1/*
2 * Copyright (C) 1984-2023  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 * The option table.
13 */
14
15#include "less.h"
16#include "option.h"
17
18/*
19 * Variables controlled by command line options.
20 */
21public int quiet;               /* Should we suppress the audible bell? */
22public int no_vbell;            /* Should we suppress the visual bell? */
23public int how_search;          /* Where should forward searches start? */
24public int top_scroll;          /* Repaint screen from top?
25                                   (alternative is scroll from bottom) */
26public int pr_type;             /* Type of prompt (short, medium, long) */
27public int bs_mode;             /* How to process backspaces */
28public int know_dumb;           /* Don't complain about dumb terminals */
29public int quit_at_eof;         /* Quit after hitting end of file twice */
30public int quit_if_one_screen;  /* Quit if EOF on first screen */
31public int squeeze;             /* Squeeze multiple blank lines into one */
32public int tabstop;             /* Tab settings */
33public int back_scroll;         /* Repaint screen on backwards movement */
34public int forw_scroll;         /* Repaint screen on forward movement */
35public int caseless;            /* Do "caseless" searches */
36public int linenums;            /* Use line numbers */
37public int autobuf;             /* Automatically allocate buffers as needed */
38public int bufspace;            /* Max buffer space per file (K) */
39public int ctldisp;             /* Send control chars to screen untranslated */
40public int force_open;          /* Open the file even if not regular file */
41public int swindow;             /* Size of scrolling window */
42public int jump_sline;          /* Screen line of "jump target" */
43public long jump_sline_fraction = -1;
44public long shift_count_fraction = -1;
45public int chopline;            /* Truncate displayed lines at screen width */
46public int wordwrap;            /* Wrap lines at space */
47public int no_init;             /* Disable sending ti/te termcap strings */
48public int no_keypad;           /* Disable sending ks/ke termcap strings */
49public int twiddle;             /* Show tildes after EOF */
50public int show_attn;           /* Hilite first unread line */
51public int shift_count;         /* Number of positions to shift horizontally */
52public int status_col;          /* Display a status column */
53public int use_lessopen;        /* Use the LESSOPEN filter */
54public int quit_on_intr;        /* Quit on interrupt */
55public int follow_mode;         /* F cmd Follows file desc or file name? */
56public int oldbot;              /* Old bottom of screen behavior {{REMOVE}} */
57public int opt_use_backslash;   /* Use backslash escaping in option parsing */
58public char rscroll_char;       /* Char which marks chopped lines with -S */
59public int rscroll_attr;        /* Attribute of rscroll_char */
60public int no_hist_dups;        /* Remove dups from history list */
61public int mousecap;            /* Allow mouse for scrolling */
62public int wheel_lines;         /* Number of lines to scroll on mouse wheel scroll */
63public int perma_marks;         /* Save marks in history file */
64public int linenum_width;       /* Width of line numbers */
65public int status_col_width;    /* Width of status column */
66public int incr_search;         /* Incremental search */
67public int use_color;           /* Use UI color */
68public int want_filesize;       /* Scan to EOF if necessary to get file size */
69public int status_line;         /* Highlight entire marked lines */
70public int header_lines;        /* Freeze header lines at top of screen */
71public int header_cols;         /* Freeze header columns at left of screen */
72public int nonum_headers;       /* Don't give headers line numbers */
73public int nosearch_headers;    /* Don't search in header lines or columns */
74public int redraw_on_quit;      /* Redraw last screen after term deinit */
75public int def_search_type;     /* */
76public int exit_F_on_close;     /* Exit F command when input closes */
77public int modelines;           /* Lines to read looking for modelines */
78public int show_preproc_error;  /* Display msg when preproc exits with error */
79public int proc_backspace;      /* Special handling of backspace */
80public int proc_tab;            /* Special handling of tab */
81public int proc_return;         /* Special handling of carriage return */
82public char intr_char = CONTROL('X'); /* Char to interrupt reads */
83#if HILITE_SEARCH
84public int hilite_search;       /* Highlight matched search patterns? */
85#endif
86
87public int less_is_more = 0;    /* Make compatible with POSIX more */
88
89/*
90 * Long option names.
