1/*	$OpenBSD: fmt.c,v 1.21 2004/04/01 23:14:19 tedu Exp $	*/
2
3/* Sensible version of fmt
4 *
5 * Syntax: fmt [ options ] [ goal [ max ] ] [ filename ... ]
6 *
7 * Since the documentation for the original fmt is so poor, here
8 * is an accurate description of what this one does. It's usually
9 * the same. The *mechanism* used may differ from that suggested
10 * here. Note that we are *not* entirely compatible with fmt,
11 * because fmt gets so many things wrong.
12 *
13 * 1. Tabs are expanded, assuming 8-space tab stops.
14 *    If the `-t <n>' option is given, we assume <n>-space
15 *    tab stops instead.
16 *    Trailing blanks are removed from all lines.
17 *    x\b == nothing, for any x other than \b.
18 *    Other control characters are simply stripped. This
19 *    includes \r.
20 * 2. Each line is split into leading whitespace and
21 *    everything else. Maximal consecutive sequences of
22 *    lines with the same leading whitespace are considered
23 *    to form paragraphs, except that a blank line is always
24 *    a paragraph to itself.
25 *    If the `-p' option is given then the first line of a
26 *    paragraph is permitted to have indentation different
27 *    from that of the other lines.
28 *    If the `-m' option is given then a line that looks
29 *    like a mail message header, if it is not immediately
30 *    preceded by a non-blank non-message-header line, is
31 *    taken to start a new paragraph, which also contains
32 *    any subsequent lines with non-empty leading whitespace.
33 *    Unless the `-n' option is given, lines beginning with
34 *    a . (dot) are not formatted.
35 * 3. The "everything else" is split into words; a word
36 *    includes its trailing whitespace, and a word at the
37 *    end of a line is deemed to be followed by a single
38 *    space, or two spaces if it ends with a sentence-end
39 *    character. (See the `-d' option for how to change that.)
40 *    If the `-s' option has been given, then a word's trailing
41 *    whitespace is replaced by what it would have had if it
42 *    had occurred at end of line.
43 * 4. Each paragraph is sent to standard output as follows.
44 *    We output the leading whitespace, and then enough words
45 *    to make the line length as near as possible to the goal
46 *    without exceeding the maximum. (If a single word would
47 *    exceed the maximum, we output that anyway.) Of course
48 *    the trailing whitespace of the last word is ignored.
49 *    We then emit a newline and start again if there are any
50 *    words left.
51 *    Note that for a blank line this translates as "We emit
52 *    a newline".
53 *    If the `-l <n>' option is given, then leading whitespace
54 *    is modified slightly: <n> spaces are replaced by a tab.
55 *    Indented paragraphs (see above under `-p') make matters
56 *    more complicated than this suggests. Actually every paragraph
57 *    has two `leading whitespace' values; the value for the first
58 *    line, and the value for the most recent line. (While processing
59 *    the first line, the two are equal. When `-p' has not been
60 *    given, they are always equal.) The leading whitespace
61 *    actually output is that of the first line (for the first
62 *    line of *output*) or that of the most recent line (for
63 *    all other lines of output).
64 *    When `-m' has been given, message header paragraphs are
65 *    taken as having first-leading-whitespace empty and
66 *    subsequent-leading-whitespace two spaces.
67 *
68 * Multiple input files are formatted one at a time, so that a file
69 * never ends in the middle of a line.
70 *
71 * There's an alternative mode of operation, invoked by giving
72 * the `-c' option. In that case we just center every line,
73 * and most of the other options are ignored. This should
74 * really be in a separate program, but we must stay compatible
75 * with old `fmt'.
76 *
77 * QUERY: Should `-m' also try to do the right thing with quoted text?
78 * QUERY: `-b' to treat backslashed whitespace as old `fmt' does?
79 * QUERY: Option meaning `never join lines'?
80 * QUERY: Option meaning `split in mid-word to avoid overlong lines'?
81 * (Those last two might not be useful, since we have `fold'.)
