free(buf);
667 		return (-1);
668 	}
669 
670 	/*
671 	 * Figure out if this is an old-style (before version 241)
672 	 * or new-style lesskey file format.
673 	 */
674 	if (buf[0] != C0_LESSKEY_MAGIC || buf[1] != C1_LESSKEY_MAGIC ||
675 	    buf[2] != C2_LESSKEY_MAGIC || buf[3] != C3_LESSKEY_MAGIC)
676 		return (old_lesskey(buf, (int)len));
677 	return (new_lesskey(buf, (int)len, sysvar));
678 }
679 
680 /*
681  * Add the standard lesskey file "$HOME/.less"
682  */
683 	public void
684 add_hometable(char *envname, char *def_filename, int sysvar)
685 {
686 	char *filename;
687 	PARG parg;
688 
689 	if (envname != NULL && (filename = lgetenv(envname)) != NULL)
690 		filename = save(filename);
691 	else if (sysvar)
692 		filename = save(def_filename);
693 	else
694 		filename = homefile(def_filename);
695 	if (filename == NULL)
696 		return;
697 	if (lesskey(filename, sysvar) < 0)
698 	{
699 		parg.p_string = filename;
700 		error("Cannot use lesskey file \"%s\"", &parg);
701 	}
702 	free(filename);
703 }
704 #endif
705 
706 /*
707  * See if a char is a special line-editing command.
708  */
709 	public int
710 editchar(int c, int flags)
711 {
712 	int action;
713 	int nch;
714 	char *s;
715 	char usercmd[MAX_CMDLEN+1];
716 
717 	/*
718 	 * An editing character could actually be a sequence of characters;
719 	 * for example, an escape sequence sent by pressing the uparrow key.
720 	 * To match the editing string, we use the command decoder
721 	 * but give it the edit-commands command table
722 	 * This table is constructed to match the user's keyboard.
723 	 */
724 	if (c == erase_char || c == erase2_char)
725 		return (EC_BACKSPACE);
726 	if (c == kill_char)
727 		return (EC_LINEKILL);
728 
729 	/*
730 	 * Collect characters in a buffer.
731 	 * Start with the one we have, and get more if we need them.
732 	 */
733 	nch = 0;
734 	do {
735 	  	if (nch > 0)
736 			c = getcc();
737 		usercmd[nch] = c;
738 		usercmd[nch+1] = '\0';
739 		nch++;
740 		action = ecmd_decode(usercmd, &s);
741 	} while (action == A_PREFIX);
742 
743 	if (flags & EC_NORIGHTLEFT)
744 	{
745 		switch (action)
746 		{
747 		case EC_RIGHT:
748 		case EC_LEFT:
749 			action = A_INVALID;
750 			break;
751 		}
752 	}
753 #if CMD_HISTORY
754 	if (flags & EC_NOHISTORY)
755 	{
756 		/*
757 		 * The caller says there is no history list.
758 		 * Reject any history-manipulation action.
759 		 */
760 		switch (action)
761 		{
762 		case EC_UP:
763 		case EC_DOWN:
764 			action = A_INVALID;
765 			break;
766 		}
767 	}
768 #endif
769 #if TAB_COMPLETE_FILENAME
770 	if (flags & EC_NOCOMPLETE)
771 	{
772 		/*
773 		 * The caller says we don't want any filename completion cmds.
774 		 * Reject them.
775 		 */
776 		switch (action)
777 		{
778 		case EC_F_COMPLETE:
779 		case EC_B_COMPLETE:
780 		case EC_EXPAND:
781 			action = A_INVALID;
782 			break;
783 		}
784 	}
785 #endif
786 	if ((flags & EC_PEEK) || action == A_INVALID)
787 	{
788 		/*
789 		 * We're just peeking, or we didn't understand the command.
790 		 * Unget all the characters we read in the loop above.
791 		 * This does NOT include the original character that was
792 		 * passed in as a parameter.
793 		 */
794 		while (nch > 1)
795 		{
796 			ungetcc(usercmd[--nch]);
797 		}
798 	} else
799 	{
800 		if (s != NULL)
801 			ungetsc(s);
802 	}
803 	return action;
804 }
805 
806