91 */
92static struct optname a_optname      = { "search-skip-screen",   NULL };
93static struct optname b_optname      = { "buffers",              NULL };
94static struct optname B__optname     = { "auto-buffers",         NULL };
95static struct optname c_optname      = { "clear-screen",         NULL };
96static struct optname d_optname      = { "dumb",                 NULL };
97static struct optname D__optname     = { "color",                NULL };
98static struct optname e_optname      = { "quit-at-eof",          NULL };
99static struct optname f_optname      = { "force",                NULL };
100static struct optname F__optname     = { "quit-if-one-screen",   NULL };
101#if HILITE_SEARCH
102static struct optname g_optname      = { "hilite-search",        NULL };
103#endif
104static struct optname h_optname      = { "max-back-scroll",      NULL };
105static struct optname i_optname      = { "ignore-case",          NULL };
106static struct optname j_optname      = { "jump-target",          NULL };
107static struct optname J__optname     = { "status-column",        NULL };
108#if USERFILE
109static struct optname k_optname      = { "lesskey-file",         NULL };
110#if HAVE_LESSKEYSRC
111static struct optname ks_optname     = { "lesskey-src",          NULL };
112#endif /* HAVE_LESSKEYSRC */
113#endif
114static struct optname K__optname     = { "quit-on-intr",         NULL };
115static struct optname L__optname     = { "no-lessopen",          NULL };
116static struct optname m_optname      = { "long-prompt",          NULL };
117static struct optname n_optname      = { "line-numbers",         NULL };
118#if LOGFILE
119static struct optname o_optname      = { "log-file",             NULL };
120static struct optname O__optname     = { "LOG-FILE",             NULL };
121#endif
122static struct optname p_optname      = { "pattern",              NULL };
123static struct optname P__optname     = { "prompt",               NULL };
124static struct optname q2_optname     = { "silent",               NULL };
125static struct optname q_optname      = { "quiet",                &q2_optname };
126static struct optname r_optname      = { "raw-control-chars",    NULL };
127static struct optname s_optname      = { "squeeze-blank-lines",  NULL };
128static struct optname S__optname     = { "chop-long-lines",      NULL };
129#if TAGS
130static struct optname t_optname      = { "tag",                  NULL };
131static struct optname T__optname     = { "tag-file",             NULL };
132#endif
133static struct optname u_optname      = { "underline-special",    NULL };
134static struct optname V__optname     = { "version",              NULL };
135static struct optname w_optname      = { "hilite-unread",        NULL };
136static struct optname x_optname      = { "tabs",                 NULL };
137static struct optname X__optname     = { "no-init",              NULL };
138static struct optname y_optname      = { "max-forw-scroll",      NULL };
139static struct optname z_optname      = { "window",               NULL };
140static struct optname quote_optname  = { "quotes",               NULL };
141static struct optname tilde_optname  = { "tilde",                NULL };
142static struct optname query_optname  = { "help",                 NULL };
143static struct optname pound_optname  = { "shift",                NULL };
144static struct optname keypad_optname = { "no-keypad",            NULL };
145static struct optname oldbot_optname = { "old-bot",              NULL };
146static struct optname follow_optname = { "follow-name",          NULL };
147static struct optname use_backslash_optname = { "use-backslash", NULL };
148static struct optname rscroll_optname = { "rscroll", NULL };
149static struct optname nohistdups_optname = { "no-histdups",      NULL };
150static struct optname mousecap_optname = { "mouse",              NULL };
151static struct optname wheel_lines_optname = { "wheel-lines",     NULL };
152static struct optname perma_marks_optname = { "save-marks",      NULL };
153static struct optname linenum_width_optname = { "line-num-width", NULL };
154static struct optname status_col_width_optname = { "status-col-width", NULL };
155static struct optname incr_search_optname = { "incsearch",       NULL };
156static struct optname use_color_optname = { "use-color",         NULL };
157static struct optname want_filesize_optname = { "file-size",     NULL };
158static struct optname status_line_optname = { "status-line",     NULL };
159static struct optname header_optname = { "header",               NULL };
160static struct optname nonum_headers_optname = { "no-number-headers", NULL };
161static struct optname nosearch_headers_optname = { "no-search-headers", NULL };
162static struct optname redraw_on_quit_optname = { "redraw-on-quit", NULL };
163static struct optname search_type_optname = { "search-options", NULL };
164static struct optname exit_F_on_close_optname = { "exit-follow-on-close", NULL };
165static struct optname modelines_optname = { "modelines", NULL };
166static struct optname no_vbell_optname = { "no-vbell", NULL };
167static struct optname intr_optname = { "intr", NULL };
168static struct optname wordwrap_optname = { "wordwrap", NULL };
169static struct optname show_preproc_error_optname = { "show-preproc-errors", NULL };
170static struct optname proc_backspace_optname = { "proc-backspace", NULL };
171static struct optname proc_tab_optname = { "proc-tab", NULL };
172static struct optname proc_return_optname = { "proc-return", NULL };
173#if LESSTEST
174static struct optname ttyin_name_optname = { "tty",              NULL };
175#endif /*LESSTEST*/
176
177
178/*
179 * Table of all options and their semantics.