82 *
83 * Differences from old `fmt':
84 *
85 *   - We have many more options. Options that aren't understood
86 *     generate a lengthy usage message, rather than being
87 *     treated as filenames.
88 *   - Even with `-m', our handling of message headers is
89 *     significantly different. (And much better.)
90 *   - We don't treat `\ ' as non-word-breaking.
91 *   - Downward changes of indentation start new paragraphs
92 *     for us, as well as upward. (I think old `fmt' behaves
93 *     in the way it does in order to allow indented paragraphs,
94 *     but this is a broken way of making indented paragraphs
95 *     behave right.)
96 *   - Given the choice of going over or under |goal_length|
97 *     by the same amount, we go over; old `fmt' goes under.
98 *   - We treat `?' as ending a sentence, and not `:'. Old `fmt'
99 *     does the reverse.
100 *   - We return approved return codes. Old `fmt' returns
101 *     1 for some errors, and *the number of unopenable files*
102 *     when that was all that went wrong.
103 *   - We have fewer crashes and more helpful error messages.
104 *   - We don't turn spaces into tabs at starts of lines unless
105 *     specifically requested.
106 *   - New `fmt' is somewhat smaller and slightly faster than
107 *     old `fmt'.
108 *
109 * Bugs:
110 *
111 *   None known. There probably are some, though.
112 *
113 * Portability:
114 *
115 *   I believe this code to be pretty portable. It does require
116 *   that you have `getopt'. If you need to include "getopt.h"
117 *   for this (e.g., if your system didn't come with `getopt'
118 *   and you installed it yourself) then you should arrange for
119 *   NEED_getopt_h to be #defined.
120 *
121 *   Everything here should work OK even on nasty 16-bit
122 *   machines and nice 64-bit ones. However, it's only really
123 *   been tested on my FreeBSD machine. Your mileage may vary.
124 */
125
126/* Copyright (c) 1997 Gareth McCaughan. All rights reserved.
127 *
128 * Redistribution and use of this code, in source or binary forms,
129 * with or without modification, are permitted subject to the following
130 * conditions:
131 *
132 *  - Redistribution of source code must retain the above copyright
133 *    notice, this list of conditions and the following disclaimer.
134 *
135 *  - If you distribute modified source code it must also include
136 *    a notice saying that it has been modified, and giving a brief
137 *    description of what changes have been made.
138 *
139 * Disclaimer: I am not responsible for the results of using this code.
140 *             If it formats your hard disc, sends obscene messages to
141 *             your boss and kills your children then that's your problem
142 *             not mine. I give absolutely no warranty of any sort as to
143 *             what the program will do, and absolutely refuse to be held
144 *             liable for any consequences of your using it.
145 *             Thank you. Have a nice day.
146 */
147
148/* RCS change log:
149 * Revision 1.5  1998/03/02 18:02:21  gjm11
150 * Minor changes for portability.
151 *
152 * Revision 1.4  1997/10/01 11:51:28  gjm11
153 * Repair broken indented-paragraph handling.
154 * Add mail message header stuff.
155 * Improve comments and layout.
156 * Make usable with non-BSD systems.
157 * Add revision display to usage message.
158 *
159 * Revision 1.3  1997/09/30 16:24:47  gjm11
160 * Add copyright notice, rcsid string and log message.
161 *
162 * Revision 1.2  1997/09/30 16:13:39  gjm11
163 * Add options: -d <chars>, -l <width>, -p, -s, -t <width>, -h .
164 * Parse options with `getopt'. Clean up code generally.
165 * Make comments more accurate.
166 *
167 * Revision 1.1  1997/09/30 11:29:57  gjm11
168 * Initial revision
169 */
170
171#ifndef lint
172static const char copyright[] =
173"Copyright (c) 1997 Gareth McCaughan. All rights reserved.\n";
174#endif	/* not lint */
175#include <sys/cdefs.h>
176__FBSDID("$FreeBSD$");
177
178#include <err.h>
179#include <limits.h>
180#include <locale.h>
181#include <stdio.h>
182#include <stdlib.h>
183#include <string.h>
184#include <sysexits.h>
185#include <unistd.h>
186#include <wchar.h>
187#include <wctype.h>
188
189/* Something that, we hope, will never be a genuine line length,
190 * indentation etc.
