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
37extern int erase_char, erase2_char, kill_char;
38extern 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
47static 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
168static 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 */
209struct 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 */
219static struct tablelist *list_fcmd_tables = NULL;
220static struct tablelist *list_ecmd_tables = NULL;
221static struct tablelist *list_var_tables = NULL;
222static struct tablelist *list_sysvar_tables = NULL;
223
224
225/*
226 * Expand special key abbreviations in a command table.
227 */
228	static void
229expand_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
290init_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
320add_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
350add_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
362add_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
374add_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
387cmd_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
479cmd_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
506fcmd_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
517ecmd_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 *
529lgetenv(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
554gint(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
568old_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
589new_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
643lesskey(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
713add_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
742editchar(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