180 *
181 * For BOOL and TRIPLE options, odesc[0], odesc[1], odesc[2] are
182 * the description of the option when set to 0, 1 or 2, respectively.
183 * For NUMBER options, odesc[0] is the prompt to use when entering
184 * a new value, and odesc[1] is the description, which should contain
185 * one %d which is replaced by the value of the number.
186 * For STRING options, odesc[0] is the prompt to use when entering
187 * a new value, and odesc[1], if not NULL, is the set of characters
188 * that are valid in the string.
189 */
190static struct loption option[] =
191{
192	{ 'a', &a_optname,
193		TRIPLE, OPT_ONPLUS, &how_search, NULL,
194		{
195			"Search includes displayed screen",
196			"Search skips displayed screen",
197			"Search includes all of displayed screen"
198		}
199	},
200
201	{ 'b', &b_optname,
202		NUMBER|INIT_HANDLER, 64, &bufspace, opt_b,
203		{
204			"Max buffer space per file (K): ",
205			"Max buffer space per file: %dK",
206			NULL
207		}
208	},
209	{ 'B', &B__optname,
210		BOOL, OPT_ON, &autobuf, NULL,
211		{
212			"Don't automatically allocate buffers",
213			"Automatically allocate buffers when needed",
214			NULL
215		}
216	},
217	{ 'c', &c_optname,
218		TRIPLE, OPT_OFF, &top_scroll, NULL,
219		{
220			"Repaint by scrolling from bottom of screen",
221			"Repaint by painting from top of screen",
222			"Repaint by painting from top of screen"
223		}
224	},
225	{ 'd', &d_optname,
226		BOOL|NO_TOGGLE, OPT_OFF, &know_dumb, NULL,
227		{
228			"Assume intelligent terminal",
229			"Assume dumb terminal",
230			NULL
231		}
232	},
233	{ 'D', &D__optname,
234		STRING|REPAINT|NO_QUERY, 0, NULL, opt_D,
235		{
236			"color desc: ",
237			NULL,
238			NULL
239		}
240	},
241	{ 'e', &e_optname,
242		TRIPLE, OPT_OFF, &quit_at_eof, NULL,
243		{
244			"Don't quit at end-of-file",
245			"Quit at end-of-file",
246			"Quit immediately at end-of-file"
247		}
248	},
249	{ 'f', &f_optname,
250		BOOL, OPT_OFF, &force_open, NULL,
251		{
252			"Open only regular files",
253			"Open even non-regular files",
254			NULL
255		}
256	},
257	{ 'F', &F__optname,
258		BOOL, OPT_OFF, &quit_if_one_screen, NULL,
259		{
260			"Don't quit if end-of-file on first screen",
261			"Quit if end-of-file on first screen",
262			NULL
263		}
264	},
265#if HILITE_SEARCH
266	{ 'g', &g_optname,
267		TRIPLE|HL_REPAINT, OPT_ONPLUS, &hilite_search, NULL,
268		{
269			"Don't highlight search matches",
270			"Highlight matches for previous search only",
271			"Highlight all matches for previous search pattern",
272		}
273	},
274#endif
275	{ 'h', &h_optname,
276		NUMBER, -1, &back_scroll, NULL,
277		{
278			"Backwards scroll limit: ",
279			"Backwards scroll limit is %d lines",
280			NULL
281		}
282	},
283	{ 'i', &i_optname,
284		TRIPLE|HL_REPAINT, OPT_OFF, &caseless, opt_i,
285		{
286			"Case is significant in searches",
287			"Ignore case in searches",
288			"Ignore case in searches and in patterns"
289		}
290	},
291	{ 'j', &j_optname,
292		STRING, 0, NULL, opt_j,
293		{
294			"Target line: ",
295			"0123456789.-",
296			NULL
297		}
298	},
299	{ 'J', &J__optname,
300		BOOL|REPAINT, OPT_OFF, &status_col, NULL,
301		{
302			"Don't display a status column",
303			"Display a status column",
304			NULL
305		}
306	},
307#if USERFILE
308	{ 'k', &k_optname,
309		STRING|NO_TOGGLE|NO_QUERY, 0, NULL, opt_k,
310		{ NULL, NULL, NULL }
311	},