191 */
192#define SILLY ((size_t)-1)
193
194/* I used to use |strtoul| for this, but (1) not all systems have it
195 * and (2) it's probably better to use |strtol| to detect negative
196 * numbers better.
197 * If |fussyp==0| then we don't complain about non-numbers
198 * (returning 0 instead), but we do complain about bad numbers.
199 */
200static size_t
201get_positive(const char *s, const char *err_mess, int fussyP)
202{
203	char *t;
204	long result = strtol(s, &t, 0);
205
206	if (*t) {
207		if (fussyP)
208			goto Lose;
209		else
210			return 0;
211	}
212	if (result <= 0) {
213Lose:		errx(EX_USAGE, "%s", err_mess);
214	}
215	return (size_t)result;
216}
217
218static size_t
219get_nonnegative(const char *s, const char *err_mess, int fussyP)
220{
221	char *t;
222	long result = strtol(s, &t, 0);
223
224	if (*t) {
225		if (fussyP)
226			goto Lose;
227		else
228			return 0;
229	}
230	if (result < 0) {
231Lose:		errx(EX_USAGE, "%s", err_mess);
232	}
233	return (size_t)result;
234}
235
236/* Global variables */
237
238static int centerP = 0;			/* Try to center lines? */
239static size_t goal_length = 0;		/* Target length for output lines */
240static size_t max_length = 0;		/* Maximum length for output lines */
241static int coalesce_spaces_P = 0;	/* Coalesce multiple whitespace -> ' ' ? */
242static int allow_indented_paragraphs = 0;	/* Can first line have diff. ind.? */
243static int tab_width = 8;		/* Number of spaces per tab stop */
244static size_t output_tab_width = 8;	/* Ditto, when squashing leading spaces */
245static const wchar_t *sentence_enders = L".?!";	/* Double-space after these */
246static int grok_mail_headers = 0;	/* treat embedded mail headers magically? */
247static int format_troff = 0;		/* Format troff? */
248
249static int n_errors = 0;		/* Number of failed files. Return on exit. */
250static wchar_t *output_buffer = NULL;	/* Output line will be built here */
251static size_t x;			/* Horizontal position in output line */
252static size_t x0;			/* Ditto, ignoring leading whitespace */
253static size_t output_buffer_length = 0;
254static size_t pending_spaces;		/* Spaces to add before next word */
255static int output_in_paragraph = 0;	/* Any of current para written out yet? */
256
257/* Prototypes */
258
259static void process_named_file(const char *);
260static void process_stream(FILE *, const char *);
261static size_t indent_length(const wchar_t *, size_t);
262static int might_be_header(const wchar_t *);
263static void new_paragraph(size_t, size_t);
264static void output_word(size_t, size_t, const wchar_t *, size_t, size_t);
265static void output_indent(size_t);
266static void center_stream(FILE *, const char *);
267static wchar_t *get_line(FILE *, size_t *);
268static void *xrealloc(void *, size_t);
269
270#define XMALLOC(x) xrealloc(0,x)
271
272/* Here is perhaps the right place to mention that this code is
273 * all in top-down order. Hence, |main| comes first.
274 */
275int
276main(int argc, char *argv[])
277{
278	int ch;				/* used for |getopt| processing */
279	wchar_t *tmp;
280	size_t len;
281	const char *src;
282
283	(void)setlocale(LC_CTYPE, "");
284
285	/* 1. Grok parameters. */
286
287	while ((ch = getopt(argc, argv, "0123456789cd:hl:mnpst:w:")) != -1)
288		switch (ch) {
289		case 'c':
290			centerP = 1;
291			format_troff = 1;
292			continue;
293		case 'd':
294			src = optarg;
295			len = mbsrtowcs(NULL, &src, 0, NULL);
296			if (len == (size_t)-1)
297				err(EX_USAGE, "bad sentence-ending character set");
298			tmp = XMALLOC((len + 1) * sizeof(wchar_t));
299			mbsrtowcs(tmp, &src, len + 1, NULL);
300			sentence_enders = tmp;
301			continue;
302		case 'l':
303			output_tab_width
304			    = get_nonnegative(optarg, "output tab width must be non-negative", 1);
305			continue;
306		case 'm':
307			grok_mail_headers = 1;
308			continue;
309		case 'n':
310			format_troff = 1;
311			continue;
312		case 'p':
313			allow_indented_paragraphs = 1;
314			continue;
315		case 's':
316			coalesce_spaces_P = 1;
317			continue;
318		case 't':
319			tab_width = get_positive(optarg, "tab width must be positive", 1);
320			continue;
321		case 'w':
322			goal_length = get_positive(optarg, "width must be positive", 1);
323			max_length = goal_length;
324			continue;
325		case '0': case '1': case '2': case '3': case '4': case '5':
326		case '6': case '7': case '8': case '9':
327			/*
328			 * XXX  this is not a stylistically approved use of
329			 * getopt()
330			 */
331			if (goal_length == 0) {
332				char *p;
333
334				p = argv[optind - 1];
335				if (p[0] == '-' && p[1] == ch && !p[2])
336					goal_length = get_positive(++p, "width must be nonzero", 1);
337				else
338					goal_length = get_positive(argv[optind] + 1,
339					    "width must be nonzero", 1);
340				max_length = goal_length;
341			}
342			continue;
343		case 'h':
344		default:
345			fprintf(stderr,
346			    "usage:   fmt [-cmps] [-d chars] [-l num] [-t num]\n"
347			    "             [-w width | -width | goal [maximum]] [file ...]\n"
348			    "Options: -c     center each line instead of formatting\n"
349			    "         -d <chars> double-space after <chars> at line end\n"
350			    "         -l <n> turn each <n> spaces at start of line into a tab\n"
351			    "         -m     try to make sure mail header lines stay separate\n"
352			    "         -n     format lines beginning with a dot\n"
353			    "         -p     allow indented paragraphs\n"
354			    "         -s     coalesce whitespace inside lines\n"
355			    "         -t <n> have tabs every <n> columns\n"
356			    "         -w <n> set maximum width to <n>\n"
357			    "         goal   set target width to goal\n");
358			exit(ch == 'h' ? 0 : EX_USAGE);
359		}
360	argc -= optind;
361	argv += optind;
362
363	/* [ goal [ maximum ] ] */
364
365	if (argc > 0 && goal_length == 0
366	    && (goal_length = get_positive(*argv, "goal length must be positive", 0))
367	    != 0) {
368		--argc;
369		++argv;
370		if (argc > 0
371		    && (max_length = get_positive(*argv, "max length must be positive", 0))
372		    != 0) {
373			--argc;
374			++argv;
375			if (max_length < goal_length)
376				errx(EX_USAGE, "max length must be >= goal length");
377		}
378	}
379	if (goal_length == 0)
380		goal_length = 65;
381	if (max_length == 0)
382		max_length = goal_length + 10;
383	if (max_length >= SIZE_T_MAX / sizeof(wchar_t))
384		errx(EX_USAGE, "max length too large");
385	/* really needn't be longer */
386	output_buffer = XMALLOC((max_length + 1) * sizeof(wchar_t));
387
388	/* 2. Process files. */
389
390	if (argc > 0) {
391		while (argc-- > 0)
392			process_named_file(*argv++);
393	} else {
394		process_stream(stdin, "standard input");
395	}
396
397	/* We're done. */
398
399	return n_errors ? EX_NOINPUT : 0;
400
401}
402
403/* Process a single file, given its name.