312#if HAVE_LESSKEYSRC
313	{ OLETTER_NONE, &ks_optname,
314		STRING|NO_TOGGLE|NO_QUERY, 0, NULL, opt_ks,
315		{ NULL, NULL, NULL }
316	},
317#endif /* HAVE_LESSKEYSRC */
318#endif
319	{ 'K', &K__optname,
320		BOOL, OPT_OFF, &quit_on_intr, NULL,
321		{
322			"Interrupt (ctrl-C) returns to prompt",
323			"Interrupt (ctrl-C) exits less",
324			NULL
325		}
326	},
327	{ 'L', &L__optname,
328		BOOL, OPT_ON, &use_lessopen, NULL,
329		{
330			"Don't use the LESSOPEN filter",
331			"Use the LESSOPEN filter",
332			NULL
333		}
334	},
335	{ 'm', &m_optname,
336		TRIPLE, OPT_OFF, &pr_type, NULL,
337		{
338			"Short prompt",
339			"Medium prompt",
340			"Long prompt"
341		}
342	},
343	{ 'n', &n_optname,
344		TRIPLE|REPAINT, OPT_ON, &linenums, NULL,
345		{
346			"Don't use line numbers",
347			"Use line numbers",
348			"Constantly display line numbers"
349		}
350	},
351#if LOGFILE
352	{ 'o', &o_optname,
353		STRING, 0, NULL, opt_o,
354		{ "log file: ", NULL, NULL }
355	},
356	{ 'O', &O__optname,
357		STRING, 0, NULL, opt__O,
358		{ "Log file: ", NULL, NULL }
359	},
360#endif
361	{ 'p', &p_optname,
362		STRING|NO_TOGGLE|NO_QUERY, 0, NULL, opt_p,
363		{ NULL, NULL, NULL }
364	},
365	{ 'P', &P__optname,
366		STRING, 0, NULL, opt__P,
367		{ "prompt: ", NULL, NULL }
368	},
369	{ 'q', &q_optname,
370		TRIPLE, OPT_OFF, &quiet, NULL,
371		{
372			"Ring the bell for errors AND at eof/bof",
373			"Ring the bell for errors but not at eof/bof",
374			"Never ring the bell"
375		}
376	},
377	{ 'r', &r_optname,
378		TRIPLE|REPAINT, OPT_OFF, &ctldisp, NULL,
379		{
380			"Display control characters as ^X",
381			"Display control characters directly (not recommended)",
382			"Display ANSI sequences directly, other control characters as ^X"
383		}
384	},
385	{ 's', &s_optname,
386		BOOL|REPAINT, OPT_OFF, &squeeze, NULL,
387		{
388			"Display all blank lines",
389			"Squeeze multiple blank lines",
390			NULL
391		}
392	},
393	{ 'S', &S__optname,
394		BOOL|REPAINT, OPT_OFF, &chopline, NULL,
395		{
396			"Fold long lines",
397			"Chop long lines",
398			NULL
399		}
400	},
401#if TAGS
402	{ 't', &t_optname,
403		STRING|NO_QUERY, 0, NULL, opt_t,
404		{ "tag: ", NULL, NULL }
405	},
406	{ 'T', &T__optname,
407		STRING, 0, NULL, opt__T,
408		{ "tags file: ", NULL, NULL }
409	},
410#endif
411	{ 'u', &u_optname,
412		TRIPLE|REPAINT|HL_REPAINT, OPT_OFF, &bs_mode, NULL,
413		{
414			"Display underlined text in underline mode",
415			"Backspaces cause overstrike",
416			"Print backspace as ^H"
417		}
418	},
419	{ 'V', &V__optname,
420		NOVAR, 0, NULL, opt__V,
421		{ NULL, NULL, NULL }
422	},
423	{ 'w', &w_optname,
424		TRIPLE|REPAINT, OPT_OFF, &show_attn, NULL,
425		{
426			"Don't highlight first unread line",
427			"Highlight first unread line after forward-screen",
428			"Highlight first unread line after any forward movement",
429		}
430	},
431	{ 'x', &x_optname,
432		STRING|REPAINT, 0, NULL, opt_x,
433		{
434			"Tab stops: ",
435			"0123456789,",
436			NULL
437		}
438	},
439	{ 'X', &X__optname,
440		BOOL|NO_TOGGLE, OPT_OFF, &no_init, NULL,
441		{
442			"Send init/deinit strings to terminal",
443			"Don't use init/deinit strings",
444			NULL
445		}
446	},
447	{ 'y', &y_optname,
448		NUMBER, -1, &forw_scroll, NULL,
449		{
450			"Forward scroll limit: ",
451			"Forward scroll limit is %d lines",
452			NULL
453		}
454	},
455	{ 'z', &z_optname,
456		NUMBER, -1, &swindow, NULL,