404 */
405static void
406process_named_file(const char *name)
407{
408	FILE *f = fopen(name, "r");
409
410	if (!f) {
411		warn("%s", name);
412		++n_errors;
413	} else {
414		process_stream(f, name);
415		if (ferror(f)) {
416			warn("%s", name);
417			++n_errors;
418		}
419		fclose(f);
420	}
421}
422
423/* Types of mail header continuation lines:
424 */
425typedef enum {
426	hdr_ParagraphStart = -1,
427	hdr_NonHeader = 0,
428	hdr_Header = 1,
429	hdr_Continuation = 2
430} HdrType;
431
432/* Process a stream. This is where the real work happens,
433 * except that centering is handled separately.
434 */
435static void
436process_stream(FILE *stream, const char *name)
437{
438	size_t last_indent = SILLY;	/* how many spaces in last indent? */
439	size_t para_line_number = 0;	/* how many lines already read in this para? */
440	size_t first_indent = SILLY;	/* indentation of line 0 of paragraph */
441	HdrType prev_header_type = hdr_ParagraphStart;
442
443	/* ^-- header_type of previous line; -1 at para start */
444	wchar_t *line;
445	size_t length;
446
447	if (centerP) {
448		center_stream(stream, name);
449		return;
450	}
451	while ((line = get_line(stream, &length)) != NULL) {
452		size_t np = indent_length(line, length);
453
454		{
455			HdrType header_type = hdr_NonHeader;
456
457			if (grok_mail_headers && prev_header_type != hdr_NonHeader) {
458				if (np == 0 && might_be_header(line))
459					header_type = hdr_Header;
460				else if (np > 0 && prev_header_type > hdr_NonHeader)
461					header_type = hdr_Continuation;
462			}
463			/*
464			 * We need a new paragraph if and only if: this line
465			 * is blank, OR it's a troff request (and we don't
466			 * format troff), OR it's a mail header, OR it's not
467			 * a mail header AND the last line was one, OR the
468			 * indentation has changed AND the line isn't a mail
469			 * header continuation line AND this isn't the
470			 * second line of an indented paragraph.
471			 */
472			if (length == 0
473			    || (line[0] == '.' && !format_troff)
474			    || header_type == hdr_Header
475			    || (header_type == hdr_NonHeader && prev_header_type > hdr_NonHeader)
476			    || (np != last_indent
477			    && header_type != hdr_Continuation
478			    && (!allow_indented_paragraphs || para_line_number != 1))) {
479				new_paragraph(output_in_paragraph ? last_indent : first_indent, np);
480				para_line_number = 0;
481				first_indent = np;
482				last_indent = np;
483				if (header_type == hdr_Header)
484					last_indent = 2;	/* for cont. lines */
485				if (length == 0 || (line[0] == '.' && !format_troff)) {
486					if (length == 0)
487						putwchar('\n');
488					else
489						wprintf(L"%.*ls\n", (int)length,
490						    line);
491					prev_header_type = hdr_ParagraphStart;
492					continue;
493				}
494			} else {
495				/*
496				 * If this is an indented paragraph other
497				 * than a mail header continuation, set
498				 * |last_indent|.
499				 */
500				if (np != last_indent &&
501				    header_type != hdr_Continuation)
502					last_indent = np;
503			}
504			prev_header_type = header_type;
505		}
506
507		{
508			size_t n = np;
509
510			while (n < length) {
511				/* Find word end and count spaces after it */
512				size_t word_length = 0, space_length = 0;
513
514				while (n + word_length < length &&
515				    line[n + word_length] != ' ')
516					++word_length;
517				space_length = word_length;
518				while (n + space_length < length &&
519				    line[n + space_length] == ' ')
520					++space_length;
521				/* Send the word to the output machinery. */
522				output_word(first_indent, last_indent,
523				    line + n, word_length,
524				    space_length - word_length);
525				n += space_length;
526			}
527		}
528		++para_line_number;
529	}
530	new_paragraph(output_in_paragraph ? last_indent : first_indent, 0);
531	if (ferror(stream)) {
532		warn("%s", name);
533		++n_errors;
534	}
535}
536
537/* How long is the indent on this line?
538 */
539static size_t
540indent_length(const wchar_t *line, size_t length)
541{
542	size_t n = 0;
543
544	while (n < length && *line++ == ' ')
545		++n;
546	return n;
547}
548
549/* Might this line be a mail header?
550 * We deem a line to be a possible header if it matches the
551 * Perl regexp /^[A-Z][-A-Za-z0-9]*:\s/. This is *not* the same
552 * as in RFC whatever-number-it-is; we want to be gratuitously
553 * conservative to avoid mangling ordinary civilised text.
554 */
555static int
556might_be_header(const wchar_t *line)
557{
558	if (!iswupper(*line++))
559		return 0;
560	while (*line && (iswalnum(*line) || *line == '-'))
561		++line;
562	return (*line == ':' && iswspace(line[1]));
563}
564
565/* Begin a new paragraph with an indent of |indent| spaces.
566 */
567static void
568new_paragraph(size_t old_indent, size_t indent)
569{
570	if (output_buffer_length) {
571		if (old_indent > 0)
572			output_indent(old_indent);
573		wprintf(L"%.*ls\n", (int)output_buffer_length, output_buffer);
574	}
575	x = indent;
576	x0 = 0;
577	output_buffer_length = 0;
578	pending_spaces = 0;
579	output_in_paragraph = 0;
580}
581
582/* Output spaces or tabs for leading indentation.
583 */
584static void
585output_indent(size_t n_spaces)
586{
587	if (output_tab_width) {
588		while (n_spaces >= output_tab_width) {
589			putwchar('\t');
590			n_spaces -= output_tab_width;
591		}
592	}
593	while (n_spaces-- > 0)
594		putwchar(' ');
595}
596
597/* Output a single word, or add it to the buffer.
598 * indent0 and indent1 are the indents to use on the first and subsequent
599 * lines of a paragraph. They'll often be the same, of course.
600 */
601static void
602output_word(size_t indent0, size_t indent1, const wchar_t *word, size_t length, size_t spaces)
603{
604	size_t new_x;
605	size_t indent = output_in_paragraph ? indent1 : indent0;
606	size_t width;
607	const wchar_t *p;
608	int cwidth;
609
610	for (p = word, width = 0; p < &word[length]; p++)
611		width += (cwidth = wcwidth(*p)) > 0 ? cwidth : 1;
612
613	new_x = x + pending_spaces + width;
614
615	/*
616	 * If either |spaces==0| (at end of line) or |coalesce_spaces_P|
617	 * (squashing internal whitespace), then add just one space; except
618	 * that if the last character was a sentence-ender we actually add
619	 * two spaces.
620	 */
621	if (coalesce_spaces_P || spaces == 0)
622		spaces = wcschr(sentence_enders, word[length - 1]) ? 2 : 1;
623
624	if (new_x <= goal_length) {
625		/*
626		 * After adding the word we still aren't at the goal length,
627		 * so clearly we add it to the buffer rather than outputing
628		 * it.
629		 */
630		wmemset(output_buffer + output_buffer_length, L' ',
631		    pending_spaces);
632		x0 += pending_spaces;
633		x += pending_spaces;
634		output_buffer_length += pending_spaces;
635		wmemcpy(output_buffer + output_buffer_length, word, length);
636		x0 += width;
637		x += width;
638		output_buffer_length += length;
639		pending_spaces = spaces;
640	} else {
641		/*
642		 * Adding the word takes us past the goal. Print the
643		 * line-so-far, and the word too iff either (1) the lsf is
644		 * empty or (2) that makes us nearer the goal but doesn't
645		 * take us over the limit, or (3) the word on its own takes
646		 * us over the limit. In case (3) we put a newline in
647		 * between.
648		 */
649		if (indent > 0)
650			output_indent(indent);
651		wprintf(L"%.*ls", (int)output_buffer_length, output_buffer);
652		if (x0 == 0 || (new_x <= max_length &&
653		    new_x - goal_length <= goal_length - x)) {
654			wprintf(L"%*ls", (int)pending_spaces, L"");
655			goto write_out_word;
656		} else {
657			/*
658			 * If the word takes us over the limit on its own,
659			 * just spit it out and don't bother buffering it.