457		{
458			"Scroll window size: ",
459			"Scroll window size is %d lines",
460			NULL
461		}
462	},
463	{ '"', &quote_optname,
464		STRING, 0, NULL, opt_quote,
465		{ "quotes: ", NULL, NULL }
466	},
467	{ '~', &tilde_optname,
468		BOOL|REPAINT, OPT_ON, &twiddle, NULL,
469		{
470			"Don't show tildes after end of file",
471			"Show tildes after end of file",
472			NULL
473		}
474	},
475	{ '?', &query_optname,
476		NOVAR, 0, NULL, opt_query,
477		{ NULL, NULL, NULL }
478	},
479	{ '#', &pound_optname,
480		STRING, 0, NULL, opt_shift,
481		{
482			"Horizontal shift: ",
483			"0123456789.",
484			NULL
485		}
486	},
487	{ OLETTER_NONE, &keypad_optname,
488		BOOL|NO_TOGGLE, OPT_OFF, &no_keypad, NULL,
489		{
490			"Use keypad mode",
491			"Don't use keypad mode",
492			NULL
493		}
494	},
495	{ OLETTER_NONE, &oldbot_optname,
496		BOOL, OPT_OFF, &oldbot, NULL,
497		{
498			"Use new bottom of screen behavior",
499			"Use old bottom of screen behavior",
500			NULL
501		}
502	},
503	{ OLETTER_NONE, &follow_optname,
504		BOOL, FOLLOW_DESC, &follow_mode, NULL,
505		{
506			"F command follows file descriptor",
507			"F command follows file name",
508			NULL
509		}
510	},
511	{ OLETTER_NONE, &use_backslash_optname,
512		BOOL, OPT_OFF, &opt_use_backslash, NULL,
513		{
514			"Use backslash escaping in command line parameters",
515			"Don't use backslash escaping in command line parameters",
516			NULL
517		}
518	},
519	{ OLETTER_NONE, &rscroll_optname,
520		STRING|REPAINT|INIT_HANDLER, 0, NULL, opt_rscroll,
521		{ "rscroll character: ", NULL, NULL }
522	},
523	{ OLETTER_NONE, &nohistdups_optname,
524		BOOL, OPT_OFF, &no_hist_dups, NULL,
525		{
526			"Allow duplicates in history list",
527			"Remove duplicates from history list",
528			NULL
529		}
530	},
531	{ OLETTER_NONE, &mousecap_optname,
532		TRIPLE, OPT_OFF, &mousecap, opt_mousecap,
533		{
534			"Ignore mouse input",
535			"Use the mouse for scrolling",
536			"Use the mouse for scrolling (reverse)"
537		}
538	},
539	{ OLETTER_NONE, &wheel_lines_optname,
540		NUMBER|INIT_HANDLER, 0, &wheel_lines, opt_wheel_lines,
541		{
542			"Lines to scroll on mouse wheel: ",
543			"Scroll %d line(s) on mouse wheel",
544			NULL
545		}
546	},
547	{ OLETTER_NONE, &perma_marks_optname,
548		BOOL, OPT_OFF, &perma_marks, NULL,
549		{
550			"Don't save marks in history file",
551			"Save marks in history file",
552			NULL
553		}
554	},
555	{ OLETTER_NONE, &linenum_width_optname,
556		NUMBER|REPAINT, MIN_LINENUM_WIDTH, &linenum_width, opt_linenum_width,
557		{
558			"Line number width: ",
559			"Line number width is %d chars",
560			NULL
561		}
562	},
563	{ OLETTER_NONE, &status_col_width_optname,
564		NUMBER|REPAINT, 2, &status_col_width, opt_status_col_width,
565		{
566			"Status column width: ",
567			"Status column width is %d chars",
568			NULL
569		}
570	},
571	{ OLETTER_NONE, &incr_search_optname,
572		BOOL, OPT_OFF, &incr_search, NULL,
573		{
574			"Incremental search is off",
575			"Incremental search is on",
576			NULL
577		}
578	},
579	{ OLETTER_NONE, &use_color_optname,
580		BOOL|REPAINT, OPT_OFF, &use_color, NULL,
581		{
582			"Don't use color",
583			"Use color",
584			NULL
585		}
586	},
587	{ OLETTER_NONE, &want_filesize_optname,
588		BOOL|REPAINT, OPT_OFF, &want_filesize, opt_filesize,
589		{
590			"Don't get size of each file",
591			"Get size of each file",
592			NULL
593		}
594	},
595	{ OLETTER_NONE, &status_line_optname,
596		BOOL|REPAINT, OPT_OFF, &status_line, NULL,
597		{
598			"Don't color each line with its status column color",
599			"Color each line with its status column color",
600			NULL
601		}
602	},
603	{ OLETTER_NONE, &header_optname,
604		STRING|REPAINT, 0, NULL, opt_header,
605		{
606			"Header lines: ",
607			NULL,
608			NULL
609		}
610	},
611	{ OLETTER_NONE, &nonum_headers_optname,
612		BOOL|REPAINT, 0, &nonum_headers, NULL,
613		{
614			"Number header lines",
615			"Don't number header lines",
616			NULL
617		}
618	},
619	{ OLETTER_NONE, &nosearch_headers_optname,
620		BOOL|HL_REPAINT, 0, &nosearch_headers, NULL,
621		{
622			"Search includes header lines",
623			"Search does not include header lines",
624			NULL
625		}
626	},
627	{ OLETTER_NONE, &redraw_on_quit_optname,
628		BOOL, OPT_OFF, &redraw_on_quit, NULL,
629		{
630			"Don't redraw screen when quitting",
631			"Redraw last screen when quitting",
632			NULL
633		}
634	},
635	{ OLETTER_NONE, &search_type_optname,
636		STRING, 0, NULL, opt_search_type,
637		{
638			"Search options: ",
639			NULL,
640			NULL
641		}
642	},
643	{ OLETTER_NONE, &exit_F_on_close_optname,
644		BOOL, OPT_OFF, &exit_F_on_close, NULL,
645		{
646			"Don't exit F command when input closes",
647			"Exit F command when input closes",
648			NULL
649		}
650	},
651	{ OLETTER_NONE, &no_vbell_optname,
652		BOOL, OPT_OFF, &no_vbell, NULL,
653		{
654			"Display visual bell",
655			"Don't display visual bell",
656			NULL
657		}
658	},
659	{ OLETTER_NONE, &modelines_optname,
660		NUMBER, 0, &modelines, NULL,
661		{
662			"Lines to read looking for modelines: ",
663			"Read %d lines looking for modelines",
664			NULL
665		}
666	},
667	{ OLETTER_NONE, &intr_optname,
668		STRING, 0, NULL, opt_intr,
669		{ "interrupt character: ", NULL, NULL }
670	},
671	{ OLETTER_NONE, &wordwrap_optname,
672		BOOL|REPAINT, OPT_OFF, &wordwrap, NULL,
673		{
674			"Wrap lines at any character",
675			"Wrap lines at spaces",
676			NULL
677		}
678	},
679	{ OLETTER_NONE, &show_preproc_error_optname,
680		BOOL, OPT_OFF, &show_preproc_error, NULL,
681		{
682			"Don't show error message if preprocessor fails",
683			"Show error message if preprocessor fails",
684			NULL
685		}
686	},
687	{ OLETTER_NONE, &proc_backspace_optname,
688		TRIPLE|REPAINT|HL_REPAINT, OPT_OFF, &proc_backspace, NULL,
689		{
690			"Backspace handling is specified by the -U option",
691			"Display underline text in underline mode",
692			"Print backspaces as ^H"
693		}
694	},
695	{ OLETTER_NONE, &proc_tab_optname,
696		TRIPLE|REPAINT|HL_REPAINT, OPT_OFF, &proc_tab, NULL,
697		{
698			"Tab handling is specified by the -U option",
699			"Expand tabs to spaces",
700			"Print tabs as ^I"
701		}
702	},
703	{ OLETTER_NONE, &proc_return_optname,
704		TRIPLE|REPAINT|HL_REPAINT, OPT_OFF, &proc_return, NULL,
705		{
706			"Carriage return handling is specified by the -U option",
707			"Delete carriage return before newline",
708			"Print carriage return as ^M"
709		}
710	},
711#if LESSTEST
712	{ OLETTER_NONE, &ttyin_name_optname,
713		STRING|NO_TOGGLE, 0, NULL, opt_ttyin_name,
714		{
715			NULL,
716			NULL,
717			NULL
718		}
719	},
720#endif /*LESSTEST*/
721	{ '\0', NULL, NOVAR, 0, NULL, NULL, { NULL, NULL, NULL } }
722};
723
724
725/*
726 * Initialize each option to its default value.