660			 */
661			if (indent + width > max_length) {
662				putwchar('\n');
663				if (indent > 0)
664					output_indent(indent);
665		write_out_word:
666				wprintf(L"%.*ls", (int)length, word);
667				x0 = 0;
668				x = indent1;
669				pending_spaces = 0;
670				output_buffer_length = 0;
671			} else {
672				wmemcpy(output_buffer, word, length);
673				x0 = width;
674				x = width + indent1;
675				pending_spaces = spaces;
676				output_buffer_length = length;
677			}
678		}
679		putwchar('\n');
680		output_in_paragraph = 1;
681	}
682}
683
684/* Process a stream, but just center its lines rather than trying to
685 * format them neatly.
686 */
687static void
688center_stream(FILE *stream, const char *name)
689{
690	wchar_t *line, *p;
691	size_t length;
692	size_t width;
693	int cwidth;
694
695	while ((line = get_line(stream, &length)) != NULL) {
696		size_t l = length;
697
698		while (l > 0 && iswspace(*line)) {
699			++line;
700			--l;
701		}
702		length = l;
703		for (p = line, width = 0; p < &line[length]; p++)
704			width += (cwidth = wcwidth(*p)) > 0 ? cwidth : 1;
705		l = width;
706		while (l < goal_length) {
707			putwchar(' ');
708			l += 2;
709		}
710		wprintf(L"%.*ls\n", (int)length, line);
711	}
712	if (ferror(stream)) {
713		warn("%s", name);
714		++n_errors;
715	}
716}
717
718/* Get a single line from a stream. Expand tabs, strip control
719 * characters and trailing whitespace, and handle backspaces.
720 * Return the address of the buffer containing the line, and
721 * put the length of the line in |lengthp|.
722 * This can cope with arbitrarily long lines, and with lines
723 * without terminating \n.
724 * If there are no characters left or an error happens, we
725 * return 0.
726 * Don't confuse |spaces_pending| here with the global
727 * |pending_spaces|.
728 */
729static wchar_t *
730get_line(FILE *stream, size_t *lengthp)
731{
732	static wchar_t *buf = NULL;
733	static size_t length = 0;
734	size_t len = 0;
735	wint_t ch;
736	size_t spaces_pending = 0;
737	int troff = 0;
738	size_t col = 0;
739	int cwidth;
740
741	if (buf == NULL) {
742		length = 100;
743		buf = XMALLOC(length * sizeof(wchar_t));
744	}
745	while ((ch = getwc(stream)) != '\n' && ch != WEOF) {
746		if (len + spaces_pending == 0 && ch == '.' && !format_troff)
747			troff = 1;
748		if (ch == ' ')
749			++spaces_pending;
750		else if (troff || iswprint(ch)) {
751			while (len + spaces_pending >= length) {
752				length *= 2;
753				buf = xrealloc(buf, length * sizeof(wchar_t));
754			}
755			while (spaces_pending > 0) {
756				--spaces_pending;
757				buf[len++] = ' ';
758				col++;
759			}
760			buf[len++] = ch;
761			col += (cwidth = wcwidth(ch)) > 0 ? cwidth : 1;
762		} else if (ch == '\t')
763			spaces_pending += tab_width -
764			    (col + spaces_pending) % tab_width;
765		else if (ch == '\b') {
766			if (len)
767				--len;
768			if (col)
769				--col;
770		}
771	}
772	*lengthp = len;
773	return (len > 0 || ch != WEOF) ? buf : 0;
774}
775
776/* (Re)allocate some memory, exiting with an error if we can't.
777 */
778static void *
779xrealloc(void *ptr, size_t nbytes)
780{
781	void *p = realloc(ptr, nbytes);
782
783	if (p == NULL)
784		errx(EX_OSERR, "out of memory");
785	return p;
786}
787