727 */
728public void init_option(void)
729{
730	struct loption *o;
731	char *p;
732
733	p = lgetenv("LESS_IS_MORE");
734	if (!isnullenv(p))
735		less_is_more = 1;
736
737	for (o = option;  o->oletter != '\0';  o++)
738	{
739		/*
740		 * Set each variable to its default.
741		 */
742		if (o->ovar != NULL)
743			*(o->ovar) = o->odefault;
744		if (o->otype & INIT_HANDLER)
745			(*(o->ofunc))(INIT, (char *) NULL);
746	}
747}
748
749/*
750 * Find an option in the option table, given its option letter.
751 */
752public struct loption * findopt(int c)
753{
754	struct loption *o;
755
756	for (o = option;  o->oletter != '\0';  o++)
757	{
758		if (o->oletter == c)
759			return (o);
760		if ((o->otype & TRIPLE) && ASCII_TO_UPPER(o->oletter) == c)
761			return (o);
762	}
763	return (NULL);
764}
765
766/*
767 *
768 */
769static int is_optchar(char c)
770{
771	if (ASCII_IS_UPPER(c))
772		return 1;
773	if (ASCII_IS_LOWER(c))
774		return 1;
775	if (c == '-')
776		return 1;
777	return 0;
778}
779
780/*
781 * Find an option in the option table, given its option name.
782 * p_optname is the (possibly partial) name to look for, and
783 * is updated to point after the matched name.
784 * p_oname if non-NULL is set to point to the full option name.
785 */
786public struct loption * findopt_name(char **p_optname, char **p_oname, int *p_err)
787{
788	char *optname = *p_optname;
789	struct loption *o;
790	struct optname *oname;
791	int len;
792	int uppercase;
793	struct loption *maxo = NULL;
794	struct optname *maxoname = NULL;
795	int maxlen = 0;
796	int ambig = 0;
797	int exact = 0;
798
799	/*
800	 * Check all options.
801	 */
802	for (o = option;  o->oletter != '\0';  o++)
803	{
804		/*
805		 * Check all names for this option.
806		 */
807		for (oname = o->onames;  oname != NULL;  oname = oname->onext)
808		{
809			/*
810			 * Try normal match first (uppercase == 0),
811			 * then, then if it's a TRIPLE option,
812			 * try uppercase match (uppercase == 1).
813			 */
814			for (uppercase = 0;  uppercase <= 1;  uppercase++)
815			{
816				len = sprefix(optname, oname->oname, uppercase);
817				if (len <= 0 || is_optchar(optname[len]))
818				{
819					/*
820					 * We didn't use all of the option name.
821					 */
822					continue;
823				}
824				if (!exact && len == maxlen)
825					/*
826					 * Already had a partial match,
827					 * and now there's another one that
828					 * matches the same length.
829					 */
830					ambig = 1;
831				else if (len > maxlen)
832				{
833					/*
834					 * Found a better match than
835					 * the one we had.
836					 */
837					maxo = o;
838					maxoname = oname;
839					maxlen = len;
840					ambig = 0;
841					exact = (len == (int)strlen(oname->oname));
842				}
843				if (!(o->otype & TRIPLE))
844					break;
845			}
846		}
847	}
848	if (ambig)
849	{
850		/*
851		 * Name matched more than one option.
852		 */
853		if (p_err != NULL)
854			*p_err = OPT_AMBIG;
855		return (NULL);
856	}
857	*p_optname = optname + maxlen;
858	if (p_oname != NULL)
859		*p_oname = maxoname == NULL ? NULL : maxoname->oname;
860	return (maxo);
861}
862